refactor(arbiter-client): rewrite errors to terrros

Reviewed-on: #34

.gitignore

@@ -1 +1,5 @@
-target/
+target/
+scripts/__pycache__/
+.DS_Store
+.cargo/config.toml
+.vscode/

.vscode/settings.json

@@ -1,3 +0,0 @@
-{
-    "git.enabled": false
-}

.woodpecker/server-lint.yaml

@@ -22,4 +22,4 @@ steps:
       - apt-get update && apt-get install -y pkg-config
       - mise install rust 
       - mise install protoc
-      - mise exec rust -- cargo clippy --all-targets --all-features -- -D warnings
+      - mise exec rust -- cargo clippy --all -- -D warnings

.woodpecker/useragent-analyze.yaml

@@ -0,0 +1,18 @@
+when:
+  - event: pull_request
+    path:
+      include: ['.woodpecker/useragent-*.yaml', 'useragent/**']
+  - event: push
+    branch: main
+    path:
+      include: ['.woodpecker/useragent-*.yaml', 'useragent/**']
+
+steps:
+  - name: analyze
+    image: jdxcode/mise:latest
+    commands:
+      - mise install flutter 
+      - mise install protoc
+      # Reruns codegen to catch protocol drift
+      - mise codegen 
+      - cd useragent/ && flutter analyze

AGENTS.md

@@ -0,0 +1,128 @@
+# AGENTS.md
+
+This file provides guidance to Codex (Codex.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Arbiter is a **permissioned signing service** for cryptocurrency wallets. It consists of:
+- **`server/`** — Rust gRPC daemon that holds encrypted keys and enforces policies
+- **`useragent/`** — Flutter desktop app (macOS/Windows) with a Rust backend via Rinf
+- **`protobufs/`** — Protocol Buffer definitions shared between server and client
+
+The vault never exposes key material; it only produces signatures when requests satisfy configured policies.
+
+## Toolchain Setup
+
+Tools are managed via [mise](https://mise.jdx.dev/). Install all required tools:
+```sh
+mise install
+```
+
+Key versions: Rust 1.93.0 (with clippy), Flutter 3.38.9-stable, protoc 29.6, diesel_cli 2.3.6 (sqlite).
+
+## Server (Rust workspace at `server/`)
+
+### Crates
+
+| Crate | Purpose |
+|---|---|
+| `arbiter-proto` | Generated gRPC stubs + protobuf types; compiled from `protobufs/*.proto` via `tonic-prost-build` |
+| `arbiter-server` | Main daemon — actors, DB, EVM policy engine, gRPC service implementation |
+| `arbiter-useragent` | Rust client library for the user agent side of the gRPC protocol |
+| `arbiter-client` | Rust client library for SDK clients |
+
+### Common Commands
+
+```sh
+cd server
+
+# Build
+cargo build
+
+# Run the server daemon
+cargo run -p arbiter-server
+
+# Run all tests (preferred over cargo test)
+cargo nextest run
+
+# Run a single test
+cargo nextest run <test_name>
+
+# Lint
+cargo clippy
+
+# Security audit
+cargo audit
+
+# Check unused dependencies
+cargo shear
+
+# Run snapshot tests and update snapshots
+cargo insta review
+```
+
+### Architecture
+
+The server is actor-based using the **kameo** crate. All long-lived state lives in `GlobalActors`:
+
+- **`Bootstrapper`** — Manages the one-time bootstrap token written to `~/.arbiter/bootstrap_token` on first run.
+- **`KeyHolder`** — Holds the encrypted root key and manages the Sealed/Unsealed vault state machine. On unseal, decrypts the root key into a `memsafe` hardened memory cell.
+- **`MessageRouter`** — Coordinates streaming messages between user agents and SDK clients.
+- **`EvmActor`** — Handles EVM transaction policy enforcement and signing.
+
+Per-connection actors live under `actors/user_agent/` and `actors/client/`, each with `auth` (challenge-response authentication) and `session` (post-auth operations) sub-modules.
+
+**Database:** SQLite via `diesel-async` + `bb8` connection pool. Schema managed by embedded Diesel migrations in `crates/arbiter-server/migrations/`. DB file lives at `~/.arbiter/arbiter.sqlite`. Tests use a temp-file DB via `db::create_test_pool()`.
+
+**Cryptography:**
+- Authentication: ed25519 (challenge-response, nonce-tracked per peer)
+- Encryption at rest: XChaCha20-Poly1305 (versioned via `scheme` field for transparent migration on unseal)
+- Password KDF: Argon2
+- Unseal transport: X25519 ephemeral key exchange
+- TLS: self-signed certificate (aws-lc-rs backend), fingerprint distributed via `ArbiterUrl`
+
+**Protocol:** gRPC with Protocol Buffers. The `ArbiterUrl` type encodes host, port, CA cert, and bootstrap token into a single shareable string (printed to console on first run).
+
+### Proto Regeneration
+
+When `.proto` files in `protobufs/` change, rebuild to regenerate:
+```sh
+cd server && cargo build -p arbiter-proto
+```
+
+### Database Migrations
+
+```sh
+# Create a new migration
+diesel migration generate <name> --migration-dir crates/arbiter-server/migrations
+
+# Run migrations manually (server also runs them on startup)
+diesel migration run --migration-dir crates/arbiter-server/migrations
+```
+
+## User Agent (Flutter + Rinf at `useragent/`)
+
+The Flutter app uses [Rinf](https://rinf.cunarist.org) to call Rust code. The Rust logic lives in `useragent/native/hub/` as a separate crate that uses `arbiter-useragent` for the gRPC client.
+
+Communication between Dart and Rust uses typed **signals** defined in `useragent/native/hub/src/signals/`. After modifying signal structs, regenerate Dart bindings:
+
+```sh
+cd useragent && rinf gen
+```
+
+### Common Commands
+
+```sh
+cd useragent
+
+# Run the app (macOS or Windows)
+flutter run
+
+# Regenerate Rust↔Dart signal bindings
+rinf gen
+
+# Analyze Dart code
+flutter analyze
+```
+
+The Rinf Rust entry point is `useragent/native/hub/src/lib.rs`. It spawns actors defined in `useragent/native/hub/src/actors/` which handle Dart↔server communication via signals.

CLAUDE.md

@@ -0,0 +1,128 @@
+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+Arbiter is a **permissioned signing service** for cryptocurrency wallets. It consists of:
+- **`server/`** — Rust gRPC daemon that holds encrypted keys and enforces policies
+- **`useragent/`** — Flutter desktop app (macOS/Windows) with a Rust backend via Rinf
+- **`protobufs/`** — Protocol Buffer definitions shared between server and client
+
+The vault never exposes key material; it only produces signatures when requests satisfy configured policies.
+
+## Toolchain Setup
+
+Tools are managed via [mise](https://mise.jdx.dev/). Install all required tools:
+```sh
+mise install
+```
+
+Key versions: Rust 1.93.0 (with clippy), Flutter 3.38.9-stable, protoc 29.6, diesel_cli 2.3.6 (sqlite).
+
+## Server (Rust workspace at `server/`)
+
+### Crates
+
+| Crate | Purpose |
+|---|---|
+| `arbiter-proto` | Generated gRPC stubs + protobuf types; compiled from `protobufs/*.proto` via `tonic-prost-build` |
+| `arbiter-server` | Main daemon — actors, DB, EVM policy engine, gRPC service implementation |
+| `arbiter-useragent` | Rust client library for the user agent side of the gRPC protocol |
+| `arbiter-client` | Rust client library for SDK clients |
+
+### Common Commands
+
+```sh
+cd server
+
+# Build
+cargo build
+
+# Run the server daemon
+cargo run -p arbiter-server
+
+# Run all tests (preferred over cargo test)
+cargo nextest run
+
+# Run a single test
+cargo nextest run <test_name>
+
+# Lint
+cargo clippy
+
+# Security audit
+cargo audit
+
+# Check unused dependencies
+cargo shear
+
+# Run snapshot tests and update snapshots
+cargo insta review
+```
+
+### Architecture
+
+The server is actor-based using the **kameo** crate. All long-lived state lives in `GlobalActors`:
+
+- **`Bootstrapper`** — Manages the one-time bootstrap token written to `~/.arbiter/bootstrap_token` on first run.
+- **`KeyHolder`** — Holds the encrypted root key and manages the Sealed/Unsealed vault state machine. On unseal, decrypts the root key into a `memsafe` hardened memory cell.
+- **`MessageRouter`** — Coordinates streaming messages between user agents and SDK clients.
+- **`EvmActor`** — Handles EVM transaction policy enforcement and signing.
+
+Per-connection actors live under `actors/user_agent/` and `actors/client/`, each with `auth` (challenge-response authentication) and `session` (post-auth operations) sub-modules.
+
+**Database:** SQLite via `diesel-async` + `bb8` connection pool. Schema managed by embedded Diesel migrations in `crates/arbiter-server/migrations/`. DB file lives at `~/.arbiter/arbiter.sqlite`. Tests use a temp-file DB via `db::create_test_pool()`.
+
+**Cryptography:**
+- Authentication: ed25519 (challenge-response, nonce-tracked per peer)
+- Encryption at rest: XChaCha20-Poly1305 (versioned via `scheme` field for transparent migration on unseal)
+- Password KDF: Argon2
+- Unseal transport: X25519 ephemeral key exchange
+- TLS: self-signed certificate (aws-lc-rs backend), fingerprint distributed via `ArbiterUrl`
+
+**Protocol:** gRPC with Protocol Buffers. The `ArbiterUrl` type encodes host, port, CA cert, and bootstrap token into a single shareable string (printed to console on first run).
+
+### Proto Regeneration
+
+When `.proto` files in `protobufs/` change, rebuild to regenerate:
+```sh
+cd server && cargo build -p arbiter-proto
+```
+
+### Database Migrations
+
+```sh
+# Create a new migration
+diesel migration generate <name> --migration-dir crates/arbiter-server/migrations
+
+# Run migrations manually (server also runs them on startup)
+diesel migration run --migration-dir crates/arbiter-server/migrations
+```
+
+## User Agent (Flutter + Rinf at `useragent/`)
+
+The Flutter app uses [Rinf](https://rinf.cunarist.org) to call Rust code. The Rust logic lives in `useragent/native/hub/` as a separate crate that uses `arbiter-useragent` for the gRPC client.
+
+Communication between Dart and Rust uses typed **signals** defined in `useragent/native/hub/src/signals/`. After modifying signal structs, regenerate Dart bindings:
+
+```sh
+cd useragent && rinf gen
+```
+
+### Common Commands
+
+```sh
+cd useragent
+
+# Run the app (macOS or Windows)
+flutter run
+
+# Regenerate Rust↔Dart signal bindings
+rinf gen
+
+# Analyze Dart code
+flutter analyze
+```
+
+The Rinf Rust entry point is `useragent/native/hub/src/lib.rs`. It spawns actors defined in `useragent/native/hub/src/actors/` which handle Dart↔server communication via signals.

IMPLEMENTATION.md

@@ -4,6 +4,66 @@ This document covers concrete technology choices and dependencies. For the archi
 
 ---
 
+## Client Connection Flow
+
+### Authentication Result Semantics
+
+Authentication no longer uses an implicit success-only response shape. Both `client` and `user-agent` return explicit auth status enums over the wire.
+
+- **Client:** `AuthResult` may return `SUCCESS`, `INVALID_KEY`, `INVALID_SIGNATURE`, `APPROVAL_DENIED`, `NO_USER_AGENTS_ONLINE`, or `INTERNAL`
+- **User-agent:** `AuthResult` may return `SUCCESS`, `INVALID_KEY`, `INVALID_SIGNATURE`, `BOOTSTRAP_REQUIRED`, `TOKEN_INVALID`, or `INTERNAL`
+
+This makes transport-level failures and actor/domain-level auth failures distinct:
+
+- **Transport/protocol failures** are surfaced as stream/status errors
+- **Authentication failures** are surfaced as successful protocol responses carrying an explicit auth status
+
+Clients are expected to handle these status codes directly and present the concrete failure reason to the user.
+
+### New Client Approval
+
+When a client whose public key is not yet in the database connects, all connected user agents are asked to approve the connection. The first agent to respond determines the outcome; remaining requests are cancelled via a watch channel.
+
+```mermaid
+flowchart TD
+    A([Client connects]) --> B[Receive AuthChallengeRequest]
+    B --> C{pubkey in DB?}
+
+    C -- yes --> D[Read nonce\nIncrement nonce in DB]
+    D --> G
+
+    C -- no --> E[Ask all UserAgents:\nClientConnectionRequest]
+    E --> F{First response}
+    F -- denied --> Z([Reject connection])
+    F -- approved --> F2[Cancel remaining\nUserAgent requests]
+    F2 --> F3[INSERT client\nnonce = 1]
+    F3 --> G[Send AuthChallenge\nwith nonce]
+
+    G --> H[Receive AuthChallengeSolution]
+    H --> I{Signature valid?}
+    I -- no --> Z
+    I -- yes --> J([Session started])
+```
+
+### Known Issue: Concurrent Registration Race (TOCTOU)
+
+Two connections presenting the same previously-unknown public key can race through the approval flow simultaneously:
+
+1. Both check the DB → neither is registered.
+2. Both request approval from user agents → both receive approval.
+3. Both `INSERT` the client record → the second insert silently overwrites the first, resetting the nonce.
+
+This means the first connection's nonce is invalidated by the second, causing its challenge verification to fail. A fix requires either serialising new-client registration (e.g. an in-memory lock keyed on pubkey) or replacing the separate check + insert with an `INSERT OR IGNORE` / upsert guarded by a unique constraint on `public_key`.
+
+### Nonce Semantics
+
+The `program_client.nonce` column stores the **next usable nonce** — i.e. it is always one ahead of the nonce last issued in a challenge.
+
+- **New client:** inserted with `nonce = 1`; the first challenge is issued with `nonce = 0`.
+- **Existing client:** the current DB value is read and used as the challenge nonce, then immediately incremented within the same exclusive transaction, preventing replay.
+
+---
+
 ## Cryptography
 
 ### Authentication
@@ -22,9 +82,97 @@ This document covers concrete technology choices and dependencies. For the archi
 ## Communication
 
 - **Protocol:** gRPC with Protocol Buffers
+- **Request/response matching:** multiplexed over a single bidirectional stream using per-connection request IDs
 - **Server identity distribution:** `ServerInfo` protobuf struct containing the TLS public key fingerprint
 - **Future consideration:** grpc-web lacks bidirectional stream support, so a browser-based wallet may require protojson over WebSocket
 
+### Request Multiplexing
+
+Both `client` and `user-agent` connections support multiple in-flight requests over one gRPC bidi stream.
+
+- Every request carries a monotonically increasing request ID
+- Every normal response echoes the request ID it corresponds to
+- Out-of-band server messages omit the response ID entirely
+- The server rejects already-seen request IDs at the transport adapter boundary before business logic sees the message
+
+This keeps request correlation entirely in transport/client connection code while leaving actor and domain handlers unaware of request IDs.
+
+---
+
+## EVM Policy Engine
+
+### Overview
+
+The EVM engine classifies incoming transactions, enforces grant constraints, and records executions. It is the sole path through which a wallet key is used for signing.
+
+The central abstraction is the `Policy` trait. Each implementation handles one semantic transaction category and owns its own database tables for grant storage and transaction logging.
+
+### Transaction Evaluation Flow
+
+`Engine::evaluate_transaction` runs the following steps in order:
+
+1. **Classify** — Each registered policy's `analyze(context)` inspects the transaction fields (`chain`, `to`, `value`, `calldata`). The first one returning `Some(meaning)` wins. If none match, the transaction is rejected as `UnsupportedTransactionType`.
+2. **Find grant** — `Policy::try_find_grant` queries for a non-revoked grant covering this wallet, client, chain, and target address.
+3. **Check shared constraints** — `check_shared_constraints` runs in the engine before any policy-specific logic. It enforces the validity window, gas fee caps, and transaction count rate limit (see below).
+4. **Evaluate** — `Policy::evaluate` checks the decoded meaning against the grant's policy-specific constraints and returns any violations.
+5. **Record** — If `RunKind::Execution` and there are no violations, the engine writes to `evm_transaction_log` and calls `Policy::record_transaction` for any policy-specific logging (e.g., token transfer volume).
+
+### Policy Trait
+
+| Method | Purpose |
+|---|---|
+| `analyze` | Pure — classifies a transaction into a typed `Meaning`, or `None` if this policy doesn't apply |
+| `evaluate` | Checks the `Meaning` against a `Grant`; returns a list of `EvalViolation`s |
+| `create_grant` | Inserts policy-specific rows; returns the specific grant ID |
+| `try_find_grant` | Finds a matching non-revoked grant for the given `EvalContext` |
+| `find_all_grants` | Returns all non-revoked grants (used for listing) |
+| `record_transaction` | Persists policy-specific data after execution |
+
+`analyze` and `evaluate` are intentionally separate: classification is pure and cheap, while evaluation may involve DB queries (e.g., fetching past transfer volume).
+
+### Registered Policies
+
+**EtherTransfer** — plain ETH transfers (empty calldata)
+
+- Grant requires: allowlist of recipient addresses + one volumetric rate limit (max ETH over a time window)
+- Violations: recipient not in allowlist, cumulative ETH volume exceeded
+
+**TokenTransfer** — ERC-20 `transfer(address,uint256)` calls
+
+- Recognised by ABI-decoding the `transfer(address,uint256)` selector against a static registry of known token contracts (`arbiter_tokens_registry`)
+- Grant requires: token contract address, optional recipient restriction, zero or more volumetric rate limits
+- Violations: recipient mismatch, any volumetric limit exceeded
+
+### Grant Model
+
+Every grant has two layers:
+
+- **Shared (`evm_basic_grant`)** — wallet, chain, validity period, gas fee caps, transaction count rate limit. One row per grant regardless of type.
+- **Specific** — policy-owned tables (`evm_ether_transfer_grant`, `evm_token_transfer_grant`, etc.) holding type-specific configuration.
+
+`find_all_grants` uses a `#[diesel::auto_type]` base join between the specific and shared tables, then batch-loads related rows (targets, volume limits) in two additional queries to avoid N+1.
+
+The engine exposes `list_all_grants` which collects across all policy types into `Vec<Grant<SpecificGrant>>` via a blanket `From<Grant<S>> for Grant<SpecificGrant>` conversion.
+
+### Shared Constraints (enforced by the engine)
+
+These are checked centrally in `check_shared_constraints` before policy evaluation:
+
+| Constraint | Fields | Behaviour |
+|---|---|---|
+| Validity window | `valid_from`, `valid_until` | Emits `InvalidTime` if current time is outside the range |
+| Gas fee cap | `max_gas_fee_per_gas`, `max_priority_fee_per_gas` | Emits `GasLimitExceeded` if either cap is breached |
+| Tx count rate limit | `rate_limit` (`count` + `window`) | Counts rows in `evm_transaction_log` within the window; emits `RateLimitExceeded` if at or above the limit |
+
+---
+
+### Known Limitations
+
+- **Only EIP-1559 transactions are supported.** Legacy and EIP-2930 types are rejected outright.
+- **No opaque-calldata (unknown contract) grant type.** The architecture describes a category for unrecognised contracts, but no policy implements it yet. Any transaction that is not a plain ETH transfer or a known ERC-20 transfer is unconditionally rejected.
+- **Token registry is static.** Tokens are recognised only if they appear in the hard-coded `arbiter_tokens_registry` crate. There is no mechanism to register additional contracts at runtime.
+- **Nonce management is not implemented.** The architecture lists nonce deduplication as a core responsibility, but no nonce tracking or enforcement exists yet.
+
 ---
 
 ## Memory Protection

app/.dart_tool/extension_discovery/README.md

@@ -0,0 +1,31 @@
+Extension Discovery Cache
+=========================
+
+This folder is used by `package:extension_discovery` to cache lists of
+packages that contains extensions for other packages.
+
+DO NOT USE THIS FOLDER
+----------------------
+
+ * Do not read (or rely) the contents of this folder.
+ * Do write to this folder.
+
+If you're interested in the lists of extensions stored in this folder use the
+API offered by package `extension_discovery` to get this information.
+
+If this package doesn't work for your use-case, then don't try to read the
+contents of this folder. It may change, and will not remain stable.
+
+Use package `extension_discovery`
+---------------------------------
+
+If you want to access information from this folder.
+
+Feel free to delete this folder
+-------------------------------
+
+Files in this folder act as a cache, and the cache is discarded if the files
+are older than the modification time of `.dart_tool/package_config.json`.
+
+Hence, it should never be necessary to clear this cache manually, if you find a
+need to do please file a bug.

app/.dart_tool/extension_discovery/vs_code.json

@@ -0,0 +1 @@
+{"version":2,"entries":[{"package":"app","rootUri":"../","packageUri":"lib/"}]}

mise.lock

@@ -1,7 +1,37 @@
+# @generated - this file is auto-generated by `mise lock` https://mise.jdx.dev/dev-tools/mise-lock.html
+
+[[tools.ast-grep]]
+version = "0.42.0"
+backend = "aqua:ast-grep/ast-grep"
+
+[tools.ast-grep."platforms.linux-arm64"]
+checksum = "sha256:5c830eae8456569e2f7212434ed9c238f58dca412d76045418ed6d394a755836"
+url = "https://github.com/ast-grep/ast-grep/releases/download/0.42.0/app-aarch64-unknown-linux-gnu.zip"
+
+[tools.ast-grep."platforms.linux-x64"]
+checksum = "sha256:e825a05603f0bcc4cd9076c4cc8c9abd6d008b7cd07d9aa3cc323ba4b8606651"
+url = "https://github.com/ast-grep/ast-grep/releases/download/0.42.0/app-x86_64-unknown-linux-gnu.zip"
+
+[tools.ast-grep."platforms.macos-arm64"]
+checksum = "sha256:fc300d5293b1c770a5aece03a8a193b92e71e87cec726c28096990691a582620"
+url = "https://github.com/ast-grep/ast-grep/releases/download/0.42.0/app-aarch64-apple-darwin.zip"
+
+[tools.ast-grep."platforms.macos-x64"]
+checksum = "sha256:979ffe611327056f4730a1ae71b0209b3b830f58b22c6ed194cda34f55400db2"
+url = "https://github.com/ast-grep/ast-grep/releases/download/0.42.0/app-x86_64-apple-darwin.zip"
+
+[tools.ast-grep."platforms.windows-x64"]
+checksum = "sha256:55836fa1b2c65dc7d61615a4d9368622a0d2371a76d28b9a165e5a3ab6ae32a4"
+url = "https://github.com/ast-grep/ast-grep/releases/download/0.42.0/app-x86_64-pc-windows-msvc.zip"
+
 [[tools."cargo:cargo-audit"]]
 version = "0.22.1"
 backend = "cargo:cargo-audit"
 
+[[tools."cargo:cargo-edit"]]
+version = "0.13.9"
+backend = "cargo:cargo-edit"
+
 [[tools."cargo:cargo-features"]]
 version = "1.0.0"
 backend = "cargo:cargo-features"
@@ -42,6 +72,10 @@ backend = "cargo:diesel_cli"
 default-features = "false"
 features = "sqlite,sqlite-bundled"
 
+[[tools."cargo:rinf_cli"]]
+version = "8.9.1"
+backend = "cargo:rinf_cli"
+
 [[tools.flutter]]
 version = "3.38.9-stable"
 backend = "asdf:flutter"
@@ -49,11 +83,50 @@ backend = "asdf:flutter"
 [[tools.protoc]]
 version = "29.6"
 backend = "aqua:protocolbuffers/protobuf/protoc"
-"platforms.linux-arm64" = { checksum = "sha256:2594ff4fcae8cb57310d394d0961b236190ad9c5efbfdf1f597ea471d424fe79", url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-linux-aarch_64.zip"}
-"platforms.linux-x64" = { checksum = "sha256:48785a926e73ffa3f68e2f22b14e7b849620c7a1d36809ac9249a5495e280323", url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-linux-x86_64.zip"}
-"platforms.macos-arm64" = { checksum = "sha256:b9576b5fa1a1ef3fe13a8c91d9d8204b46545759bea5ae155cd6ba2ea4cdaeed", url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-osx-aarch_64.zip"}
-"platforms.macos-x64" = { checksum = "sha256:312f04713946921cc0187ef34df80241ddca1bab6f564c636885fd2cc90d3f88", url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-osx-x86_64.zip"}
-"platforms.windows-x64" = { checksum = "sha256:1ebd7c87baffb9f1c47169b640872bf5fb1e4408079c691af527be9561d8f6f7", url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-win64.zip"}
+
+[tools.protoc."platforms.linux-arm64"]
+checksum = "sha256:2594ff4fcae8cb57310d394d0961b236190ad9c5efbfdf1f597ea471d424fe79"
+url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-linux-aarch_64.zip"
+
+[tools.protoc."platforms.linux-x64"]
+checksum = "sha256:48785a926e73ffa3f68e2f22b14e7b849620c7a1d36809ac9249a5495e280323"
+url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-linux-x86_64.zip"
+
+[tools.protoc."platforms.macos-arm64"]
+checksum = "sha256:b9576b5fa1a1ef3fe13a8c91d9d8204b46545759bea5ae155cd6ba2ea4cdaeed"
+url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-osx-aarch_64.zip"
+
+[tools.protoc."platforms.macos-x64"]
+checksum = "sha256:312f04713946921cc0187ef34df80241ddca1bab6f564c636885fd2cc90d3f88"
+url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-osx-x86_64.zip"
+
+[tools.protoc."platforms.windows-x64"]
+checksum = "sha256:1ebd7c87baffb9f1c47169b640872bf5fb1e4408079c691af527be9561d8f6f7"
+url = "https://github.com/protocolbuffers/protobuf/releases/download/v29.6/protoc-29.6-win64.zip"
+
+[[tools.python]]
+version = "3.14.3"
+backend = "core:python"
+
+[tools.python."platforms.linux-arm64"]
+checksum = "sha256:be0f4dc2932f762292b27d46ea7d3e8e66ddf3969a5eb0254a229015ed402625"
+url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260303/cpython-3.14.3+20260303-aarch64-unknown-linux-gnu-install_only_stripped.tar.gz"
+
+[tools.python."platforms.linux-x64"]
+checksum = "sha256:0a73413f89efd417871876c9accaab28a9d1e3cd6358fbfff171a38ec99302f0"
+url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260303/cpython-3.14.3+20260303-x86_64-unknown-linux-gnu-install_only_stripped.tar.gz"
+
+[tools.python."platforms.macos-arm64"]
+checksum = "sha256:4703cdf18b26798fde7b49b6b66149674c25f97127be6a10dbcf29309bdcdcdb"
+url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260303/cpython-3.14.3+20260303-aarch64-apple-darwin-install_only_stripped.tar.gz"
+
+[tools.python."platforms.macos-x64"]
+checksum = "sha256:76f1cc26e3d262eae8ca546a93e8bded10cf0323613f7e246fea2e10a8115eb7"
+url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260303/cpython-3.14.3+20260303-x86_64-apple-darwin-install_only_stripped.tar.gz"
+
+[tools.python."platforms.windows-x64"]
+checksum = "sha256:950c5f21a015c1bdd1337f233456df2470fab71e4d794407d27a84cb8b9909a0"
+url = "https://github.com/astral-sh/python-build-standalone/releases/download/20260303/cpython-3.14.3+20260303-x86_64-pc-windows-msvc-install_only_stripped.tar.gz"
 
 [[tools.rust]]
 version = "1.93.0"

mise.toml

@@ -9,3 +9,14 @@ protoc = "29.6"
 "cargo:cargo-nextest" = "0.9.126"
 "cargo:cargo-shear" = "latest"
 "cargo:cargo-insta" = "1.46.3"
+python = "3.14.3"
+ast-grep = "0.42.0"
+"cargo:cargo-edit" = "0.13.9"
+
+[tasks.codegen]
+sources = ['protobufs/*.proto']
+outputs = ['useragent/lib/proto/*']
+run = '''
+dart pub global activate protoc_plugin && \
+protoc --dart_out=grpc:useragent/lib/proto --proto_path=protobufs/ protobufs/*.proto
+'''

protobufs/arbiter.proto

@@ -2,7 +2,6 @@ syntax = "proto3";
 
 package arbiter;
 
-import "auth.proto";
 import "client.proto";
 import "user_agent.proto";
 
@@ -12,6 +11,6 @@ message ServerInfo {
 }
 
 service ArbiterService {
-  rpc Client(stream ClientRequest) returns (stream ClientResponse);
-  rpc UserAgent(stream UserAgentRequest) returns (stream UserAgentResponse);
+  rpc Client(stream arbiter.client.ClientRequest) returns (stream arbiter.client.ClientResponse);
+  rpc UserAgent(stream arbiter.user_agent.UserAgentRequest) returns (stream arbiter.user_agent.UserAgentResponse);
 }

protobufs/auth.proto

@@ -1,35 +0,0 @@
-syntax = "proto3";
-
-package arbiter.auth;
-
-import "google/protobuf/timestamp.proto";
-
-message AuthChallengeRequest {
-  bytes pubkey = 1;
-  optional string bootstrap_token = 2;
-}
-
-message AuthChallenge {
-  bytes pubkey = 1;
-  int32 nonce = 2;
-}
-
-message AuthChallengeSolution {
-  bytes signature = 1;
-}
-
-message AuthOk {}
-
-message ClientMessage {
-  oneof payload {
-    AuthChallengeRequest auth_challenge_request = 1;
-    AuthChallengeSolution auth_challenge_solution = 2;
-  }
-}
-
-message ServerMessage {
-  oneof payload {
-    AuthChallenge auth_challenge = 1;
-    AuthOk auth_ok = 2;
-  }
-}

protobufs/client.proto

@@ -1,17 +1,57 @@
 syntax = "proto3";
 
-package arbiter;
+package arbiter.client;
 
-import "auth.proto";
+import "evm.proto";
+import "google/protobuf/empty.proto";
+
+message AuthChallengeRequest {
+  bytes pubkey = 1;
+}
+
+message AuthChallenge {
+  bytes pubkey = 1;
+  int32 nonce = 2;
+}
+
+message AuthChallengeSolution {
+  bytes signature = 1;
+}
+
+enum AuthResult {
+  AUTH_RESULT_UNSPECIFIED = 0;
+  AUTH_RESULT_SUCCESS = 1;
+  AUTH_RESULT_INVALID_KEY = 2;
+  AUTH_RESULT_INVALID_SIGNATURE = 3;
+  AUTH_RESULT_APPROVAL_DENIED = 4;
+  AUTH_RESULT_NO_USER_AGENTS_ONLINE = 5;
+  AUTH_RESULT_INTERNAL = 6;
+}
+
+enum VaultState {
+  VAULT_STATE_UNSPECIFIED = 0;
+  VAULT_STATE_UNBOOTSTRAPPED = 1;
+  VAULT_STATE_SEALED = 2;
+  VAULT_STATE_UNSEALED = 3;
+  VAULT_STATE_ERROR = 4;
+}
 
 message ClientRequest {
+  int32 request_id = 4;
   oneof payload {
-    arbiter.auth.ClientMessage auth_message = 1;
+    AuthChallengeRequest auth_challenge_request = 1;
+    AuthChallengeSolution auth_challenge_solution = 2;
+    google.protobuf.Empty query_vault_state = 3;
   }
 }
 
 message ClientResponse {
+  optional int32 request_id = 7;
   oneof payload {
-    arbiter.auth.ServerMessage auth_message = 1;
+    AuthChallenge auth_challenge = 1;
+    AuthResult auth_result = 2;
+    arbiter.evm.EvmSignTransactionResponse evm_sign_transaction = 3;
+    arbiter.evm.EvmAnalyzeTransactionResponse evm_analyze_transaction = 4;
+    VaultState vault_state = 6;
   }
 }

protobufs/evm.proto

@@ -0,0 +1,216 @@
+syntax = "proto3";
+
+package arbiter.evm;
+
+import "google/protobuf/empty.proto";
+import "google/protobuf/timestamp.proto";
+
+enum EvmError {
+  EVM_ERROR_UNSPECIFIED = 0;
+  EVM_ERROR_VAULT_SEALED = 1;
+  EVM_ERROR_INTERNAL = 2;
+}
+
+message WalletEntry {
+  bytes address = 1; // 20-byte Ethereum address
+}
+
+message WalletList {
+  repeated WalletEntry wallets = 1;
+}
+
+message WalletCreateResponse {
+  oneof result {
+    WalletEntry wallet = 1;
+    EvmError error = 2;
+  }
+}
+
+message WalletListResponse {
+  oneof result {
+    WalletList wallets = 1;
+    EvmError error = 2;
+  }
+}
+
+// --- Grant types ---
+
+message TransactionRateLimit {
+  uint32 count = 1;
+  int64 window_secs = 2;
+}
+
+message VolumeRateLimit {
+  bytes max_volume = 1; // U256 as big-endian bytes
+  int64 window_secs = 2;
+}
+
+message SharedSettings {
+  int32 wallet_id = 1;
+  uint64 chain_id = 2;
+  optional google.protobuf.Timestamp valid_from = 3;
+  optional google.protobuf.Timestamp valid_until = 4;
+  optional bytes max_gas_fee_per_gas = 5; // U256 as big-endian bytes
+  optional bytes max_priority_fee_per_gas = 6; // U256 as big-endian bytes
+  optional TransactionRateLimit rate_limit = 7;
+}
+
+message EtherTransferSettings {
+  repeated bytes targets = 1; // list of 20-byte Ethereum addresses
+  VolumeRateLimit limit = 2;
+}
+
+message TokenTransferSettings {
+  bytes token_contract = 1; // 20-byte Ethereum address
+  optional bytes target = 2; // 20-byte Ethereum address; absent means any recipient allowed
+  repeated VolumeRateLimit volume_limits = 3;
+}
+
+message SpecificGrant {
+  oneof grant {
+    EtherTransferSettings ether_transfer = 1;
+    TokenTransferSettings token_transfer = 2;
+  }
+}
+
+message EtherTransferMeaning {
+  bytes to = 1; // 20-byte Ethereum address
+  bytes value = 2; // U256 as big-endian bytes
+}
+
+message TokenInfo {
+  string symbol = 1;
+  bytes address = 2; // 20-byte Ethereum address
+  uint64 chain_id = 3;
+}
+
+// Mirror of token_transfers::Meaning
+message TokenTransferMeaning {
+  TokenInfo token = 1;
+  bytes to = 2; // 20-byte Ethereum address
+  bytes value = 3; // U256 as big-endian bytes
+}
+
+// Mirror of policies::SpecificMeaning
+message SpecificMeaning {
+  oneof meaning {
+    EtherTransferMeaning ether_transfer = 1;
+    TokenTransferMeaning token_transfer = 2;
+  }
+}
+
+// --- Eval error types ---
+message GasLimitExceededViolation {
+  optional bytes max_gas_fee_per_gas = 1; // U256 as big-endian bytes
+  optional bytes max_priority_fee_per_gas = 2; // U256 as big-endian bytes
+}
+
+message EvalViolation {
+  oneof kind {
+    bytes invalid_target = 1; // 20-byte Ethereum address
+    GasLimitExceededViolation gas_limit_exceeded = 2;
+    google.protobuf.Empty rate_limit_exceeded = 3;
+    google.protobuf.Empty volumetric_limit_exceeded = 4;
+    google.protobuf.Empty invalid_time = 5;
+    google.protobuf.Empty invalid_transaction_type = 6;
+  }
+}
+
+// Transaction was classified but no grant covers it
+message NoMatchingGrantError {
+  SpecificMeaning meaning = 1;
+}
+
+// Transaction was classified and a grant was found, but constraints were violated
+message PolicyViolationsError {
+  SpecificMeaning meaning = 1;
+  repeated EvalViolation violations = 2;
+}
+
+// top-level error returned when transaction evaluation fails
+message TransactionEvalError {
+  oneof kind {
+    google.protobuf.Empty contract_creation_not_supported = 1;
+    google.protobuf.Empty unsupported_transaction_type = 2;
+    NoMatchingGrantError no_matching_grant = 3;
+    PolicyViolationsError policy_violations = 4;
+  }
+}
+
+// --- UserAgent grant management ---
+message EvmGrantCreateRequest {
+  int32 client_id = 1;
+  SharedSettings shared = 2;
+  SpecificGrant specific = 3;
+}
+
+message EvmGrantCreateResponse {
+  oneof result {
+    int32 grant_id = 1;
+    EvmError error = 2;
+  }
+}
+
+message EvmGrantDeleteRequest {
+  int32 grant_id = 1;
+}
+
+message EvmGrantDeleteResponse {
+  oneof result {
+    google.protobuf.Empty ok = 1;
+    EvmError error = 2;
+  }
+}
+
+// Basic grant info returned in grant listings
+message GrantEntry {
+  int32 id = 1;
+  int32 client_id = 2;
+  SharedSettings shared = 3;
+  SpecificGrant specific = 4;
+}
+
+message EvmGrantListRequest {
+  optional int32 wallet_id = 1;
+}
+
+message EvmGrantListResponse {
+  oneof result {
+    EvmGrantList grants = 1;
+    EvmError error = 2;
+  }
+}
+
+message EvmGrantList {
+  repeated GrantEntry grants = 1;
+}
+
+// --- Client transaction operations ---
+
+message EvmSignTransactionRequest {
+  bytes wallet_address = 1; // 20-byte Ethereum address
+  bytes rlp_transaction = 2; // RLP-encoded EIP-1559 transaction (unsigned)
+}
+
+// oneof because signing and evaluation happen atomically — a signing failure
+// is always either an eval error or an internal error, never a partial success
+message EvmSignTransactionResponse {
+  oneof result {
+    bytes signature = 1; // 65-byte signature: r[32] || s[32] || v[1]
+    TransactionEvalError eval_error = 2;
+    EvmError error = 3;
+  }
+}
+
+message EvmAnalyzeTransactionRequest {
+  bytes wallet_address = 1; // 20-byte Ethereum address
+  bytes rlp_transaction = 2; // RLP-encoded EIP-1559 transaction
+}
+
+message EvmAnalyzeTransactionResponse {
+  oneof result {
+    SpecificMeaning meaning = 1;
+    TransactionEvalError eval_error = 2;
+    EvmError error = 3;
+  }
+}

protobufs/user_agent.proto

@@ -1,10 +1,91 @@
 syntax = "proto3";
 
-package arbiter;
+package arbiter.user_agent;
 
-import "auth.proto";
+import "evm.proto";
 import "google/protobuf/empty.proto";
 
+enum KeyType {
+  KEY_TYPE_UNSPECIFIED = 0;
+  KEY_TYPE_ED25519 = 1;
+  KEY_TYPE_ECDSA_SECP256K1 = 2;
+  KEY_TYPE_RSA = 3;
+}
+
+// --- SDK client management ---
+
+enum SdkClientError {
+  SDK_CLIENT_ERROR_UNSPECIFIED = 0;
+  SDK_CLIENT_ERROR_ALREADY_EXISTS = 1;
+  SDK_CLIENT_ERROR_NOT_FOUND = 2;
+  SDK_CLIENT_ERROR_HAS_RELATED_DATA = 3; // hard-delete blocked by FK (client has grants or transaction logs)
+  SDK_CLIENT_ERROR_INTERNAL = 4;
+}
+
+message SdkClientApproveRequest {
+  bytes pubkey = 1; // 32-byte ed25519 public key
+}
+
+message SdkClientRevokeRequest {
+  int32 client_id = 1;
+}
+
+message SdkClientEntry {
+  int32 id = 1;
+  bytes pubkey = 2;
+  int32 created_at = 3;
+}
+
+message SdkClientList {
+  repeated SdkClientEntry clients = 1;
+}
+
+message SdkClientApproveResponse {
+  oneof result {
+    SdkClientEntry client = 1;
+    SdkClientError error = 2;
+  }
+}
+
+message SdkClientRevokeResponse {
+  oneof result {
+    google.protobuf.Empty ok = 1;
+    SdkClientError error = 2;
+  }
+}
+
+message SdkClientListResponse {
+  oneof result {
+    SdkClientList clients = 1;
+    SdkClientError error = 2;
+  }
+}
+
+message AuthChallengeRequest {
+  bytes pubkey = 1;
+  optional string bootstrap_token = 2;
+  KeyType key_type = 3;
+}
+
+message AuthChallenge {
+  int32 nonce = 2;
+  reserved 1;
+}
+
+message AuthChallengeSolution {
+  bytes signature = 1;
+}
+
+enum AuthResult {
+  AUTH_RESULT_UNSPECIFIED = 0;
+  AUTH_RESULT_SUCCESS = 1;
+  AUTH_RESULT_INVALID_KEY = 2;
+  AUTH_RESULT_INVALID_SIGNATURE = 3;
+  AUTH_RESULT_BOOTSTRAP_REQUIRED = 4;
+  AUTH_RESULT_TOKEN_INVALID = 5;
+  AUTH_RESULT_INTERNAL = 6;
+}
+
 message UnsealStart {
   bytes client_pubkey = 1;
 }
@@ -18,6 +99,12 @@ message UnsealEncryptedKey {
   bytes associated_data = 3;
 }
 
+message BootstrapEncryptedKey {
+  bytes nonce = 1;
+  bytes ciphertext = 2;
+  bytes associated_data = 3;
+}
+
 enum UnsealResult {
   UNSEAL_RESULT_UNSPECIFIED = 0;
   UNSEAL_RESULT_SUCCESS = 1;
@@ -25,6 +112,13 @@ enum UnsealResult {
   UNSEAL_RESULT_UNBOOTSTRAPPED = 3;
 }
 
+enum BootstrapResult {
+  BOOTSTRAP_RESULT_UNSPECIFIED = 0;
+  BOOTSTRAP_RESULT_SUCCESS = 1;
+  BOOTSTRAP_RESULT_ALREADY_BOOTSTRAPPED = 2;
+  BOOTSTRAP_RESULT_INVALID_KEY = 3;
+}
+
 enum VaultState {
   VAULT_STATE_UNSPECIFIED = 0;
   VAULT_STATE_UNBOOTSTRAPPED = 1;
@@ -33,19 +127,53 @@ enum VaultState {
   VAULT_STATE_ERROR = 4;
 }
 
+message SdkClientConnectionRequest {
+  bytes pubkey = 1;
+}
+
+message SdkClientConnectionResponse {
+  bool approved = 1;
+}
+
+message SdkClientConnectionCancel {}
+
 message UserAgentRequest {
+  int32 id = 16;
   oneof payload {
-    arbiter.auth.ClientMessage auth_message = 1;
-    UnsealStart unseal_start = 2;
-    UnsealEncryptedKey unseal_encrypted_key = 3;
-    google.protobuf.Empty query_vault_state = 4;
+    AuthChallengeRequest auth_challenge_request = 1;
+    AuthChallengeSolution auth_challenge_solution = 2;
+    UnsealStart unseal_start = 3;
+    UnsealEncryptedKey unseal_encrypted_key = 4;
+    google.protobuf.Empty query_vault_state = 5;
+    google.protobuf.Empty evm_wallet_create = 6;
+    google.protobuf.Empty evm_wallet_list = 7;
+    arbiter.evm.EvmGrantCreateRequest evm_grant_create = 8;
+    arbiter.evm.EvmGrantDeleteRequest evm_grant_delete = 9;
+    arbiter.evm.EvmGrantListRequest evm_grant_list = 10;
+    SdkClientConnectionResponse sdk_client_connection_response = 11;
+    SdkClientApproveRequest sdk_client_approve = 12;
+    SdkClientRevokeRequest sdk_client_revoke = 13;
+    google.protobuf.Empty sdk_client_list = 14;
+    BootstrapEncryptedKey bootstrap_encrypted_key = 15;
   }
 }
 message UserAgentResponse {
+  optional int32 id = 16;
   oneof payload {
-    arbiter.auth.ServerMessage auth_message = 1;
-    UnsealStartResponse unseal_start_response = 2;
-    UnsealResult unseal_result = 3;
-    VaultState vault_state = 4;
+    AuthChallenge auth_challenge = 1;
+    AuthResult auth_result = 2;
+    UnsealStartResponse unseal_start_response = 3;
+    UnsealResult unseal_result = 4;
+    VaultState vault_state = 5;
+    arbiter.evm.WalletCreateResponse evm_wallet_create = 6;
+    arbiter.evm.WalletListResponse evm_wallet_list = 7;
+    arbiter.evm.EvmGrantCreateResponse evm_grant_create = 8;
+    arbiter.evm.EvmGrantDeleteResponse evm_grant_delete = 9;
+    arbiter.evm.EvmGrantListResponse evm_grant_list = 10;
+    SdkClientConnectionResponse sdk_client_connection_response = 11;
+    SdkClientApproveResponse sdk_client_approve_response = 12;
+    SdkClientRevokeResponse sdk_client_revoke_response = 13;
+    SdkClientListResponse sdk_client_list_response = 14;
+    BootstrapResult bootstrap_result = 15;
   }
 }

scripts/gen_erc20_registry.py

@@ -0,0 +1,150 @@
+#!/usr/bin/env python3
+"""
+Fetch the Uniswap default token list and emit Rust `TokenInfo` statics.
+
+Usage:
+    python3 gen_erc20_registry.py                       # fetch from IPFS
+    python3 gen_erc20_registry.py tokens.json           # local file
+    python3 gen_erc20_registry.py tokens.json out.rs    # custom output file
+"""
+
+import json
+import re
+import sys
+import unicodedata
+import urllib.request
+
+UNISWAP_URL = "https://ipfs.io/ipns/tokens.uniswap.org"
+
+SOLANA_CHAIN_ID = 501000101
+IDENTIFIER_RE = re.compile(r"[^A-Za-z0-9]+")
+
+
+def load_tokens(source=None):
+    if source:
+        with open(source) as f:
+            return json.load(f)
+    req = urllib.request.Request(
+        UNISWAP_URL,
+        headers={"Accept": "application/json", "User-Agent": "gen_tokens/1.0"},
+    )
+    with urllib.request.urlopen(req, timeout=60) as resp:
+        return json.loads(resp.read())
+
+
+def escape(s: str) -> str:
+    return s.replace("\\", "\\\\").replace('"', '\\"')
+
+
+def to_screaming_case(name: str) -> str:
+    normalized = unicodedata.normalize("NFKD", name or "")
+    ascii_name = normalized.encode("ascii", "ignore").decode("ascii")
+    snake = IDENTIFIER_RE.sub("_", ascii_name).strip("_").upper()
+    if not snake:
+        snake = "TOKEN"
+    if snake[0].isdigit():
+        snake = f"TOKEN_{snake}"
+    return snake
+
+
+def static_name_for_token(token: dict, used_names: set[str]) -> str:
+    base = to_screaming_case(token.get("name", ""))
+    if base not in used_names:
+        used_names.add(base)
+        return base
+
+    address = token["address"]
+    suffix = f"{token['chainId']}_{address[2:].upper()[-8:]}"
+    candidate = f"{base}_{suffix}"
+
+    i = 2
+    while candidate in used_names:
+        candidate = f"{base}_{suffix}_{i}"
+        i += 1
+
+    used_names.add(candidate)
+    return candidate
+
+
+def main():
+    source = sys.argv[1] if len(sys.argv) > 1 else None
+    output = sys.argv[2] if len(sys.argv) > 2 else "generated_tokens.rs"
+    data = load_tokens(source)
+    tokens = data["tokens"]
+
+    # Deduplicate by (chainId, address)
+    seen = set()
+    unique = []
+    for t in tokens:
+        key = (t["chainId"], t["address"].lower())
+        if key not in seen:
+            seen.add(key)
+            unique.append(t)
+
+    unique.sort(key=lambda t: (t["chainId"], t.get("symbol", "").upper()))
+    evm_tokens = [t for t in unique if t["chainId"] != SOLANA_CHAIN_ID]
+
+    ver = data["version"]
+    lines = []
+    w = lines.append
+
+    w(
+        f"// Auto-generated from Uniswap token list v{ver['major']}.{ver['minor']}.{ver['patch']}"
+    )
+    w(f"// {len(evm_tokens)} tokens")
+    w("// DO NOT EDIT - regenerate with gen_erc20_registry.py")
+    w("")
+
+    used_static_names = set()
+    token_statics = []
+    for t in evm_tokens:
+        static_name = static_name_for_token(t, used_static_names)
+        token_statics.append((static_name, t))
+
+    for static_name, t in token_statics:
+        addr = t["address"]
+        name = escape(t.get("name", ""))
+        symbol = escape(t.get("symbol", ""))
+        decimals = t.get("decimals", 18)
+        logo = t.get("logoURI")
+        chain = t["chainId"]
+
+        logo_val = f'Some("{escape(logo)}")' if logo else "None"
+
+        w(f"pub static {static_name}: TokenInfo = TokenInfo {{")
+        w(f'    name: "{name}",')
+        w(f'    symbol: "{symbol}",')
+        w(f"    decimals: {decimals},")
+        w(f'    contract: address!("{addr}"),')
+        w(f"    chain: {chain},")
+        w(f"    logo_uri: {logo_val},")
+        w("};")
+        w("")
+
+    w("pub static TOKENS: &[&TokenInfo] = &[")
+    for static_name, _ in token_statics:
+        w(f"    &{static_name},")
+    w("];")
+    w("")
+    w("pub fn get_token(")
+    w("    chain_id: alloy::primitives::ChainId,")
+    w("    address: alloy::primitives::Address,")
+    w(") -> Option<&'static TokenInfo> {")
+    w("    match (chain_id, address) {")
+    for static_name, t in token_statics:
+        w(
+            f'        ({t["chainId"]}, addr) if addr == address!("{t["address"]}") => Some(&{static_name}),'
+        )
+    w("        _ => None,")
+    w("    }")
+    w("}")
+    w("")
+
+    with open(output, "w") as f:
+        f.write("\n".join(lines))
+
+    print(f"Wrote {len(token_statics)} tokens to {output}")
+
+
+if __name__ == "__main__":
+    main()

server/.cargo/audit.toml

@@ -0,0 +1,13 @@
+[advisories]
+# RUSTSEC-2023-0071: Marvin Attack timing side-channel in rsa crate.
+# No fixed version is available upstream.
+# RSA support is required for Windows Hello / KeyCredentialManager
+# (https://learn.microsoft.com/en-us/uwp/api/windows.security.credentials.keycredentialmanager.requestcreateasync),
+# which only issues RSA-2048 keys.
+# Mitigations in place:
+#   - Signing uses BlindedSigningKey (PSS+SHA-256), which applies blinding to
+#     protect the private key from timing recovery during signing.
+#   - RSA decryption is never performed; we only verify public-key signatures.
+#   - The attack requires local, high-resolution timing access against the
+#     signing process, which is not exposed in our threat model.
+ignore = ["RUSTSEC-2023-0071"]

server/Cargo.toml

@@ -1,34 +1,44 @@
 [workspace]
-members = [
-    "crates/arbiter-client",
-    "crates/arbiter-proto",
-    "crates/arbiter-server",
-    "crates/arbiter-useragent",
-]
+members = ["crates/*"]
 resolver = "3"
 
+[workspace.lints.clippy]
+disallowed-methods = "deny"
+
 
 [workspace.dependencies]
-tonic = { version = "0.14.3", features = ["deflate", "gzip", "tls-connect-info", "zstd"] }
+tonic = { version = "0.14.5", features = [
+    "deflate",
+    "gzip",
+    "tls-connect-info",
+    "zstd",
+] }
 tracing = "0.1.44"
-tokio = { version = "1.49.0", features = ["full"] }
+tokio = { version = "1.50.0", features = ["full"] }
 ed25519-dalek = { version = "3.0.0-pre.6", features = ["rand_core"] }
-chrono = { version = "0.4.43", features = ["serde"] }
+chrono = { version = "0.4.44", features = ["serde"] }
 rand = "0.10.0"
-rustls = "0.23.36"
+rustls = { version = "0.23.37", features = ["aws-lc-rs"] }
 smlang = "0.8.0"
 miette = { version = "7.6.0", features = ["fancy", "serde"] }
 thiserror = "2.0.18"
 async-trait = "0.1.89"
-futures = "0.3.31"
+futures = "0.3.32"
 tokio-stream = { version = "0.1.18", features = ["full"] }
 kameo = "0.19.2"
+prost-types = { version = "0.14.3", features = ["chrono"] }
 x25519-dalek = { version = "2.0.1", features = ["getrandom"] }
 rstest = "0.26.1"
 rustls-pki-types = "1.14.0"
+alloy = "1.7.3"
 rcgen = { version = "0.14.7", features = [
     "aws_lc_rs",
     "pem",
     "x509-parser",
     "zeroize",
 ], default-features = false }
+k256 = { version = "0.13.4", features = ["ecdsa", "pkcs8"] }
+rsa = { version = "0.9", features = ["sha2"] }
+sha2 = "0.10"
+spki = "0.7"
+terrors = { version = "0.5", git = "https://github.com/CleverWild/terrors" }

server/clippy.toml

@@ -0,0 +1,9 @@
+disallowed-methods = [
+    # RSA decryption is forbidden: the rsa crate has RUSTSEC-2023-0071 (Marvin Attack).
+    # We only use RSA for Windows Hello (KeyCredentialManager) public-key verification — decryption
+    # is never required and must not be introduced.
+    { path = "rsa::RsaPrivateKey::decrypt", reason = "RSA decryption is forbidden (RUSTSEC-2023-0071 Marvin Attack). Only PSS signing/verification is permitted." },
+    { path = "rsa::RsaPrivateKey::decrypt_blinded", reason = "RSA decryption is forbidden (RUSTSEC-2023-0071 Marvin Attack). Only PSS signing/verification is permitted." },
+    { path = "rsa::traits::Decryptor::decrypt", reason = "RSA decryption is forbidden (RUSTSEC-2023-0071 Marvin Attack). This blocks decrypt() on rsa::{pkcs1v15,oaep}::DecryptingKey." },
+    { path = "rsa::traits::RandomizedDecryptor::decrypt_with_rng", reason = "RSA decryption is forbidden (RUSTSEC-2023-0071 Marvin Attack). This blocks decrypt_with_rng() on rsa::{pkcs1v15,oaep}::DecryptingKey." },
+]

server/crates/arbiter-client/Cargo.toml

@@ -5,4 +5,23 @@ edition = "2024"
 repository = "https://git.markettakers.org/MarketTakers/arbiter"
 license = "Apache-2.0"
 
+[lints]
+workspace = true
+
+[features]
+evm = ["dep:alloy"]
+
 [dependencies]
+arbiter-proto.path = "../arbiter-proto"
+alloy = { workspace = true, optional = true }
+tonic.workspace = true
+tonic.features = ["tls-aws-lc"]
+tokio.workspace = true
+tokio-stream.workspace = true
+ed25519-dalek.workspace = true
+thiserror.workspace = true
+http = "1.4.0"
+rustls-webpki = { version = "0.103.10", features = ["aws-lc-rs"] }
+async-trait.workspace = true
+rand.workspace = true
+terrors.workspace = true

server/crates/arbiter-client/src/auth.rs

@@ -0,0 +1,103 @@
+use arbiter_proto::{
+    format_challenge,
+    proto::client::{
+        AuthChallengeRequest, AuthChallengeSolution, AuthResult, ClientRequest,
+        client_request::Payload as ClientRequestPayload,
+        client_response::Payload as ClientResponsePayload,
+    },
+};
+use ed25519_dalek::Signer as _;
+use terrors::OneOf;
+
+use crate::{
+    errors::{
+        ConnectError, MissingAuthChallengeError, UnexpectedAuthResponseError, map_auth_code_error,
+    },
+    transport::{ClientTransport, next_request_id},
+};
+
+async fn send_auth_challenge_request(
+    transport: &mut ClientTransport,
+    key: &ed25519_dalek::SigningKey,
+) -> std::result::Result<(), ConnectError> {
+    transport
+        .send(ClientRequest {
+            request_id: next_request_id(),
+            payload: Some(ClientRequestPayload::AuthChallengeRequest(
+                AuthChallengeRequest {
+                    pubkey: key.verifying_key().to_bytes().to_vec(),
+                },
+            )),
+        })
+        .await
+        .map_err(|_| OneOf::new(UnexpectedAuthResponseError))
+}
+
+async fn receive_auth_challenge(
+    transport: &mut ClientTransport,
+) -> std::result::Result<arbiter_proto::proto::client::AuthChallenge, ConnectError> {
+    let response = transport
+        .recv()
+        .await
+        .map_err(|_| OneOf::new(MissingAuthChallengeError))?;
+
+    let payload = response
+        .payload
+        .ok_or_else(|| OneOf::new(MissingAuthChallengeError))?;
+    match payload {
+        ClientResponsePayload::AuthChallenge(challenge) => Ok(challenge),
+        ClientResponsePayload::AuthResult(result) => Err(map_auth_code_error(result)),
+        _ => Err(OneOf::new(UnexpectedAuthResponseError)),
+    }
+}
+
+async fn send_auth_challenge_solution(
+    transport: &mut ClientTransport,
+    key: &ed25519_dalek::SigningKey,
+    challenge: arbiter_proto::proto::client::AuthChallenge,
+) -> std::result::Result<(), ConnectError> {
+    let challenge_payload = format_challenge(challenge.nonce, &challenge.pubkey);
+    let signature = key.sign(&challenge_payload).to_bytes().to_vec();
+
+    transport
+        .send(ClientRequest {
+            request_id: next_request_id(),
+            payload: Some(ClientRequestPayload::AuthChallengeSolution(
+                AuthChallengeSolution { signature },
+            )),
+        })
+        .await
+        .map_err(|_| OneOf::new(UnexpectedAuthResponseError))
+}
+
+async fn receive_auth_confirmation(
+    transport: &mut ClientTransport,
+) -> std::result::Result<(), ConnectError> {
+    let response = transport
+        .recv()
+        .await
+        .map_err(|_| OneOf::new(UnexpectedAuthResponseError))?;
+
+    let payload = response
+        .payload
+        .ok_or_else(|| OneOf::new(UnexpectedAuthResponseError))?;
+    match payload {
+        ClientResponsePayload::AuthResult(result)
+            if AuthResult::try_from(result).ok() == Some(AuthResult::Success) =>
+        {
+            Ok(())
+        }
+        ClientResponsePayload::AuthResult(result) => Err(map_auth_code_error(result)),
+        _ => Err(OneOf::new(UnexpectedAuthResponseError)),
+    }
+}
+
+pub(crate) async fn authenticate(
+    transport: &mut ClientTransport,
+    key: &ed25519_dalek::SigningKey,
+) -> std::result::Result<(), ConnectError> {
+    send_auth_challenge_request(transport, key).await?;
+    let challenge = receive_auth_challenge(transport).await?;
+    send_auth_challenge_solution(transport, key, challenge).await?;
+    receive_auth_confirmation(transport).await
+}

server/crates/arbiter-client/src/client.rs

@@ -0,0 +1,82 @@
+use arbiter_proto::{proto::arbiter_service_client::ArbiterServiceClient, url::ArbiterUrl};
+use std::sync::Arc;
+use terrors::{Broaden as _, OneOf};
+use tokio::sync::{Mutex, mpsc};
+use tokio_stream::wrappers::ReceiverStream;
+use tonic::transport::ClientTlsConfig;
+
+use crate::{
+    auth::authenticate,
+    errors::ConnectError,
+    storage::{FileSigningKeyStorage, SigningKeyStorage},
+    transport::{BUFFER_LENGTH, ClientTransport},
+};
+
+#[cfg(feature = "evm")]
+use crate::errors::{ClientConnectionClosedError, ClientError};
+
+#[cfg(feature = "evm")]
+use crate::wallets::evm::ArbiterEvmWallet;
+
+pub struct ArbiterClient {
+    #[allow(dead_code)]
+    transport: Arc<Mutex<ClientTransport>>,
+}
+
+impl ArbiterClient {
+    pub async fn connect(url: ArbiterUrl) -> Result<Self, ConnectError> {
+        let storage = FileSigningKeyStorage::from_default_location().broaden()?;
+        Self::connect_with_storage(url, &storage).await
+    }
+
+    pub async fn connect_with_storage<S: SigningKeyStorage>(
+        url: ArbiterUrl,
+        storage: &S,
+    ) -> Result<Self, ConnectError> {
+        let key = storage.load_or_create().broaden()?;
+        Self::connect_with_key(url, key).await
+    }
+
+    pub async fn connect_with_key(
+        url: ArbiterUrl,
+        key: ed25519_dalek::SigningKey,
+    ) -> Result<Self, ConnectError> {
+        let anchor = webpki::anchor_from_trusted_cert(&url.ca_cert)
+            .map_err(OneOf::new)?
+            .to_owned();
+        let tls = ClientTlsConfig::new().trust_anchor(anchor);
+
+        let channel = tonic::transport::Channel::from_shared(format!("{}:{}", url.host, url.port))
+            .map_err(OneOf::new)?
+            .tls_config(tls)
+            .map_err(OneOf::new)?
+            .connect()
+            .await
+            .map_err(OneOf::new)?;
+
+        let mut client = ArbiterServiceClient::new(channel);
+        let (tx, rx) = mpsc::channel(BUFFER_LENGTH);
+        let response_stream = client
+            .client(ReceiverStream::new(rx))
+            .await
+            .map_err(OneOf::new)?
+            .into_inner();
+
+        let mut transport = ClientTransport {
+            sender: tx,
+            receiver: response_stream,
+        };
+
+        authenticate(&mut transport, &key).await?;
+
+        Ok(Self {
+            transport: Arc::new(Mutex::new(transport)),
+        })
+    }
+
+    #[cfg(feature = "evm")]
+    pub async fn evm_wallets(&self) -> Result<Vec<ArbiterEvmWallet>, ClientError> {
+        let _ = &self.transport;
+        Err(OneOf::new(ClientConnectionClosedError))
+    }
+}

server/crates/arbiter-client/src/errors.rs

@@ -0,0 +1,127 @@
+use terrors::OneOf;
+use thiserror::Error;
+
+#[cfg(feature = "evm")]
+use alloy::{primitives::ChainId, signers::Error as AlloySignerError};
+
+pub type StorageError = OneOf<(std::io::Error, InvalidKeyLengthError)>;
+
+pub type ConnectError = OneOf<(
+    tonic::transport::Error,
+    http::uri::InvalidUri,
+    webpki::Error,
+    tonic::Status,
+    MissingAuthChallengeError,
+    ApprovalDeniedError,
+    NoUserAgentsOnlineError,
+    UnexpectedAuthResponseError,
+    std::io::Error,
+    InvalidKeyLengthError,
+)>;
+
+pub type ClientError = OneOf<(tonic::Status, ClientConnectionClosedError)>;
+
+pub(crate) type ClientTransportError =
+    OneOf<(TransportChannelClosedError, TransportConnectionClosedError)>;
+
+#[cfg(feature = "evm")]
+pub(crate) type EvmWalletError = OneOf<(
+    EvmChainIdMismatchError,
+    EvmHashSigningUnsupportedError,
+    EvmTransactionSigningUnsupportedError,
+)>;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("Invalid signing key length in storage: expected {expected} bytes, got {actual} bytes")]
+pub struct InvalidKeyLengthError {
+    pub expected: usize,
+    pub actual: usize,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("Auth challenge was not returned by server")]
+pub struct MissingAuthChallengeError;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("Client approval denied by User Agent")]
+pub struct ApprovalDeniedError;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("No User Agents online to approve client")]
+pub struct NoUserAgentsOnlineError;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("Unexpected auth response payload")]
+pub struct UnexpectedAuthResponseError;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("Connection closed by server")]
+pub struct ClientConnectionClosedError;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("Transport channel closed")]
+pub struct TransportChannelClosedError;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("Connection closed by server")]
+pub struct TransportConnectionClosedError;
+
+#[cfg(feature = "evm")]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("Transaction chain id mismatch: signer {signer}, tx {tx}")]
+pub struct EvmChainIdMismatchError {
+    pub signer: ChainId,
+    pub tx: ChainId,
+}
+
+#[cfg(feature = "evm")]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("hash-only signing is not supported for ArbiterEvmWallet; use transaction signing")]
+pub struct EvmHashSigningUnsupportedError;
+
+#[cfg(feature = "evm")]
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Error)]
+#[error("transaction signing is not supported by current arbiter.client protocol")]
+pub struct EvmTransactionSigningUnsupportedError;
+
+pub(crate) fn map_auth_code_error(code: i32) -> ConnectError {
+    use arbiter_proto::proto::client::AuthResult;
+
+    match AuthResult::try_from(code).unwrap_or(AuthResult::Unspecified) {
+        AuthResult::ApprovalDenied => OneOf::new(ApprovalDeniedError),
+        AuthResult::NoUserAgentsOnline => OneOf::new(NoUserAgentsOnlineError),
+        AuthResult::Unspecified
+        | AuthResult::Success
+        | AuthResult::InvalidKey
+        | AuthResult::InvalidSignature
+        | AuthResult::Internal => OneOf::new(UnexpectedAuthResponseError),
+    }
+}
+
+#[cfg(feature = "evm")]
+impl From<EvmChainIdMismatchError> for AlloySignerError {
+    fn from(value: EvmChainIdMismatchError) -> Self {
+        AlloySignerError::TransactionChainIdMismatch {
+            signer: value.signer,
+            tx: value.tx,
+        }
+    }
+}
+
+#[cfg(feature = "evm")]
+impl From<EvmHashSigningUnsupportedError> for AlloySignerError {
+    fn from(_value: EvmHashSigningUnsupportedError) -> Self {
+        AlloySignerError::other(
+            "hash-only signing is not supported for ArbiterEvmWallet; use transaction signing",
+        )
+    }
+}
+
+#[cfg(feature = "evm")]
+impl From<EvmTransactionSigningUnsupportedError> for AlloySignerError {
+    fn from(_value: EvmTransactionSigningUnsupportedError) -> Self {
+        AlloySignerError::other(
+            "transaction signing is not supported by current arbiter.client protocol",
+        )
+    }
+}

server/crates/arbiter-client/src/lib.rs

@@ -1,14 +1,13 @@
-pub fn add(left: u64, right: u64) -> u64 {
-    left + right
-}
+mod auth;
+mod client;
+mod errors;
+mod storage;
+mod transport;
+pub mod wallets;
 
-#[cfg(test)]
-mod tests {
-    use super::*;
+pub use client::ArbiterClient;
+pub use errors::{ClientError, ConnectError, StorageError};
+pub use storage::{FileSigningKeyStorage, SigningKeyStorage};
 
-    #[test]
-    fn it_works() {
-        let result = add(2, 2);
-        assert_eq!(result, 4);
-    }
-}
+#[cfg(feature = "evm")]
+pub use wallets::evm::ArbiterEvmWallet;

server/crates/arbiter-client/src/storage.rs

@@ -0,0 +1,130 @@
+use arbiter_proto::home_path;
+use std::path::{Path, PathBuf};
+use terrors::OneOf;
+
+use crate::errors::{InvalidKeyLengthError, StorageError};
+
+pub trait SigningKeyStorage {
+    fn load_or_create(&self) -> std::result::Result<ed25519_dalek::SigningKey, StorageError>;
+}
+
+#[derive(Debug, Clone)]
+pub struct FileSigningKeyStorage {
+    path: PathBuf,
+}
+
+impl FileSigningKeyStorage {
+    pub const DEFAULT_FILE_NAME: &str = "sdk_client_ed25519.key";
+
+    pub fn new(path: impl Into<PathBuf>) -> Self {
+        Self { path: path.into() }
+    }
+
+    pub fn from_default_location() -> std::result::Result<Self, StorageError> {
+        Ok(Self::new(
+            home_path()
+                .map_err(OneOf::new)?
+                .join(Self::DEFAULT_FILE_NAME),
+        ))
+    }
+
+    fn read_key(path: &Path) -> std::result::Result<ed25519_dalek::SigningKey, StorageError> {
+        let bytes = std::fs::read(path).map_err(OneOf::new)?;
+        let raw: [u8; 32] = bytes.try_into().map_err(|v: Vec<u8>| {
+            OneOf::new(InvalidKeyLengthError {
+                expected: 32,
+                actual: v.len(),
+            })
+        })?;
+        Ok(ed25519_dalek::SigningKey::from_bytes(&raw))
+    }
+}
+
+impl SigningKeyStorage for FileSigningKeyStorage {
+    fn load_or_create(&self) -> std::result::Result<ed25519_dalek::SigningKey, StorageError> {
+        if let Some(parent) = self.path.parent() {
+            std::fs::create_dir_all(parent).map_err(OneOf::new)?;
+        }
+
+        if self.path.exists() {
+            return Self::read_key(&self.path);
+        }
+
+        let key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
+        let raw_key = key.to_bytes();
+
+        // Use create_new to prevent accidental overwrite if another process creates the key first.
+        match std::fs::OpenOptions::new()
+            .create_new(true)
+            .write(true)
+            .open(&self.path)
+        {
+            Ok(mut file) => {
+                use std::io::Write as _;
+                file.write_all(&raw_key).map_err(OneOf::new)?;
+                Ok(key)
+            }
+            Err(err) if err.kind() == std::io::ErrorKind::AlreadyExists => {
+                Self::read_key(&self.path)
+            }
+            Err(err) => Err(OneOf::new(err)),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::{FileSigningKeyStorage, SigningKeyStorage};
+    use crate::errors::InvalidKeyLengthError;
+
+    fn unique_temp_key_path() -> std::path::PathBuf {
+        let nanos = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .expect("clock should be after unix epoch")
+            .as_nanos();
+        std::env::temp_dir().join(format!(
+            "arbiter-client-key-{}-{}.bin",
+            std::process::id(),
+            nanos
+        ))
+    }
+
+    #[test]
+    fn file_storage_creates_and_reuses_key() {
+        let path = unique_temp_key_path();
+        let storage = FileSigningKeyStorage::new(path.clone());
+
+        let key_a = storage
+            .load_or_create()
+            .expect("first load_or_create should create key");
+        let key_b = storage
+            .load_or_create()
+            .expect("second load_or_create should read same key");
+
+        assert_eq!(key_a.to_bytes(), key_b.to_bytes());
+        assert!(path.exists());
+
+        std::fs::remove_file(path).expect("temp key file should be removable");
+    }
+
+    #[test]
+    fn file_storage_rejects_invalid_key_length() {
+        let path = unique_temp_key_path();
+        std::fs::write(&path, [42u8; 31]).expect("should write invalid key file");
+        let storage = FileSigningKeyStorage::new(path.clone());
+
+        let err = storage
+            .load_or_create()
+            .expect_err("storage should reject non-32-byte key file");
+
+        match err.narrow::<InvalidKeyLengthError, _>() {
+            Ok(invalid_len) => {
+                assert_eq!(invalid_len.expected, 32);
+                assert_eq!(invalid_len.actual, 31);
+            }
+            Err(other) => panic!("unexpected io error: {other:?}"),
+        }
+
+        std::fs::remove_file(path).expect("temp key file should be removable");
+    }
+}

server/crates/arbiter-client/src/transport.rs

@@ -0,0 +1,42 @@
+use arbiter_proto::proto::client::{ClientRequest, ClientResponse};
+use std::sync::atomic::{AtomicI32, Ordering};
+use terrors::OneOf;
+use tokio::sync::mpsc;
+
+use crate::errors::{
+    ClientTransportError, TransportChannelClosedError, TransportConnectionClosedError,
+};
+
+pub(crate) const BUFFER_LENGTH: usize = 16;
+static NEXT_REQUEST_ID: AtomicI32 = AtomicI32::new(1);
+
+pub(crate) fn next_request_id() -> i32 {
+    NEXT_REQUEST_ID.fetch_add(1, Ordering::Relaxed)
+}
+
+pub(crate) struct ClientTransport {
+    pub(crate) sender: mpsc::Sender<ClientRequest>,
+    pub(crate) receiver: tonic::Streaming<ClientResponse>,
+}
+
+impl ClientTransport {
+    pub(crate) async fn send(
+        &mut self,
+        request: ClientRequest,
+    ) -> std::result::Result<(), ClientTransportError> {
+        self.sender
+            .send(request)
+            .await
+            .map_err(|_| OneOf::new(TransportChannelClosedError))
+    }
+
+    pub(crate) async fn recv(
+        &mut self,
+    ) -> std::result::Result<ClientResponse, ClientTransportError> {
+        match self.receiver.message().await {
+            Ok(Some(resp)) => Ok(resp),
+            Ok(None) => Err(OneOf::new(TransportConnectionClosedError)),
+            Err(_) => Err(OneOf::new(TransportConnectionClosedError)),
+        }
+    }
+}

server/crates/arbiter-client/src/wallets/evm.rs

@@ -0,0 +1,97 @@
+use alloy::{
+    consensus::SignableTransaction,
+    network::TxSigner,
+    primitives::{Address, B256, ChainId, Signature},
+    signers::{Result, Signer},
+};
+use async_trait::async_trait;
+use std::sync::Arc;
+use terrors::OneOf;
+use tokio::sync::Mutex;
+
+use crate::{
+    errors::{
+        EvmChainIdMismatchError, EvmHashSigningUnsupportedError,
+        EvmTransactionSigningUnsupportedError, EvmWalletError,
+    },
+    transport::ClientTransport,
+};
+
+pub struct ArbiterEvmWallet {
+    transport: Arc<Mutex<ClientTransport>>,
+    address: Address,
+    chain_id: Option<ChainId>,
+}
+
+impl ArbiterEvmWallet {
+    #[allow(dead_code)]
+    pub(crate) fn new(transport: Arc<Mutex<ClientTransport>>, address: Address) -> Self {
+        Self {
+            transport,
+            address,
+            chain_id: None,
+        }
+    }
+
+    pub fn address(&self) -> Address {
+        self.address
+    }
+
+    pub fn with_chain_id(mut self, chain_id: ChainId) -> Self {
+        self.chain_id = Some(chain_id);
+        self
+    }
+
+    fn validate_chain_id(
+        &self,
+        tx: &mut dyn SignableTransaction<Signature>,
+    ) -> std::result::Result<(), EvmWalletError> {
+        if let Some(chain_id) = self.chain_id
+            && !tx.set_chain_id_checked(chain_id)
+        {
+            return Err(OneOf::new(EvmChainIdMismatchError {
+                signer: chain_id,
+                tx: tx.chain_id().unwrap(),
+            }));
+        }
+
+        Ok(())
+    }
+}
+
+#[async_trait]
+impl Signer for ArbiterEvmWallet {
+    async fn sign_hash(&self, _hash: &B256) -> Result<Signature> {
+        Err(EvmWalletError::new(EvmHashSigningUnsupportedError).into())
+    }
+
+    fn address(&self) -> Address {
+        self.address
+    }
+
+    fn chain_id(&self) -> Option<ChainId> {
+        self.chain_id
+    }
+
+    fn set_chain_id(&mut self, chain_id: Option<ChainId>) {
+        self.chain_id = chain_id;
+    }
+}
+
+#[async_trait]
+impl TxSigner<Signature> for ArbiterEvmWallet {
+    fn address(&self) -> Address {
+        self.address
+    }
+
+    async fn sign_transaction(
+        &self,
+        tx: &mut dyn SignableTransaction<Signature>,
+    ) -> Result<Signature> {
+        let _transport = self.transport.lock().await;
+        self.validate_chain_id(tx)
+            .map_err(OneOf::into::<alloy::signers::Error>)?;
+
+        Err(EvmWalletError::new(EvmTransactionSigningUnsupportedError).into())
+    }
+}

server/crates/arbiter-client/src/wallets/mod.rs

@@ -0,0 +1,2 @@
+#[cfg(feature = "evm")]
+pub mod evm;

server/crates/arbiter-proto/Cargo.toml

@@ -9,7 +9,8 @@ license = "Apache-2.0"
 tonic.workspace = true
 tokio.workspace = true
 futures.workspace = true
-tonic-prost = "0.14.3"
+hex = "0.4.3"
+tonic-prost = "0.14.5"
 prost = "0.14.3"
 kameo.workspace = true
 url = "2.5.8"
@@ -17,11 +18,14 @@ miette.workspace = true
 thiserror.workspace = true
 rustls-pki-types.workspace = true
 base64 = "0.22.1"
+prost-types.workspace = true
 tracing.workspace = true
-
+async-trait.workspace = true
+tokio-stream.workspace = true
 
 [build-dependencies]
-tonic-prost-build = "0.14.3"
+tonic-prost-build = "0.14.5"
+protoc-bin-vendored = "3"
 
 [dev-dependencies]
 rstest.workspace = true
@@ -30,5 +34,3 @@ rcgen.workspace = true
 
 [package.metadata.cargo-shear]
 ignored = ["tonic-prost", "prost", "kameo"]
-
-

server/crates/arbiter-proto/build.rs

@@ -1,21 +1,32 @@
+use std::path::PathBuf;
 use tonic_prost_build::configure;
 
 static PROTOBUF_DIR: &str = "../../../protobufs";
 
 fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let manifest_dir = PathBuf::from(std::env::var("CARGO_MANIFEST_DIR")?);
+    let protobuf_dir = manifest_dir.join(PROTOBUF_DIR);
+    let protoc_include = protoc_bin_vendored::include_path()?;
+    let protoc_path = protoc_bin_vendored::protoc_bin_path()?;
 
-    println!("cargo::rerun-if-changed={PROTOBUF_DIR}");
+    unsafe {
+        std::env::set_var("PROTOC", &protoc_path);
+        std::env::set_var("PROTOC_INCLUDE", &protoc_include);
+    }
+
+    println!("cargo::rerun-if-changed={}", protobuf_dir.display());
 
     configure()
         .message_attribute(".", "#[derive(::kameo::Reply)]")
+        .compile_well_known_types(true)
         .compile_protos(
             &[
-                format!("{}/arbiter.proto", PROTOBUF_DIR),
-                format!("{}/auth.proto", PROTOBUF_DIR),
+                protobuf_dir.join("arbiter.proto"),
+                protobuf_dir.join("user_agent.proto"),
+                protobuf_dir.join("client.proto"),
+                protobuf_dir.join("evm.proto"),
             ],
-            &[PROTOBUF_DIR.to_string()],
-        )
-        
-        .unwrap();
+            &[protobuf_dir],
+        )?;
     Ok(())
 }

server/crates/arbiter-proto/src/lib.rs

@@ -3,13 +3,25 @@ pub mod url;
 
 use base64::{Engine, prelude::BASE64_STANDARD};
 
-use crate::proto::auth::AuthChallenge;
+pub mod google {
+    pub mod protobuf {
+        tonic::include_proto!("google.protobuf");
+    }
+}
 
 pub mod proto {
     tonic::include_proto!("arbiter");
 
-    pub mod auth {
-        tonic::include_proto!("arbiter.auth");
+    pub mod user_agent {
+        tonic::include_proto!("arbiter.user_agent");
+    }
+
+    pub mod client {
+        tonic::include_proto!("arbiter.client");
+    }
+
+    pub mod evm {
+        tonic::include_proto!("arbiter.evm");
     }
 }
 
@@ -28,7 +40,7 @@ pub fn home_path() -> Result<std::path::PathBuf, std::io::Error> {
     Ok(arbiter_home)
 }
 
-pub fn format_challenge(challenge: &AuthChallenge) -> Vec<u8> {
-    let concat_form = format!("{}:{}", challenge.nonce, BASE64_STANDARD.encode(&challenge.pubkey));
-    concat_form.into_bytes().to_vec()
+pub fn format_challenge(nonce: i32, pubkey: &[u8]) -> Vec<u8> {
+    let concat_form = format!("{}:{}", nonce, BASE64_STANDARD.encode(pubkey));
+    concat_form.into_bytes()
 }

server/crates/arbiter-proto/src/transport.rs

@@ -1,371 +1,163 @@
-//! Transport abstraction layer for bridging gRPC bidirectional streaming with kameo actors.
+//! Transport-facing abstractions shared by protocol/session code.
 //!
-//! This module provides a clean separation between the gRPC transport layer and business logic
-//! by modeling the connection as two linked kameo actors:
+//! This module defines a small set of transport traits that actors and other
+//! protocol code can depend on without knowing anything about the concrete
+//! transport underneath.
 //!
-//! - A **transport actor** ([`GrpcTransportActor`]) that owns the gRPC stream and channel,
-//!   forwarding inbound messages to the business actor and outbound messages to the client.
-//! - A **business logic actor** that receives inbound messages from the transport actor and
-//!   sends outbound messages back through the transport actor.
+//! The abstraction is split into:
+//! - [`Sender`] for outbound delivery
+//! - [`Receiver`] for inbound delivery
+//! - [`Bi`] as the combined duplex form (`Sender + Receiver`)
 //!
-//! The [`wire()`] function sets up bidirectional linking between the two actors, ensuring
-//! that if either actor dies, the other is notified and can shut down gracefully.
+//! This split lets code depend only on the half it actually needs. For
+//! example, some actor/session code only sends out-of-band messages, while
+//! auth/state-machine code may need full duplex access.
 //!
-//! # Terminology
+//! [`Bi`] remains intentionally minimal and transport-agnostic:
+//! - [`Receiver::recv`] yields inbound messages
+//! - [`Sender::send`] accepts outbound messages
 //!
-//! - **InboundMessage**: a message received by the transport actor from the channel/socket
-//!   and forwarded to the business actor.
-//! - **OutboundMessage**: a message produced by the business actor and sent to the transport
-//!   actor to be forwarded to the channel/socket.
+//! Transport-specific adapters, including protobuf or gRPC bridges, live in the
+//! crates that own those boundaries rather than in `arbiter-proto`.
 //!
-//! # Architecture
+//! [`Bi`] deliberately does not model request/response correlation. Some
+//! transports may carry multiplexed request/response traffic, some may emit
+//! out-of-band messages, and some may be one-message-at-a-time state machines.
+//! Correlation concerns such as request IDs, pending response maps, and
+//! out-of-band routing belong in the adapter or connection layer built on top
+//! of [`Bi`], not in this abstraction itself.
 //!
-//! ```text
-//! gRPC Stream ──InboundMessage──▶ GrpcTransportActor ──tell(InboundMessage)──▶ BusinessActor
-//!                                 ▲                                    │
-//!                                 └─tell(Result<OutboundMessage, _>)────┘
-//!                                 │
-//!                          mpsc::Sender ──▶ Client
-//! ```
+//! # Generic Ordering Rule
 //!
-//! # Example
+//! This module consistently uses `Inbound` first and `Outbound` second in
+//! generic parameter lists.
 //!
-//! ```rust,ignore
-//! let (tx, rx) = mpsc::channel(1000);
-//! let context = server_context.clone();
+//! For [`Receiver`], [`Sender`], and [`Bi`], this means:
+//! - `Receiver<Inbound>`
+//! - `Sender<Outbound>`
+//! - `Bi<Inbound, Outbound>`
 //!
-//! wire(
-//!     |transport_ref| MyBusinessActor::new(context, transport_ref),
-//!     |business_recipient, business_id| GrpcTransportActor {
-//!         sender: tx,
-//!         receiver: grpc_stream,
-//!         business_logic_actor: business_recipient,
-//!         business_logic_actor_id: business_id,
-//!     },
-//! ).await;
+//! Concretely, for [`Bi`]:
+//! - `recv() -> Option<Inbound>`
+//! - `send(Outbound)`
 //!
-//! Ok(Response::new(ReceiverStream::new(rx)))
-//! ```
+//! [`expect_message`] is a small helper for linear protocol steps: it reads one
+//! inbound message from a transport and extracts a typed value from it, failing
+//! if the channel closes or the message shape is not what the caller expected.
+//!
+//! [`DummyTransport`] is a no-op implementation useful for tests and local
+//! actor execution where no real stream exists.
+//!
+//! # Design Notes
+//!
+//! - [`Bi::send`] returns [`Error`] only for transport delivery failures, such
+//!   as a closed outbound channel.
+//! - [`Bi::recv`] returns `None` when the underlying transport closes.
+//! - Message translation is intentionally out of scope for this module.
 
-use futures::{Stream, StreamExt};
-use kameo::{
-    Actor,
-    actor::{ActorRef, PreparedActor, Recipient, Spawn, WeakActorRef},
-    mailbox::Signal,
-    prelude::Message,
-};
-use tokio::{
-    select,
-    sync::mpsc::{self, error::SendError},
-};
-use tonic::{Status, Streaming};
-use tracing::{debug, error};
+use std::marker::PhantomData;
 
-/// A bidirectional stream abstraction for sans-io testing.
-///
-/// Combines a [`Stream`] of incoming messages with the ability to [`send`](Bi::send)
-/// outgoing responses. This trait allows business logic to be tested without a real
-/// gRPC connection by swapping in an in-memory implementation.
-///
-/// # Type Parameters
-/// - `T`: `InboundMessage` received from the channel/socket (e.g., `UserAgentRequest`)
-/// - `U`: `OutboundMessage` sent to the channel/socket (e.g., `UserAgentResponse`)
-pub trait Bi<T, U>: Stream<Item = Result<T, Status>> + Send + Sync + 'static {
-    type Error;
-    fn send(
-        &mut self,
-        item: Result<U, Status>,
-    ) -> impl std::future::Future<Output = Result<(), Self::Error>> + Send;
+use async_trait::async_trait;
+
+/// Errors returned by transport adapters implementing [`Bi`].
+#[derive(thiserror::Error, Debug)]
+pub enum Error {
+    #[error("Transport channel is closed")]
+    ChannelClosed,
+    #[error("Unexpected message received")]
+    UnexpectedMessage,
 }
 
-/// Concrete [`Bi`] implementation backed by a tonic gRPC [`Streaming`] and an [`mpsc::Sender`].
-///
-/// This is the production implementation used in gRPC service handlers. The `request_stream`
-/// receives messages from the client, and `response_sender` sends responses back.
-pub struct BiStream<T, U> {
-    pub request_stream: Streaming<T>,
-    pub response_sender: mpsc::Sender<Result<U, Status>>,
-}
-
-impl<T, U> Stream for BiStream<T, U>
+/// Receives one message from `transport` and extracts a value from it using
+/// `extractor`. Returns [`Error::ChannelClosed`] if the transport closes and
+/// [`Error::UnexpectedMessage`] if `extractor` returns `None`.
+pub async fn expect_message<T, Inbound, Outbound, Target, F>(
+    transport: &mut T,
+    extractor: F,
+) -> Result<Target, Error>
 where
-    T: Send + 'static,
-    U: Send + 'static,
+    T: Bi<Inbound, Outbound> + ?Sized,
+    F: FnOnce(Inbound) -> Option<Target>,
 {
-    type Item = Result<T, Status>;
-
-    fn poll_next(
-        mut self: std::pin::Pin<&mut Self>,
-        cx: &mut std::task::Context<'_>,
-    ) -> std::task::Poll<Option<Self::Item>> {
-        self.request_stream.poll_next_unpin(cx)
-    }
+    let msg = transport.recv().await.ok_or(Error::ChannelClosed)?;
+    extractor(msg).ok_or(Error::UnexpectedMessage)
 }
 
-impl<T, U> Bi<T, U> for BiStream<T, U>
-where
-    T: Send + 'static,
-    U: Send + 'static,
-{
-    type Error = SendError<Result<U, Status>>;
-
-    async fn send(&mut self, item: Result<U, Status>) -> Result<(), Self::Error> {
-        self.response_sender.send(item).await
-    }
+#[async_trait]
+pub trait Sender<Outbound>: Send + Sync {
+    async fn send(&mut self, item: Outbound) -> Result<(), Error>;
 }
 
-/// Marker trait for transport actors that can receive outbound messages of type `T`.
-///
-/// Implement this on your transport actor to indicate it can handle outbound messages
-/// produced by the business actor. Requires the actor to implement [`Message<Result<T, E>>`]
-/// so business logic can forward responses via [`tell()`](ActorRef::tell).
-///
-/// # Example
-///
-/// ```rust,ignore
-/// #[derive(Actor)]
-/// struct MyTransportActor { /* ... */ }
-///
-/// impl Message<Result<MyResponse, MyError>> for MyTransportActor {
-///     type Reply = ();
-///     async fn handle(&mut self, msg: Result<MyResponse, MyError>, _ctx: &mut Context<Self, Self::Reply>) -> Self::Reply {
-///         // forward outbound message to channel/socket
-///     }
-/// }
-///
-/// impl TransportActor<MyResponse, MyError> for MyTransportActor {}
-/// ```
-pub trait TransportActor<Outbound: Send + 'static, DomainError: Send + 'static>:
-    Actor + Send + Message<Result<Outbound, DomainError>>
-{
+#[async_trait]
+pub trait Receiver<Inbound>: Send + Sync  {
+    async fn recv(&mut self) -> Option<Inbound>;
 }
 
-/// A kameo actor that bridges a gRPC bidirectional stream with a business logic actor.
+/// Minimal bidirectional transport abstraction used by protocol code.
 ///
-/// This actor owns the gRPC [`Streaming`] receiver and an [`mpsc::Sender`] for responses.
-/// It multiplexes between its own mailbox (for outbound messages from the business actor)
-/// and the gRPC stream (for inbound client messages) using [`tokio::select!`].
+/// `Bi<Inbound, Outbound>` is the combined duplex form of [`Sender`] and
+/// [`Receiver`].
 ///
-/// # Message Flow
+/// It models a channel with:
+/// - inbound items of type `Inbound` read via [`Bi::recv`]
+/// - outbound items of type `Outbound` written via [`Bi::send`]
 ///
-/// - **Inbound**: Messages from the gRPC stream are forwarded to `business_logic_actor`
-///   via [`tell()`](Recipient::tell).
-/// - **Outbound**: The business actor sends `Result<Outbound, DomainError>` messages to this
-///   actor, which forwards them through the `sender` channel to the gRPC response stream.
-///
-/// # Lifecycle
-///
-/// - If the business logic actor dies (detected via actor linking), this actor stops,
-///   which closes the gRPC stream.
-/// - If the gRPC stream closes or errors, this actor stops, which (via linking) notifies
-///   the business actor.
-/// - Error responses (`Err(DomainError)`) are forwarded to the client and then the actor stops,
-///   closing the connection.
-///
-/// # Type Parameters
-/// - `Outbound`: `OutboundMessage` sent to the client (e.g., `UserAgentResponse`)
-/// - `Inbound`: `InboundMessage` received from the client (e.g., `UserAgentRequest`)
-/// - `E`: The domain error type, must implement `Into<tonic::Status>` for gRPC conversion
-pub struct GrpcTransportActor<Outbound, Inbound, DomainError>
-where
-    Outbound: Send + 'static,
-    Inbound: Send + 'static,
-    DomainError: Into<tonic::Status> + Send + 'static,
-{
-    sender: mpsc::Sender<Result<Outbound, tonic::Status>>,
-    receiver: tonic::Streaming<Inbound>,
-    business_logic_actor: Recipient<Inbound>,
-    _error: std::marker::PhantomData<DomainError>,
+/// It does not imply request/response sequencing, one-at-a-time exchange, or
+/// any built-in correlation mechanism between inbound and outbound items.
+pub trait Bi<Inbound, Outbound>: Sender<Outbound> + Receiver<Inbound> + Send + Sync {}
+
+pub trait SplittableBi<Inbound, Outbound>: Bi<Inbound, Outbound> {
+    type Sender: Sender<Outbound>;
+    type Receiver: Receiver<Inbound>;
+
+    fn split(self) -> (Self::Sender, Self::Receiver);
+    fn from_parts(sender: Self::Sender, receiver: Self::Receiver) -> Self;
 }
 
-impl<Outbound, Inbound, DomainError> GrpcTransportActor<Outbound, Inbound, DomainError>
-where
-    Outbound: Send + 'static,
-    Inbound: Send + 'static,
-    DomainError: Into<tonic::Status> + Send + 'static,
-{
-    pub fn new(
-        sender: mpsc::Sender<Result<Outbound, tonic::Status>>,
-        receiver: tonic::Streaming<Inbound>,
-        business_logic_actor: Recipient<Inbound>,
-    ) -> Self {
+/// No-op [`Bi`] transport for tests and manual actor usage.
+///
+/// `send` drops all items and succeeds. [`Bi::recv`] never resolves and therefore
+/// does not busy-wait or spuriously close the stream.
+pub struct DummyTransport<Inbound, Outbound> {
+    _marker: PhantomData<(Inbound, Outbound)>,
+}
+
+impl<Inbound, Outbound> Default for DummyTransport<Inbound, Outbound> {
+    fn default() -> Self {
         Self {
-            sender,
-            receiver,
-            business_logic_actor,
-            _error: std::marker::PhantomData,
+            _marker: PhantomData,
         }
     }
 }
 
-impl<Outbound, Inbound, E> Actor for GrpcTransportActor<Outbound, Inbound, E>
+#[async_trait]
+impl<Inbound, Outbound> Sender<Outbound> for DummyTransport<Inbound, Outbound>
 where
-    Outbound: Send + 'static,
-    Inbound: Send + 'static,
-    E: Into<tonic::Status> + Send + 'static,
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
 {
-    type Args = Self;
-
-    type Error = ();
-
-    async fn on_start(args: Self::Args, _: ActorRef<Self>) -> Result<Self, Self::Error> {
-        Ok(args)
-    }
-
-    fn on_link_died(
-        &mut self,
-        _: WeakActorRef<Self>,
-        id: kameo::prelude::ActorId,
-        _: kameo::prelude::ActorStopReason,
-    ) -> impl Future<
-        Output = Result<std::ops::ControlFlow<kameo::prelude::ActorStopReason>, Self::Error>,
-    > + Send {
-        async move {
-            if id == self.business_logic_actor.id() {
-                error!("Business logic actor died, stopping GrpcTransportActor");
-                Ok(std::ops::ControlFlow::Break(
-                    kameo::prelude::ActorStopReason::Normal,
-                ))
-            } else {
-                debug!(
-                    "Linked actor {} died, but it's not the business logic actor, ignoring",
-                    id
-                );
-                Ok(std::ops::ControlFlow::Continue(()))
-            }
-        }
-    }
-
-    async fn next(
-        &mut self,
-        _: WeakActorRef<Self>,
-        mailbox_rx: &mut kameo::prelude::MailboxReceiver<Self>,
-    ) -> Option<kameo::mailbox::Signal<Self>> {
-        select! {
-            msg = mailbox_rx.recv() => {
-                msg
-            }
-            recv_msg = self.receiver.next() => {
-                match recv_msg {
-                    Some(Ok(msg)) => {
-                        match self.business_logic_actor.tell(msg).await {
-                            Ok(_) => None,
-                            Err(e) => {
-                                // TODO: this would probably require better error handling - or resending if backpressure is the issue
-                                error!("Failed to send message to business logic actor: {}", e);
-                                Some(Signal::Stop)
-                            }
-                        }
-                    }
-                    Some(Err(e)) => {
-                        error!("Received error from stream: {}, stopping GrpcTransportActor", e);
-                        Some(Signal::Stop)
-                    }
-                    None => {
-                        error!("Receiver channel closed, stopping GrpcTransportActor");
-                        Some(Signal::Stop)
-                    }
-                }
-            }
-        }
+    async fn send(&mut self, _item: Outbound) -> Result<(), Error> {
+        Ok(())
     }
 }
 
-impl<Outbound, Inbound, E> Message<Result<Outbound, E>> for GrpcTransportActor<Outbound, Inbound, E>
+#[async_trait]
+impl<Inbound, Outbound> Receiver<Inbound> for DummyTransport<Inbound, Outbound>
 where
-    Outbound: Send + 'static,
-    Inbound: Send + 'static,
-    E: Into<tonic::Status> + Send + 'static,
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
 {
-    type Reply = ();
-
-    async fn handle(
-        &mut self,
-        msg: Result<Outbound, E>,
-        ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
-    ) -> Self::Reply {
-        let is_err = msg.is_err();
-        let grpc_msg = msg.map_err(Into::into);
-        match self.sender.send(grpc_msg).await {
-            Ok(_) => {
-                if is_err {
-                    ctx.stop();
-                }
-            }
-            Err(e) => {
-                error!("Failed to send message: {}", e);
-                ctx.stop();
-            }
-        }
+    async fn recv(&mut self) -> Option<Inbound> {
+        std::future::pending::<()>().await;
+        None
     }
 }
 
-impl<Outbound, Inbound, E> TransportActor<Outbound, E> for GrpcTransportActor<Outbound, Inbound, E>
+impl<Inbound, Outbound> Bi<Inbound, Outbound> for DummyTransport<Inbound, Outbound>
 where
-    Outbound: Send + 'static,
-    Inbound: Send + 'static,
-    E: Into<tonic::Status> + Send + 'static,
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
 {
 }
 
-/// Wires together a transport actor and a business logic actor with bidirectional linking.
-///
-/// This function handles the chicken-and-egg problem of two actors that need references
-/// to each other at construction time. It uses kameo's [`PreparedActor`] to obtain
-/// [`ActorRef`]s before spawning, then links both actors so that if either dies,
-/// the other is notified via [`on_link_died`](Actor::on_link_died).
-///
-/// The business actor receives a type-erased [`Recipient<Result<Outbound, DomainError>>`] instead of an
-/// `ActorRef<Transport>`, keeping it decoupled from the concrete transport implementation.
-///
-/// # Type Parameters
-/// - `Transport`: The transport actor type (e.g., [`GrpcTransportActor`])
-/// - `Inbound`: `InboundMessage` received by the business actor from the transport
-/// - `Outbound`: `OutboundMessage` sent by the business actor back to the transport
-/// - `Business`: The business logic actor
-/// - `BusinessCtor`: Closure that receives a prepared business actor and transport recipient,
-///   spawns the business actor, and returns its [`ActorRef`]
-/// - `TransportCtor`: Closure that receives a prepared transport actor, a recipient for
-///   inbound messages, and the business actor id, then spawns the transport actor
-///
-/// # Returns
-/// A tuple of `(transport_ref, business_ref)` — actor references for both spawned actors.
-pub async fn wire<
-    Transport,
-    Inbound,
-    Outbound,
-    DomainError,
-    Business,
-    BusinessCtor,
-    TransportCtor,
->(
-    business_ctor: BusinessCtor,
-    transport_ctor: TransportCtor,
-) -> (ActorRef<Transport>, ActorRef<Business>)
-where
-    Transport: TransportActor<Outbound, DomainError>,
-    Inbound: Send + 'static,
-    Outbound: Send + 'static,
-    DomainError: Send + 'static,
-    Business: Actor + Message<Inbound> + Send + 'static,
-    BusinessCtor: FnOnce(PreparedActor<Business>, Recipient<Result<Outbound, DomainError>>),
-    TransportCtor:
-        FnOnce(PreparedActor<Transport>, Recipient<Inbound>),
-{
-    let prepared_business: PreparedActor<Business> = Spawn::prepare();
-    let prepared_transport: PreparedActor<Transport> = Spawn::prepare();
-
-    let business_ref = prepared_business.actor_ref().clone();
-    let transport_ref = prepared_transport.actor_ref().clone();
-
-    transport_ref.link(&business_ref).await;
-    business_ref.link(&transport_ref).await;
-
-    let recipient = transport_ref.clone().recipient();
-    business_ctor(prepared_business, recipient);
-    let business_recipient = business_ref.clone().recipient();
-    transport_ctor(prepared_transport, business_recipient);
-
-
-    (transport_ref, business_ref)
-}
+pub mod grpc;

server/crates/arbiter-proto/src/transport/grpc.rs

@@ -0,0 +1,106 @@
+use async_trait::async_trait;
+use futures::StreamExt;
+use tokio::sync::mpsc;
+use tokio_stream::wrappers::ReceiverStream;
+
+use super::{Bi, Receiver, Sender};
+
+pub struct GrpcSender<Outbound> {
+    tx: mpsc::Sender<Result<Outbound, tonic::Status>>,
+}
+
+#[async_trait]
+impl<Outbound> Sender<Result<Outbound, tonic::Status>> for GrpcSender<Outbound>
+where
+    Outbound: Send + Sync + 'static,
+{
+    async fn send(&mut self, item: Result<Outbound, tonic::Status>) -> Result<(), super::Error> {
+        self.tx
+            .send(item)
+            .await
+            .map_err(|_| super::Error::ChannelClosed)
+    }
+}
+
+pub struct GrpcReceiver<Inbound> {
+    rx: tonic::Streaming<Inbound>,
+}
+#[async_trait]
+impl<Inbound> Receiver<Result<Inbound, tonic::Status>> for GrpcReceiver<Inbound>
+where
+    Inbound: Send + Sync + 'static,
+{
+    async fn recv(&mut self) -> Option<Result<Inbound, tonic::Status>> {
+        self.rx.next().await
+    }
+}
+
+pub struct GrpcBi<Inbound, Outbound> {
+    sender: GrpcSender<Outbound>,
+    receiver: GrpcReceiver<Inbound>,
+}
+
+impl<Inbound, Outbound> GrpcBi<Inbound, Outbound>
+where
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
+{
+    pub fn from_bi_stream(
+        receiver: tonic::Streaming<Inbound>,
+    ) -> (Self, ReceiverStream<Result<Outbound, tonic::Status>>) {
+        let (tx, rx) = mpsc::channel(10);
+        let sender = GrpcSender { tx };
+        let receiver = GrpcReceiver { rx: receiver };
+        let bi = GrpcBi { sender, receiver };
+        (bi, ReceiverStream::new(rx))
+    }
+}
+
+#[async_trait]
+impl<Inbound, Outbound> Sender<Result<Outbound, tonic::Status>> for GrpcBi<Inbound, Outbound>
+where
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
+{
+    async fn send(&mut self, item: Result<Outbound, tonic::Status>) -> Result<(), super::Error> {
+        self.sender.send(item).await
+    }
+}
+
+#[async_trait]
+impl<Inbound, Outbound> Receiver<Result<Inbound, tonic::Status>> for GrpcBi<Inbound, Outbound>
+where
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
+{
+    async fn recv(&mut self) -> Option<Result<Inbound, tonic::Status>> {
+        self.receiver.recv().await
+    }
+}
+
+impl<Inbound, Outbound> Bi<Result<Inbound, tonic::Status>, Result<Outbound, tonic::Status>>
+    for GrpcBi<Inbound, Outbound>
+where
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
+{
+}
+
+impl<Inbound, Outbound>
+    super::SplittableBi<Result<Inbound, tonic::Status>, Result<Outbound, tonic::Status>>
+    for GrpcBi<Inbound, Outbound>
+where
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
+{
+    type Sender = GrpcSender<Outbound>;
+    type Receiver = GrpcReceiver<Inbound>;
+
+    fn split(self) -> (Self::Sender, Self::Receiver) {
+        (self.sender, self.receiver)
+    }
+
+    fn from_parts(sender: Self::Sender, receiver: Self::Receiver) -> Self {
+        GrpcBi { sender, receiver }
+    }
+}

server/crates/arbiter-proto/src/url.rs

@@ -20,7 +20,7 @@ impl Display for ArbiterUrl {
             "{ARBITER_URL_SCHEME}://{}:{}?{CERT_QUERY_KEY}={}",
             self.host,
             self.port,
-            BASE64_URL_SAFE.encode(self.ca_cert.to_vec())
+            BASE64_URL_SAFE.encode(&self.ca_cert)
         );
         if let Some(token) = &self.bootstrap_token {
             base.push_str(&format!("&{BOOTSTRAP_TOKEN_QUERY_KEY}={}", token));

server/crates/arbiter-server/Cargo.toml

@@ -5,9 +5,12 @@ edition = "2024"
 repository = "https://git.markettakers.org/MarketTakers/arbiter"
 license = "Apache-2.0"
 
+[lints]
+workspace = true
+
 [dependencies]
-diesel = { version = "2.3.6", features = ["chrono", "returning_clauses_for_sqlite_3_35", "serde_json", "time", "uuid"] }
-diesel-async = { version = "0.7.4", features = [
+diesel = { version = "2.3.7", features = ["chrono", "returning_clauses_for_sqlite_3_35", "serde_json", "time", "uuid"] }
+diesel-async = { version = "0.8.0", features = [
     "bb8",
     "migrations",
     "sqlite",
@@ -24,6 +27,7 @@ rustls.workspace = true
 smlang.workspace = true
 miette.workspace = true
 thiserror.workspace = true
+fatality = "0.1.1"
 diesel_migrations = { version = "2.3.1", features = ["sqlite"] }
 async-trait.workspace = true
 secrecy = "0.10.3"
@@ -40,8 +44,15 @@ x25519-dalek.workspace = true
 chacha20poly1305 = { version = "0.10.1", features = ["std"] }
 argon2 = { version = "0.5.3", features = ["zeroize"] }
 restructed = "0.2.2"
-strum = { version = "0.27.2", features = ["derive"] }
+strum = { version = "0.28.0", features = ["derive"] }
 pem = "3.0.6"
+k256.workspace = true
+rsa.workspace = true
+sha2.workspace = true
+spki.workspace = true
+alloy.workspace = true
+prost-types.workspace = true
+arbiter-tokens-registry.path = "../arbiter-tokens-registry"
 
 [dev-dependencies]
 insta = "1.46.3"

server/crates/arbiter-server/migrations/2026-02-14-171124-0000_init/up.sql

@@ -46,6 +46,7 @@ create table if not exists useragent_client (
     id integer not null primary key,
     nonce integer not null default(1), -- used for auth challenge
     public_key blob not null,
+    key_type integer not null default(1), -- 1=Ed25519, 2=ECDSA(secp256k1)
     created_at integer not null default(unixepoch ('now')),
     updated_at integer not null default(unixepoch ('now'))
 ) STRICT;
@@ -56,4 +57,105 @@ create table if not exists program_client (
     public_key blob not null,
     created_at integer not null default(unixepoch ('now')),
     updated_at integer not null default(unixepoch ('now'))
-) STRICT;
+) STRICT;
+
+create table if not exists evm_wallet (
+    id integer not null primary key,
+    address blob not null, -- 20-byte Ethereum address
+    aead_encrypted_id integer not null references aead_encrypted (id) on delete RESTRICT,
+    created_at integer not null default(unixepoch ('now'))
+) STRICT;
+
+create unique index if not exists uniq_evm_wallet_address on evm_wallet (address);
+create unique index if not exists uniq_evm_wallet_aead on evm_wallet (aead_encrypted_id);
+
+create table if not exists evm_ether_transfer_limit (
+    id integer not null primary key,
+    window_secs integer not null,           -- window duration in seconds
+    max_volume blob not null                -- big-endian 32-byte U256
+) STRICT;
+
+-- Shared grant properties: client scope, timeframe, fee caps, and rate limit
+create table if not exists evm_basic_grant (
+    id integer not null primary key,
+    wallet_id integer not null references evm_wallet(id) on delete restrict, 
+    client_id integer not null references program_client(id) on delete restrict,
+    chain_id integer not null,              -- EIP-155 chain ID
+    valid_from integer,                     -- unix timestamp (seconds), null = no lower bound
+    valid_until integer,                    -- unix timestamp (seconds), null = no upper bound
+    max_gas_fee_per_gas blob,               -- big-endian 32-byte U256, null = unlimited
+    max_priority_fee_per_gas blob,          -- big-endian 32-byte U256, null = unlimited
+    rate_limit_count integer,               -- max transactions in window, null = unlimited
+    rate_limit_window_secs integer,         -- window duration in seconds, null = unlimited
+    revoked_at integer,                     -- unix timestamp when revoked, null = still active
+    created_at integer not null default(unixepoch('now'))
+) STRICT;
+
+-- Shared transaction log for all EVM grants, used for rate limit tracking and auditing
+create table if not exists evm_transaction_log (
+    id integer not null primary key,
+    grant_id integer not null references evm_basic_grant(id) on delete restrict,
+    client_id integer not null references program_client(id) on delete restrict,
+    wallet_id integer not null references evm_wallet(id) on delete restrict,
+    chain_id integer not null,
+    eth_value blob not null,     -- always present on any EVM tx
+    signed_at integer not null default(unixepoch('now'))
+) STRICT;
+
+create index if not exists idx_evm_basic_grant_wallet_chain on evm_basic_grant(client_id, wallet_id, chain_id);
+
+-- ===============================
+-- ERC20 token transfer grant
+-- ===============================
+create table if not exists evm_token_transfer_grant (
+    id integer not null primary key,
+    basic_grant_id integer not null unique references evm_basic_grant(id) on delete cascade,
+    token_contract blob not null,            -- 20-byte ERC20 contract address
+    receiver blob                            -- 20-byte recipient address or null if every recipient allowed
+) STRICT;
+
+-- Per-window volume limits for token transfer grants
+create table if not exists evm_token_transfer_volume_limit (
+    id integer not null primary key,
+    grant_id integer not null references evm_token_transfer_grant(id) on delete cascade,
+    window_secs integer not null,           -- window duration in seconds
+    max_volume blob not null                -- big-endian 32-byte U256
+) STRICT;
+
+-- Log table for token transfer grant usage
+create table if not exists evm_token_transfer_log (
+    id integer not null primary key,
+    grant_id integer not null references evm_token_transfer_grant(id) on delete restrict,
+    log_id integer not null references evm_transaction_log(id) on delete restrict,
+    chain_id integer not null,              -- EIP-155 chain ID
+    token_contract blob not null,           -- 20-byte ERC20 contract address
+    recipient_address blob not null,        -- 20-byte recipient address
+    value blob not null,                    -- big-endian 32-byte U256
+    created_at integer not null default(unixepoch('now'))
+) STRICT;
+
+create index if not exists idx_token_transfer_log_grant on evm_token_transfer_log(grant_id);
+create index if not exists idx_token_transfer_log_log_id on evm_token_transfer_log(log_id);
+create index if not exists idx_token_transfer_log_chain on evm_token_transfer_log(chain_id);
+
+
+-- ===============================
+-- Ether transfer grant (uses base log)
+-- ===============================
+create table if not exists evm_ether_transfer_grant (
+    id integer not null primary key,
+    basic_grant_id integer not null unique references evm_basic_grant(id) on delete cascade,
+    limit_id integer not null references evm_ether_transfer_limit(id) on delete restrict
+) STRICT;
+
+-- Specific recipient addresses for an ether transfer grant
+create table if not exists evm_ether_transfer_grant_target (
+    id integer not null primary key,
+    grant_id integer not null references evm_ether_transfer_grant(id) on delete cascade,
+    address blob not null                   -- 20-byte recipient address
+) STRICT;
+
+create unique index if not exists uniq_ether_transfer_target on evm_ether_transfer_grant_target(grant_id, address);
+
+CREATE UNIQUE INDEX program_client_public_key_unique
+    ON program_client (public_key);

server/crates/arbiter-server/src/actors/bootstrap.rs

@@ -3,12 +3,7 @@ use diesel::QueryDsl;
 use diesel_async::RunQueryDsl;
 use kameo::{Actor, messages};
 use miette::Diagnostic;
-use rand::{
-    RngExt,
-    distr::{Alphanumeric},
-    make_rng,
-    rngs::StdRng,
-};
+use rand::{RngExt, distr::Alphanumeric, make_rng, rngs::StdRng};
 use thiserror::Error;
 
 use crate::db::{self, DatabasePool, schema};
@@ -61,7 +56,6 @@ impl Bootstrapper {
 
         drop(conn);
 
-
         let token = if row_count == 0 {
             let token = generate_token().await?;
             Some(token)

server/crates/arbiter-server/src/actors/client.rs

@@ -1,12 +0,0 @@
-use arbiter_proto::{
-    proto::{ClientRequest, ClientResponse},
-    transport::Bi,
-};
-
-use crate::ServerContext;
-
-pub(crate) async fn handle_client(
-    _context: ServerContext,
-    _bistream: impl Bi<ClientRequest, ClientResponse>,
-) {
-}

server/crates/arbiter-server/src/actors/client/auth.rs

@@ -0,0 +1,249 @@
+use arbiter_proto::{
+    format_challenge,
+    transport::{Bi, expect_message},
+};
+use diesel::{
+    ExpressionMethods as _, OptionalExtension as _, QueryDsl as _, dsl::insert_into, update,
+};
+use diesel_async::RunQueryDsl as _;
+use ed25519_dalek::{Signature, VerifyingKey};
+use kameo::error::SendError;
+use tracing::error;
+
+use crate::{
+    actors::{
+        client::ClientConnection,
+        router::{self, RequestClientApproval},
+    },
+    db::{self, schema::program_client},
+};
+
+#[derive(thiserror::Error, Debug, Clone, PartialEq, Eq)]
+pub enum Error {
+    #[error("Database pool unavailable")]
+    DatabasePoolUnavailable,
+    #[error("Database operation failed")]
+    DatabaseOperationFailed,
+    #[error("Invalid challenge solution")]
+    InvalidChallengeSolution,
+    #[error("Client approval request failed")]
+    ApproveError(#[from] ApproveError),
+    #[error("Transport error")]
+    Transport,
+}
+
+#[derive(thiserror::Error, Debug, Clone, PartialEq, Eq)]
+pub enum ApproveError {
+    #[error("Internal error")]
+    Internal,
+    #[error("Client connection denied by user agents")]
+    Denied,
+    #[error("Upstream error: {0}")]
+    Upstream(router::ApprovalError),
+}
+
+#[derive(Debug, Clone)]
+pub enum Inbound {
+    AuthChallengeRequest { pubkey: VerifyingKey },
+    AuthChallengeSolution { signature: Signature },
+}
+
+#[derive(Debug, Clone)]
+pub enum Outbound {
+    AuthChallenge { pubkey: VerifyingKey, nonce: i32 },
+    AuthSuccess,
+}
+
+/// Atomically reads and increments the nonce for a known client.
+/// Returns `None` if the pubkey is not registered.
+async fn get_nonce(db: &db::DatabasePool, pubkey: &VerifyingKey) -> Result<Option<i32>, Error> {
+    let pubkey_bytes = pubkey.as_bytes().to_vec();
+
+    let mut conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::DatabasePoolUnavailable
+    })?;
+
+    conn.exclusive_transaction(|conn| {
+        let pubkey_bytes = pubkey_bytes.clone();
+        Box::pin(async move {
+            let Some((client_id, current_nonce)) = program_client::table
+                .filter(program_client::public_key.eq(&pubkey_bytes))
+                .select((program_client::id, program_client::nonce))
+                .first::<(i32, i32)>(conn)
+                .await
+                .optional()?
+            else {
+                return Result::<_, diesel::result::Error>::Ok(None);
+            };
+
+            update(program_client::table)
+                .filter(program_client::public_key.eq(&pubkey_bytes))
+                .set(program_client::nonce.eq(current_nonce + 1))
+                .execute(conn)
+                .await?;
+
+            let _ = client_id;
+            Ok(Some(current_nonce))
+        })
+    })
+    .await
+    .map_err(|e| {
+        error!(error = ?e, "Database error");
+        Error::DatabaseOperationFailed
+    })
+}
+
+async fn approve_new_client(
+    actors: &crate::actors::GlobalActors,
+    pubkey: VerifyingKey,
+) -> Result<(), Error> {
+    let result = actors
+        .router
+        .ask(RequestClientApproval {
+            client_pubkey: pubkey,
+        })
+        .await;
+
+    match result {
+        Ok(true) => Ok(()),
+        Ok(false) => Err(Error::ApproveError(ApproveError::Denied)),
+        Err(SendError::HandlerError(e)) => {
+            error!(error = ?e, "Approval upstream error");
+            Err(Error::ApproveError(ApproveError::Upstream(e)))
+        }
+        Err(e) => {
+            error!(error = ?e, "Approval request to router failed");
+            Err(Error::ApproveError(ApproveError::Internal))
+        }
+    }
+}
+
+enum InsertClientResult {
+    Inserted,
+    AlreadyExists,
+}
+
+async fn insert_client(
+    db: &db::DatabasePool,
+    pubkey: &VerifyingKey,
+) -> Result<InsertClientResult, Error> {
+    let now = std::time::SystemTime::now()
+        .duration_since(std::time::UNIX_EPOCH)
+        .unwrap_or_default()
+        .as_secs() as i32;
+
+    let mut conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::DatabasePoolUnavailable
+    })?;
+
+    match insert_into(program_client::table)
+        .values((
+            program_client::public_key.eq(pubkey.as_bytes().to_vec()),
+            program_client::nonce.eq(1), // pre-incremented; challenge uses 0
+            program_client::created_at.eq(now),
+            program_client::updated_at.eq(now),
+        ))
+        .execute(&mut conn)
+        .await
+    {
+        Ok(_) => {}
+        Err(diesel::result::Error::DatabaseError(
+            diesel::result::DatabaseErrorKind::UniqueViolation,
+            _,
+        )) => return Ok(InsertClientResult::AlreadyExists),
+        Err(e) => {
+            error!(error = ?e, "Failed to insert new client");
+            return Err(Error::DatabaseOperationFailed);
+        }
+    }
+
+    let client_id = program_client::table
+        .filter(program_client::public_key.eq(pubkey.as_bytes().to_vec()))
+        .order(program_client::id.desc())
+        .select(program_client::id)
+        .first::<i32>(&mut conn)
+        .await
+        .map_err(|e| {
+            error!(error = ?e, "Failed to load inserted client id");
+            Error::DatabaseOperationFailed
+        })?;
+
+    let _ = client_id;
+    Ok(InsertClientResult::Inserted)
+}
+
+async fn challenge_client<T>(
+    transport: &mut T,
+    pubkey: VerifyingKey,
+    nonce: i32,
+) -> Result<(), Error>
+where
+    T: Bi<Inbound, Result<Outbound, Error>> + ?Sized,
+{
+    transport
+        .send(Ok(Outbound::AuthChallenge { pubkey, nonce }))
+        .await
+        .map_err(|e| {
+            error!(error = ?e, "Failed to send auth challenge");
+            Error::Transport
+        })?;
+
+    let signature = expect_message(transport, |req: Inbound| match req {
+        Inbound::AuthChallengeSolution { signature } => Some(signature),
+        _ => None,
+    })
+    .await
+    .map_err(|e| {
+        error!(error = ?e, "Failed to receive challenge solution");
+        Error::Transport
+    })?;
+
+    let formatted = format_challenge(nonce, pubkey.as_bytes());
+
+    pubkey.verify_strict(&formatted, &signature).map_err(|_| {
+        error!("Challenge solution verification failed");
+        Error::InvalidChallengeSolution
+    })?;
+
+    Ok(())
+}
+
+pub async fn authenticate<T>(
+    props: &mut ClientConnection,
+    transport: &mut T,
+) -> Result<VerifyingKey, Error>
+where
+    T: Bi<Inbound, Result<Outbound, Error>> + Send + ?Sized,
+{
+    let Some(Inbound::AuthChallengeRequest { pubkey }) = transport.recv().await
+    else {
+        return Err(Error::Transport);
+    };
+
+    let nonce = match get_nonce(&props.db, &pubkey).await? {
+        Some(nonce) => nonce,
+        None => {
+            approve_new_client(&props.actors, pubkey).await?;
+            match insert_client(&props.db, &pubkey).await? {
+                InsertClientResult::Inserted => 0,
+                InsertClientResult::AlreadyExists => match get_nonce(&props.db, &pubkey).await? {
+                    Some(nonce) => nonce,
+                    None => return Err(Error::DatabaseOperationFailed),
+                },
+            }
+        }
+    };
+
+    challenge_client(transport, pubkey, nonce).await?;
+    transport
+        .send(Ok(Outbound::AuthSuccess))
+        .await
+        .map_err(|e| {
+            error!(error = ?e, "Failed to send auth success");
+            Error::Transport
+        })?;
+
+    Ok(pubkey)
+}

server/crates/arbiter-server/src/actors/client/mod.rs

@@ -0,0 +1,38 @@
+use arbiter_proto::transport::Bi;
+use kameo::actor::Spawn;
+use tracing::{error, info};
+
+use crate::{
+    actors::{GlobalActors, client::session::ClientSession},
+    db,
+};
+
+pub struct ClientConnection {
+    pub(crate) db: db::DatabasePool,
+    pub(crate) actors: GlobalActors,
+}
+
+impl ClientConnection {
+    pub fn new(db: db::DatabasePool, actors: GlobalActors) -> Self {
+        Self { db, actors }
+    }
+}
+
+pub mod auth;
+pub mod session;
+
+pub async fn connect_client<T>(mut props: ClientConnection, transport: &mut T)
+where
+    T: Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> + Send + ?Sized,
+{
+    match auth::authenticate(&mut props, transport).await {
+        Ok(_pubkey) => {
+            ClientSession::spawn(ClientSession::new(props));
+            info!("Client authenticated, session started");
+        }
+        Err(err) => {
+            let _ = transport.send(Err(err.clone())).await;
+            error!(?err, "Authentication failed, closing connection");
+        }
+    }
+}

server/crates/arbiter-server/src/actors/client/session.rs

@@ -0,0 +1,71 @@
+use kameo::{Actor, messages};
+use tracing::error;
+
+use crate::{
+    actors::{
+        GlobalActors, client::ClientConnection, keyholder::KeyHolderState, router::RegisterClient,
+    },
+    db,
+};
+
+pub struct ClientSession {
+    props: ClientConnection,
+}
+
+impl ClientSession {
+    pub(crate) fn new(props: ClientConnection) -> Self {
+        Self { props }
+    }
+}
+
+#[messages]
+impl ClientSession {
+    #[message]
+    pub(crate) async fn handle_query_vault_state(&mut self) -> Result<KeyHolderState, Error> {
+        use crate::actors::keyholder::GetState;
+
+        let vault_state = match self.props.actors.key_holder.ask(GetState {}).await {
+            Ok(state) => state,
+            Err(err) => {
+                error!(?err, actor = "client", "keyholder.query.failed");
+                return Err(Error::Internal);
+            }
+        };
+
+        Ok(vault_state)
+    }
+}
+
+impl Actor for ClientSession {
+    type Args = Self;
+
+    type Error = Error;
+
+    async fn on_start(
+        args: Self::Args,
+        this: kameo::prelude::ActorRef<Self>,
+    ) -> Result<Self, Self::Error> {
+        args.props
+            .actors
+            .router
+            .ask(RegisterClient { actor: this })
+            .await
+            .map_err(|_| Error::ConnectionRegistrationFailed)?;
+        Ok(args)
+    }
+}
+
+impl ClientSession {
+    pub fn new_test(db: db::DatabasePool, actors: GlobalActors) -> Self {
+        let props = ClientConnection::new(db, actors);
+        Self { props }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Connection registration failed")]
+    ConnectionRegistrationFailed,
+    #[error("Internal error")]
+    Internal,
+}

server/crates/arbiter-server/src/actors/evm/mod.rs

@@ -0,0 +1,270 @@
+use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
+use diesel::{
+    ExpressionMethods, OptionalExtension as _, QueryDsl, SelectableHelper as _, dsl::insert_into,
+};
+use diesel_async::RunQueryDsl;
+use kameo::{Actor, actor::ActorRef, messages};
+use rand::{SeedableRng, rng, rngs::StdRng};
+
+use crate::{
+    actors::keyholder::{CreateNew, Decrypt, KeyHolder},
+    db::{
+        self, DatabasePool,
+        models::{self, SqliteTimestamp},
+        schema,
+    },
+    evm::{
+        self, ListGrantsError, RunKind,
+        policies::{
+            FullGrant, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning,
+            ether_transfer::EtherTransfer, token_transfers::TokenTransfer,
+        },
+    },
+    safe_cell::{SafeCell, SafeCellHandle as _},
+};
+
+pub use crate::evm::safe_signer;
+
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum SignTransactionError {
+    #[error("Wallet not found")]
+    #[diagnostic(code(arbiter::evm::sign::wallet_not_found))]
+    WalletNotFound,
+
+    #[error("Database error: {0}")]
+    #[diagnostic(code(arbiter::evm::sign::database))]
+    Database(#[from] diesel::result::Error),
+
+    #[error("Database pool error: {0}")]
+    #[diagnostic(code(arbiter::evm::sign::pool))]
+    Pool(#[from] db::PoolError),
+
+    #[error("Keyholder error: {0}")]
+    #[diagnostic(code(arbiter::evm::sign::keyholder))]
+    Keyholder(#[from] crate::actors::keyholder::Error),
+
+    #[error("Keyholder mailbox error")]
+    #[diagnostic(code(arbiter::evm::sign::keyholder_send))]
+    KeyholderSend,
+
+    #[error("Signing error: {0}")]
+    #[diagnostic(code(arbiter::evm::sign::signing))]
+    Signing(#[from] alloy::signers::Error),
+
+    #[error("Policy error: {0}")]
+    #[diagnostic(code(arbiter::evm::sign::vet))]
+    Vet(#[from] evm::VetError),
+}
+
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum Error {
+    #[error("Keyholder error: {0}")]
+    #[diagnostic(code(arbiter::evm::keyholder))]
+    Keyholder(#[from] crate::actors::keyholder::Error),
+
+    #[error("Keyholder mailbox error")]
+    #[diagnostic(code(arbiter::evm::keyholder_send))]
+    KeyholderSend,
+
+    #[error("Database error: {0}")]
+    #[diagnostic(code(arbiter::evm::database))]
+    Database(#[from] diesel::result::Error),
+
+    #[error("Database pool error: {0}")]
+    #[diagnostic(code(arbiter::evm::database_pool))]
+    DatabasePool(#[from] db::PoolError),
+
+    #[error("Grant creation error: {0}")]
+    #[diagnostic(code(arbiter::evm::creation))]
+    Creation(#[from] evm::CreationError),
+}
+
+#[derive(Actor)]
+pub struct EvmActor {
+    pub keyholder: ActorRef<KeyHolder>,
+    pub db: DatabasePool,
+    pub rng: StdRng,
+    pub engine: evm::Engine,
+}
+
+impl EvmActor {
+    pub fn new(keyholder: ActorRef<KeyHolder>, db: DatabasePool) -> Self {
+        // is it safe to seed rng from system once?
+        // todo: audit
+        let rng = StdRng::from_rng(&mut rng());
+        let engine = evm::Engine::new(db.clone());
+        Self {
+            keyholder,
+            db,
+            rng,
+            engine,
+        }
+    }
+}
+
+#[messages]
+impl EvmActor {
+    #[message]
+    pub async fn generate(&mut self) -> Result<Address, Error> {
+        let (mut key_cell, address) = safe_signer::generate(&mut self.rng);
+
+        let plaintext = key_cell.read_inline(|reader| SafeCell::new(reader.to_vec()));
+
+        let aead_id: i32 = self
+            .keyholder
+            .ask(CreateNew { plaintext })
+            .await
+            .map_err(|_| Error::KeyholderSend)?;
+
+        let mut conn = self.db.get().await?;
+        insert_into(schema::evm_wallet::table)
+            .values(&models::NewEvmWallet {
+                address: address.as_slice().to_vec(),
+                aead_encrypted_id: aead_id,
+            })
+            .execute(&mut conn)
+            .await?;
+
+        Ok(address)
+    }
+
+    #[message]
+    pub async fn list_wallets(&self) -> Result<Vec<Address>, Error> {
+        let mut conn = self.db.get().await?;
+        let rows: Vec<models::EvmWallet> = schema::evm_wallet::table
+            .select(models::EvmWallet::as_select())
+            .load(&mut conn)
+            .await?;
+
+        Ok(rows
+            .into_iter()
+            .map(|w| Address::from_slice(&w.address))
+            .collect())
+    }
+}
+
+#[messages]
+impl EvmActor {
+    #[message]
+    pub async fn useragent_create_grant(
+        &mut self,
+        client_id: i32,
+        basic: SharedGrantSettings,
+        grant: SpecificGrant,
+    ) -> Result<i32, evm::CreationError> {
+        match grant {
+            SpecificGrant::EtherTransfer(settings) => {
+                self.engine
+                    .create_grant::<EtherTransfer>(
+                        client_id,
+                        FullGrant {
+                            basic,
+                            specific: settings,
+                        },
+                    )
+                    .await
+            }
+            SpecificGrant::TokenTransfer(settings) => {
+                self.engine
+                    .create_grant::<TokenTransfer>(
+                        client_id,
+                        FullGrant {
+                            basic,
+                            specific: settings,
+                        },
+                    )
+                    .await
+            }
+        }
+    }
+
+    #[message]
+    pub async fn useragent_delete_grant(&mut self, grant_id: i32) -> Result<(), Error> {
+        let mut conn = self.db.get().await?;
+        diesel::update(schema::evm_basic_grant::table)
+            .filter(schema::evm_basic_grant::id.eq(grant_id))
+            .set(schema::evm_basic_grant::revoked_at.eq(SqliteTimestamp::now()))
+            .execute(&mut conn)
+            .await?;
+        Ok(())
+    }
+
+    #[message]
+    pub async fn useragent_list_grants(&mut self) -> Result<Vec<Grant<SpecificGrant>>, Error> {
+        match self.engine.list_all_grants().await {
+            Ok(grants) => Ok(grants),
+            Err(ListGrantsError::Database(db)) => Err(Error::Database(db)),
+            Err(ListGrantsError::Pool(pool)) => Err(Error::DatabasePool(pool)),
+        }
+    }
+
+    #[message]
+    pub async fn shared_analyze_transaction(
+        &mut self,
+        client_id: i32,
+        wallet_address: Address,
+        transaction: TxEip1559,
+    ) -> Result<SpecificMeaning, SignTransactionError> {
+        let mut conn = self.db.get().await?;
+        let wallet = schema::evm_wallet::table
+            .select(models::EvmWallet::as_select())
+            .filter(schema::evm_wallet::address.eq(wallet_address.as_slice()))
+            .first(&mut conn)
+            .await
+            .optional()?
+            .ok_or(SignTransactionError::WalletNotFound)?;
+        drop(conn);
+
+        let meaning = self
+            .engine
+            .evaluate_transaction(
+                wallet.id,
+                client_id,
+                transaction.clone(),
+                RunKind::Execution,
+            )
+            .await?;
+
+        Ok(meaning)
+    }
+
+    #[message]
+    pub async fn client_sign_transaction(
+        &mut self,
+        client_id: i32,
+        wallet_address: Address,
+        mut transaction: TxEip1559,
+    ) -> Result<Signature, SignTransactionError> {
+        let mut conn = self.db.get().await?;
+        let wallet = schema::evm_wallet::table
+            .select(models::EvmWallet::as_select())
+            .filter(schema::evm_wallet::address.eq(wallet_address.as_slice()))
+            .first(&mut conn)
+            .await
+            .optional()?
+            .ok_or(SignTransactionError::WalletNotFound)?;
+        drop(conn);
+
+        let raw_key: SafeCell<Vec<u8>> = self
+            .keyholder
+            .ask(Decrypt {
+                aead_id: wallet.aead_encrypted_id,
+            })
+            .await
+            .map_err(|_| SignTransactionError::KeyholderSend)?;
+
+        let signer = safe_signer::SafeSigner::from_cell(raw_key)?;
+
+        self.engine
+            .evaluate_transaction(
+                wallet.id,
+                client_id,
+                transaction.clone(),
+                RunKind::Execution,
+            )
+            .await?;
+
+        use alloy::network::TxSignerSync as _;
+        Ok(signer.sign_transaction_sync(&mut transaction)?)
+    }
+}

server/crates/arbiter-server/src/actors/keyholder/encryption/v1.rs

@@ -5,12 +5,13 @@ use chacha20poly1305::{
     AeadInPlace, Key, KeyInit as _, XChaCha20Poly1305, XNonce,
     aead::{AeadMut, Error, Payload},
 };
-use memsafe::MemSafe;
 use rand::{
     Rng as _, SeedableRng,
     rngs::{StdRng, SysRng},
 };
 
+use crate::safe_cell::{SafeCell, SafeCellHandle as _};
+
 pub const ROOT_KEY_TAG: &[u8] = "arbiter/seal/v1".as_bytes();
 pub const TAG: &[u8] = "arbiter/private-key/v1".as_bytes();
 
@@ -47,40 +48,37 @@ impl<'a> TryFrom<&'a [u8]> for Nonce {
     }
 }
 
-pub struct KeyCell(pub MemSafe<Key>);
-impl From<MemSafe<Key>> for KeyCell {
-    fn from(value: MemSafe<Key>) -> Self {
+pub struct KeyCell(pub SafeCell<Key>);
+impl From<SafeCell<Key>> for KeyCell {
+    fn from(value: SafeCell<Key>) -> Self {
         Self(value)
     }
 }
-impl TryFrom<MemSafe<Vec<u8>>> for KeyCell {
+impl TryFrom<SafeCell<Vec<u8>>> for KeyCell {
     type Error = ();
 
-    fn try_from(mut value: MemSafe<Vec<u8>>) -> Result<Self, Self::Error> {
-        let value = value.read().unwrap();
+    fn try_from(mut value: SafeCell<Vec<u8>>) -> Result<Self, Self::Error> {
+        let value = value.read();
         if value.len() != size_of::<Key>() {
             return Err(());
         }
-        let mut cell = MemSafe::new(Key::default()).unwrap();
-        {
-            let mut cell_write = cell.write().unwrap();
-            let cell_slice: &mut [u8] = cell_write.as_mut();
-            cell_slice.copy_from_slice(&value);
-        }
+        let cell = SafeCell::new_inline(|cell_write: &mut Key| {
+            cell_write.copy_from_slice(&value);
+        });
         Ok(Self(cell))
     }
 }
 
 impl KeyCell {
     pub fn new_secure_random() -> Self {
-        let mut key = MemSafe::new(Key::default()).unwrap();
-        {
-            let mut key_buffer = key.write().unwrap();
-            let key_buffer: &mut [u8] = key_buffer.as_mut();
-
+        let key = SafeCell::new_inline(|key_buffer: &mut Key| {
+            #[allow(
+                clippy::unwrap_used,
+                reason = "Rng failure is unrecoverable and should panic"
+            )]
             let mut rng = StdRng::try_from_rng(&mut SysRng).unwrap();
             rng.fill_bytes(key_buffer);
-        }
+        });
 
         key.into()
     }
@@ -91,7 +89,7 @@ impl KeyCell {
         associated_data: &[u8],
         mut buffer: impl AsMut<Vec<u8>>,
     ) -> Result<(), Error> {
-        let key_reader = self.0.read().unwrap();
+        let key_reader = self.0.read();
         let key_ref = key_reader.deref();
         let cipher = XChaCha20Poly1305::new(key_ref);
         let nonce = XNonce::from_slice(nonce.0.as_ref());
@@ -102,13 +100,13 @@ impl KeyCell {
         &mut self,
         nonce: &Nonce,
         associated_data: &[u8],
-        buffer: &mut MemSafe<Vec<u8>>,
+        buffer: &mut SafeCell<Vec<u8>>,
     ) -> Result<(), Error> {
-        let key_reader = self.0.read().unwrap();
+        let key_reader = self.0.read();
         let key_ref = key_reader.deref();
         let cipher = XChaCha20Poly1305::new(key_ref);
         let nonce = XNonce::from_slice(nonce.0.as_ref());
-        let mut buffer = buffer.write().unwrap();
+        let mut buffer = buffer.write();
         let buffer: &mut Vec<u8> = buffer.as_mut();
         cipher.decrypt_in_place(nonce, associated_data, buffer)
     }
@@ -119,7 +117,7 @@ impl KeyCell {
         associated_data: &[u8],
         plaintext: impl AsRef<[u8]>,
     ) -> Result<Vec<u8>, Error> {
-        let key_reader = self.0.read().unwrap();
+        let key_reader = self.0.read();
         let key_ref = key_reader.deref();
         let mut cipher = XChaCha20Poly1305::new(key_ref);
         let nonce = XNonce::from_slice(nonce.0.as_ref());
@@ -139,6 +137,10 @@ pub type Salt = [u8; ArgonSalt::RECOMMENDED_LENGTH];
 
 pub fn generate_salt() -> Salt {
     let mut salt = Salt::default();
+    #[allow(
+        clippy::unwrap_used,
+        reason = "Rng failure is unrecoverable and should panic"
+    )]
     let mut rng = StdRng::try_from_rng(&mut SysRng).unwrap();
     rng.fill_bytes(&mut salt);
     salt
@@ -146,19 +148,23 @@ pub fn generate_salt() -> Salt {
 
 /// User password might be of different length, have not enough entropy, etc...
 /// Derive a fixed-length key from the password using Argon2id, which is designed for password hashing and key derivation.
-pub fn derive_seal_key(mut password: MemSafe<Vec<u8>>, salt: &Salt) -> KeyCell {
+pub fn derive_seal_key(mut password: SafeCell<Vec<u8>>, salt: &Salt) -> KeyCell {
+    #[allow(clippy::unwrap_used)]
     let params = argon2::Params::new(262_144, 3, 4, None).unwrap();
     let hasher = Argon2::new(Algorithm::Argon2id, argon2::Version::V0x13, params);
-    let mut key = MemSafe::new(Key::default()).unwrap();
-    {
-        let password_source = password.read().unwrap();
-        let mut key_buffer = key.write().unwrap();
+    let mut key = SafeCell::new(Key::default());
+    password.read_inline(|password_source| {
+        let mut key_buffer = key.write();
         let key_buffer: &mut [u8] = key_buffer.as_mut();
 
+        #[allow(
+            clippy::unwrap_used,
+            reason = "Better fail completely than return a weak key"
+        )]
         hasher
             .hash_password_into(password_source.deref(), salt, key_buffer)
             .unwrap();
-    }
+    });
 
     key.into()
 }
@@ -166,20 +172,20 @@ pub fn derive_seal_key(mut password: MemSafe<Vec<u8>>, salt: &Salt) -> KeyCell {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use memsafe::MemSafe;
+    use crate::safe_cell::SafeCell;
 
     #[test]
     pub fn derive_seal_key_deterministic() {
         static PASSWORD: &[u8] = b"password";
-        let password = MemSafe::new(PASSWORD.to_vec()).unwrap();
-        let password2 = MemSafe::new(PASSWORD.to_vec()).unwrap();
+        let password = SafeCell::new(PASSWORD.to_vec());
+        let password2 = SafeCell::new(PASSWORD.to_vec());
         let salt = generate_salt();
 
         let mut key1 = derive_seal_key(password, &salt);
         let mut key2 = derive_seal_key(password2, &salt);
 
-        let key1_reader = key1.0.read().unwrap();
-        let key2_reader = key2.0.read().unwrap();
+        let key1_reader = key1.0.read();
+        let key2_reader = key2.0.read();
 
         assert_eq!(key1_reader.deref(), key2_reader.deref());
     }
@@ -187,11 +193,11 @@ mod tests {
     #[test]
     pub fn successful_derive() {
         static PASSWORD: &[u8] = b"password";
-        let password = MemSafe::new(PASSWORD.to_vec()).unwrap();
+        let password = SafeCell::new(PASSWORD.to_vec());
         let salt = generate_salt();
 
         let mut key = derive_seal_key(password, &salt);
-        let key_reader = key.0.read().unwrap();
+        let key_reader = key.0.read();
         let key_ref = key_reader.deref();
 
         assert_ne!(key_ref.as_slice(), &[0u8; 32][..]);
@@ -200,7 +206,7 @@ mod tests {
     #[test]
     pub fn encrypt_decrypt() {
         static PASSWORD: &[u8] = b"password";
-        let password = MemSafe::new(PASSWORD.to_vec()).unwrap();
+        let password = SafeCell::new(PASSWORD.to_vec());
         let salt = generate_salt();
 
         let mut key = derive_seal_key(password, &salt);
@@ -212,12 +218,12 @@ mod tests {
             .unwrap();
         assert_ne!(buffer, b"secret data");
 
-        let mut buffer = MemSafe::new(buffer).unwrap();
+        let mut buffer = SafeCell::new(buffer);
 
         key.decrypt_in_place(&nonce, associated_data, &mut buffer)
             .unwrap();
 
-        let buffer = buffer.read().unwrap();
+        let buffer = buffer.read();
         assert_eq!(*buffer, b"secret data");
     }
 

server/crates/arbiter-server/src/actors/keyholder/mod.rs

@@ -1,24 +1,28 @@
+use chrono::Utc;
 use diesel::{
     ExpressionMethods as _, OptionalExtension, QueryDsl, SelectableHelper,
     dsl::{insert_into, update},
 };
 use diesel_async::{AsyncConnection, RunQueryDsl};
 use kameo::{Actor, Reply, messages};
-use memsafe::MemSafe;
 use strum::{EnumDiscriminants, IntoDiscriminant};
 use tracing::{error, info};
 
-use crate::db::{
-    self,
-    models::{self, RootKeyHistory},
-    schema::{self},
+use crate::safe_cell::SafeCell;
+use crate::{
+    db::{
+        self,
+        models::{self, RootKeyHistory},
+        schema::{self},
+    },
+    safe_cell::SafeCellHandle as _,
 };
 use encryption::v1::{self, KeyCell, Nonce};
 
 pub mod encryption;
 
 #[derive(Default, EnumDiscriminants)]
-#[strum_discriminants(derive(Reply), vis(pub))]
+#[strum_discriminants(derive(Reply), vis(pub), name(KeyHolderState))]
 enum State {
     #[default]
     Unbootstrapped,
@@ -135,7 +139,7 @@ impl KeyHolder {
     }
 
     #[message]
-    pub async fn bootstrap(&mut self, seal_key_raw: MemSafe<Vec<u8>>) -> Result<(), Error> {
+    pub async fn bootstrap(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
         if !matches!(self.state, State::Unbootstrapped) {
             return Err(Error::AlreadyBootstrapped);
         }
@@ -147,16 +151,15 @@ impl KeyHolder {
         let root_key_nonce = v1::Nonce::default();
         let data_encryption_nonce = v1::Nonce::default();
 
-        let root_key_ciphertext: Vec<u8> = {
-            let root_key_reader = root_key.0.read().unwrap();
-            let root_key_reader = root_key_reader.as_slice();
+        let root_key_ciphertext: Vec<u8> = root_key.0.read_inline(|reader| {
+            let root_key_reader = reader.as_slice();
             seal_key
                 .encrypt(&root_key_nonce, v1::ROOT_KEY_TAG, root_key_reader)
                 .map_err(|err| {
                     error!(?err, "Fatal bootstrap error");
                     Error::Encryption(err)
-                })?
-        };
+                })
+        })?;
 
         let mut conn = self.db.get().await?;
 
@@ -198,7 +201,7 @@ impl KeyHolder {
     }
 
     #[message]
-    pub async fn try_unseal(&mut self, seal_key_raw: MemSafe<Vec<u8>>) -> Result<(), Error> {
+    pub async fn try_unseal(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
         let State::Sealed {
             root_key_history_id,
         } = &self.state
@@ -224,7 +227,7 @@ impl KeyHolder {
         })?;
         let mut seal_key = v1::derive_seal_key(seal_key_raw, &salt);
 
-        let mut root_key = MemSafe::new(current_key.ciphertext.clone()).unwrap();
+        let mut root_key = SafeCell::new(current_key.ciphertext.clone());
 
         let nonce = v1::Nonce::try_from(current_key.root_key_encryption_nonce.as_slice()).map_err(
             |_| {
@@ -255,7 +258,7 @@ impl KeyHolder {
 
     // Decrypts the `aead_encrypted` entry with the given ID and returns the plaintext
     #[message]
-    pub async fn decrypt(&mut self, aead_id: i32) -> Result<MemSafe<Vec<u8>>, Error> {
+    pub async fn decrypt(&mut self, aead_id: i32) -> Result<SafeCell<Vec<u8>>, Error> {
         let State::Unsealed { root_key, .. } = &mut self.state else {
             return Err(Error::NotBootstrapped);
         };
@@ -278,14 +281,14 @@ impl KeyHolder {
             );
             Error::BrokenDatabase
         })?;
-        let mut output = MemSafe::new(row.ciphertext).unwrap();
+        let mut output = SafeCell::new(row.ciphertext);
         root_key.decrypt_in_place(&nonce, v1::TAG, &mut output)?;
         Ok(output)
     }
 
     // Creates new `aead_encrypted` entry in the database and returns it's ID
     #[message]
-    pub async fn create_new(&mut self, mut plaintext: MemSafe<Vec<u8>>) -> Result<i32, Error> {
+    pub async fn create_new(&mut self, mut plaintext: SafeCell<Vec<u8>>) -> Result<i32, Error> {
         let State::Unsealed {
             root_key,
             root_key_history_id,
@@ -298,7 +301,7 @@ impl KeyHolder {
         // Borrow checker note: &mut borrow a few lines above is disjoint from this field
         let nonce = Self::get_new_nonce(&self.db, *root_key_history_id).await?;
 
-        let mut ciphertext_buffer = plaintext.write().unwrap();
+        let mut ciphertext_buffer = plaintext.write();
         let ciphertext_buffer: &mut Vec<u8> = ciphertext_buffer.as_mut();
         root_key.encrypt_in_place(&nonce, v1::TAG, &mut *ciphertext_buffer)?;
 
@@ -312,7 +315,7 @@ impl KeyHolder {
                 current_nonce: nonce.to_vec(),
                 schema_version: 1,
                 associated_root_key_id: *root_key_history_id,
-                created_at: chrono::Utc::now().timestamp() as i32,
+                created_at: Utc::now().into(),
             })
             .returning(schema::aead_encrypted::id)
             .get_result(&mut conn)
@@ -322,7 +325,7 @@ impl KeyHolder {
     }
 
     #[message]
-    pub fn get_state(&self) -> StateDiscriminants {
+    pub fn get_state(&self) -> KeyHolderState {
         self.state.discriminant()
     }
 
@@ -345,17 +348,19 @@ impl KeyHolder {
 #[cfg(test)]
 mod tests {
     use diesel::SelectableHelper;
-    
-    use diesel_async::RunQueryDsl;
-    use memsafe::MemSafe;
 
-    use crate::db::{self};
+    use diesel_async::RunQueryDsl;
+
+    use crate::{
+        db::{self},
+        safe_cell::SafeCell,
+    };
 
     use super::*;
 
     async fn bootstrapped_actor(db: &db::DatabasePool) -> KeyHolder {
         let mut actor = KeyHolder::new(db.clone()).await.unwrap();
-        let seal_key = MemSafe::new(b"test-seal-key".to_vec()).unwrap();
+        let seal_key = SafeCell::new(b"test-seal-key".to_vec());
         actor.bootstrap(seal_key).await.unwrap();
         actor
     }
@@ -390,7 +395,7 @@ mod tests {
         assert_eq!(root_row.data_encryption_nonce, n2.to_vec());
 
         let id = actor
-            .create_new(MemSafe::new(b"post-interleave".to_vec()).unwrap())
+            .create_new(SafeCell::new(b"post-interleave".to_vec()))
             .await
             .unwrap();
         let row: models::AeadEncrypted = schema::aead_encrypted::table

server/crates/arbiter-server/src/actors/mod.rs

@@ -3,13 +3,15 @@ use miette::Diagnostic;
 use thiserror::Error;
 
 use crate::{
-    actors::{bootstrap::Bootstrapper, keyholder::KeyHolder},
+    actors::{bootstrap::Bootstrapper, evm::EvmActor, keyholder::KeyHolder, router::MessageRouter},
     db,
 };
 
 pub mod bootstrap;
 pub mod client;
+mod evm;
 pub mod keyholder;
+pub mod router;
 pub mod user_agent;
 
 #[derive(Error, Debug, Diagnostic)]
@@ -28,13 +30,18 @@ pub enum SpawnError {
 pub struct GlobalActors {
     pub key_holder: ActorRef<KeyHolder>,
     pub bootstrapper: ActorRef<Bootstrapper>,
+    pub router: ActorRef<MessageRouter>,
+    pub evm: ActorRef<EvmActor>,
 }
 
 impl GlobalActors {
     pub async fn spawn(db: db::DatabasePool) -> Result<Self, SpawnError> {
+        let key_holder = KeyHolder::spawn(KeyHolder::new(db.clone()).await?);
         Ok(Self {
             bootstrapper: Bootstrapper::spawn(Bootstrapper::new(&db).await?),
-            key_holder: KeyHolder::spawn(KeyHolder::new(db.clone()).await?),
+            evm: EvmActor::spawn(EvmActor::new(key_holder.clone(), db)),
+            key_holder,
+            router: MessageRouter::spawn(MessageRouter::default()),
         })
     }
 }

server/crates/arbiter-server/src/actors/router/mod.rs

@@ -0,0 +1,173 @@
+use std::{collections::HashMap, ops::ControlFlow};
+
+use ed25519_dalek::VerifyingKey;
+use kameo::{
+    Actor,
+    actor::{ActorId, ActorRef},
+    messages,
+    prelude::{ActorStopReason, Context, WeakActorRef},
+    reply::DelegatedReply,
+};
+use tokio::{sync::watch, task::JoinSet};
+use tracing::{info, warn};
+
+use crate::actors::{
+    client::session::ClientSession,
+    user_agent::session::{RequestNewClientApproval, UserAgentSession},
+};
+
+#[derive(Default)]
+pub struct MessageRouter {
+    pub user_agents: HashMap<ActorId, ActorRef<UserAgentSession>>,
+    pub clients: HashMap<ActorId, ActorRef<ClientSession>>,
+}
+
+impl Actor for MessageRouter {
+    type Args = Self;
+
+    type Error = ();
+
+    async fn on_start(args: Self::Args, _: ActorRef<Self>) -> Result<Self, Self::Error> {
+        Ok(args)
+    }
+
+    async fn on_link_died(
+        &mut self,
+        _: WeakActorRef<Self>,
+        id: ActorId,
+        _: ActorStopReason,
+    ) -> Result<ControlFlow<ActorStopReason>, Self::Error> {
+        if self.user_agents.remove(&id).is_some() {
+            info!(
+                ?id,
+                actor = "MessageRouter",
+                event = "useragent.disconnected"
+            );
+        } else if self.clients.remove(&id).is_some() {
+            info!(?id, actor = "MessageRouter", event = "client.disconnected");
+        } else {
+            info!(
+                ?id,
+                actor = "MessageRouter",
+                event = "unknown.actor.disconnected"
+            );
+        }
+        Ok(ControlFlow::Continue(()))
+    }
+}
+
+#[derive(Debug, thiserror::Error, Clone, PartialEq, Eq, Hash)]
+pub enum ApprovalError {
+    #[error("No user agents connected")]
+    NoUserAgentsConnected,
+}
+
+async fn request_client_approval(
+    user_agents: &[WeakActorRef<UserAgentSession>],
+    client_pubkey: VerifyingKey,
+) -> Result<bool, ApprovalError> {
+    if user_agents.is_empty() {
+        return Err(ApprovalError::NoUserAgentsConnected);
+    }
+
+    let mut pool = JoinSet::new();
+    let (cancel_tx, cancel_rx) = watch::channel(());
+
+    for weak_ref in user_agents {
+        match weak_ref.upgrade() {
+            Some(agent) => {
+                let cancel_rx = cancel_rx.clone();
+                pool.spawn(async move {
+                    agent
+                        .ask(RequestNewClientApproval {
+                            client_pubkey,
+                            cancel_flag: cancel_rx.clone(),
+                        })
+                        .await
+                });
+            }
+            None => {
+                warn!(
+                    id = weak_ref.id().to_string(),
+                    actor = "MessageRouter",
+                    event = "useragent.disconnected_before_approval"
+                );
+            }
+        }
+    }
+
+    while let Some(result) = pool.join_next().await {
+        match result {
+            Ok(Ok(approved)) => {
+                // cancel other pending requests
+                let _ = cancel_tx.send(());
+                return Ok(approved);
+            }
+            Ok(Err(err)) => {
+                warn!(
+                    ?err,
+                    actor = "MessageRouter",
+                    event = "useragent.approval_error"
+                );
+            }
+            Err(err) => {
+                warn!(
+                    ?err,
+                    actor = "MessageRouter",
+                    event = "useragent.approval_task_failed"
+                );
+            }
+        }
+    }
+
+    Err(ApprovalError::NoUserAgentsConnected)
+}
+
+#[messages]
+impl MessageRouter {
+    #[message(ctx)]
+    pub async fn register_user_agent(
+        &mut self,
+        actor: ActorRef<UserAgentSession>,
+        ctx: &mut Context<Self, ()>,
+    ) {
+        info!(id = %actor.id(), actor = "MessageRouter", event = "useragent.connected");
+        ctx.actor_ref().link(&actor).await;
+        self.user_agents.insert(actor.id(), actor);
+    }
+
+    #[message(ctx)]
+    pub async fn register_client(
+        &mut self,
+        actor: ActorRef<ClientSession>,
+        ctx: &mut Context<Self, ()>,
+    ) {
+        info!(id = %actor.id(), actor = "MessageRouter", event = "client.connected");
+        ctx.actor_ref().link(&actor).await;
+        self.clients.insert(actor.id(), actor);
+    }
+
+    #[message(ctx)]
+    pub async fn request_client_approval(
+        &mut self,
+        client_pubkey: VerifyingKey,
+        ctx: &mut Context<Self, DelegatedReply<Result<bool, ApprovalError>>>,
+    ) -> DelegatedReply<Result<bool, ApprovalError>> {
+        let (reply, Some(reply_sender)) = ctx.reply_sender() else {
+            unreachable!("Expected `request_client_approval` to have callback channel");
+        };
+
+        let weak_refs = self
+            .user_agents
+            .values()
+            .map(|agent| agent.downgrade())
+            .collect::<Vec<_>>();
+
+        tokio::task::spawn(async move {
+            let result = request_client_approval(&weak_refs, client_pubkey).await;
+            reply_sender.send(result);
+        });
+
+        reply
+    }
+}

server/crates/arbiter-server/src/actors/user_agent/auth.rs

@@ -0,0 +1,101 @@
+use arbiter_proto::transport::Bi;
+use tracing::error;
+
+use crate::actors::user_agent::{
+    AuthPublicKey, UserAgentConnection,
+    auth::state::{AuthContext, AuthStateMachine},
+};
+
+mod state;
+use state::*;
+
+#[derive(Debug, Clone)]
+pub enum Inbound {
+    AuthChallengeRequest {
+        pubkey: AuthPublicKey,
+        bootstrap_token: Option<String>,
+    },
+    AuthChallengeSolution {
+        signature: Vec<u8>,
+    },
+}
+
+#[derive(Debug)]
+pub enum Error {
+    UnregisteredPublicKey,
+    InvalidChallengeSolution,
+    InvalidBootstrapToken,
+    Internal { details: String },
+    Transport,
+}
+
+impl Error {
+    fn internal(details: impl Into<String>) -> Self {
+        Self::Internal {
+            details: details.into(),
+        }
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum Outbound {
+    AuthChallenge { nonce: i32 },
+    AuthSuccess,
+}
+
+fn parse_auth_event(payload: Inbound) -> AuthEvents {
+    match payload {
+        Inbound::AuthChallengeRequest {
+            pubkey,
+            bootstrap_token: None,
+        } => AuthEvents::AuthRequest(ChallengeRequest { pubkey }),
+        Inbound::AuthChallengeRequest {
+            pubkey,
+            bootstrap_token: Some(token),
+        } => AuthEvents::BootstrapAuthRequest(BootstrapAuthRequest { pubkey, token }),
+        Inbound::AuthChallengeSolution { signature } => {
+            AuthEvents::ReceivedSolution(ChallengeSolution {
+                solution: signature,
+            })
+        }
+    }
+}
+
+pub async fn authenticate<T>(
+    props: &mut UserAgentConnection,
+    transport: T,
+) -> Result<AuthPublicKey, Error>
+where
+    T: Bi<Inbound, Result<Outbound, Error>> + Send,
+{
+    let mut state = AuthStateMachine::new(AuthContext::new(props, transport));
+
+    loop {
+        // `state` holds a mutable reference to `props` so we can't access it directly here
+        let Some(payload) = state.context_mut().transport.recv().await else {
+            return Err(Error::Transport);
+        };
+
+        match state.process_event(parse_auth_event(payload)).await {
+            Ok(AuthStates::AuthOk(key)) => return Ok(key.clone()),
+            Err(AuthError::ActionFailed(err)) => {
+                error!(?err, "State machine action failed");
+                return Err(err);
+            }
+            Err(AuthError::GuardFailed(err)) => {
+                error!(?err, "State machine guard failed");
+                return Err(err);
+            }
+            Err(AuthError::InvalidEvent) => {
+                error!("Invalid event for current state");
+                return Err(Error::InvalidChallengeSolution);
+            }
+            Err(AuthError::TransitionsFailed) => {
+                error!("Invalid state transition");
+                return Err(Error::InvalidChallengeSolution);
+            }
+
+            _ => (),
+        }
+    }
+}

server/crates/arbiter-server/src/actors/user_agent/auth/state.rs

@@ -0,0 +1,222 @@
+use arbiter_proto::transport::Bi;
+use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, update};
+use diesel_async::RunQueryDsl;
+use tracing::error;
+
+use super::Error;
+use crate::{
+    actors::{
+        bootstrap::ConsumeToken,
+        user_agent::{AuthPublicKey, UserAgentConnection, auth::Outbound},
+    },
+    db::schema,
+};
+
+pub struct ChallengeRequest {
+    pub pubkey: AuthPublicKey,
+}
+
+pub struct BootstrapAuthRequest {
+    pub pubkey: AuthPublicKey,
+    pub token: String,
+}
+
+pub struct ChallengeContext {
+    pub challenge_nonce: i32,
+    pub key: AuthPublicKey,
+}
+
+pub struct ChallengeSolution {
+    pub solution: Vec<u8>,
+}
+
+smlang::statemachine!(
+    name: Auth,
+    custom_error: true,
+    transitions: {
+        *Init + AuthRequest(ChallengeRequest) / async prepare_challenge = SentChallenge(ChallengeContext),
+        Init + BootstrapAuthRequest(BootstrapAuthRequest) / async verify_bootstrap_token = AuthOk(AuthPublicKey),
+        SentChallenge(ChallengeContext) + ReceivedSolution(ChallengeSolution) / async verify_solution = AuthOk(AuthPublicKey),
+    }
+);
+
+async fn create_nonce(db: &crate::db::DatabasePool, pubkey_bytes: &[u8]) -> Result<i32, Error> {
+    let mut db_conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::internal("Database unavailable")
+    })?;
+    db_conn
+        .exclusive_transaction(|conn| {
+            Box::pin(async move {
+                let current_nonce = schema::useragent_client::table
+                    .filter(schema::useragent_client::public_key.eq(pubkey_bytes.to_vec()))
+                    .select(schema::useragent_client::nonce)
+                    .first::<i32>(conn)
+                    .await?;
+
+                update(schema::useragent_client::table)
+                    .filter(schema::useragent_client::public_key.eq(pubkey_bytes.to_vec()))
+                    .set(schema::useragent_client::nonce.eq(current_nonce + 1))
+                    .execute(conn)
+                    .await?;
+
+                Result::<_, diesel::result::Error>::Ok(current_nonce)
+            })
+        })
+        .await
+        .optional()
+        .map_err(|e| {
+            error!(error = ?e, "Database error");
+            Error::internal("Database operation failed")
+        })?
+        .ok_or_else(|| {
+            error!(?pubkey_bytes, "Public key not found in database");
+            Error::UnregisteredPublicKey
+        })
+}
+
+async fn register_key(db: &crate::db::DatabasePool, pubkey: &AuthPublicKey) -> Result<(), Error> {
+    let pubkey_bytes = pubkey.to_stored_bytes();
+    let key_type = pubkey.key_type();
+    let mut conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::internal("Database unavailable")
+    })?;
+
+    diesel::insert_into(schema::useragent_client::table)
+        .values((
+            schema::useragent_client::public_key.eq(pubkey_bytes),
+            schema::useragent_client::nonce.eq(1),
+            schema::useragent_client::key_type.eq(key_type),
+        ))
+        .execute(&mut conn)
+        .await
+        .map_err(|e| {
+            error!(error = ?e, "Database error");
+            Error::internal("Database operation failed")
+        })?;
+
+    Ok(())
+}
+
+pub struct AuthContext<'a, T> {
+    pub(super) conn: &'a mut UserAgentConnection,
+    pub(super) transport: T,
+}
+
+impl<'a, T> AuthContext<'a, T> {
+    pub fn new(conn: &'a mut UserAgentConnection, transport: T) -> Self {
+        Self { conn, transport }
+    }
+}
+
+impl<T> AuthStateMachineContext for AuthContext<'_, T>
+where
+    T: Bi<super::Inbound, Result<super::Outbound, Error>> + Send,
+{
+    type Error = Error;
+
+    async fn prepare_challenge(
+        &mut self,
+        ChallengeRequest { pubkey }: ChallengeRequest,
+    ) -> Result<ChallengeContext, Self::Error> {
+        let stored_bytes = pubkey.to_stored_bytes();
+        let nonce = create_nonce(&self.conn.db, &stored_bytes).await?;
+
+        self.transport
+            .send(Ok(Outbound::AuthChallenge { nonce }))
+            .await
+            .map_err(|e| {
+                error!(?e, "Failed to send auth challenge");
+                Error::Transport
+            })?;
+
+        Ok(ChallengeContext {
+            challenge_nonce: nonce,
+            key: pubkey,
+        })
+    }
+
+    #[allow(missing_docs)]
+    #[allow(clippy::result_unit_err)]
+    async fn verify_bootstrap_token(
+        &mut self,
+        BootstrapAuthRequest { pubkey, token }: BootstrapAuthRequest,
+    ) -> Result<AuthPublicKey, Self::Error> {
+        let token_ok: bool = self
+            .conn
+            .actors
+            .bootstrapper
+            .ask(ConsumeToken {
+                token: token.clone(),
+            })
+            .await
+            .map_err(|e| {
+                error!(?e, "Failed to consume bootstrap token");
+                Error::internal("Failed to consume bootstrap token")
+            })?;
+
+        if !token_ok {
+            error!("Invalid bootstrap token provided");
+            return Err(Error::InvalidBootstrapToken);
+        }
+
+        register_key(&self.conn.db, &pubkey).await?;
+
+        self.transport
+            .send(Ok(Outbound::AuthSuccess))
+            .await
+            .map_err(|_| Error::Transport)?;
+
+        Ok(pubkey)
+    }
+
+    #[allow(missing_docs)]
+    #[allow(clippy::unused_unit)]
+    async fn verify_solution(
+        &mut self,
+        ChallengeContext {
+            challenge_nonce,
+            key,
+        }: &ChallengeContext,
+        ChallengeSolution { solution }: ChallengeSolution,
+    ) -> Result<AuthPublicKey, Self::Error> {
+        let formatted = arbiter_proto::format_challenge(*challenge_nonce, &key.to_stored_bytes());
+
+        let valid = match key {
+            AuthPublicKey::Ed25519(vk) => {
+                let sig = solution.as_slice().try_into().map_err(|_| {
+                    error!(?solution, "Invalid Ed25519 signature length");
+                    Error::InvalidChallengeSolution
+                })?;
+                vk.verify_strict(&formatted, &sig).is_ok()
+            }
+            AuthPublicKey::EcdsaSecp256k1(vk) => {
+                use k256::ecdsa::signature::Verifier as _;
+                let sig = k256::ecdsa::Signature::try_from(solution.as_slice()).map_err(|_| {
+                    error!(?solution, "Invalid ECDSA signature bytes");
+                    Error::InvalidChallengeSolution
+                })?;
+                vk.verify(&formatted, &sig).is_ok()
+            }
+            AuthPublicKey::Rsa(pk) => {
+                use rsa::signature::Verifier as _;
+                let verifying_key = rsa::pss::VerifyingKey::<sha2::Sha256>::new(pk.clone());
+                let sig = rsa::pss::Signature::try_from(solution.as_slice()).map_err(|_| {
+                    error!(?solution, "Invalid RSA signature bytes");
+                    Error::InvalidChallengeSolution
+                })?;
+                verifying_key.verify(&formatted, &sig).is_ok()
+            }
+        };
+
+        if valid {
+            self.transport
+                .send(Ok(Outbound::AuthSuccess))
+                .await
+                .map_err(|_| Error::Transport)?;
+        }
+
+        Ok(key.clone())
+    }
+}

server/crates/arbiter-server/src/actors/user_agent/error.rs

@@ -1,57 +0,0 @@
-use tonic::Status;
-
-use crate::db;
-
-#[derive(Debug, thiserror::Error)]
-pub enum UserAgentError {
-    #[error("Missing payload in request")]
-    MissingPayload,
-
-    #[error("Invalid bootstrap token")]
-    InvalidBootstrapToken,
-
-    #[error("Public key not registered")]
-    PubkeyNotRegistered,
-
-    #[error("Invalid public key format")]
-    InvalidPubkey,
-
-    #[error("Invalid signature length")]
-    InvalidSignatureLength,
-
-    #[error("Invalid challenge solution")]
-    InvalidChallengeSolution,
-
-    #[error("Invalid state for operation")]
-    InvalidState,
-
-    #[error("Actor unavailable")]
-    ActorUnavailable,
-
-    #[error("Database error")]
-    Database(#[from] diesel::result::Error),
-
-    #[error("Database pool error")]
-    DatabasePool(#[from] db::PoolError),
-}
-
-impl From<UserAgentError> for Status {
-    fn from(err: UserAgentError) -> Self {
-        match err {
-            UserAgentError::MissingPayload
-            | UserAgentError::InvalidBootstrapToken
-            | UserAgentError::InvalidPubkey
-            | UserAgentError::InvalidSignatureLength => Status::invalid_argument(err.to_string()),
-
-            UserAgentError::PubkeyNotRegistered | UserAgentError::InvalidChallengeSolution => {
-                Status::unauthenticated(err.to_string())
-            }
-
-            UserAgentError::InvalidState => Status::failed_precondition(err.to_string()),
-
-            UserAgentError::ActorUnavailable
-            | UserAgentError::Database(_)
-            | UserAgentError::DatabasePool(_) => Status::internal(err.to_string()),
-        }
-    }
-}

server/crates/arbiter-server/src/actors/user_agent/mod.rs

@@ -1,401 +1,94 @@
-use std::{ops::DerefMut, sync::Mutex};
-
-use arbiter_proto::proto::{
-    UnsealEncryptedKey, UnsealResult, UnsealStart, UnsealStartResponse, UserAgentRequest,
-    UserAgentResponse,
-    auth::{
-        self, AuthChallengeRequest, AuthOk, ClientMessage as ClientAuthMessage,
-        ServerMessage as AuthServerMessage,
-        client_message::Payload as ClientAuthPayload,
-        server_message::Payload as ServerAuthPayload,
-    },
-    user_agent_request::Payload as UserAgentRequestPayload,
-    user_agent_response::Payload as UserAgentResponsePayload,
-};
-use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
-use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, dsl::update};
-use diesel_async::RunQueryDsl;
-use ed25519_dalek::VerifyingKey;
-use kameo::{Actor, actor::Recipient, error::SendError, messages, prelude::Message};
-use memsafe::MemSafe;
-use tracing::{error, info};
-use x25519_dalek::{EphemeralSecret, PublicKey};
-
 use crate::{
-    ServerContext,
-    actors::{
-        GlobalActors,
-        bootstrap::ConsumeToken,
-        keyholder::{self, TryUnseal},
-        user_agent::state::{
-            ChallengeContext, DummyContext, UnsealContext, UserAgentEvents, UserAgentStateMachine,
-            UserAgentStates,
-        },
-    },
-    db::{self, schema},
+    actors::GlobalActors,
+    db::{self, models::KeyType},
 };
 
-mod error;
-mod state;
-
-pub use error::UserAgentError;
-
-#[derive(Actor)]
-pub struct UserAgentActor {
-    db: db::DatabasePool,
-    actors: GlobalActors,
-    state: UserAgentStateMachine<DummyContext>,
-    transport: Recipient<Result<UserAgentResponse, UserAgentError>>,
+/// Abstraction over Ed25519 / ECDSA-secp256k1 / RSA public keys used during the auth handshake.
+#[derive(Clone, Debug)]
+pub enum AuthPublicKey {
+    Ed25519(ed25519_dalek::VerifyingKey),
+    /// Compressed SEC1 public key; signature bytes are raw 64-byte (r||s).
+    EcdsaSecp256k1(k256::ecdsa::VerifyingKey),
+    /// RSA-2048+ public key (Windows Hello / KeyCredentialManager); signature bytes are PSS+SHA-256.
+    Rsa(rsa::RsaPublicKey),
 }
 
-impl UserAgentActor {
-    pub(crate) fn new(
-        context: ServerContext,
-        transport: Recipient<Result<UserAgentResponse, UserAgentError>>,
-    ) -> Self {
-        Self {
-            db: context.db.clone(),
-            actors: context.actors.clone(),
-            state: UserAgentStateMachine::new(DummyContext),
-            transport,
-        }
-    }
-
-    pub fn new_manual(
-        db: db::DatabasePool,
-        actors: GlobalActors,
-        transport: Recipient<Result<UserAgentResponse, UserAgentError>>,
-    ) -> Self {
-        Self {
-            db,
-            actors,
-            state: UserAgentStateMachine::new(DummyContext),
-            transport,
-        }
-    }
-
-    async fn process_request(&mut self, req: UserAgentRequest) -> Output {
-        let msg = req.payload.ok_or_else(|| {
-            error!(actor = "useragent", "Received message with no payload");
-            UserAgentError::MissingPayload
-        })?;
-
-        match msg {
-            UserAgentRequestPayload::AuthMessage(ClientAuthMessage {
-                payload: Some(ClientAuthPayload::AuthChallengeRequest(req)),
-            }) => self.handle_auth_challenge_request(req).await,
-            UserAgentRequestPayload::AuthMessage(ClientAuthMessage {
-                payload: Some(ClientAuthPayload::AuthChallengeSolution(solution)),
-            }) => self.handle_auth_challenge_solution(solution).await,
-            UserAgentRequestPayload::UnsealStart(unseal_start) => {
-                self.handle_unseal_request(unseal_start).await
-            }
-            UserAgentRequestPayload::UnsealEncryptedKey(unseal_encrypted_key) => {
-                self.handle_unseal_encrypted_key(unseal_encrypted_key).await
-            }
-            _ => Err(UserAgentError::MissingPayload),
-        }
-    }
-
-    fn transition(&mut self, event: UserAgentEvents) -> Result<(), UserAgentError> {
-        self.state.process_event(event).map_err(|e| {
-            error!(?e, "State transition failed");
-            UserAgentError::InvalidState
-        })?;
-        Ok(())
-    }
-
-    async fn auth_with_bootstrap_token(
-        &mut self,
-        pubkey: ed25519_dalek::VerifyingKey,
-        token: String,
-    ) -> Output {
-        let token_ok: bool = self
-            .actors
-            .bootstrapper
-            .ask(ConsumeToken { token })
-            .await
-            .map_err(|e| {
-                error!(?pubkey, "Failed to consume bootstrap token: {e}");
-                UserAgentError::ActorUnavailable
-            })?;
-
-        if !token_ok {
-            error!(?pubkey, "Invalid bootstrap token provided");
-            return Err(UserAgentError::InvalidBootstrapToken);
-        }
-
-        {
-            let mut conn = self.db.get().await?;
-
-            diesel::insert_into(schema::useragent_client::table)
-                .values((
-                    schema::useragent_client::public_key.eq(pubkey.as_bytes().to_vec()),
-                    schema::useragent_client::nonce.eq(1),
-                ))
-                .execute(&mut conn)
-                .await?;
-        }
-
-        self.transition(UserAgentEvents::ReceivedBootstrapToken)?;
-
-        Ok(auth_response(ServerAuthPayload::AuthOk(AuthOk {})))
-    }
-
-    async fn auth_with_challenge(&mut self, pubkey: VerifyingKey, pubkey_bytes: Vec<u8>) -> Output {
-        let nonce: Option<i32> = {
-            let mut db_conn = self.db.get().await?;
-            db_conn
-                .exclusive_transaction(|conn| {
-                    Box::pin(async move {
-                        let current_nonce = schema::useragent_client::table
-                            .filter(
-                                schema::useragent_client::public_key.eq(pubkey.as_bytes().to_vec()),
-                            )
-                            .select(schema::useragent_client::nonce)
-                            .first::<i32>(conn)
-                            .await?;
-
-                        update(schema::useragent_client::table)
-                            .filter(
-                                schema::useragent_client::public_key.eq(pubkey.as_bytes().to_vec()),
-                            )
-                            .set(schema::useragent_client::nonce.eq(current_nonce + 1))
-                            .execute(conn)
-                            .await?;
-
-                        Result::<_, diesel::result::Error>::Ok(current_nonce)
-                    })
-                })
-                .await
-                .optional()?
-        };
-
-        let Some(nonce) = nonce else {
-            error!(?pubkey, "Public key not found in database");
-            return Err(UserAgentError::PubkeyNotRegistered);
-        };
-
-        let challenge = auth::AuthChallenge {
-            pubkey: pubkey_bytes,
-            nonce,
-        };
-
-        self.transition(UserAgentEvents::SentChallenge(ChallengeContext {
-            challenge: challenge.clone(),
-            key: pubkey,
-        }))?;
-
-        info!(
-            ?pubkey,
-            ?challenge,
-            "Sent authentication challenge to client"
-        );
-
-        Ok(auth_response(ServerAuthPayload::AuthChallenge(challenge)))
-    }
-
-    fn verify_challenge_solution(
-        &self,
-        solution: &auth::AuthChallengeSolution,
-    ) -> Result<(bool, &ChallengeContext), UserAgentError> {
-        let UserAgentStates::WaitingForChallengeSolution(challenge_context) = self.state.state()
-        else {
-            error!("Received challenge solution in invalid state");
-            return Err(UserAgentError::InvalidState);
-        };
-        let formatted_challenge = arbiter_proto::format_challenge(&challenge_context.challenge);
-
-        let signature = solution.signature.as_slice().try_into().map_err(|_| {
-            error!(?solution, "Invalid signature length");
-            UserAgentError::InvalidSignatureLength
-        })?;
-
-        let valid = challenge_context
-            .key
-            .verify_strict(&formatted_challenge, &signature)
-            .is_ok();
-
-        Ok((valid, challenge_context))
-    }
-}
-
-type Output = Result<UserAgentResponse, UserAgentError>;
-
-fn auth_response(payload: ServerAuthPayload) -> UserAgentResponse {
-    UserAgentResponse {
-        payload: Some(UserAgentResponsePayload::AuthMessage(AuthServerMessage {
-            payload: Some(payload),
-        })),
-    }
-}
-
-fn unseal_response(payload: UserAgentResponsePayload) -> UserAgentResponse {
-    UserAgentResponse {
-        payload: Some(payload),
-    }
-}
-
-#[messages]
-impl UserAgentActor {
-    #[message]
-    pub async fn handle_unseal_request(&mut self, req: UnsealStart) -> Output {
-        let secret = EphemeralSecret::random();
-        let public_key = PublicKey::from(&secret);
-
-        let client_pubkey_bytes: [u8; 32] = req
-            .client_pubkey
-            .try_into()
-            .map_err(|_| UserAgentError::InvalidPubkey)?;
-
-        let client_public_key = PublicKey::from(client_pubkey_bytes);
-
-        self.transition(UserAgentEvents::UnsealRequest(UnsealContext {
-            secret: Mutex::new(Some(secret)),
-            client_public_key,
-        }))?;
-
-        Ok(unseal_response(
-            UserAgentResponsePayload::UnsealStartResponse(UnsealStartResponse {
-                server_pubkey: public_key.as_bytes().to_vec(),
-            }),
-        ))
-    }
-
-    #[message]
-    pub async fn handle_unseal_encrypted_key(&mut self, req: UnsealEncryptedKey) -> Output {
-        let UserAgentStates::WaitingForUnsealKey(unseal_context) = self.state.state() else {
-            error!("Received unseal encrypted key in invalid state");
-            return Err(UserAgentError::InvalidState);
-        };
-        let ephemeral_secret = {
-            let mut secret_lock = unseal_context.secret.lock().unwrap();
-            let secret = secret_lock.take();
-            match secret {
-                Some(secret) => secret,
-                None => {
-                    drop(secret_lock);
-                    error!("Ephemeral secret already taken");
-                    self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                    return Ok(unseal_response(UserAgentResponsePayload::UnsealResult(
-                        UnsealResult::InvalidKey.into(),
-                    )));
-                }
-            }
-        };
-
-        let nonce = XNonce::from_slice(&req.nonce);
-
-        let shared_secret = ephemeral_secret.diffie_hellman(&unseal_context.client_public_key);
-        let cipher = XChaCha20Poly1305::new(shared_secret.as_bytes().into());
-
-        let mut seal_key_buffer = MemSafe::new(req.ciphertext.clone()).unwrap();
-
-        let decryption_result = {
-            let mut write_handle = seal_key_buffer.write().unwrap();
-            let write_handle = write_handle.deref_mut();
-            cipher.decrypt_in_place(nonce, &req.associated_data, write_handle)
-        };
-
-        match decryption_result {
-            Ok(_) => {
-                match self
-                    .actors
-                    .key_holder
-                    .ask(TryUnseal {
-                        seal_key_raw: seal_key_buffer,
-                    })
-                    .await
-                {
-                    Ok(_) => {
-                        info!("Successfully unsealed key with client-provided key");
-                        self.transition(UserAgentEvents::ReceivedValidKey)?;
-                        Ok(unseal_response(UserAgentResponsePayload::UnsealResult(
-                            UnsealResult::Success.into(),
-                        )))
-                    }
-                    Err(SendError::HandlerError(keyholder::Error::InvalidKey)) => {
-                        self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                        Ok(unseal_response(UserAgentResponsePayload::UnsealResult(
-                            UnsealResult::InvalidKey.into(),
-                        )))
-                    }
-                    Err(SendError::HandlerError(err)) => {
-                        error!(?err, "Keyholder failed to unseal key");
-                        self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                        Ok(unseal_response(UserAgentResponsePayload::UnsealResult(
-                            UnsealResult::InvalidKey.into(),
-                        )))
-                    }
-                    Err(err) => {
-                        error!(?err, "Failed to send unseal request to keyholder");
-                        self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                        Err(UserAgentError::ActorUnavailable)
-                    }
-                }
-            }
-            Err(err) => {
-                error!(?err, "Failed to decrypt unseal key");
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                Ok(unseal_response(UserAgentResponsePayload::UnsealResult(
-                    UnsealResult::InvalidKey.into(),
-                )))
+impl AuthPublicKey {
+    /// Canonical bytes stored in DB and echoed back in the challenge.
+    /// Ed25519: raw 32 bytes. ECDSA: SEC1 compressed 33 bytes. RSA: DER-encoded SPKI.
+    pub fn to_stored_bytes(&self) -> Vec<u8> {
+        match self {
+            AuthPublicKey::Ed25519(k) => k.to_bytes().to_vec(),
+            // SEC1 compressed (33 bytes) is the natural compact format for secp256k1
+            AuthPublicKey::EcdsaSecp256k1(k) => k.to_encoded_point(true).as_bytes().to_vec(),
+            AuthPublicKey::Rsa(k) => {
+                use rsa::pkcs8::EncodePublicKey as _;
+                #[allow(clippy::expect_used)]
+                k.to_public_key_der()
+                    .expect("rsa SPKI encoding is infallible")
+                    .to_vec()
             }
         }
     }
 
-    #[message]
-    pub async fn handle_auth_challenge_request(&mut self, req: AuthChallengeRequest) -> Output {
-        let pubkey = req
-            .pubkey
-            .as_array()
-            .ok_or(UserAgentError::InvalidPubkey)?;
-        let pubkey = VerifyingKey::from_bytes(pubkey).map_err(|_err| {
-            error!(?pubkey, "Failed to convert to VerifyingKey");
-            UserAgentError::InvalidPubkey
-        })?;
-
-        self.transition(UserAgentEvents::AuthRequest)?;
-
-        match req.bootstrap_token {
-            Some(token) => self.auth_with_bootstrap_token(pubkey, token).await,
-            None => self.auth_with_challenge(pubkey, req.pubkey).await,
-        }
-    }
-
-    #[message]
-    pub async fn handle_auth_challenge_solution(
-        &mut self,
-        solution: auth::AuthChallengeSolution,
-    ) -> Output {
-        let (valid, challenge_context) = self.verify_challenge_solution(&solution)?;
-
-        if valid {
-            info!(
-                ?challenge_context,
-                "Client provided valid solution to authentication challenge"
-            );
-            self.transition(UserAgentEvents::ReceivedGoodSolution)?;
-            Ok(auth_response(ServerAuthPayload::AuthOk(AuthOk {})))
-        } else {
-            error!("Client provided invalid solution to authentication challenge");
-            self.transition(UserAgentEvents::ReceivedBadSolution)?;
-            Err(UserAgentError::InvalidChallengeSolution)
+    pub fn key_type(&self) -> KeyType {
+        match self {
+            AuthPublicKey::Ed25519(_) => KeyType::Ed25519,
+            AuthPublicKey::EcdsaSecp256k1(_) => KeyType::EcdsaSecp256k1,
+            AuthPublicKey::Rsa(_) => KeyType::Rsa,
         }
     }
 }
 
-impl Message<UserAgentRequest> for UserAgentActor {
-    type Reply = ();
+impl TryFrom<(KeyType, Vec<u8>)> for AuthPublicKey {
+    type Error = &'static str;
 
-    async fn handle(
-        &mut self,
-        msg: UserAgentRequest,
-        _ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
-    ) -> Self::Reply {
-        let result = self.process_request(msg).await;
-        if let Err(e) = self.transport.tell(result).await {
-            error!(actor = "useragent", "Failed to send response to transport: {}", e);
+    fn try_from(value: (KeyType, Vec<u8>)) -> Result<Self, Self::Error> {
+        let (key_type, bytes) = value;
+        match key_type {
+            KeyType::Ed25519 => {
+                let bytes: [u8; 32] = bytes.try_into().map_err(|_| "invalid Ed25519 key length")?;
+                let key = ed25519_dalek::VerifyingKey::from_bytes(&bytes)
+                    .map_err(|_e| "invalid Ed25519 key")?;
+                Ok(AuthPublicKey::Ed25519(key))
+            }
+            KeyType::EcdsaSecp256k1 => {
+                let point =
+                    k256::EncodedPoint::from_bytes(&bytes).map_err(|_e| "invalid ECDSA key")?;
+                let key = k256::ecdsa::VerifyingKey::from_encoded_point(&point)
+                    .map_err(|_e| "invalid ECDSA key")?;
+                Ok(AuthPublicKey::EcdsaSecp256k1(key))
+            }
+            KeyType::Rsa => {
+                use rsa::pkcs8::DecodePublicKey as _;
+                let key = rsa::RsaPublicKey::from_public_key_der(&bytes)
+                    .map_err(|_e| "invalid RSA key")?;
+                Ok(AuthPublicKey::Rsa(key))
+            }
         }
     }
 }
+
+// Messages, sent by user agent to connection client without having a request
+#[derive(Debug)]
+pub enum OutOfBand {
+    ClientConnectionRequest { pubkey: ed25519_dalek::VerifyingKey },
+    ClientConnectionCancel,
+}
+
+pub struct UserAgentConnection {
+    pub(crate) db: db::DatabasePool,
+    pub(crate) actors: GlobalActors,
+}
+
+impl UserAgentConnection {
+    pub fn new(db: db::DatabasePool, actors: GlobalActors) -> Self {
+        Self { db, actors }
+    }
+}
+
+pub mod auth;
+pub mod session;
+
+pub use auth::authenticate;
+pub use session::UserAgentSession;

server/crates/arbiter-server/src/actors/user_agent/session.rs

@@ -0,0 +1,132 @@
+use std::borrow::Cow;
+
+use arbiter_proto::transport::Sender;
+use async_trait::async_trait;
+use ed25519_dalek::VerifyingKey;
+use kameo::{Actor, messages};
+use thiserror::Error;
+use tokio::sync::watch;
+use tracing::error;
+
+use crate::actors::{
+    router::RegisterUserAgent,
+    user_agent::{OutOfBand, UserAgentConnection},
+};
+
+mod state;
+use state::{DummyContext, UserAgentEvents, UserAgentStateMachine};
+
+#[derive(Debug, Error)]
+pub enum Error {
+    #[error("State transition failed")]
+    State,
+
+    #[error("Internal error: {message}")]
+    Internal { message: Cow<'static, str> },
+}
+
+impl Error {
+    pub fn internal(message: impl Into<Cow<'static, str>>) -> Self {
+        Self::Internal {
+            message: message.into(),
+        }
+    }
+}
+
+pub struct UserAgentSession {
+    props: UserAgentConnection,
+    state: UserAgentStateMachine<DummyContext>,
+    #[allow(dead_code, reason = "The session keeps ownership of the outbound transport even before the state-machine flow starts using it directly")]
+    sender: Box<dyn Sender<OutOfBand>>,
+}
+
+mod connection;
+pub(crate) use connection::{
+    BootstrapError, HandleBootstrapEncryptedKey, HandleEvmWalletCreate, HandleEvmWalletList,
+    HandleGrantCreate, HandleGrantDelete, HandleGrantList, HandleQueryVaultState,
+};
+pub use connection::{HandleUnsealEncryptedKey, HandleUnsealRequest, UnsealError};
+
+impl UserAgentSession {
+    pub(crate) fn new(props: UserAgentConnection, sender: Box<dyn Sender<OutOfBand>>) -> Self {
+        Self {
+            props,
+            state: UserAgentStateMachine::new(DummyContext),
+            sender,
+        }
+    }
+
+    pub fn new_test(db: crate::db::DatabasePool, actors: crate::actors::GlobalActors) -> Self {
+        struct DummySender;
+
+        #[async_trait]
+        impl Sender<OutOfBand> for DummySender {
+            async fn send(
+                &mut self,
+                _item: OutOfBand,
+            ) -> Result<(), arbiter_proto::transport::Error> {
+                Ok(())
+            }
+        }
+
+        Self::new(UserAgentConnection::new(db, actors), Box::new(DummySender))
+    }
+
+    fn transition(&mut self, event: UserAgentEvents) -> Result<(), Error> {
+        self.state.process_event(event).map_err(|e| {
+            error!(?e, "State transition failed");
+            Error::State
+        })?;
+        Ok(())
+    }
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message]
+    pub async fn request_new_client_approval(
+        &mut self,
+        client_pubkey: VerifyingKey,
+        mut cancel_flag: watch::Receiver<()>,
+    ) -> Result<bool, ()> {
+        if self
+            .sender
+            .send(OutOfBand::ClientConnectionRequest {
+                pubkey: client_pubkey,
+            })
+            .await
+            .is_err()
+        {
+            return Err(());
+        }
+
+        let _ = cancel_flag.changed().await;
+
+        let _ = self.sender.send(OutOfBand::ClientConnectionCancel).await;
+        Ok(false)
+    }
+}
+
+impl Actor for UserAgentSession {
+    type Args = Self;
+
+    type Error = Error;
+
+    async fn on_start(
+        args: Self::Args,
+        this: kameo::prelude::ActorRef<Self>,
+    ) -> Result<Self, Self::Error> {
+        args.props
+            .actors
+            .router
+            .ask(RegisterUserAgent {
+                actor: this.clone(),
+            })
+            .await
+            .map_err(|err| {
+                error!(?err, "Failed to register user agent connection with router");
+                Error::internal("Failed to register user agent connection with router")
+            })?;
+        Ok(args)
+    }
+}

server/crates/arbiter-server/src/actors/user_agent/session/connection.rs

@@ -0,0 +1,354 @@
+use std::sync::Mutex;
+
+use alloy::primitives::Address;
+use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
+use kameo::error::SendError;
+use kameo::messages;
+use tracing::{error, info};
+use x25519_dalek::{EphemeralSecret, PublicKey};
+
+use crate::actors::keyholder::KeyHolderState;
+use crate::actors::user_agent::session::Error;
+use crate::evm::policies::{Grant, SpecificGrant};
+use crate::safe_cell::SafeCell;
+use crate::{
+    actors::{
+        evm::{
+            Generate, ListWallets, UseragentCreateGrant, UseragentDeleteGrant, UseragentListGrants,
+        },
+        keyholder::{self, Bootstrap, TryUnseal},
+        user_agent::session::{
+                UserAgentSession,
+                state::{UnsealContext, UserAgentEvents, UserAgentStates},
+            },
+    },
+    safe_cell::SafeCellHandle as _,
+};
+
+impl UserAgentSession {
+    fn take_unseal_secret(&mut self) -> Result<(EphemeralSecret, PublicKey), Error> {
+        let UserAgentStates::WaitingForUnsealKey(unseal_context) = self.state.state() else {
+            error!("Received encrypted key in invalid state");
+            return Err(Error::internal("Invalid state for unseal encrypted key"));
+        };
+
+        let ephemeral_secret = {
+            #[allow(
+                clippy::unwrap_used,
+                reason = "Mutex poison is unrecoverable and should panic"
+            )]
+            let mut secret_lock = unseal_context.secret.lock().unwrap();
+            let secret = secret_lock.take();
+            match secret {
+                Some(secret) => secret,
+                None => {
+                    drop(secret_lock);
+                    error!("Ephemeral secret already taken");
+                    return Err(Error::internal("Ephemeral secret already taken"));
+                }
+            }
+        };
+
+        Ok((ephemeral_secret, unseal_context.client_public_key))
+    }
+
+    fn decrypt_client_key_material(
+        ephemeral_secret: EphemeralSecret,
+        client_public_key: PublicKey,
+        nonce: &[u8],
+        ciphertext: &[u8],
+        associated_data: &[u8],
+    ) -> Result<SafeCell<Vec<u8>>, ()> {
+        let nonce = XNonce::from_slice(nonce);
+
+        let shared_secret = ephemeral_secret.diffie_hellman(&client_public_key);
+        let cipher = XChaCha20Poly1305::new(shared_secret.as_bytes().into());
+
+        let mut key_buffer = SafeCell::new(ciphertext.to_vec());
+
+        let decryption_result = key_buffer.write_inline(|write_handle| {
+            cipher.decrypt_in_place(nonce, associated_data, write_handle)
+        });
+
+        match decryption_result {
+            Ok(_) => Ok(key_buffer),
+            Err(err) => {
+                error!(?err, "Failed to decrypt encrypted key material");
+                Err(())
+            }
+        }
+    }
+}
+
+pub struct UnsealStartResponse {
+    pub server_pubkey: PublicKey,
+}
+
+#[derive(Debug, Error)]
+pub enum UnsealError {
+    #[error("Invalid key provided for unsealing")]
+    InvalidKey,
+    #[error("Internal error during unsealing process")]
+    General(#[from] super::Error),
+}
+
+#[derive(Debug, Error)]
+pub enum BootstrapError {
+    #[error("Invalid key provided for bootstrapping")]
+    InvalidKey,
+    #[error("Vault is already bootstrapped")]
+    AlreadyBootstrapped,
+
+    #[error("Internal error during bootstrapping process")]
+    General(#[from] super::Error),
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message]
+    pub async fn handle_unseal_request(
+        &mut self,
+        client_pubkey: x25519_dalek::PublicKey,
+    ) -> Result<UnsealStartResponse, Error> {
+        let secret = EphemeralSecret::random();
+        let public_key = PublicKey::from(&secret);
+
+        self.transition(UserAgentEvents::UnsealRequest(UnsealContext {
+            secret: Mutex::new(Some(secret)),
+            client_public_key: client_pubkey,
+        }))?;
+
+        Ok(UnsealStartResponse {
+            server_pubkey: public_key,
+        })
+    }
+
+    #[message]
+    pub async fn handle_unseal_encrypted_key(
+        &mut self,
+        nonce: Vec<u8>,
+        ciphertext: Vec<u8>,
+        associated_data: Vec<u8>,
+    ) -> Result<(), UnsealError> {
+        let (ephemeral_secret, client_public_key) = match self.take_unseal_secret() {
+            Ok(values) => values,
+            Err(Error::State) => {
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                return Err(UnsealError::InvalidKey);
+            }
+            Err(_err) => {
+                return Err(Error::internal("Failed to take unseal secret").into());
+            }
+        };
+
+        let seal_key_buffer = match Self::decrypt_client_key_material(
+            ephemeral_secret,
+            client_public_key,
+            &nonce,
+            &ciphertext,
+            &associated_data,
+        ) {
+            Ok(buffer) => buffer,
+            Err(()) => {
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                return Err(UnsealError::InvalidKey);
+            }
+        };
+
+        match self
+            .props
+            .actors
+            .key_holder
+            .ask(TryUnseal {
+                seal_key_raw: seal_key_buffer,
+            })
+            .await
+        {
+            Ok(_) => {
+                info!("Successfully unsealed key with client-provided key");
+                self.transition(UserAgentEvents::ReceivedValidKey)?;
+                Ok(())
+            }
+            Err(SendError::HandlerError(keyholder::Error::InvalidKey)) => {
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                Err(UnsealError::InvalidKey)
+            }
+            Err(SendError::HandlerError(err)) => {
+                error!(?err, "Keyholder failed to unseal key");
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                Err(UnsealError::InvalidKey)
+            }
+            Err(err) => {
+                error!(?err, "Failed to send unseal request to keyholder");
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                Err(Error::internal("Vault actor error").into())
+            }
+        }
+    }
+
+    #[message]
+    pub(crate) async fn handle_bootstrap_encrypted_key(
+        &mut self,
+        nonce: Vec<u8>,
+        ciphertext: Vec<u8>,
+        associated_data: Vec<u8>,
+    ) -> Result<(), BootstrapError> {
+        let (ephemeral_secret, client_public_key) = match self.take_unseal_secret() {
+            Ok(values) => values,
+            Err(Error::State) => {
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                return Err(BootstrapError::InvalidKey);
+            }
+            Err(err) => return Err(err.into()),
+        };
+
+        let seal_key_buffer = match Self::decrypt_client_key_material(
+            ephemeral_secret,
+            client_public_key,
+            &nonce,
+            &ciphertext,
+            &associated_data,
+        ) {
+            Ok(buffer) => buffer,
+            Err(()) => {
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                return Err(BootstrapError::InvalidKey);
+            }
+        };
+
+        match self
+            .props
+            .actors
+            .key_holder
+            .ask(Bootstrap {
+                seal_key_raw: seal_key_buffer,
+            })
+            .await
+        {
+            Ok(_) => {
+                info!("Successfully bootstrapped vault with client-provided key");
+                self.transition(UserAgentEvents::ReceivedValidKey)?;
+                Ok(())
+            }
+            Err(SendError::HandlerError(keyholder::Error::AlreadyBootstrapped)) => {
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                Err(BootstrapError::AlreadyBootstrapped)
+            }
+            Err(SendError::HandlerError(err)) => {
+                error!(?err, "Keyholder failed to bootstrap vault");
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                Err(BootstrapError::InvalidKey)
+            }
+            Err(err) => {
+                error!(?err, "Failed to send bootstrap request to keyholder");
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                Err(BootstrapError::General(Error::internal(
+                    "Vault actor error",
+                )))
+            }
+        }
+    }
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message]
+    pub(crate) async fn handle_query_vault_state(&mut self) -> Result<KeyHolderState, Error> {
+        use crate::actors::keyholder::GetState;
+
+        let vault_state = match self.props.actors.key_holder.ask(GetState {}).await {
+            Ok(state) => state,
+            Err(err) => {
+                error!(?err, actor = "useragent", "keyholder.query.failed");
+                return Err(Error::internal("Vault is in broken state"));
+            }
+        };
+
+        Ok(vault_state)
+    }
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message]
+    pub(crate) async fn handle_evm_wallet_create(&mut self) -> Result<Address, Error> {
+        match self.props.actors.evm.ask(Generate {}).await {
+            Ok(address) => Ok(address),
+            Err(SendError::HandlerError(err)) => Err(Error::internal(format!(
+                "EVM wallet generation failed: {err}"
+            ))),
+            Err(err) => {
+                error!(?err, "EVM actor unreachable during wallet create");
+                Err(Error::internal("EVM actor unreachable"))
+            }
+        }
+    }
+
+    #[message]
+    pub(crate) async fn handle_evm_wallet_list(&mut self) -> Result<Vec<Address>, Error> {
+        match self.props.actors.evm.ask(ListWallets {}).await {
+            Ok(wallets) => Ok(wallets),
+            Err(err) => {
+                error!(?err, "EVM wallet list failed");
+                Err(Error::internal("Failed to list EVM wallets"))
+            }
+        }
+    }
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message]
+    pub(crate) async fn handle_grant_list(&mut self) -> Result<Vec<Grant<SpecificGrant>>, Error> {
+        match self.props.actors.evm.ask(UseragentListGrants {}).await {
+            Ok(grants) => Ok(grants),
+            Err(err) => {
+                error!(?err, "EVM grant list failed");
+                Err(Error::internal("Failed to list EVM grants"))
+            }
+        }
+    }
+
+    #[message]
+    pub(crate) async fn handle_grant_create(
+        &mut self,
+        client_id: i32,
+        basic: crate::evm::policies::SharedGrantSettings,
+        grant: crate::evm::policies::SpecificGrant,
+    ) -> Result<i32, Error> {
+        match self
+            .props
+            .actors
+            .evm
+            .ask(UseragentCreateGrant {
+                client_id,
+                basic,
+                grant,
+            })
+            .await
+        {
+            Ok(grant_id) => Ok(grant_id),
+            Err(err) => {
+                error!(?err, "EVM grant create failed");
+                Err(Error::internal("Failed to create EVM grant"))
+            }
+        }
+    }
+
+    #[message]
+    pub(crate) async fn handle_grant_delete(&mut self, grant_id: i32) -> Result<(), Error> {
+        match self
+            .props
+            .actors
+            .evm
+            .ask(UseragentDeleteGrant { grant_id })
+            .await
+        {
+            Ok(()) => Ok(()),
+            Err(err) => {
+                error!(?err, "EVM grant delete failed");
+                Err(Error::internal("Failed to delete EVM grant"))
+            }
+        }
+    }
+}

server/crates/arbiter-server/src/actors/user_agent/session/state.rs

@@ -0,0 +1,27 @@
+use std::sync::Mutex;
+
+use x25519_dalek::{EphemeralSecret, PublicKey};
+
+pub struct UnsealContext {
+    pub client_public_key: PublicKey,
+    pub secret: Mutex<Option<EphemeralSecret>>,
+}
+
+smlang::statemachine!(
+    name: UserAgent,
+    custom_error: false,
+    transitions: {
+        *Idle + UnsealRequest(UnsealContext) / generate_temp_keypair = WaitingForUnsealKey(UnsealContext),
+        WaitingForUnsealKey(UnsealContext) + ReceivedValidKey = Unsealed,
+        WaitingForUnsealKey(UnsealContext) + ReceivedInvalidKey = Idle,
+    }
+);
+
+pub struct DummyContext;
+impl UserAgentStateMachineContext for DummyContext {
+    #[allow(missing_docs)]
+    #[allow(clippy::unused_unit)]
+    fn generate_temp_keypair(&mut self, event_data: UnsealContext) -> Result<UnsealContext, ()> {
+        Ok(event_data)
+    }
+}

server/crates/arbiter-server/src/actors/user_agent/state.rs

@@ -1,51 +0,0 @@
-use std::sync::Mutex;
-
-use arbiter_proto::proto::auth::AuthChallenge;
-use ed25519_dalek::VerifyingKey;
-use x25519_dalek::{EphemeralSecret, PublicKey};
-
-/// Context for state machine with validated key and sent challenge
-/// Challenge is then transformed to bytes using shared function and verified
-#[derive(Clone, Debug)]
-pub struct ChallengeContext {
-    pub challenge: AuthChallenge,
-    pub key: VerifyingKey,
-}
-
-pub struct UnsealContext {
-    pub client_public_key: PublicKey,
-    pub secret: Mutex<Option<EphemeralSecret>>,
-}
-
-smlang::statemachine!(
-    name: UserAgent,
-    custom_error: false,
-    transitions: {
-        *Init + AuthRequest =  ReceivedAuthRequest,
-        ReceivedAuthRequest + ReceivedBootstrapToken = Idle,
-
-        ReceivedAuthRequest + SentChallenge(ChallengeContext) / move_challenge = WaitingForChallengeSolution(ChallengeContext),
-
-        WaitingForChallengeSolution(ChallengeContext) + ReceivedGoodSolution = Idle,
-        WaitingForChallengeSolution(ChallengeContext) + ReceivedBadSolution = AuthError, // block further transitions, but connection should close anyway
-
-        Idle + UnsealRequest(UnsealContext) / generate_temp_keypair = WaitingForUnsealKey(UnsealContext),
-        WaitingForUnsealKey(UnsealContext) + ReceivedValidKey = Unsealed,
-        WaitingForUnsealKey(UnsealContext) + ReceivedInvalidKey = Idle,
-    }
-);
-
-pub struct DummyContext;
-impl UserAgentStateMachineContext for DummyContext {
-    #[allow(missing_docs)]
-    #[allow(clippy::unused_unit)]
-    fn generate_temp_keypair(&mut self, event_data: UnsealContext) -> Result<UnsealContext, ()> {
-        Ok(event_data)
-    }
-
-    #[allow(missing_docs)]
-    #[allow(clippy::unused_unit)]
-    fn move_challenge(&mut self, event_data: ChallengeContext) -> Result<ChallengeContext, ()> {
-        Ok(event_data)
-    }
-}

server/crates/arbiter-server/src/context/tls.rs

@@ -8,7 +8,7 @@ use rcgen::{
     BasicConstraints, Certificate, CertificateParams, CertifiedIssuer, DistinguishedName, DnType,
     IsCa, Issuer, KeyPair, KeyUsagePurpose,
 };
-use rustls::pki_types::{pem::PemObject};
+use rustls::pki_types::pem::PemObject;
 use thiserror::Error;
 use tonic::transport::CertificateDer;
 
@@ -59,10 +59,7 @@ pub enum InitError {
 pub type PemCert = String;
 
 pub fn encode_cert_to_pem(cert: &CertificateDer) -> PemCert {
-    pem::encode_config(
-        &Pem::new("CERTIFICATE", cert.to_vec()),
-        ENCODE_CONFIG,
-    )
+    pem::encode_config(&Pem::new("CERTIFICATE", cert.to_vec()), ENCODE_CONFIG)
 }
 
 #[allow(unused)]
@@ -94,6 +91,10 @@ impl TlsCa {
 
         let cert_key_pem = certified_issuer.key().serialize_pem();
 
+        #[allow(
+            clippy::unwrap_used,
+            reason = "Broken cert couldn't bootstrap server anyway"
+        )]
         let issuer = Issuer::from_ca_cert_pem(
             &certified_issuer.pem(),
             KeyPair::from_pem(cert_key_pem.as_ref()).unwrap(),

server/crates/arbiter-server/src/db/mod.rs

@@ -44,6 +44,14 @@ pub enum DatabaseSetupError {
     Pool(#[from] PoolInitError),
 }
 
+#[derive(Error, Debug)]
+pub enum DatabaseError {
+    #[error("Database connection error")]
+    Pool(#[from] PoolError),
+    #[error("Database query error")]
+    Connection(#[from] diesel::result::Error),
+}
+
 #[tracing::instrument(level = "info")]
 fn database_path() -> Result<std::path::PathBuf, DatabaseSetupError> {
     let arbiter_home = arbiter_proto::home_path().map_err(DatabaseSetupError::HomeDir)?;
@@ -92,6 +100,7 @@ fn initialize_database(url: &str) -> Result<(), DatabaseSetupError> {
 #[tracing::instrument(level = "info")]
 pub async fn create_pool(url: Option<&str>) -> Result<DatabasePool, DatabaseSetupError> {
     let database_url = url.map(String::from).unwrap_or(
+        #[allow(clippy::expect_used)]
         database_path()?
             .to_str()
             .expect("database path is not valid UTF-8")
@@ -135,11 +144,13 @@ pub async fn create_test_pool() -> DatabasePool {
     let tempfile_name = Alphanumeric.sample_string(&mut rand::rng(), 16);
 
     let file = std::env::temp_dir().join(tempfile_name);
-    let url = format!(
-        "{}?mode=rwc",
-        file.to_str().expect("temp file path is not valid UTF-8")
-    );
+    #[allow(clippy::expect_used)]
+    let url = file
+        .to_str()
+        .expect("temp file path is not valid UTF-8")
+        .to_string();
 
+    #[allow(clippy::expect_used)]
     create_pool(Some(&url))
         .await
         .expect("Failed to create test database pool")

server/crates/arbiter-server/src/db/models.rs

@@ -1,14 +1,113 @@
 #![allow(unused)]
 #![allow(clippy::all)]
 
-use crate::db::schema::{self, aead_encrypted, arbiter_settings, root_key_history, tls_history};
+use crate::db::schema::{
+    self, aead_encrypted, arbiter_settings, evm_basic_grant, evm_ether_transfer_grant,
+    evm_ether_transfer_grant_target, evm_ether_transfer_limit, evm_token_transfer_grant,
+    evm_token_transfer_log, evm_token_transfer_volume_limit, evm_transaction_log, evm_wallet,
+    root_key_history, tls_history,
+};
+use chrono::{DateTime, Utc};
 use diesel::{prelude::*, sqlite::Sqlite};
 use restructed::Models;
 
 pub mod types {
     use chrono::{DateTime, Utc};
-    pub struct SqliteTimestamp(DateTime<Utc>);
+    use diesel::{
+        deserialize::{FromSql, FromSqlRow},
+        expression::AsExpression,
+        serialize::{IsNull, ToSql},
+        sql_types::Integer,
+        sqlite::{Sqlite, SqliteType},
+    };
+
+    #[derive(Debug, FromSqlRow, AsExpression)]
+    #[diesel(sql_type = Integer)]
+    #[repr(transparent)] // hint compiler to optimize the wrapper struct away
+    pub struct SqliteTimestamp(pub DateTime<Utc>);
+    impl SqliteTimestamp {
+        pub fn now() -> Self {
+            SqliteTimestamp(Utc::now())
+        }
+    }
+
+    impl From<chrono::DateTime<Utc>> for SqliteTimestamp {
+        fn from(dt: chrono::DateTime<Utc>) -> Self {
+            SqliteTimestamp(dt)
+        }
+    }
+    impl From<SqliteTimestamp> for chrono::DateTime<Utc> {
+        fn from(ts: SqliteTimestamp) -> Self {
+            ts.0
+        }
+    }
+
+    impl ToSql<Integer, Sqlite> for SqliteTimestamp {
+        fn to_sql<'b>(
+            &'b self,
+            out: &mut diesel::serialize::Output<'b, '_, Sqlite>,
+        ) -> diesel::serialize::Result {
+            let unix_timestamp = self.0.timestamp() as i32;
+            out.set_value(unix_timestamp);
+            Ok(IsNull::No)
+        }
+    }
+
+    impl FromSql<Integer, Sqlite> for SqliteTimestamp {
+        fn from_sql(
+            mut bytes: <Sqlite as diesel::backend::Backend>::RawValue<'_>,
+        ) -> diesel::deserialize::Result<Self> {
+            let Some(SqliteType::Long) = bytes.value_type() else {
+                return Err(format!(
+                    "Expected Integer type for SqliteTimestamp, got {:?}",
+                    bytes.value_type()
+                )
+                .into());
+            };
+
+            let unix_timestamp = bytes.read_long();
+            let datetime =
+                DateTime::from_timestamp(unix_timestamp, 0).ok_or("Timestamp is out of bounds")?;
+
+            Ok(SqliteTimestamp(datetime))
+        }
+    }
+
+    /// Key algorithm stored in the `useragent_client.key_type` column.
+    /// Values must stay stable — they are persisted in the database.
+    #[derive(Debug, Clone, Copy, PartialEq, Eq, FromSqlRow, AsExpression, strum::FromRepr)]
+    #[diesel(sql_type = Integer)]
+    #[repr(i32)]
+    pub enum KeyType {
+        Ed25519 = 1,
+        EcdsaSecp256k1 = 2,
+        Rsa = 3,
+    }
+
+    impl ToSql<Integer, Sqlite> for KeyType {
+        fn to_sql<'b>(
+            &'b self,
+            out: &mut diesel::serialize::Output<'b, '_, Sqlite>,
+        ) -> diesel::serialize::Result {
+            out.set_value(*self as i32);
+            Ok(IsNull::No)
+        }
+    }
+
+    impl FromSql<Integer, Sqlite> for KeyType {
+        fn from_sql(
+            mut bytes: <Sqlite as diesel::backend::Backend>::RawValue<'_>,
+        ) -> diesel::deserialize::Result<Self> {
+            let Some(SqliteType::Long) = bytes.value_type() else {
+                return Err("Expected Integer for KeyType".into());
+            };
+            let discriminant = bytes.read_long();
+            KeyType::from_repr(discriminant as i32)
+                .ok_or_else(|| format!("Unknown KeyType discriminant: {discriminant}").into())
+        }
+    }
 }
+pub use types::*;
 
 #[derive(Models, Queryable, Debug, Insertable, Selectable)]
 #[view(
@@ -25,7 +124,7 @@ pub struct AeadEncrypted {
     pub current_nonce: Vec<u8>,
     pub schema_version: i32,
     pub associated_root_key_id: i32, // references root_key_history.id
-    pub created_at: i32,
+    pub created_at: SqliteTimestamp,
 }
 
 #[derive(Models, Queryable, Debug, Insertable, Selectable)]
@@ -58,9 +157,9 @@ pub struct TlsHistory {
     pub id: i32,
     pub cert: String,
     pub cert_key: String, // PEM Encoded private key
-    pub ca_cert: String, // PEM Encoded certificate for cert signing
-    pub ca_key: String, // PEM Encoded public key for cert signing
-    pub created_at: i32,
+    pub ca_cert: String,  // PEM Encoded certificate for cert signing
+    pub ca_key: String,   // PEM Encoded public key for cert signing
+    pub created_at: SqliteTimestamp,
 }
 
 #[derive(Queryable, Debug, Insertable, Selectable)]
@@ -68,25 +167,173 @@ pub struct TlsHistory {
 pub struct ArbiterSettings {
     pub id: i32,
     pub root_key_id: Option<i32>, // references root_key_history.id
-    pub tls_id: Option<i32>, // references tls_history.id
+    pub tls_id: Option<i32>,      // references tls_history.id
 }
 
-#[derive(Queryable, Debug)]
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_wallet, check_for_backend(Sqlite))]
+#[view(
+    NewEvmWallet,
+    derive(Insertable),
+    omit(id, created_at),
+    attributes_with = "deriveless"
+)]
+pub struct EvmWallet {
+    pub id: i32,
+    pub address: Vec<u8>,
+    pub aead_encrypted_id: i32,
+    pub created_at: SqliteTimestamp,
+}
+
+#[derive(Queryable, Debug, Insertable, Selectable)]
 #[diesel(table_name = schema::program_client, check_for_backend(Sqlite))]
 pub struct ProgramClient {
     pub id: i32,
-    pub public_key: Vec<u8>,
     pub nonce: i32,
-    pub created_at: i32,
-    pub updated_at: i32,
+    pub public_key: Vec<u8>,
+    pub created_at: SqliteTimestamp,
+    pub updated_at: SqliteTimestamp,
 }
 
 #[derive(Queryable, Debug)]
 #[diesel(table_name = schema::useragent_client, check_for_backend(Sqlite))]
 pub struct UseragentClient {
     pub id: i32,
-    pub public_key: Vec<u8>,
     pub nonce: i32,
-    pub created_at: i32,
-    pub updated_at: i32,
+    pub public_key: Vec<u8>,
+    pub created_at: SqliteTimestamp,
+    pub updated_at: SqliteTimestamp,
+    pub key_type: KeyType,
+}
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_ether_transfer_limit, check_for_backend(Sqlite))]
+#[view(
+    NewEvmEtherTransferLimit,
+    derive(Insertable),
+    omit(id, created_at),
+    attributes_with = "deriveless"
+)]
+pub struct EvmEtherTransferLimit {
+    pub id: i32,
+    pub window_secs: i32,
+    pub max_volume: Vec<u8>,
+}
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_basic_grant, check_for_backend(Sqlite))]
+#[view(
+    NewEvmBasicGrant,
+    derive(Insertable),
+    omit(id, created_at),
+    attributes_with = "deriveless"
+)]
+pub struct EvmBasicGrant {
+    pub id: i32,
+    pub wallet_id: i32, // references evm_wallet.id
+    pub client_id: i32, // references program_client.id
+    pub chain_id: i32,
+    pub valid_from: Option<SqliteTimestamp>,
+    pub valid_until: Option<SqliteTimestamp>,
+    pub max_gas_fee_per_gas: Option<Vec<u8>>,
+    pub max_priority_fee_per_gas: Option<Vec<u8>>,
+    pub rate_limit_count: Option<i32>,
+    pub rate_limit_window_secs: Option<i32>,
+    pub revoked_at: Option<SqliteTimestamp>,
+    pub created_at: SqliteTimestamp,
+}
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_transaction_log, check_for_backend(Sqlite))]
+#[view(
+    NewEvmTransactionLog,
+    derive(Insertable),
+    omit(id),
+    attributes_with = "deriveless"
+)]
+pub struct EvmTransactionLog {
+    pub id: i32,
+    pub grant_id: i32,
+    pub client_id: i32,
+    pub wallet_id: i32,
+    pub chain_id: i32,
+    pub eth_value: Vec<u8>,
+    pub signed_at: SqliteTimestamp,
+}
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_ether_transfer_grant, check_for_backend(Sqlite))]
+#[view(
+    NewEvmEtherTransferGrant,
+    derive(Insertable),
+    omit(id),
+    attributes_with = "deriveless"
+)]
+pub struct EvmEtherTransferGrant {
+    pub id: i32,
+    pub basic_grant_id: i32,
+    pub limit_id: i32, // references evm_ether_transfer_limit.id
+}
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_ether_transfer_grant_target, check_for_backend(Sqlite))]
+#[view(
+    NewEvmEtherTransferGrantTarget,
+    derive(Insertable),
+    omit(id),
+    attributes_with = "deriveless"
+)]
+pub struct EvmEtherTransferGrantTarget {
+    pub id: i32,
+    pub grant_id: i32,
+    pub address: Vec<u8>,
+}
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_token_transfer_grant, check_for_backend(Sqlite))]
+#[view(
+    NewEvmTokenTransferGrant,
+    derive(Insertable),
+    omit(id),
+    attributes_with = "deriveless"
+)]
+pub struct EvmTokenTransferGrant {
+    pub id: i32,
+    pub basic_grant_id: i32,
+    pub token_contract: Vec<u8>,
+    pub receiver: Option<Vec<u8>>,
+}
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_token_transfer_volume_limit, check_for_backend(Sqlite))]
+#[view(
+    NewEvmTokenTransferVolumeLimit,
+    derive(Insertable),
+    omit(id),
+    attributes_with = "deriveless"
+)]
+pub struct EvmTokenTransferVolumeLimit {
+    pub id: i32,
+    pub grant_id: i32,
+    pub window_secs: i32,
+    pub max_volume: Vec<u8>,
+}
+
+#[derive(Models, Queryable, Debug, Insertable, Selectable)]
+#[diesel(table_name = evm_token_transfer_log, check_for_backend(Sqlite))]
+#[view(
+    NewEvmTokenTransferLog,
+    derive(Insertable),
+    omit(id, created_at),
+    attributes_with = "deriveless"
+)]
+pub struct EvmTokenTransferLog {
+    pub id: i32,
+    pub grant_id: i32,
+    pub log_id: i32,
+    pub chain_id: i32,
+    pub token_contract: Vec<u8>,
+    pub recipient_address: Vec<u8>,
+    pub value: Vec<u8>,
+    pub created_at: SqliteTimestamp,
 }

server/crates/arbiter-server/src/db/schema.rs

@@ -20,6 +20,99 @@ diesel::table! {
     }
 }
 
+diesel::table! {
+    evm_basic_grant (id) {
+        id -> Integer,
+        wallet_id -> Integer,
+        client_id -> Integer,
+        chain_id -> Integer,
+        valid_from -> Nullable<Integer>,
+        valid_until -> Nullable<Integer>,
+        max_gas_fee_per_gas -> Nullable<Binary>,
+        max_priority_fee_per_gas -> Nullable<Binary>,
+        rate_limit_count -> Nullable<Integer>,
+        rate_limit_window_secs -> Nullable<Integer>,
+        revoked_at -> Nullable<Integer>,
+        created_at -> Integer,
+    }
+}
+
+diesel::table! {
+    evm_ether_transfer_grant (id) {
+        id -> Integer,
+        basic_grant_id -> Integer,
+        limit_id -> Integer,
+    }
+}
+
+diesel::table! {
+    evm_ether_transfer_grant_target (id) {
+        id -> Integer,
+        grant_id -> Integer,
+        address -> Binary,
+    }
+}
+
+diesel::table! {
+    evm_ether_transfer_limit (id) {
+        id -> Integer,
+        window_secs -> Integer,
+        max_volume -> Binary,
+    }
+}
+
+diesel::table! {
+    evm_token_transfer_grant (id) {
+        id -> Integer,
+        basic_grant_id -> Integer,
+        token_contract -> Binary,
+        receiver -> Nullable<Binary>,
+    }
+}
+
+diesel::table! {
+    evm_token_transfer_log (id) {
+        id -> Integer,
+        grant_id -> Integer,
+        log_id -> Integer,
+        chain_id -> Integer,
+        token_contract -> Binary,
+        recipient_address -> Binary,
+        value -> Binary,
+        created_at -> Integer,
+    }
+}
+
+diesel::table! {
+    evm_token_transfer_volume_limit (id) {
+        id -> Integer,
+        grant_id -> Integer,
+        window_secs -> Integer,
+        max_volume -> Binary,
+    }
+}
+
+diesel::table! {
+    evm_transaction_log (id) {
+        id -> Integer,
+        grant_id -> Integer,
+        client_id -> Integer,
+        wallet_id -> Integer,
+        chain_id -> Integer,
+        eth_value -> Binary,
+        signed_at -> Integer,
+    }
+}
+
+diesel::table! {
+    evm_wallet (id) {
+        id -> Integer,
+        address -> Binary,
+        aead_encrypted_id -> Integer,
+        created_at -> Integer,
+    }
+}
+
 diesel::table! {
     program_client (id) {
         id -> Integer,
@@ -60,16 +153,36 @@ diesel::table! {
         public_key -> Binary,
         created_at -> Integer,
         updated_at -> Integer,
+        key_type -> Integer,
     }
 }
 
 diesel::joinable!(aead_encrypted -> root_key_history (associated_root_key_id));
 diesel::joinable!(arbiter_settings -> root_key_history (root_key_id));
 diesel::joinable!(arbiter_settings -> tls_history (tls_id));
+diesel::joinable!(evm_basic_grant -> evm_wallet (wallet_id));
+diesel::joinable!(evm_basic_grant -> program_client (client_id));
+diesel::joinable!(evm_ether_transfer_grant -> evm_basic_grant (basic_grant_id));
+diesel::joinable!(evm_ether_transfer_grant -> evm_ether_transfer_limit (limit_id));
+diesel::joinable!(evm_ether_transfer_grant_target -> evm_ether_transfer_grant (grant_id));
+diesel::joinable!(evm_token_transfer_grant -> evm_basic_grant (basic_grant_id));
+diesel::joinable!(evm_token_transfer_log -> evm_token_transfer_grant (grant_id));
+diesel::joinable!(evm_token_transfer_log -> evm_transaction_log (log_id));
+diesel::joinable!(evm_token_transfer_volume_limit -> evm_token_transfer_grant (grant_id));
+diesel::joinable!(evm_wallet -> aead_encrypted (aead_encrypted_id));
 
 diesel::allow_tables_to_appear_in_same_query!(
     aead_encrypted,
     arbiter_settings,
+    evm_basic_grant,
+    evm_ether_transfer_grant,
+    evm_ether_transfer_grant_target,
+    evm_ether_transfer_limit,
+    evm_token_transfer_grant,
+    evm_token_transfer_log,
+    evm_token_transfer_volume_limit,
+    evm_transaction_log,
+    evm_wallet,
     program_client,
     root_key_history,
     tls_history,

server/crates/arbiter-server/src/evm/abi.rs

@@ -0,0 +1,84 @@
+use alloy::sol;
+
+sol! {
+    interface IERC20 {
+        event Transfer(address indexed from, address indexed to, uint256 value);
+        event Approval(address indexed owner, address indexed spender, uint256 value);
+
+        function totalSupply() external view returns (uint256);
+        function balanceOf(address account) external view returns (uint256);
+        function transfer(address to, uint256 value) external returns (bool);
+        function allowance(address owner, address spender) external view returns (uint256);
+        function approve(address spender, uint256 value) external returns (bool);
+        function transferFrom(address from, address to, uint256 value) external returns (bool);
+    }
+}
+
+sol! {
+    /// ERC-721: Non-Fungible Token Standard.
+    #[derive(Debug)]
+    interface IERC721 {
+        event Transfer(address indexed from, address indexed to, uint256 indexed tokenId);
+        event Approval(address indexed owner, address indexed approved, uint256 indexed tokenId);
+        event ApprovalForAll(address indexed owner, address indexed operator, bool approved);
+
+        function balanceOf(address owner) external view returns (uint256 balance);
+        function ownerOf(uint256 tokenId) external view returns (address owner);
+        function safeTransferFrom(address from, address to, uint256 tokenId) external;
+        function safeTransferFrom(address from, address to, uint256 tokenId, bytes calldata data) external;
+        function transferFrom(address from, address to, uint256 tokenId) external;
+        function approve(address to, uint256 tokenId) external;
+        function setApprovalForAll(address operator, bool approved) external;
+        function getApproved(uint256 tokenId) external view returns (address operator);
+        function isApprovedForAll(address owner, address operator) external view returns (bool);
+    }
+}
+
+sol! {
+    /// Wrapped Ether — the only functions beyond ERC-20 that matter.
+    #[derive(Debug)]
+    interface IWETH {
+        function deposit() external payable;
+        function withdraw(uint256 wad) external;
+    }
+}
+
+sol! {
+    /// Permit2 — Uniswap's canonical token approval manager.
+    /// Replaces per-contract ERC-20 approve() with a single approval hub.
+    #[derive(Debug)]
+    interface IPermit2 {
+        struct TokenPermissions {
+            address token;
+            uint256 amount;
+        }
+
+        struct PermitSingle {
+            TokenPermissions details;
+            address spender;
+            uint256 sigDeadline;
+        }
+
+        struct PermitBatch {
+            TokenPermissions[] details;
+            address spender;
+            uint256 sigDeadline;
+        }
+
+        struct AllowanceTransferDetails {
+            address from;
+            address to;
+            uint160 amount;
+            address token;
+        }
+
+        function approve(address token, address spender, uint160 amount, uint48 expiration) external;
+        function permit(address owner, PermitSingle calldata permitSingle, bytes calldata signature) external;
+        function permit(address owner, PermitBatch calldata permitBatch, bytes calldata signature) external;
+        function transferFrom(address from, address to, uint160 amount, address token) external;
+        function transferFrom(AllowanceTransferDetails[] calldata transferDetails) external;
+
+        function allowance(address user, address token, address spender)
+            external view returns (uint160 amount, uint48 expiration, uint48 nonce);
+    }
+}

server/crates/arbiter-server/src/evm/mod.rs

@@ -0,0 +1,338 @@
+pub mod abi;
+pub mod safe_signer;
+
+use alloy::{
+    consensus::TxEip1559,
+    primitives::{TxKind, U256},
+};
+use chrono::Utc;
+use diesel::{ExpressionMethods as _, QueryDsl, QueryResult, insert_into, sqlite::Sqlite};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+
+use crate::{
+    db::{
+        self,
+        models::{EvmBasicGrant, NewEvmBasicGrant, NewEvmTransactionLog, SqliteTimestamp},
+        schema::{self, evm_transaction_log},
+    },
+    evm::policies::{
+        DatabaseID, EvalContext, EvalViolation, FullGrant, Grant, Policy, SharedGrantSettings,
+        SpecificGrant, SpecificMeaning, ether_transfer::EtherTransfer,
+        token_transfers::TokenTransfer,
+    },
+};
+
+pub mod policies;
+mod utils;
+
+/// Errors that can only occur once the transaction meaning is known (during policy evaluation)
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum PolicyError {
+    #[error("Database connection pool error")]
+    #[diagnostic(code(arbiter_server::evm::policy_error::pool))]
+    Pool(#[from] db::PoolError),
+    #[error("Database returned error")]
+    #[diagnostic(code(arbiter_server::evm::policy_error::database))]
+    Database(#[from] diesel::result::Error),
+    #[error("Transaction violates policy: {0:?}")]
+    #[diagnostic(code(arbiter_server::evm::policy_error::violation))]
+    Violations(Vec<EvalViolation>),
+    #[error("No matching grant found")]
+    #[diagnostic(code(arbiter_server::evm::policy_error::no_matching_grant))]
+    NoMatchingGrant,
+}
+
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum VetError {
+    #[error("Contract creation transactions are not supported")]
+    #[diagnostic(code(arbiter_server::evm::vet_error::contract_creation_unsupported))]
+    ContractCreationNotSupported,
+    #[error("Engine can't classify this transaction")]
+    #[diagnostic(code(arbiter_server::evm::vet_error::unsupported))]
+    UnsupportedTransactionType,
+    #[error("Policy evaluation failed: {1}")]
+    #[diagnostic(code(arbiter_server::evm::vet_error::evaluated))]
+    Evaluated(SpecificMeaning, #[source] PolicyError),
+}
+
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum SignError {
+    #[error("Database connection pool error")]
+    #[diagnostic(code(arbiter_server::evm::database_error))]
+    Pool(#[from] db::PoolError),
+    #[error("Database returned error")]
+    #[diagnostic(code(arbiter_server::evm::database_error))]
+    Database(#[from] diesel::result::Error),
+}
+
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum AnalyzeError {
+    #[error("Engine doesn't support granting permissions for contract creation")]
+    #[diagnostic(code(arbiter_server::evm::analyze_error::contract_creation_not_supported))]
+    ContractCreationNotSupported,
+
+    #[error("Unsupported transaction type")]
+    #[diagnostic(code(arbiter_server::evm::analyze_error::unsupported_transaction_type))]
+    UnsupportedTransactionType,
+}
+
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum CreationError {
+    #[error("Database connection pool error")]
+    #[diagnostic(code(arbiter_server::evm::creation_error::database_error))]
+    Pool(#[from] db::PoolError),
+
+    #[error("Database returned error")]
+    #[diagnostic(code(arbiter_server::evm::creation_error::database_error))]
+    Database(#[from] diesel::result::Error),
+}
+
+#[derive(Debug, thiserror::Error, miette::Diagnostic)]
+pub enum ListGrantsError {
+    #[error("Database connection pool error")]
+    #[diagnostic(code(arbiter_server::evm::list_grants_error::pool))]
+    Pool(#[from] db::PoolError),
+
+    #[error("Database returned error")]
+    #[diagnostic(code(arbiter_server::evm::list_grants_error::database))]
+    Database(#[from] diesel::result::Error),
+}
+
+/// Controls whether a transaction should be executed or only validated
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum RunKind {
+    /// Validate and record the transaction
+    Execution,
+    /// Validate only, do not record
+    CheckOnly,
+}
+
+async fn check_shared_constraints(
+    context: &EvalContext,
+    shared: &SharedGrantSettings,
+    shared_grant_id: DatabaseID,
+    conn: &mut impl AsyncConnection<Backend = Sqlite>,
+) -> QueryResult<Vec<EvalViolation>> {
+    let mut violations = Vec::new();
+    let now = Utc::now();
+
+    // Validity window
+    if shared.valid_from.is_some_and(|t| now < t) || shared.valid_until.is_some_and(|t| now > t) {
+        violations.push(EvalViolation::InvalidTime);
+    }
+
+    // Gas fee caps
+    let fee_exceeded = shared
+        .max_gas_fee_per_gas
+        .is_some_and(|cap| U256::from(context.max_fee_per_gas) > cap);
+    let priority_exceeded = shared
+        .max_priority_fee_per_gas
+        .is_some_and(|cap| U256::from(context.max_priority_fee_per_gas) > cap);
+    if fee_exceeded || priority_exceeded {
+        violations.push(EvalViolation::GasLimitExceeded {
+            max_gas_fee_per_gas: shared.max_gas_fee_per_gas,
+            max_priority_fee_per_gas: shared.max_priority_fee_per_gas,
+        });
+    }
+
+    // Transaction count rate limit
+    if let Some(rate_limit) = &shared.rate_limit {
+        let window_start = SqliteTimestamp(now - rate_limit.window);
+        let count: i64 = evm_transaction_log::table
+            .filter(evm_transaction_log::grant_id.eq(shared_grant_id))
+            .filter(evm_transaction_log::signed_at.ge(window_start))
+            .count()
+            .get_result(conn)
+            .await?;
+
+        if count >= rate_limit.count as i64 {
+            violations.push(EvalViolation::RateLimitExceeded);
+        }
+    }
+
+    Ok(violations)
+}
+
+// Supporting only EIP-1559 transactions for now, but we can easily extend this to support legacy transactions if needed
+pub struct Engine {
+    db: db::DatabasePool,
+}
+
+impl Engine {
+    async fn vet_transaction<P: Policy>(
+        &self,
+        context: EvalContext,
+        meaning: &P::Meaning,
+        run_kind: RunKind,
+    ) -> Result<(), PolicyError> {
+        let mut conn = self.db.get().await?;
+
+        let grant = P::try_find_grant(&context, &mut conn)
+            .await?
+            .ok_or(PolicyError::NoMatchingGrant)?;
+
+        let mut violations =
+            check_shared_constraints(&context, &grant.shared, grant.shared_grant_id, &mut conn)
+                .await?;
+        violations.extend(P::evaluate(&context, meaning, &grant, &mut conn).await?);
+
+        if !violations.is_empty() {
+            return Err(PolicyError::Violations(violations));
+        } else if run_kind == RunKind::Execution {
+            conn.transaction(|conn| {
+                Box::pin(async move {
+                    let log_id: i32 = insert_into(evm_transaction_log::table)
+                        .values(&NewEvmTransactionLog {
+                            grant_id: grant.shared_grant_id,
+                            client_id: context.client_id,
+                            wallet_id: context.wallet_id,
+                            chain_id: context.chain as i32,
+                            eth_value: utils::u256_to_bytes(context.value).to_vec(),
+                            signed_at: Utc::now().into(),
+                        })
+                        .returning(evm_transaction_log::id)
+                        .get_result(conn)
+                        .await?;
+
+                    P::record_transaction(&context, meaning, log_id, &grant, conn).await?;
+
+                    QueryResult::Ok(())
+                })
+            })
+            .await?;
+        }
+
+        Ok(())
+    }
+}
+
+impl Engine {
+    pub fn new(db: db::DatabasePool) -> Self {
+        Self { db }
+    }
+
+    pub async fn create_grant<P: Policy>(
+        &self,
+        client_id: i32,
+        full_grant: FullGrant<P::Settings>,
+    ) -> Result<i32, CreationError> {
+        let mut conn = self.db.get().await?;
+
+        let id = conn
+            .transaction(|conn| {
+                Box::pin(async move {
+                    use schema::evm_basic_grant;
+
+                    let basic_grant: EvmBasicGrant = insert_into(evm_basic_grant::table)
+                        .values(&NewEvmBasicGrant {
+                            wallet_id: full_grant.basic.wallet_id,
+                            chain_id: full_grant.basic.chain as i32,
+                            client_id,
+                            valid_from: full_grant.basic.valid_from.map(SqliteTimestamp),
+                            valid_until: full_grant.basic.valid_until.map(SqliteTimestamp),
+                            max_gas_fee_per_gas: full_grant
+                                .basic
+                                .max_gas_fee_per_gas
+                                .map(|fee| utils::u256_to_bytes(fee).to_vec()),
+                            max_priority_fee_per_gas: full_grant
+                                .basic
+                                .max_priority_fee_per_gas
+                                .map(|fee| utils::u256_to_bytes(fee).to_vec()),
+                            rate_limit_count: full_grant
+                                .basic
+                                .rate_limit
+                                .as_ref()
+                                .map(|rl| rl.count as i32),
+                            rate_limit_window_secs: full_grant
+                                .basic
+                                .rate_limit
+                                .as_ref()
+                                .map(|rl| rl.window.num_seconds() as i32),
+                            revoked_at: None,
+                        })
+                        .returning(evm_basic_grant::all_columns)
+                        .get_result(conn)
+                        .await?;
+
+                    P::create_grant(&basic_grant, &full_grant.specific, conn).await
+                })
+            })
+            .await?;
+
+        Ok(id)
+    }
+
+    pub async fn list_all_grants(&self) -> Result<Vec<Grant<SpecificGrant>>, ListGrantsError> {
+        let mut conn = self.db.get().await?;
+
+        let mut grants: Vec<Grant<SpecificGrant>> = Vec::new();
+
+        grants.extend(
+            EtherTransfer::find_all_grants(&mut conn)
+                .await?
+                .into_iter()
+                .map(|g| Grant {
+                    id: g.id,
+                    shared_grant_id: g.shared_grant_id,
+                    shared: g.shared,
+                    settings: SpecificGrant::EtherTransfer(g.settings),
+                }),
+        );
+        grants.extend(
+            TokenTransfer::find_all_grants(&mut conn)
+                .await?
+                .into_iter()
+                .map(|g| Grant {
+                    id: g.id,
+                    shared_grant_id: g.shared_grant_id,
+                    shared: g.shared,
+                    settings: SpecificGrant::TokenTransfer(g.settings),
+                }),
+        );
+
+        Ok(grants)
+    }
+
+    pub async fn evaluate_transaction(
+        &self,
+        wallet_id: i32,
+        client_id: i32,
+        transaction: TxEip1559,
+        run_kind: RunKind,
+    ) -> Result<SpecificMeaning, VetError> {
+        let TxKind::Call(to) = transaction.to else {
+            return Err(VetError::ContractCreationNotSupported);
+        };
+        let context = policies::EvalContext {
+            wallet_id,
+            client_id,
+            chain: transaction.chain_id,
+            to,
+            value: transaction.value,
+            calldata: transaction.input.clone(),
+            max_fee_per_gas: transaction.max_fee_per_gas,
+            max_priority_fee_per_gas: transaction.max_priority_fee_per_gas,
+        };
+
+        if let Some(meaning) = EtherTransfer::analyze(&context) {
+            return match self
+                .vet_transaction::<EtherTransfer>(context, &meaning, run_kind)
+                .await
+            {
+                Ok(()) => Ok(meaning.into()),
+                Err(e) => Err(VetError::Evaluated(meaning.into(), e)),
+            };
+        }
+        if let Some(meaning) = TokenTransfer::analyze(&context) {
+            return match self
+                .vet_transaction::<TokenTransfer>(context, &meaning, run_kind)
+                .await
+            {
+                Ok(()) => Ok(meaning.into()),
+                Err(e) => Err(VetError::Evaluated(meaning.into(), e)),
+            };
+        }
+
+        Err(VetError::UnsupportedTransactionType)
+    }
+}

server/crates/arbiter-server/src/evm/policies.rs

@@ -0,0 +1,212 @@
+use std::fmt::Display;
+
+use alloy::primitives::{Address, Bytes, ChainId, U256};
+use chrono::{DateTime, Duration, Utc};
+use diesel::{
+    ExpressionMethods as _, QueryDsl, SelectableHelper, result::QueryResult, sqlite::Sqlite,
+};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use miette::Diagnostic;
+use thiserror::Error;
+
+use crate::{
+    db::models::{self, EvmBasicGrant},
+    evm::utils,
+};
+
+pub mod ether_transfer;
+pub mod token_transfers;
+
+#[derive(Debug, Clone)]
+pub struct EvalContext {
+    // Which wallet is this transaction for
+    pub client_id: i32,
+    pub wallet_id: i32,
+
+    // The transaction data
+    pub chain: ChainId,
+    pub to: Address,
+    pub value: U256,
+    pub calldata: Bytes,
+
+    // Gas pricing (EIP-1559)
+    pub max_fee_per_gas: u128,
+    pub max_priority_fee_per_gas: u128,
+}
+
+#[derive(Debug, Error, Diagnostic)]
+pub enum EvalViolation {
+    #[error("This grant doesn't allow transactions to the target address {target}")]
+    #[diagnostic(code(arbiter_server::evm::eval_violation::invalid_target))]
+    InvalidTarget { target: Address },
+
+    #[error("Gas limit exceeded for this grant")]
+    #[diagnostic(code(arbiter_server::evm::eval_violation::gas_limit_exceeded))]
+    GasLimitExceeded {
+        max_gas_fee_per_gas: Option<U256>,
+        max_priority_fee_per_gas: Option<U256>,
+    },
+
+    #[error("Rate limit exceeded for this grant")]
+    #[diagnostic(code(arbiter_server::evm::eval_violation::rate_limit_exceeded))]
+    RateLimitExceeded,
+
+    #[error("Transaction exceeds volumetric limits of the grant")]
+    #[diagnostic(code(arbiter_server::evm::eval_violation::volumetric_limit_exceeded))]
+    VolumetricLimitExceeded,
+
+    #[error("Transaction is outside of the grant's validity period")]
+    #[diagnostic(code(arbiter_server::evm::eval_violation::invalid_time))]
+    InvalidTime,
+
+    #[error("Transaction type is not allowed by this grant")]
+    #[diagnostic(code(arbiter_server::evm::eval_violation::invalid_transaction_type))]
+    InvalidTransactionType,
+}
+
+pub type DatabaseID = i32;
+
+#[derive(Debug)]
+pub struct Grant<PolicySettings> {
+    pub id: DatabaseID,
+    pub shared_grant_id: DatabaseID, // ID of the basic grant for shared-logic checks like rate limits and validity periods
+    pub shared: SharedGrantSettings,
+    pub settings: PolicySettings,
+}
+
+pub trait Policy: Sized {
+    type Settings: Send + Sync + 'static + Into<SpecificGrant>;
+    type Meaning: Display + std::fmt::Debug + Send + Sync + 'static + Into<SpecificMeaning>;
+
+    fn analyze(context: &EvalContext) -> Option<Self::Meaning>;
+
+    // Evaluate whether a transaction with the given meaning complies with the provided grant, and return any violations if not
+    // Empty vector means transaction is compliant with the grant
+    fn evaluate(
+        context: &EvalContext,
+        meaning: &Self::Meaning,
+        grant: &Grant<Self::Settings>,
+        db: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> impl Future<Output = QueryResult<Vec<EvalViolation>>> + Send;
+
+    // Create a new grant in the database based on the provided grant details, and return its ID
+    fn create_grant(
+        basic: &models::EvmBasicGrant,
+        grant: &Self::Settings,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> impl std::future::Future<Output = QueryResult<DatabaseID>> + Send;
+
+    // Try to find an existing grant that matches the transaction context, and return its details if found
+    // Additionally, return ID of basic grant for shared-logic checks like rate limits and validity periods
+    fn try_find_grant(
+        context: &EvalContext,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> impl Future<Output = QueryResult<Option<Grant<Self::Settings>>>> + Send;
+
+    // Return all non-revoked grants, eagerly loading policy-specific settings
+    fn find_all_grants(
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> impl Future<Output = QueryResult<Vec<Grant<Self::Settings>>>> + Send;
+
+    // Records, updates or deletes rate limits
+    // In other words, records grant-specific things after transaction is executed
+    fn record_transaction(
+        context: &EvalContext,
+        meaning: &Self::Meaning,
+        log_id: i32,
+        grant: &Grant<Self::Settings>,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> impl Future<Output = QueryResult<()>> + Send;
+}
+
+pub enum ReceiverTarget {
+    Specific(Vec<Address>), // only allow transfers to these addresses
+    Any,                    // allow transfers to any address
+}
+
+// Classification of what transaction does
+#[derive(Debug)]
+pub enum SpecificMeaning {
+    EtherTransfer(ether_transfer::Meaning),
+    TokenTransfer(token_transfers::Meaning),
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct TransactionRateLimit {
+    pub count: u32,
+    pub window: Duration,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct VolumeRateLimit {
+    pub max_volume: U256,
+    pub window: Duration,
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct SharedGrantSettings {
+    pub wallet_id: i32,
+    pub client_id: i32,
+    pub chain: ChainId,
+
+    pub valid_from: Option<DateTime<Utc>>,
+    pub valid_until: Option<DateTime<Utc>>,
+
+    pub max_gas_fee_per_gas: Option<U256>,
+    pub max_priority_fee_per_gas: Option<U256>,
+
+    pub rate_limit: Option<TransactionRateLimit>,
+}
+
+impl SharedGrantSettings {
+    fn try_from_model(model: EvmBasicGrant) -> QueryResult<Self> {
+        Ok(Self {
+            wallet_id: model.wallet_id,
+            client_id: model.client_id,
+            chain: model.chain_id as u64, // safe because chain_id is stored as i32 but is guaranteed to be a valid ChainId by the API when creating grants
+            valid_from: model.valid_from.map(Into::into),
+            valid_until: model.valid_until.map(Into::into),
+            max_gas_fee_per_gas: model
+                .max_gas_fee_per_gas
+                .map(|b| utils::try_bytes_to_u256(&b))
+                .transpose()?,
+            max_priority_fee_per_gas: model
+                .max_priority_fee_per_gas
+                .map(|b| utils::try_bytes_to_u256(&b))
+                .transpose()?,
+            rate_limit: match (model.rate_limit_count, model.rate_limit_window_secs) {
+                (Some(count), Some(window_secs)) => Some(TransactionRateLimit {
+                    count: count as u32,
+                    window: Duration::seconds(window_secs as i64),
+                }),
+                _ => None,
+            },
+        })
+    }
+
+    pub async fn query_by_id(
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+        id: i32,
+    ) -> diesel::result::QueryResult<Self> {
+        use crate::db::schema::evm_basic_grant;
+
+        let basic_grant: EvmBasicGrant = evm_basic_grant::table
+            .select(EvmBasicGrant::as_select())
+            .filter(evm_basic_grant::id.eq(id))
+            .first::<EvmBasicGrant>(conn)
+            .await?;
+
+        Self::try_from_model(basic_grant)
+    }
+}
+
+#[derive(Debug, Clone)]
+pub enum SpecificGrant {
+    EtherTransfer(ether_transfer::Settings),
+    TokenTransfer(token_transfers::Settings),
+}
+
+pub struct FullGrant<PolicyGrant> {
+    pub basic: SharedGrantSettings,
+    pub specific: PolicyGrant,
+}

server/crates/arbiter-server/src/evm/policies/ether_transfer/mod.rs

@@ -0,0 +1,348 @@
+use std::collections::HashMap;
+use std::fmt::Display;
+
+use alloy::primitives::{Address, U256};
+use chrono::{DateTime, Duration, Utc};
+use diesel::dsl::{auto_type, insert_into};
+use diesel::sqlite::Sqlite;
+use diesel::{ExpressionMethods, JoinOnDsl, prelude::*};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+
+use crate::db::models::{
+    EvmBasicGrant, EvmEtherTransferGrant, EvmEtherTransferGrantTarget, EvmEtherTransferLimit,
+    NewEvmEtherTransferLimit, SqliteTimestamp,
+};
+use crate::db::schema::{evm_basic_grant, evm_ether_transfer_limit, evm_transaction_log};
+use crate::evm::policies::{
+    Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
+};
+use crate::{
+    db::{
+        models::{self, NewEvmEtherTransferGrant, NewEvmEtherTransferGrantTarget},
+        schema::{evm_ether_transfer_grant, evm_ether_transfer_grant_target},
+    },
+    evm::{policies::Policy, utils},
+};
+
+#[auto_type]
+fn grant_join() -> _ {
+    evm_ether_transfer_grant::table.inner_join(
+        evm_basic_grant::table.on(evm_ether_transfer_grant::basic_grant_id.eq(evm_basic_grant::id)),
+    )
+}
+
+use super::{DatabaseID, EvalContext, EvalViolation};
+
+// Plain ether transfer
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Meaning {
+    to: Address,
+    value: U256,
+}
+impl Display for Meaning {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "Ether transfer of {} to {}", self.value, self.to)
+    }
+}
+impl From<Meaning> for SpecificMeaning {
+    fn from(val: Meaning) -> SpecificMeaning {
+        SpecificMeaning::EtherTransfer(val)
+    }
+}
+
+// A grant for ether transfers, which can be scoped to specific target addresses and volume limits
+#[derive(Debug, Clone)]
+pub struct Settings {
+    pub target: Vec<Address>,
+    pub limit: VolumeRateLimit,
+}
+
+impl From<Settings> for SpecificGrant {
+    fn from(val: Settings) -> SpecificGrant {
+        SpecificGrant::EtherTransfer(val)
+    }
+}
+
+async fn query_relevant_past_transaction(
+    grant_id: i32,
+    longest_window: Duration,
+    db: &mut impl AsyncConnection<Backend = Sqlite>,
+) -> QueryResult<Vec<(U256, DateTime<Utc>)>> {
+    let past_transactions: Vec<(Vec<u8>, SqliteTimestamp)> = evm_transaction_log::table
+        .filter(evm_transaction_log::grant_id.eq(grant_id))
+        .filter(
+            evm_transaction_log::signed_at.ge(SqliteTimestamp(chrono::Utc::now() - longest_window)),
+        )
+        .select((
+            evm_transaction_log::eth_value,
+            evm_transaction_log::signed_at,
+        ))
+        .load(db)
+        .await?;
+    let past_transaction: Vec<(U256, DateTime<Utc>)> = past_transactions
+        .into_iter()
+        .filter_map(|(value_bytes, timestamp)| {
+            let value = utils::bytes_to_u256(&value_bytes)?;
+            Some((value, timestamp.0))
+        })
+        .collect();
+    Ok(past_transaction)
+}
+
+async fn check_rate_limits(
+    grant: &Grant<Settings>,
+    db: &mut impl AsyncConnection<Backend = Sqlite>,
+) -> QueryResult<Vec<EvalViolation>> {
+    let mut violations = Vec::new();
+    let window = grant.settings.limit.window;
+
+    let past_transaction = query_relevant_past_transaction(grant.id, window, db).await?;
+
+    let window_start = chrono::Utc::now() - grant.settings.limit.window;
+    let cumulative_volume: U256 = past_transaction
+        .iter()
+        .filter(|(_, timestamp)| timestamp >= &window_start)
+        .fold(U256::default(), |acc, (value, _)| acc + *value);
+
+    if cumulative_volume > grant.settings.limit.max_volume {
+        violations.push(EvalViolation::VolumetricLimitExceeded);
+    }
+
+    Ok(violations)
+}
+
+pub struct EtherTransfer;
+impl Policy for EtherTransfer {
+    type Settings = Settings;
+
+    type Meaning = Meaning;
+
+    fn analyze(context: &EvalContext) -> Option<Self::Meaning> {
+        if !context.calldata.is_empty() {
+            return None;
+        }
+
+        Some(Meaning {
+            to: context.to,
+            value: context.value,
+        })
+    }
+
+    async fn evaluate(
+        _: &EvalContext,
+        meaning: &Self::Meaning,
+        grant: &Grant<Self::Settings>,
+        db: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> QueryResult<Vec<EvalViolation>> {
+        let mut violations = Vec::new();
+
+        // Check if the target address is within the grant's allowed targets
+        if !grant.settings.target.contains(&meaning.to) {
+            violations.push(EvalViolation::InvalidTarget { target: meaning.to });
+        }
+
+        let rate_violations = check_rate_limits(grant, db).await?;
+        violations.extend(rate_violations);
+
+        Ok(violations)
+    }
+
+    async fn create_grant(
+        basic: &models::EvmBasicGrant,
+        grant: &Self::Settings,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> diesel::result::QueryResult<DatabaseID> {
+        let limit_id: i32 = insert_into(evm_ether_transfer_limit::table)
+            .values(NewEvmEtherTransferLimit {
+                window_secs: grant.limit.window.num_seconds() as i32,
+                max_volume: utils::u256_to_bytes(grant.limit.max_volume).to_vec(),
+            })
+            .returning(evm_ether_transfer_limit::id)
+            .get_result(conn)
+            .await?;
+
+        let grant_id: i32 = insert_into(evm_ether_transfer_grant::table)
+            .values(&NewEvmEtherTransferGrant {
+                basic_grant_id: basic.id,
+                limit_id,
+            })
+            .returning(evm_ether_transfer_grant::id)
+            .get_result(conn)
+            .await?;
+
+        for target in &grant.target {
+            insert_into(evm_ether_transfer_grant_target::table)
+                .values(NewEvmEtherTransferGrantTarget {
+                    grant_id,
+                    address: target.to_vec(),
+                })
+                .execute(conn)
+                .await?;
+        }
+
+        Ok(grant_id)
+    }
+
+    async fn try_find_grant(
+        context: &EvalContext,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> diesel::result::QueryResult<Option<Grant<Self::Settings>>> {
+        let target_bytes = context.to.to_vec();
+
+        // Find a grant where:
+        // 1. The basic grant's wallet_id and client_id match the context
+        // 2. Any of the grant's targets match the context's `to` address
+        let grant: Option<(EvmBasicGrant, EvmEtherTransferGrant)> = evm_ether_transfer_grant::table
+            .inner_join(evm_basic_grant::table)
+            .inner_join(evm_ether_transfer_grant_target::table)
+            .filter(
+                evm_basic_grant::wallet_id
+                    .eq(context.wallet_id)
+                    .and(evm_basic_grant::client_id.eq(context.client_id))
+                    .and(evm_basic_grant::revoked_at.is_null())
+                    .and(evm_ether_transfer_grant_target::address.eq(&target_bytes)),
+            )
+            .select((
+                EvmBasicGrant::as_select(),
+                EvmEtherTransferGrant::as_select(),
+            ))
+            .first(conn)
+            .await
+            .optional()?;
+
+        let Some((basic_grant, grant)) = grant else {
+            return Ok(None);
+        };
+
+        let target_bytes: Vec<EvmEtherTransferGrantTarget> = evm_ether_transfer_grant_target::table
+            .select(EvmEtherTransferGrantTarget::as_select())
+            .filter(evm_ether_transfer_grant_target::grant_id.eq(grant.id))
+            .load(conn)
+            .await?;
+
+        let limit: EvmEtherTransferLimit = evm_ether_transfer_limit::table
+            .filter(evm_ether_transfer_limit::id.eq(grant.limit_id))
+            .select(EvmEtherTransferLimit::as_select())
+            .first::<EvmEtherTransferLimit>(conn)
+            .await?;
+
+        // Convert bytes back to Address
+        let targets: Vec<Address> = target_bytes
+            .into_iter()
+            .filter_map(|target| {
+                // TODO: Handle invalid addresses more gracefully
+                let arr: [u8; 20] = target.address.try_into().ok()?;
+                Some(Address::from(arr))
+            })
+            .collect();
+
+        let settings = Settings {
+            target: targets,
+            limit: VolumeRateLimit {
+                max_volume: utils::try_bytes_to_u256(&limit.max_volume)
+                    .map_err(|err| diesel::result::Error::DeserializationError(Box::new(err)))?,
+                window: chrono::Duration::seconds(limit.window_secs as i64),
+            },
+        };
+
+        Ok(Some(Grant {
+            id: grant.id,
+            shared_grant_id: grant.basic_grant_id,
+            shared: SharedGrantSettings::try_from_model(basic_grant)?,
+            settings,
+        }))
+    }
+
+    async fn record_transaction(
+        _context: &EvalContext,
+        _: &Self::Meaning,
+        _log_id: i32,
+        _grant: &Grant<Self::Settings>,
+        _conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> diesel::result::QueryResult<()> {
+        // Basic log is sufficient
+
+        Ok(())
+    }
+
+    async fn find_all_grants(
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> QueryResult<Vec<Grant<Self::Settings>>> {
+        let grants: Vec<(EvmBasicGrant, EvmEtherTransferGrant)> = grant_join()
+            .filter(evm_basic_grant::revoked_at.is_null())
+            .select((
+                EvmBasicGrant::as_select(),
+                EvmEtherTransferGrant::as_select(),
+            ))
+            .load(conn)
+            .await?;
+
+        if grants.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        let grant_ids: Vec<i32> = grants.iter().map(|(_, g)| g.id).collect();
+        let limit_ids: Vec<i32> = grants.iter().map(|(_, g)| g.limit_id).collect();
+
+        let all_targets: Vec<EvmEtherTransferGrantTarget> = evm_ether_transfer_grant_target::table
+            .filter(evm_ether_transfer_grant_target::grant_id.eq_any(&grant_ids))
+            .select(EvmEtherTransferGrantTarget::as_select())
+            .load(conn)
+            .await?;
+
+        let all_limits: Vec<EvmEtherTransferLimit> = evm_ether_transfer_limit::table
+            .filter(evm_ether_transfer_limit::id.eq_any(&limit_ids))
+            .select(EvmEtherTransferLimit::as_select())
+            .load(conn)
+            .await?;
+
+        let mut targets_by_grant: HashMap<i32, Vec<EvmEtherTransferGrantTarget>> = HashMap::new();
+        for target in all_targets {
+            targets_by_grant
+                .entry(target.grant_id)
+                .or_default()
+                .push(target);
+        }
+
+        let limits_by_id: HashMap<i32, EvmEtherTransferLimit> =
+            all_limits.into_iter().map(|l| (l.id, l)).collect();
+
+        grants
+            .into_iter()
+            .map(|(basic, specific)| {
+                let targets: Vec<Address> = targets_by_grant
+                    .get(&specific.id)
+                    .map(|v| v.as_slice())
+                    .unwrap_or_default()
+                    .iter()
+                    .filter_map(|t| {
+                        let arr: [u8; 20] = t.address.clone().try_into().ok()?;
+                        Some(Address::from(arr))
+                    })
+                    .collect();
+
+                let limit = limits_by_id
+                    .get(&specific.limit_id)
+                    .ok_or(diesel::result::Error::NotFound)?;
+
+                Ok(Grant {
+                    id: specific.id,
+                    shared_grant_id: specific.basic_grant_id,
+                    shared: SharedGrantSettings::try_from_model(basic)?,
+                    settings: Settings {
+                        target: targets,
+                        limit: VolumeRateLimit {
+                            max_volume: utils::try_bytes_to_u256(&limit.max_volume).map_err(
+                                |e| diesel::result::Error::DeserializationError(Box::new(e)),
+                            )?,
+                            window: Duration::seconds(limit.window_secs as i64),
+                        },
+                    },
+                })
+            })
+            .collect()
+    }
+}
+
+#[cfg(test)]
+mod tests;

server/crates/arbiter-server/src/evm/policies/ether_transfer/tests.rs

@@ -0,0 +1,386 @@
+use alloy::primitives::{Address, Bytes, U256, address};
+use chrono::{Duration, Utc};
+use diesel::{SelectableHelper, insert_into};
+use diesel_async::RunQueryDsl;
+
+use crate::db::{
+    self, DatabaseConnection,
+    models::{EvmBasicGrant, NewEvmBasicGrant, NewEvmTransactionLog, SqliteTimestamp},
+    schema::{evm_basic_grant, evm_transaction_log},
+};
+use crate::evm::{
+    policies::{EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings, VolumeRateLimit},
+    utils,
+};
+
+use super::{EtherTransfer, Settings};
+
+const WALLET_ID: i32 = 1;
+const CLIENT_ID: i32 = 2;
+const CHAIN_ID: u64 = 1;
+
+const ALLOWED: Address = address!("1111111111111111111111111111111111111111");
+const OTHER: Address = address!("2222222222222222222222222222222222222222");
+
+fn ctx(to: Address, value: U256) -> EvalContext {
+    EvalContext {
+        wallet_id: WALLET_ID,
+        client_id: CLIENT_ID,
+        chain: CHAIN_ID,
+        to,
+        value,
+        calldata: Bytes::new(),
+        max_fee_per_gas: 0,
+        max_priority_fee_per_gas: 0,
+    }
+}
+
+async fn insert_basic(conn: &mut DatabaseConnection, revoked: bool) -> EvmBasicGrant {
+    insert_into(evm_basic_grant::table)
+        .values(NewEvmBasicGrant {
+            wallet_id: WALLET_ID,
+            client_id: CLIENT_ID,
+            chain_id: CHAIN_ID as i32,
+            valid_from: None,
+            valid_until: None,
+            max_gas_fee_per_gas: None,
+            max_priority_fee_per_gas: None,
+            rate_limit_count: None,
+            rate_limit_window_secs: None,
+            revoked_at: revoked.then(|| SqliteTimestamp(Utc::now())),
+        })
+        .returning(EvmBasicGrant::as_select())
+        .get_result(conn)
+        .await
+        .unwrap()
+}
+
+fn make_settings(targets: Vec<Address>, max_volume: u64) -> Settings {
+    Settings {
+        target: targets,
+        limit: VolumeRateLimit {
+            max_volume: U256::from(max_volume),
+            window: Duration::hours(1),
+        },
+    }
+}
+
+fn shared() -> SharedGrantSettings {
+    SharedGrantSettings {
+        wallet_id: WALLET_ID,
+        chain: CHAIN_ID,
+        valid_from: None,
+        valid_until: None,
+        max_gas_fee_per_gas: None,
+        max_priority_fee_per_gas: None,
+        rate_limit: None,
+        client_id: CLIENT_ID,
+    }
+}
+
+// ── analyze ─────────────────────────────────────────────────────────────
+
+#[test]
+fn analyze_matches_empty_calldata() {
+    let m = EtherTransfer::analyze(&ctx(ALLOWED, U256::from(1_000u64))).unwrap();
+    assert_eq!(m.to, ALLOWED);
+    assert_eq!(m.value, U256::from(1_000u64));
+}
+
+#[test]
+fn analyze_rejects_nonempty_calldata() {
+    let context = EvalContext {
+        calldata: Bytes::from(vec![0xde, 0xad, 0xbe, 0xef]),
+        ..ctx(ALLOWED, U256::from(1u64))
+    };
+    assert!(EtherTransfer::analyze(&context).is_none());
+}
+
+// ── evaluate ────────────────────────────────────────────────────────────
+
+#[tokio::test]
+async fn evaluate_passes_for_allowed_target() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let grant = Grant {
+        id: 999,
+        shared_grant_id: 999,
+        shared: shared(),
+        settings: make_settings(vec![ALLOWED], 1_000_000),
+    };
+    let context = ctx(ALLOWED, U256::from(100u64));
+    let m = EtherTransfer::analyze(&context).unwrap();
+    let v = EtherTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(v.is_empty());
+}
+
+#[tokio::test]
+async fn evaluate_rejects_disallowed_target() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let grant = Grant {
+        id: 999,
+        shared_grant_id: 999,
+        shared: shared(),
+        settings: make_settings(vec![ALLOWED], 1_000_000),
+    };
+    let context = ctx(OTHER, U256::from(100u64));
+    let m = EtherTransfer::analyze(&context).unwrap();
+    let v = EtherTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        v.iter()
+            .any(|e| matches!(e, EvalViolation::InvalidTarget { .. }))
+    );
+}
+
+#[tokio::test]
+async fn evaluate_passes_when_volume_within_limit() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(vec![ALLOWED], 1_000);
+    let grant_id = EtherTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    insert_into(evm_transaction_log::table)
+        .values(NewEvmTransactionLog {
+            grant_id,
+            client_id: CLIENT_ID,
+            wallet_id: WALLET_ID,
+            chain_id: CHAIN_ID as i32,
+            eth_value: utils::u256_to_bytes(U256::from(500u64)).to_vec(),
+            signed_at: SqliteTimestamp(Utc::now()),
+        })
+        .execute(&mut *conn)
+        .await
+        .unwrap();
+
+    let grant = Grant {
+        id: grant_id,
+        shared_grant_id: basic.id,
+        shared: shared(),
+        settings,
+    };
+    let context = ctx(ALLOWED, U256::from(100u64));
+    let m = EtherTransfer::analyze(&context).unwrap();
+    let v = EtherTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        !v.iter()
+            .any(|e| matches!(e, EvalViolation::VolumetricLimitExceeded))
+    );
+}
+
+#[tokio::test]
+async fn evaluate_rejects_volume_over_limit() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(vec![ALLOWED], 1_000);
+    let grant_id = EtherTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    insert_into(evm_transaction_log::table)
+        .values(NewEvmTransactionLog {
+            grant_id,
+            client_id: CLIENT_ID,
+            wallet_id: WALLET_ID,
+            chain_id: CHAIN_ID as i32,
+            eth_value: utils::u256_to_bytes(U256::from(1_001u64)).to_vec(),
+            signed_at: SqliteTimestamp(Utc::now()),
+        })
+        .execute(&mut *conn)
+        .await
+        .unwrap();
+
+    let grant = Grant {
+        id: grant_id,
+        shared_grant_id: basic.id,
+        shared: shared(),
+        settings,
+    };
+    let context = ctx(ALLOWED, U256::from(100u64));
+    let m = EtherTransfer::analyze(&context).unwrap();
+    let v = EtherTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        v.iter()
+            .any(|e| matches!(e, EvalViolation::VolumetricLimitExceeded))
+    );
+}
+
+#[tokio::test]
+async fn evaluate_passes_at_exactly_volume_limit() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(vec![ALLOWED], 1_000);
+    let grant_id = EtherTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    // Exactly at the limit — the check is `>`, so this should not violate
+    insert_into(evm_transaction_log::table)
+        .values(NewEvmTransactionLog {
+            grant_id,
+            client_id: CLIENT_ID,
+            wallet_id: WALLET_ID,
+            chain_id: CHAIN_ID as i32,
+            eth_value: utils::u256_to_bytes(U256::from(1_000u64)).to_vec(),
+            signed_at: SqliteTimestamp(Utc::now()),
+        })
+        .execute(&mut *conn)
+        .await
+        .unwrap();
+
+    let grant = Grant {
+        id: grant_id,
+        shared_grant_id: basic.id,
+        shared: shared(),
+        settings,
+    };
+    let context = ctx(ALLOWED, U256::from(100u64));
+    let m = EtherTransfer::analyze(&context).unwrap();
+    let v = EtherTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        !v.iter()
+            .any(|e| matches!(e, EvalViolation::VolumetricLimitExceeded))
+    );
+}
+
+// ── try_find_grant ───────────────────────────────────────────────────────
+
+#[tokio::test]
+async fn try_find_grant_roundtrip() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(vec![ALLOWED], 1_000_000);
+    EtherTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let found = EtherTransfer::try_find_grant(&ctx(ALLOWED, U256::from(1u64)), &mut *conn)
+        .await
+        .unwrap();
+
+    assert!(found.is_some());
+    let g = found.unwrap();
+    assert_eq!(g.settings.target, vec![ALLOWED]);
+    assert_eq!(g.settings.limit.max_volume, U256::from(1_000_000u64));
+}
+
+#[tokio::test]
+async fn try_find_grant_revoked_returns_none() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, true).await;
+    let settings = make_settings(vec![ALLOWED], 1_000_000);
+    EtherTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let found = EtherTransfer::try_find_grant(&ctx(ALLOWED, U256::from(1u64)), &mut *conn)
+        .await
+        .unwrap();
+    assert!(found.is_none());
+}
+
+#[tokio::test]
+async fn try_find_grant_wrong_target_returns_none() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(vec![ALLOWED], 1_000_000);
+    EtherTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let found = EtherTransfer::try_find_grant(&ctx(OTHER, U256::from(1u64)), &mut *conn)
+        .await
+        .unwrap();
+    assert!(found.is_none());
+}
+
+// ── find_all_grants ──────────────────────────────────────────────────────
+
+#[tokio::test]
+async fn find_all_grants_empty_db() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+    let all = EtherTransfer::find_all_grants(&mut *conn).await.unwrap();
+    assert!(all.is_empty());
+}
+
+#[tokio::test]
+async fn find_all_grants_excludes_revoked() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let settings = make_settings(vec![ALLOWED], 1_000_000);
+    let active = insert_basic(&mut conn, false).await;
+    EtherTransfer::create_grant(&active, &settings, &mut *conn)
+        .await
+        .unwrap();
+    let revoked = insert_basic(&mut conn, true).await;
+    EtherTransfer::create_grant(&revoked, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let all = EtherTransfer::find_all_grants(&mut *conn).await.unwrap();
+    assert_eq!(all.len(), 1);
+    assert_eq!(all[0].settings.target, vec![ALLOWED]);
+}
+
+#[tokio::test]
+async fn find_all_grants_multiple_targets() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(vec![ALLOWED, OTHER], 1_000_000);
+    EtherTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let all = EtherTransfer::find_all_grants(&mut *conn).await.unwrap();
+    assert_eq!(all.len(), 1);
+    assert_eq!(all[0].settings.target.len(), 2);
+    assert_eq!(all[0].settings.limit.max_volume, U256::from(1_000_000u64));
+}
+
+#[tokio::test]
+async fn find_all_grants_multiple_grants() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic1 = insert_basic(&mut conn, false).await;
+    EtherTransfer::create_grant(&basic1, &make_settings(vec![ALLOWED], 500), &mut *conn)
+        .await
+        .unwrap();
+    let basic2 = insert_basic(&mut conn, false).await;
+    EtherTransfer::create_grant(&basic2, &make_settings(vec![OTHER], 1_000), &mut *conn)
+        .await
+        .unwrap();
+
+    let all = EtherTransfer::find_all_grants(&mut *conn).await.unwrap();
+    assert_eq!(all.len(), 2);
+}

server/crates/arbiter-server/src/evm/policies/token_transfers/mod.rs

@@ -0,0 +1,386 @@
+use std::collections::HashMap;
+
+use alloy::{
+    primitives::{Address, U256},
+    sol_types::SolCall,
+};
+use arbiter_tokens_registry::evm::nonfungible::{self, TokenInfo};
+use chrono::{DateTime, Duration, Utc};
+use diesel::dsl::{auto_type, insert_into};
+use diesel::sqlite::Sqlite;
+use diesel::{ExpressionMethods, prelude::*};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+
+use crate::db::models::{
+    EvmBasicGrant, EvmTokenTransferGrant, EvmTokenTransferVolumeLimit, NewEvmTokenTransferGrant,
+    NewEvmTokenTransferLog, NewEvmTokenTransferVolumeLimit, SqliteTimestamp,
+};
+use crate::db::schema::{
+    evm_basic_grant, evm_token_transfer_grant, evm_token_transfer_log,
+    evm_token_transfer_volume_limit,
+};
+use crate::evm::{
+    abi::IERC20::transferCall,
+    policies::{
+        Grant, Policy, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
+    },
+    utils,
+};
+
+use super::{DatabaseID, EvalContext, EvalViolation};
+
+#[auto_type]
+fn grant_join() -> _ {
+    evm_token_transfer_grant::table.inner_join(
+        evm_basic_grant::table.on(evm_token_transfer_grant::basic_grant_id.eq(evm_basic_grant::id)),
+    )
+}
+
+#[derive(Clone, Debug, PartialEq, Eq, Hash)]
+pub struct Meaning {
+    token: &'static TokenInfo,
+    to: Address,
+    value: U256,
+}
+impl std::fmt::Display for Meaning {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(
+            f,
+            "Transfer of {} {} to {}",
+            self.value, self.token.symbol, self.to
+        )
+    }
+}
+impl From<Meaning> for SpecificMeaning {
+    fn from(val: Meaning) -> SpecificMeaning {
+        SpecificMeaning::TokenTransfer(val)
+    }
+}
+
+// A grant for token transfers, which can be scoped to specific target addresses and volume limits
+#[derive(Debug, Clone)]
+pub struct Settings {
+    pub token_contract: Address,
+    pub target: Option<Address>,
+    pub volume_limits: Vec<VolumeRateLimit>,
+}
+impl From<Settings> for SpecificGrant {
+    fn from(val: Settings) -> SpecificGrant {
+        SpecificGrant::TokenTransfer(val)
+    }
+}
+
+async fn query_relevant_past_transfers(
+    grant_id: i32,
+    longest_window: Duration,
+    db: &mut impl AsyncConnection<Backend = Sqlite>,
+) -> QueryResult<Vec<(U256, DateTime<Utc>)>> {
+    let past_logs: Vec<(Vec<u8>, SqliteTimestamp)> = evm_token_transfer_log::table
+        .filter(evm_token_transfer_log::grant_id.eq(grant_id))
+        .filter(
+            evm_token_transfer_log::created_at
+                .ge(SqliteTimestamp(chrono::Utc::now() - longest_window)),
+        )
+        .select((
+            evm_token_transfer_log::value,
+            evm_token_transfer_log::created_at,
+        ))
+        .load(db)
+        .await?;
+
+    let past_transfers: Vec<(U256, DateTime<Utc>)> = past_logs
+        .into_iter()
+        .filter_map(|(value_bytes, timestamp)| {
+            let value = utils::bytes_to_u256(&value_bytes)?;
+            Some((value, timestamp.0))
+        })
+        .collect();
+
+    Ok(past_transfers)
+}
+
+async fn check_volume_rate_limits(
+    grant: &Grant<Settings>,
+    db: &mut impl AsyncConnection<Backend = Sqlite>,
+) -> QueryResult<Vec<EvalViolation>> {
+    let mut violations = Vec::new();
+
+    let Some(longest_window) = grant.settings.volume_limits.iter().map(|l| l.window).max() else {
+        return Ok(violations);
+    };
+
+    let past_transfers = query_relevant_past_transfers(grant.id, longest_window, db).await?;
+
+    for limit in &grant.settings.volume_limits {
+        let window_start = chrono::Utc::now() - limit.window;
+        let cumulative_volume: U256 = past_transfers
+            .iter()
+            .filter(|(_, timestamp)| timestamp >= &window_start)
+            .fold(U256::default(), |acc, (value, _)| acc + *value);
+
+        if cumulative_volume > limit.max_volume {
+            violations.push(EvalViolation::VolumetricLimitExceeded);
+            break;
+        }
+    }
+
+    Ok(violations)
+}
+
+pub struct TokenTransfer;
+impl Policy for TokenTransfer {
+    type Settings = Settings;
+    type Meaning = Meaning;
+
+    fn analyze(context: &EvalContext) -> Option<Self::Meaning> {
+        let token = nonfungible::get_token(context.chain, context.to)?;
+        let decoded = transferCall::abi_decode_raw_validate(&context.calldata).ok()?;
+
+        Some(Meaning {
+            token,
+            to: decoded.to,
+            value: decoded.value,
+        })
+    }
+
+    async fn evaluate(
+        context: &EvalContext,
+        meaning: &Self::Meaning,
+        grant: &Grant<Self::Settings>,
+        db: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> QueryResult<Vec<EvalViolation>> {
+        let mut violations = Vec::new();
+
+        // erc20 transfer shouldn't carry eth value
+        if !context.value.is_zero() {
+            violations.push(EvalViolation::InvalidTransactionType);
+            return Ok(violations);
+        }
+
+        if let Some(allowed) = grant.settings.target
+            && allowed != meaning.to
+        {
+            violations.push(EvalViolation::InvalidTarget { target: meaning.to });
+        }
+
+        let rate_violations = check_volume_rate_limits(grant, db).await?;
+        violations.extend(rate_violations);
+
+        Ok(violations)
+    }
+
+    async fn create_grant(
+        basic: &EvmBasicGrant,
+        grant: &Self::Settings,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> QueryResult<DatabaseID> {
+        // Store the specific receiver as bytes (None means any receiver is allowed)
+        let receiver: Option<Vec<u8>> = grant.target.map(|addr| addr.to_vec());
+
+        let grant_id: i32 = insert_into(evm_token_transfer_grant::table)
+            .values(NewEvmTokenTransferGrant {
+                basic_grant_id: basic.id,
+                token_contract: grant.token_contract.to_vec(),
+                receiver,
+            })
+            .returning(evm_token_transfer_grant::id)
+            .get_result(conn)
+            .await?;
+
+        for limit in &grant.volume_limits {
+            insert_into(evm_token_transfer_volume_limit::table)
+                .values(NewEvmTokenTransferVolumeLimit {
+                    grant_id,
+                    window_secs: limit.window.num_seconds() as i32,
+                    max_volume: utils::u256_to_bytes(limit.max_volume).to_vec(),
+                })
+                .execute(conn)
+                .await?;
+        }
+
+        Ok(grant_id)
+    }
+
+    async fn try_find_grant(
+        context: &EvalContext,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> QueryResult<Option<Grant<Self::Settings>>> {
+        let token_contract_bytes = context.to.to_vec();
+
+        let grant: Option<(EvmBasicGrant, EvmTokenTransferGrant)> = grant_join()
+            .filter(evm_basic_grant::revoked_at.is_null())
+            .filter(evm_basic_grant::wallet_id.eq(context.wallet_id))
+            .filter(evm_basic_grant::client_id.eq(context.client_id))
+            .filter(evm_token_transfer_grant::token_contract.eq(&token_contract_bytes))
+            .select((
+                EvmBasicGrant::as_select(),
+                EvmTokenTransferGrant::as_select(),
+            ))
+            .first(conn)
+            .await
+            .optional()?;
+
+        let Some((basic_grant, token_grant)) = grant else {
+            return Ok(None);
+        };
+
+        let volume_limits_db: Vec<EvmTokenTransferVolumeLimit> =
+            evm_token_transfer_volume_limit::table
+                .filter(evm_token_transfer_volume_limit::grant_id.eq(token_grant.id))
+                .select(EvmTokenTransferVolumeLimit::as_select())
+                .load(conn)
+                .await?;
+
+        let volume_limits: Vec<VolumeRateLimit> = volume_limits_db
+            .into_iter()
+            .map(|row| {
+                Ok(VolumeRateLimit {
+                    max_volume: utils::try_bytes_to_u256(&row.max_volume).map_err(|err| {
+                        diesel::result::Error::DeserializationError(Box::new(err))
+                    })?,
+                    window: Duration::seconds(row.window_secs as i64),
+                })
+            })
+            .collect::<QueryResult<Vec<_>>>()?;
+
+        let token_contract: [u8; 20] = token_grant.token_contract.try_into().map_err(|_| {
+            diesel::result::Error::DeserializationError(
+                "Invalid token contract address length".into(),
+            )
+        })?;
+
+        let target: Option<Address> = match token_grant.receiver {
+            None => None,
+            Some(bytes) => {
+                let arr: [u8; 20] = bytes.try_into().map_err(|_| {
+                    diesel::result::Error::DeserializationError(
+                        "Invalid receiver address length".into(),
+                    )
+                })?;
+                Some(Address::from(arr))
+            }
+        };
+
+        let settings = Settings {
+            token_contract: Address::from(token_contract),
+            target,
+            volume_limits,
+        };
+
+        Ok(Some(Grant {
+            id: token_grant.id,
+            shared_grant_id: token_grant.basic_grant_id,
+            shared: SharedGrantSettings::try_from_model(basic_grant)?,
+            settings,
+        }))
+    }
+
+    async fn record_transaction(
+        context: &EvalContext,
+        meaning: &Self::Meaning,
+        log_id: i32,
+        grant: &Grant<Self::Settings>,
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> QueryResult<()> {
+        insert_into(evm_token_transfer_log::table)
+            .values(NewEvmTokenTransferLog {
+                grant_id: grant.id,
+                log_id,
+                chain_id: context.chain as i32,
+                token_contract: context.to.to_vec(),
+                recipient_address: meaning.to.to_vec(),
+                value: utils::u256_to_bytes(meaning.value).to_vec(),
+            })
+            .execute(conn)
+            .await?;
+
+        Ok(())
+    }
+
+    async fn find_all_grants(
+        conn: &mut impl AsyncConnection<Backend = Sqlite>,
+    ) -> QueryResult<Vec<Grant<Self::Settings>>> {
+        let grants: Vec<(EvmBasicGrant, EvmTokenTransferGrant)> = grant_join()
+            .filter(evm_basic_grant::revoked_at.is_null())
+            .select((
+                EvmBasicGrant::as_select(),
+                EvmTokenTransferGrant::as_select(),
+            ))
+            .load(conn)
+            .await?;
+
+        if grants.is_empty() {
+            return Ok(Vec::new());
+        }
+
+        let grant_ids: Vec<i32> = grants.iter().map(|(_, g)| g.id).collect();
+
+        let all_volume_limits: Vec<EvmTokenTransferVolumeLimit> =
+            evm_token_transfer_volume_limit::table
+                .filter(evm_token_transfer_volume_limit::grant_id.eq_any(&grant_ids))
+                .select(EvmTokenTransferVolumeLimit::as_select())
+                .load(conn)
+                .await?;
+
+        let mut limits_by_grant: HashMap<i32, Vec<EvmTokenTransferVolumeLimit>> = HashMap::new();
+        for limit in all_volume_limits {
+            limits_by_grant
+                .entry(limit.grant_id)
+                .or_default()
+                .push(limit);
+        }
+
+        grants
+            .into_iter()
+            .map(|(basic, specific)| {
+                let volume_limits: Vec<VolumeRateLimit> = limits_by_grant
+                    .get(&specific.id)
+                    .map(|v| v.as_slice())
+                    .unwrap_or_default()
+                    .iter()
+                    .map(|row| {
+                        Ok(VolumeRateLimit {
+                            max_volume: utils::try_bytes_to_u256(&row.max_volume).map_err(|e| {
+                                diesel::result::Error::DeserializationError(Box::new(e))
+                            })?,
+                            window: Duration::seconds(row.window_secs as i64),
+                        })
+                    })
+                    .collect::<QueryResult<Vec<_>>>()?;
+
+                let token_contract: [u8; 20] =
+                    specific.token_contract.clone().try_into().map_err(|_| {
+                        diesel::result::Error::DeserializationError(
+                            "Invalid token contract address length".into(),
+                        )
+                    })?;
+
+                let target: Option<Address> = match &specific.receiver {
+                    None => None,
+                    Some(bytes) => {
+                        let arr: [u8; 20] = bytes.clone().try_into().map_err(|_| {
+                            diesel::result::Error::DeserializationError(
+                                "Invalid receiver address length".into(),
+                            )
+                        })?;
+                        Some(Address::from(arr))
+                    }
+                };
+
+                Ok(Grant {
+                    id: specific.id,
+                    shared_grant_id: specific.basic_grant_id,
+                    shared: SharedGrantSettings::try_from_model(basic)?,
+                    settings: Settings {
+                        token_contract: Address::from(token_contract),
+                        target,
+                        volume_limits,
+                    },
+                })
+            })
+            .collect()
+    }
+}
+
+#[cfg(test)]
+mod tests;

server/crates/arbiter-server/src/evm/policies/token_transfers/tests.rs

@@ -0,0 +1,463 @@
+use alloy::primitives::{Address, Bytes, U256, address};
+use alloy::sol_types::SolCall;
+use chrono::{Duration, Utc};
+use diesel::{SelectableHelper, insert_into};
+use diesel_async::RunQueryDsl;
+
+use crate::db::{
+    self, DatabaseConnection,
+    models::{EvmBasicGrant, NewEvmBasicGrant, SqliteTimestamp},
+    schema::evm_basic_grant,
+};
+use crate::evm::{
+    abi::IERC20::transferCall,
+    policies::{EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings, VolumeRateLimit},
+    utils,
+};
+
+use super::{Settings, TokenTransfer};
+
+// DAI on Ethereum mainnet — present in the static token registry
+const CHAIN_ID: u64 = 1;
+const DAI: Address = address!("6B175474E89094C44Da98b954EedeAC495271d0F");
+
+const WALLET_ID: i32 = 1;
+const CLIENT_ID: i32 = 2;
+
+const RECIPIENT: Address = address!("aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");
+const OTHER: Address = address!("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb");
+const UNKNOWN_TOKEN: Address = address!("cccccccccccccccccccccccccccccccccccccccc");
+
+/// Encode `transfer(to, value)` raw params (no 4-byte selector).
+/// `abi_decode_raw_validate` expects exactly this format.
+fn transfer_calldata(to: Address, value: U256) -> Bytes {
+    let mut raw = Vec::new();
+    transferCall { to, value }.abi_encode_raw(&mut raw);
+    Bytes::from(raw)
+}
+
+fn ctx(to: Address, calldata: Bytes) -> EvalContext {
+    EvalContext {
+        wallet_id: WALLET_ID,
+        client_id: CLIENT_ID,
+        chain: CHAIN_ID,
+        to,
+        value: U256::ZERO,
+        calldata,
+        max_fee_per_gas: 0,
+        max_priority_fee_per_gas: 0,
+    }
+}
+
+async fn insert_basic(conn: &mut DatabaseConnection, revoked: bool) -> EvmBasicGrant {
+    insert_into(evm_basic_grant::table)
+        .values(NewEvmBasicGrant {
+            wallet_id: WALLET_ID,
+            client_id: CLIENT_ID,
+            chain_id: CHAIN_ID as i32,
+            valid_from: None,
+            valid_until: None,
+            max_gas_fee_per_gas: None,
+            max_priority_fee_per_gas: None,
+            rate_limit_count: None,
+            rate_limit_window_secs: None,
+            revoked_at: revoked.then(|| SqliteTimestamp(Utc::now())),
+        })
+        .returning(EvmBasicGrant::as_select())
+        .get_result(conn)
+        .await
+        .unwrap()
+}
+
+fn make_settings(target: Option<Address>, max_volume: Option<u64>) -> Settings {
+    Settings {
+        token_contract: DAI,
+        target,
+        volume_limits: max_volume
+            .map(|v| {
+                vec![VolumeRateLimit {
+                    max_volume: U256::from(v),
+                    window: Duration::hours(1),
+                }]
+            })
+            .unwrap_or_default(),
+    }
+}
+
+fn shared() -> SharedGrantSettings {
+    SharedGrantSettings {
+        wallet_id: WALLET_ID,
+        chain: CHAIN_ID,
+        valid_from: None,
+        valid_until: None,
+        max_gas_fee_per_gas: None,
+        max_priority_fee_per_gas: None,
+        rate_limit: None,
+        client_id: CLIENT_ID,
+    }
+}
+
+// ── analyze ─────────────────────────────────────────────────────────────
+
+#[test]
+fn analyze_known_token_valid_calldata() {
+    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
+    let m = TokenTransfer::analyze(&ctx(DAI, calldata)).unwrap();
+    assert_eq!(m.to, RECIPIENT);
+    assert_eq!(m.value, U256::from(100u64));
+}
+
+#[test]
+fn analyze_unknown_token_returns_none() {
+    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
+    assert!(TokenTransfer::analyze(&ctx(UNKNOWN_TOKEN, calldata)).is_none());
+}
+
+#[test]
+fn analyze_invalid_calldata_returns_none() {
+    let calldata = Bytes::from(vec![0xde, 0xad, 0xbe, 0xef]);
+    assert!(TokenTransfer::analyze(&ctx(DAI, calldata)).is_none());
+}
+
+#[test]
+fn analyze_empty_calldata_returns_none() {
+    assert!(TokenTransfer::analyze(&ctx(DAI, Bytes::new())).is_none());
+}
+
+// ── evaluate ────────────────────────────────────────────────────────────
+
+#[tokio::test]
+async fn evaluate_rejects_nonzero_eth_value() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let grant = Grant {
+        id: 999,
+        shared_grant_id: 999,
+        shared: shared(),
+        settings: make_settings(None, None),
+    };
+    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
+    let mut context = ctx(DAI, calldata);
+    context.value = U256::from(1u64); // ETH attached to an ERC-20 call
+
+    let m = TokenTransfer::analyze(&EvalContext {
+        value: U256::ZERO,
+        ..context.clone()
+    })
+    .unwrap();
+    let v = TokenTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        v.iter()
+            .any(|e| matches!(e, EvalViolation::InvalidTransactionType))
+    );
+}
+
+#[tokio::test]
+async fn evaluate_passes_any_recipient_when_no_restriction() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let grant = Grant {
+        id: 999,
+        shared_grant_id: 999,
+        shared: shared(),
+        settings: make_settings(None, None),
+    };
+    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
+    let context = ctx(DAI, calldata);
+    let m = TokenTransfer::analyze(&context).unwrap();
+    let v = TokenTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(v.is_empty());
+}
+
+#[tokio::test]
+async fn evaluate_passes_matching_restricted_recipient() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let grant = Grant {
+        id: 999,
+        shared_grant_id: 999,
+        shared: shared(),
+        settings: make_settings(Some(RECIPIENT), None),
+    };
+    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
+    let context = ctx(DAI, calldata);
+    let m = TokenTransfer::analyze(&context).unwrap();
+    let v = TokenTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(v.is_empty());
+}
+
+#[tokio::test]
+async fn evaluate_rejects_wrong_restricted_recipient() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let grant = Grant {
+        id: 999,
+        shared_grant_id: 999,
+        shared: shared(),
+        settings: make_settings(Some(RECIPIENT), None),
+    };
+    let calldata = transfer_calldata(OTHER, U256::from(100u64));
+    let context = ctx(DAI, calldata);
+    let m = TokenTransfer::analyze(&context).unwrap();
+    let v = TokenTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        v.iter()
+            .any(|e| matches!(e, EvalViolation::InvalidTarget { .. }))
+    );
+}
+
+#[tokio::test]
+async fn evaluate_passes_volume_within_limit() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(None, Some(1_000));
+    let grant_id = TokenTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    // Record a past transfer of 500 (within 1000 limit)
+    use crate::db::{models::NewEvmTokenTransferLog, schema::evm_token_transfer_log};
+    insert_into(evm_token_transfer_log::table)
+        .values(NewEvmTokenTransferLog {
+            grant_id,
+            log_id: 0,
+            chain_id: CHAIN_ID as i32,
+            token_contract: DAI.to_vec(),
+            recipient_address: RECIPIENT.to_vec(),
+            value: utils::u256_to_bytes(U256::from(500u64)).to_vec(),
+        })
+        .execute(&mut *conn)
+        .await
+        .unwrap();
+
+    let grant = Grant {
+        id: grant_id,
+        shared_grant_id: basic.id,
+        shared: shared(),
+        settings,
+    };
+    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
+    let context = ctx(DAI, calldata);
+    let m = TokenTransfer::analyze(&context).unwrap();
+    let v = TokenTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        !v.iter()
+            .any(|e| matches!(e, EvalViolation::VolumetricLimitExceeded))
+    );
+}
+
+#[tokio::test]
+async fn evaluate_rejects_volume_over_limit() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(None, Some(1_000));
+    let grant_id = TokenTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    use crate::db::{models::NewEvmTokenTransferLog, schema::evm_token_transfer_log};
+    insert_into(evm_token_transfer_log::table)
+        .values(NewEvmTokenTransferLog {
+            grant_id,
+            log_id: 0,
+            chain_id: CHAIN_ID as i32,
+            token_contract: DAI.to_vec(),
+            recipient_address: RECIPIENT.to_vec(),
+            value: utils::u256_to_bytes(U256::from(1_001u64)).to_vec(),
+        })
+        .execute(&mut *conn)
+        .await
+        .unwrap();
+
+    let grant = Grant {
+        id: grant_id,
+        shared_grant_id: basic.id,
+        shared: shared(),
+        settings,
+    };
+    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
+    let context = ctx(DAI, calldata);
+    let m = TokenTransfer::analyze(&context).unwrap();
+    let v = TokenTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        v.iter()
+            .any(|e| matches!(e, EvalViolation::VolumetricLimitExceeded))
+    );
+}
+
+#[tokio::test]
+async fn evaluate_no_volume_limits_always_passes() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let grant = Grant {
+        id: 999,
+        shared_grant_id: 999,
+        shared: shared(),
+        settings: make_settings(None, None), // no volume limits
+    };
+    let calldata = transfer_calldata(RECIPIENT, U256::from(u64::MAX));
+    let context = ctx(DAI, calldata);
+    let m = TokenTransfer::analyze(&context).unwrap();
+    let v = TokenTransfer::evaluate(&context, &m, &grant, &mut *conn)
+        .await
+        .unwrap();
+    assert!(
+        !v.iter()
+            .any(|e| matches!(e, EvalViolation::VolumetricLimitExceeded))
+    );
+}
+
+// ── try_find_grant ───────────────────────────────────────────────────────
+
+#[tokio::test]
+async fn try_find_grant_roundtrip() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(Some(RECIPIENT), Some(5_000));
+    TokenTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let calldata = transfer_calldata(RECIPIENT, U256::from(100u64));
+    let found = TokenTransfer::try_find_grant(&ctx(DAI, calldata), &mut *conn)
+        .await
+        .unwrap();
+
+    assert!(found.is_some());
+    let g = found.unwrap();
+    assert_eq!(g.settings.token_contract, DAI);
+    assert_eq!(g.settings.target, Some(RECIPIENT));
+    assert_eq!(g.settings.volume_limits.len(), 1);
+    assert_eq!(g.settings.volume_limits[0].max_volume, U256::from(5_000u64));
+}
+
+#[tokio::test]
+async fn try_find_grant_revoked_returns_none() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, true).await;
+    let settings = make_settings(None, None);
+    TokenTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let calldata = transfer_calldata(RECIPIENT, U256::from(1u64));
+    let found = TokenTransfer::try_find_grant(&ctx(DAI, calldata), &mut *conn)
+        .await
+        .unwrap();
+    assert!(found.is_none());
+}
+
+#[tokio::test]
+async fn try_find_grant_unknown_token_returns_none() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(None, None);
+    TokenTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    // Query with a different token contract
+    let calldata = transfer_calldata(RECIPIENT, U256::from(1u64));
+    let found = TokenTransfer::try_find_grant(&ctx(UNKNOWN_TOKEN, calldata), &mut *conn)
+        .await
+        .unwrap();
+    assert!(found.is_none());
+}
+
+// ── find_all_grants ──────────────────────────────────────────────────────
+
+#[tokio::test]
+async fn find_all_grants_empty_db() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+    let all = TokenTransfer::find_all_grants(&mut *conn).await.unwrap();
+    assert!(all.is_empty());
+}
+
+#[tokio::test]
+async fn find_all_grants_excludes_revoked() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let settings = make_settings(None, Some(1_000));
+    let active = insert_basic(&mut conn, false).await;
+    TokenTransfer::create_grant(&active, &settings, &mut *conn)
+        .await
+        .unwrap();
+    let revoked = insert_basic(&mut conn, true).await;
+    TokenTransfer::create_grant(&revoked, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let all = TokenTransfer::find_all_grants(&mut *conn).await.unwrap();
+    assert_eq!(all.len(), 1);
+}
+
+#[tokio::test]
+async fn find_all_grants_loads_volume_limits() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let basic = insert_basic(&mut conn, false).await;
+    let settings = make_settings(None, Some(9_999));
+    TokenTransfer::create_grant(&basic, &settings, &mut *conn)
+        .await
+        .unwrap();
+
+    let all = TokenTransfer::find_all_grants(&mut *conn).await.unwrap();
+    assert_eq!(all.len(), 1);
+    assert_eq!(all[0].settings.volume_limits.len(), 1);
+    assert_eq!(
+        all[0].settings.volume_limits[0].max_volume,
+        U256::from(9_999u64)
+    );
+}
+
+#[tokio::test]
+async fn find_all_grants_multiple_grants_batch_loaded() {
+    let db = db::create_test_pool().await;
+    let mut conn = db.get().await.unwrap();
+
+    let b1 = insert_basic(&mut conn, false).await;
+    TokenTransfer::create_grant(&b1, &make_settings(None, Some(1_000)), &mut *conn)
+        .await
+        .unwrap();
+    let b2 = insert_basic(&mut conn, false).await;
+    TokenTransfer::create_grant(
+        &b2,
+        &make_settings(Some(RECIPIENT), Some(2_000)),
+        &mut *conn,
+    )
+    .await
+    .unwrap();
+
+    let all = TokenTransfer::find_all_grants(&mut *conn).await.unwrap();
+    assert_eq!(all.len(), 2);
+}

server/crates/arbiter-server/src/evm/safe_signer.rs

@@ -0,0 +1,195 @@
+use std::sync::Mutex;
+
+use crate::safe_cell::{SafeCell, SafeCellHandle as _};
+use alloy::{
+    consensus::SignableTransaction,
+    network::{TxSigner, TxSignerSync},
+    primitives::{Address, B256, ChainId, Signature},
+    signers::{Error, Result, Signer, SignerSync, utils::secret_key_to_address},
+};
+use async_trait::async_trait;
+use k256::ecdsa::{self, RecoveryId, SigningKey, signature::hazmat::PrehashSigner};
+
+/// An Ethereum signer that stores its secp256k1 secret key inside a
+/// hardware-protected [`MemSafe`] cell.
+///
+/// The underlying memory page is kept non-readable/non-writable at rest.
+/// Access is temporarily elevated only for the duration of each signing
+/// operation, then immediately revoked.
+///
+/// Because [`MemSafe::read`] requires `&mut self` while the [`Signer`] trait
+/// requires `&self`, the cell is wrapped in a [`Mutex`].
+pub struct SafeSigner {
+    key: Mutex<SafeCell<SigningKey>>,
+    address: Address,
+    chain_id: Option<ChainId>,
+}
+
+impl std::fmt::Debug for SafeSigner {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("SafeSigner")
+            .field("address", &self.address)
+            .field("chain_id", &self.chain_id)
+            .finish()
+    }
+}
+
+/// Generates a secp256k1 secret key directly inside a [`MemSafe`] cell.
+///
+/// Random bytes are written in-place into protected memory, then validated
+/// as a legal scalar on the secp256k1 curve (the scalar must be in
+/// `[1, n)` where `n` is the curve order — roughly 1-in-2^128 chance of
+/// rejection, but we retry to be correct).
+///
+/// Returns the protected key bytes and the derived Ethereum address.
+pub fn generate(rng: &mut impl rand::Rng) -> (SafeCell<[u8; 32]>, Address) {
+    loop {
+        let mut cell = SafeCell::new_inline(|w: &mut [u8; 32]| {
+            rng.fill_bytes(w);
+        });
+
+        let reader = cell.read();
+        if let Ok(sk) = SigningKey::from_slice(reader.as_ref()) {
+            let address = secret_key_to_address(&sk);
+            drop(reader);
+            return (cell, address);
+        }
+    }
+}
+
+impl SafeSigner {
+    /// Reconstructs a `SafeSigner` from key material held in a [`MemSafe`] buffer.
+    ///
+    /// The key bytes are read from protected memory, parsed as a secp256k1
+    /// scalar, and immediately moved into a new [`MemSafe`] cell. The raw
+    /// bytes are never exposed outside this function.
+    pub fn from_cell(mut cell: SafeCell<Vec<u8>>) -> Result<Self> {
+        let reader = cell.read();
+        let sk = SigningKey::from_slice(reader.as_slice()).map_err(Error::other)?;
+        drop(reader);
+        Self::new(sk)
+    }
+
+    /// Creates a new `SafeSigner` by moving the signing key into a protected
+    /// memory region.
+    pub fn new(key: SigningKey) -> Result<Self> {
+        let address = secret_key_to_address(&key);
+        let cell = SafeCell::new(key);
+        Ok(Self {
+            key: Mutex::new(cell),
+            address,
+            chain_id: None,
+        })
+    }
+
+    fn sign_hash_inner(&self, hash: &B256) -> Result<Signature> {
+        #[allow(clippy::expect_used)]
+        let mut cell = self.key.lock().expect("SafeSigner mutex poisoned");
+        let reader = cell.read();
+        let sig: (ecdsa::Signature, RecoveryId) = reader.sign_prehash(hash.as_ref())?;
+        Ok(sig.into())
+    }
+
+    fn sign_tx_inner(&self, tx: &mut dyn SignableTransaction<Signature>) -> Result<Signature> {
+        if let Some(chain_id) = self.chain_id
+            && !tx.set_chain_id_checked(chain_id)
+        {
+            return Err(Error::TransactionChainIdMismatch {
+                signer: chain_id,
+                #[allow(clippy::expect_used)]
+                tx: tx.chain_id().expect("Chain ID is guaranteed to be set"),
+            });
+        }
+        self.sign_hash_inner(&tx.signature_hash())
+            .map_err(Error::other)
+    }
+}
+
+#[async_trait]
+impl Signer for SafeSigner {
+    #[inline]
+    async fn sign_hash(&self, hash: &B256) -> Result<Signature> {
+        self.sign_hash_inner(hash)
+    }
+
+    #[inline]
+    fn address(&self) -> Address {
+        self.address
+    }
+
+    #[inline]
+    fn chain_id(&self) -> Option<ChainId> {
+        self.chain_id
+    }
+
+    #[inline]
+    fn set_chain_id(&mut self, chain_id: Option<ChainId>) {
+        self.chain_id = chain_id;
+    }
+}
+
+impl SignerSync for SafeSigner {
+    #[inline]
+    fn sign_hash_sync(&self, hash: &B256) -> Result<Signature> {
+        self.sign_hash_inner(hash)
+    }
+
+    #[inline]
+    fn chain_id_sync(&self) -> Option<ChainId> {
+        self.chain_id
+    }
+}
+
+#[async_trait]
+impl TxSigner<Signature> for SafeSigner {
+    fn address(&self) -> Address {
+        self.address
+    }
+
+    async fn sign_transaction(
+        &self,
+        tx: &mut dyn SignableTransaction<Signature>,
+    ) -> Result<Signature> {
+        self.sign_tx_inner(tx)
+    }
+}
+
+impl TxSignerSync<Signature> for SafeSigner {
+    fn address(&self) -> Address {
+        self.address
+    }
+
+    fn sign_transaction_sync(
+        &self,
+        tx: &mut dyn SignableTransaction<Signature>,
+    ) -> Result<Signature> {
+        self.sign_tx_inner(tx)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use alloy::signers::local::PrivateKeySigner;
+
+    #[test]
+    fn sign_and_recover() {
+        let pk = PrivateKeySigner::random();
+        let key = pk.into_credential();
+        let signer = SafeSigner::new(key).unwrap();
+        let message = b"hello arbiter";
+        let sig = signer.sign_message_sync(message).unwrap();
+        let recovered = sig.recover_address_from_msg(message).unwrap();
+        assert_eq!(recovered, Signer::address(&signer));
+    }
+
+    #[test]
+    fn chain_id_roundtrip() {
+        let pk = PrivateKeySigner::random();
+        let key = pk.into_credential();
+        let mut signer = SafeSigner::new(key).unwrap();
+        assert_eq!(Signer::chain_id(&signer), None);
+        signer.set_chain_id(Some(1337));
+        assert_eq!(Signer::chain_id(&signer), Some(1337));
+    }
+}

server/crates/arbiter-server/src/evm/utils.rs

@@ -0,0 +1,26 @@
+use alloy::primitives::U256;
+
+#[derive(thiserror::Error, Debug)]
+#[error("Expected {expected} bytes but got {actual} bytes")]
+pub struct LengthError {
+    pub expected: usize,
+    pub actual: usize,
+}
+
+pub fn u256_to_bytes(value: U256) -> [u8; 32] {
+    value.to_le_bytes()
+}
+pub fn bytes_to_u256(bytes: &[u8]) -> Option<U256> {
+    let bytes: [u8; 32] = bytes.try_into().ok()?;
+    Some(U256::from_le_bytes(bytes))
+}
+
+pub fn try_bytes_to_u256(bytes: &[u8]) -> diesel::result::QueryResult<U256> {
+    let bytes: [u8; 32] = bytes.try_into().map_err(|_| {
+        diesel::result::Error::DeserializationError(Box::new(LengthError {
+            expected: 32,
+            actual: bytes.len(),
+        }))
+    })?;
+    Ok(U256::from_le_bytes(bytes))
+}

server/crates/arbiter-server/src/grpc/client.rs

@@ -0,0 +1,137 @@
+use arbiter_proto::{
+    proto::client::{
+        ClientRequest, ClientResponse, VaultState as ProtoVaultState,
+        client_request::Payload as ClientRequestPayload,
+        client_response::Payload as ClientResponsePayload,
+    },
+    transport::{Receiver, Sender, grpc::GrpcBi},
+};
+use kameo::{
+    actor::{ActorRef, Spawn as _},
+    error::SendError,
+};
+use tonic::Status;
+use tracing::{info, warn};
+
+use crate::{
+    actors::{
+        client::{
+            self, ClientConnection,
+            session::{ClientSession, Error, HandleQueryVaultState},
+        },
+        keyholder::KeyHolderState,
+    },
+    grpc::request_tracker::RequestTracker,
+    utils::defer,
+};
+
+mod auth;
+
+async fn dispatch_loop(
+    mut bi: GrpcBi<ClientRequest, ClientResponse>,
+    actor: ActorRef<ClientSession>,
+    mut request_tracker: RequestTracker,
+) {
+    loop {
+        let Some(conn) = bi.recv().await else {
+            return;
+        };
+
+        if dispatch_conn_message(&mut bi, &actor, &mut request_tracker, conn)
+            .await
+            .is_err()
+        {
+            return;
+        }
+    }
+}
+
+async fn dispatch_conn_message(
+    bi: &mut GrpcBi<ClientRequest, ClientResponse>,
+    actor: &ActorRef<ClientSession>,
+    request_tracker: &mut RequestTracker,
+    conn: Result<ClientRequest, Status>,
+) -> Result<(), ()> {
+    let conn = match conn {
+        Ok(conn) => conn,
+        Err(err) => {
+            warn!(error = ?err, "Failed to receive client request");
+            return Err(());
+        }
+    };
+
+    let request_id = match request_tracker.request(conn.request_id) {
+        Ok(request_id) => request_id,
+        Err(err) => {
+            let _ = bi.send(Err(err)).await;
+            return Err(());
+        }
+    };
+    let Some(payload) = conn.payload else {
+        let _ = bi
+            .send(Err(Status::invalid_argument(
+                "Missing client request payload",
+            )))
+            .await;
+        return Err(());
+    };
+
+    let payload = match payload {
+        ClientRequestPayload::QueryVaultState(_) => ClientResponsePayload::VaultState(
+            match actor.ask(HandleQueryVaultState {}).await {
+                Ok(KeyHolderState::Unbootstrapped) => ProtoVaultState::Unbootstrapped,
+                Ok(KeyHolderState::Sealed) => ProtoVaultState::Sealed,
+                Ok(KeyHolderState::Unsealed) => ProtoVaultState::Unsealed,
+                Err(SendError::HandlerError(Error::Internal)) => ProtoVaultState::Error,
+                Err(err) => {
+                    warn!(error = ?err, "Failed to query vault state");
+                    ProtoVaultState::Error
+                }
+            }
+            .into(),
+        ),
+        payload => {
+            warn!(?payload, "Unsupported post-auth client request");
+            let _ = bi
+                .send(Err(Status::invalid_argument("Unsupported client request")))
+                .await;
+            return Err(());
+        }
+    };
+
+    bi.send(Ok(ClientResponse {
+        request_id: Some(request_id),
+        payload: Some(payload),
+    }))
+    .await
+    .map_err(|_| ())
+}
+
+pub async fn start(conn: ClientConnection, mut bi: GrpcBi<ClientRequest, ClientResponse>) {
+    let mut conn = conn;
+    let mut request_tracker = RequestTracker::default();
+    let mut response_id = None;
+
+    match auth::start(&mut conn, &mut bi, &mut request_tracker, &mut response_id).await {
+        Ok(_) => {
+            let actor =
+                client::session::ClientSession::spawn(client::session::ClientSession::new(conn));
+            let actor_for_cleanup = actor.clone();
+            let _ = defer(move || {
+                actor_for_cleanup.kill();
+            });
+
+            info!("Client authenticated successfully");
+            dispatch_loop(bi, actor, request_tracker).await;
+        }
+        Err(e) => {
+            let mut transport = auth::AuthTransportAdapter::new(
+                &mut bi,
+                &mut request_tracker,
+                &mut response_id,
+            );
+            let _ = transport.send(Err(e.clone())).await;
+            warn!(error = ?e, "Authentication failed");
+        }
+    }
+}

server/crates/arbiter-server/src/grpc/client/auth.rs

@@ -0,0 +1,173 @@
+use arbiter_proto::{
+    proto::client::{
+        AuthChallenge as ProtoAuthChallenge, AuthChallengeRequest as ProtoAuthChallengeRequest,
+        AuthChallengeSolution as ProtoAuthChallengeSolution, AuthResult as ProtoAuthResult,
+        ClientRequest, ClientResponse, client_request::Payload as ClientRequestPayload,
+        client_response::Payload as ClientResponsePayload,
+    },
+    transport::{Bi, Error as TransportError, Receiver, Sender, grpc::GrpcBi},
+};
+use async_trait::async_trait;
+use tonic::Status;
+use tracing::warn;
+
+use crate::{
+    actors::client::{self, ClientConnection, auth},
+    grpc::request_tracker::RequestTracker,
+};
+
+pub struct AuthTransportAdapter<'a> {
+    bi: &'a mut GrpcBi<ClientRequest, ClientResponse>,
+    request_tracker: &'a mut RequestTracker,
+    response_id: &'a mut Option<i32>,
+}
+
+impl<'a> AuthTransportAdapter<'a> {
+    pub fn new(
+        bi: &'a mut GrpcBi<ClientRequest, ClientResponse>,
+        request_tracker: &'a mut RequestTracker,
+        response_id: &'a mut Option<i32>,
+    ) -> Self {
+        Self {
+            bi,
+            request_tracker,
+            response_id,
+        }
+    }
+
+    fn response_to_proto(response: auth::Outbound) -> ClientResponsePayload {
+        match response {
+            auth::Outbound::AuthChallenge { pubkey, nonce } => {
+                ClientResponsePayload::AuthChallenge(ProtoAuthChallenge {
+                    pubkey: pubkey.to_bytes().to_vec(),
+                    nonce,
+                })
+            }
+            auth::Outbound::AuthSuccess => {
+                ClientResponsePayload::AuthResult(ProtoAuthResult::Success.into())
+            }
+        }
+    }
+
+    fn error_to_proto(error: auth::Error) -> ClientResponsePayload {
+        ClientResponsePayload::AuthResult(
+            match error {
+                auth::Error::InvalidChallengeSolution => ProtoAuthResult::InvalidSignature,
+                auth::Error::ApproveError(auth::ApproveError::Denied) => {
+                    ProtoAuthResult::ApprovalDenied
+                }
+                auth::Error::ApproveError(auth::ApproveError::Upstream(
+                    crate::actors::router::ApprovalError::NoUserAgentsConnected,
+                )) => ProtoAuthResult::NoUserAgentsOnline,
+                auth::Error::ApproveError(auth::ApproveError::Internal)
+                | auth::Error::DatabasePoolUnavailable
+                | auth::Error::DatabaseOperationFailed
+                | auth::Error::Transport => ProtoAuthResult::Internal,
+            }
+            .into(),
+        )
+    }
+
+    async fn send_client_response(
+        &mut self,
+        payload: ClientResponsePayload,
+    ) -> Result<(), TransportError> {
+        let request_id = self.response_id.take();
+
+        self.bi
+            .send(Ok(ClientResponse {
+                request_id,
+                payload: Some(payload),
+            }))
+            .await
+    }
+
+    async fn send_auth_result(&mut self, result: ProtoAuthResult) -> Result<(), TransportError> {
+        self.send_client_response(ClientResponsePayload::AuthResult(result.into()))
+            .await
+    }
+}
+
+#[async_trait]
+impl Sender<Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {
+    async fn send(
+        &mut self,
+        item: Result<auth::Outbound, auth::Error>,
+    ) -> Result<(), TransportError> {
+        let payload = match item {
+            Ok(message) => AuthTransportAdapter::response_to_proto(message),
+            Err(err) => AuthTransportAdapter::error_to_proto(err),
+        };
+
+        self.send_client_response(payload).await
+    }
+}
+
+#[async_trait]
+impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
+    async fn recv(&mut self) -> Option<auth::Inbound> {
+        let request = match self.bi.recv().await? {
+            Ok(request) => request,
+            Err(error) => {
+                warn!(error = ?error, "grpc client recv failed; closing stream");
+                return None;
+            }
+        };
+
+        let request_id = match self.request_tracker.request(request.request_id) {
+            Ok(request_id) => request_id,
+            Err(error) => {
+                let _ = self.bi.send(Err(error)).await;
+                return None;
+            }
+        };
+        *self.response_id = Some(request_id);
+
+        let payload = request.payload?;
+
+        match payload {
+            ClientRequestPayload::AuthChallengeRequest(ProtoAuthChallengeRequest { pubkey }) => {
+                let Ok(pubkey) = <[u8; 32]>::try_from(pubkey) else {
+                    let _ = self.send_auth_result(ProtoAuthResult::InvalidKey).await;
+                    return None;
+                };
+                let Ok(pubkey) = ed25519_dalek::VerifyingKey::from_bytes(&pubkey) else {
+                    let _ = self.send_auth_result(ProtoAuthResult::InvalidKey).await;
+                    return None;
+                };
+                Some(auth::Inbound::AuthChallengeRequest { pubkey })
+            }
+            ClientRequestPayload::AuthChallengeSolution(ProtoAuthChallengeSolution {
+                signature,
+            }) => {
+                let Ok(signature) = ed25519_dalek::Signature::try_from(signature.as_slice()) else {
+                    let _ = self
+                        .send_auth_result(ProtoAuthResult::InvalidSignature)
+                        .await;
+                    return None;
+                };
+                Some(auth::Inbound::AuthChallengeSolution { signature })
+            }
+            _ => {
+                let _ = self
+                    .bi
+                    .send(Err(Status::invalid_argument("Unsupported client auth request")))
+                    .await;
+                None
+            }
+        }
+    }
+}
+
+impl Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {}
+
+pub async fn start(
+    conn: &mut ClientConnection,
+    bi: &mut GrpcBi<ClientRequest, ClientResponse>,
+    request_tracker: &mut RequestTracker,
+    response_id: &mut Option<i32>,
+) -> Result<(), auth::Error> {
+    let mut transport = AuthTransportAdapter::new(bi, request_tracker, response_id);
+    client::auth::authenticate(conn, &mut transport).await?;
+    Ok(())
+}

server/crates/arbiter-server/src/grpc/mod.rs

@@ -0,0 +1,62 @@
+use arbiter_proto::{
+    proto::{
+        client::{ClientRequest, ClientResponse},
+        user_agent::{UserAgentRequest, UserAgentResponse},
+    },
+    transport::grpc::GrpcBi,
+};
+use tokio_stream::wrappers::ReceiverStream;
+use tonic::{Request, Response, Status, async_trait};
+use tracing::info;
+
+use crate::{
+    actors::{client::ClientConnection, user_agent::UserAgentConnection},
+    grpc::user_agent::start,
+};
+
+pub mod client;
+mod request_tracker;
+pub mod user_agent;
+
+#[async_trait]
+impl arbiter_proto::proto::arbiter_service_server::ArbiterService for super::Server {
+    type UserAgentStream = ReceiverStream<Result<UserAgentResponse, Status>>;
+    type ClientStream = ReceiverStream<Result<ClientResponse, Status>>;
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    async fn client(
+        &self,
+        request: Request<tonic::Streaming<ClientRequest>>,
+    ) -> Result<Response<Self::ClientStream>, Status> {
+        let req_stream = request.into_inner();
+        let (bi, rx) = GrpcBi::from_bi_stream(req_stream);
+        let props = ClientConnection::new(self.context.db.clone(), self.context.actors.clone());
+        tokio::spawn(client::start(props, bi));
+
+        info!(event = "connection established", "grpc.client");
+
+        Ok(Response::new(rx))
+    }
+
+    #[tracing::instrument(level = "debug", skip(self))]
+    async fn user_agent(
+        &self,
+        request: Request<tonic::Streaming<UserAgentRequest>>,
+    ) -> Result<Response<Self::UserAgentStream>, Status> {
+        let req_stream = request.into_inner();
+
+        let (bi, rx) = GrpcBi::from_bi_stream(req_stream);
+
+        tokio::spawn(start(
+            UserAgentConnection {
+                db: self.context.db.clone(),
+                actors: self.context.actors.clone(),
+            },
+            bi,
+        ));
+
+        info!(event = "connection established", "grpc.user_agent");
+
+        Ok(Response::new(rx))
+    }
+}

server/crates/arbiter-server/src/grpc/request_tracker.rs

@@ -0,0 +1,20 @@
+use tonic::Status;
+
+#[derive(Default)]
+pub struct RequestTracker {
+    next_request_id: i32,
+}
+
+impl RequestTracker {
+    pub fn request(&mut self, id: i32) -> Result<i32, Status> {
+        if id < self.next_request_id {
+            return Err(Status::invalid_argument("Duplicate request id"));
+        }
+
+        self.next_request_id = id
+            .checked_add(1)
+            .ok_or_else(|| Status::invalid_argument("Invalid request id"))?;
+
+        Ok(id)
+    }
+}

server/crates/arbiter-server/src/grpc/user_agent.rs

@@ -0,0 +1,604 @@
+use tokio::sync::mpsc;
+
+use arbiter_proto::{
+    google::protobuf::{Empty as ProtoEmpty, Timestamp as ProtoTimestamp},
+    proto::{
+        evm::{
+            EtherTransferSettings as ProtoEtherTransferSettings, EvmError as ProtoEvmError,
+            EvmGrantCreateRequest, EvmGrantCreateResponse, EvmGrantDeleteRequest,
+            EvmGrantDeleteResponse, EvmGrantList, EvmGrantListResponse, GrantEntry,
+            SharedSettings as ProtoSharedSettings, SpecificGrant as ProtoSpecificGrant,
+            TokenTransferSettings as ProtoTokenTransferSettings,
+            TransactionRateLimit as ProtoTransactionRateLimit,
+            VolumeRateLimit as ProtoVolumeRateLimit, WalletCreateResponse, WalletEntry, WalletList,
+            WalletListResponse, evm_grant_create_response::Result as EvmGrantCreateResult,
+            evm_grant_delete_response::Result as EvmGrantDeleteResult,
+            evm_grant_list_response::Result as EvmGrantListResult,
+            specific_grant::Grant as ProtoSpecificGrantType,
+            wallet_create_response::Result as WalletCreateResult,
+            wallet_list_response::Result as WalletListResult,
+        },
+        user_agent::{
+            BootstrapEncryptedKey as ProtoBootstrapEncryptedKey,
+            BootstrapResult as ProtoBootstrapResult,
+            SdkClientConnectionResponse as ProtoSdkClientConnectionResponse,
+            UnsealEncryptedKey as ProtoUnsealEncryptedKey, UnsealResult as ProtoUnsealResult,
+            UnsealStart, UserAgentRequest, UserAgentResponse, VaultState as ProtoVaultState,
+            user_agent_request::Payload as UserAgentRequestPayload,
+            user_agent_response::Payload as UserAgentResponsePayload,
+        },
+    },
+    transport::{Error as TransportError, Receiver, Sender, grpc::GrpcBi},
+};
+use async_trait::async_trait;
+use chrono::{TimeZone, Utc};
+use kameo::{
+    actor::{ActorRef, Spawn as _},
+    error::SendError,
+};
+use tonic::Status;
+use tracing::{info, warn};
+
+use crate::{
+    actors::{
+        keyholder::KeyHolderState,
+        user_agent::{
+            OutOfBand, UserAgentConnection, UserAgentSession,
+            session::{
+                BootstrapError, Error, HandleBootstrapEncryptedKey, HandleEvmWalletCreate,
+                HandleEvmWalletList, HandleGrantCreate, HandleGrantDelete, HandleGrantList,
+                HandleQueryVaultState, HandleUnsealEncryptedKey, HandleUnsealRequest, UnsealError,
+            },
+        },
+    },
+    evm::policies::{
+        Grant, SharedGrantSettings, SpecificGrant, TransactionRateLimit, VolumeRateLimit,
+        ether_transfer, token_transfers,
+    },
+    grpc::request_tracker::RequestTracker,
+    utils::defer,
+};
+use alloy::primitives::{Address, U256};
+mod auth;
+
+pub struct OutOfBandAdapter(mpsc::Sender<OutOfBand>);
+
+#[async_trait]
+impl Sender<OutOfBand> for OutOfBandAdapter {
+    async fn send(&mut self, item: OutOfBand) -> Result<(), TransportError> {
+        self.0.send(item).await.map_err(|e| {
+            warn!(error = ?e, "Failed to send out-of-band message");
+            TransportError::ChannelClosed
+        })
+    }
+}
+
+async fn dispatch_loop(
+    mut bi: GrpcBi<UserAgentRequest, UserAgentResponse>,
+    actor: ActorRef<UserAgentSession>,
+    mut receiver: mpsc::Receiver<OutOfBand>,
+    mut request_tracker: RequestTracker,
+) {
+    loop {
+        tokio::select! {
+            oob = receiver.recv() => {
+                let Some(oob) = oob else {
+                    return;
+                };
+
+                if send_out_of_band(&mut bi, oob).await.is_err() {
+                    return;
+                }
+            }
+
+            conn = bi.recv() => {
+                let Some(conn) = conn else {
+                    return;
+                };
+
+                if dispatch_conn_message(&mut bi, &actor, &mut request_tracker, conn)
+                    .await
+                    .is_err()
+                {
+                    return;
+                }
+            }
+        }
+    }
+}
+
+async fn dispatch_conn_message(
+    bi: &mut GrpcBi<UserAgentRequest, UserAgentResponse>,
+    actor: &ActorRef<UserAgentSession>,
+    request_tracker: &mut RequestTracker,
+    conn: Result<UserAgentRequest, Status>,
+) -> Result<(), ()> {
+    let conn = match conn {
+        Ok(conn) => conn,
+        Err(err) => {
+            warn!(error = ?err, "Failed to receive user agent request");
+            return Err(());
+        }
+    };
+
+    let request_id = match request_tracker.request(conn.id) {
+        Ok(request_id) => request_id,
+        Err(err) => {
+            let _ = bi.send(Err(err)).await;
+            return Err(());
+        }
+    };
+
+    let Some(payload) = conn.payload else {
+        let _ = bi
+            .send(Err(Status::invalid_argument(
+                "Missing user-agent request payload",
+            )))
+            .await;
+        return Err(());
+    };
+
+    let payload = match payload {
+        UserAgentRequestPayload::UnsealStart(UnsealStart { client_pubkey }) => {
+            let client_pubkey = match <[u8; 32]>::try_from(client_pubkey) {
+                Ok(bytes) => x25519_dalek::PublicKey::from(bytes),
+                Err(_) => {
+                    let _ = bi
+                        .send(Err(Status::invalid_argument("Invalid X25519 public key")))
+                        .await;
+                    return Err(());
+                }
+            };
+
+            match actor.ask(HandleUnsealRequest { client_pubkey }).await {
+                Ok(response) => UserAgentResponsePayload::UnsealStartResponse(
+                    arbiter_proto::proto::user_agent::UnsealStartResponse {
+                        server_pubkey: response.server_pubkey.as_bytes().to_vec(),
+                    },
+                ),
+                Err(err) => {
+                    warn!(error = ?err, "Failed to handle unseal start request");
+                    let _ = bi
+                        .send(Err(Status::internal("Failed to start unseal flow")))
+                        .await;
+                    return Err(());
+                }
+            }
+        }
+        UserAgentRequestPayload::UnsealEncryptedKey(ProtoUnsealEncryptedKey {
+            nonce,
+            ciphertext,
+            associated_data,
+        }) => UserAgentResponsePayload::UnsealResult(
+            match actor
+                .ask(HandleUnsealEncryptedKey {
+                    nonce,
+                    ciphertext,
+                    associated_data,
+                })
+                .await
+            {
+                Ok(()) => ProtoUnsealResult::Success,
+                Err(SendError::HandlerError(UnsealError::InvalidKey)) => {
+                    ProtoUnsealResult::InvalidKey
+                }
+                Err(err) => {
+                    warn!(error = ?err, "Failed to handle unseal request");
+                    let _ = bi
+                        .send(Err(Status::internal("Failed to unseal vault")))
+                        .await;
+                    return Err(());
+                }
+            }
+            .into(),
+        ),
+        UserAgentRequestPayload::BootstrapEncryptedKey(ProtoBootstrapEncryptedKey {
+            nonce,
+            ciphertext,
+            associated_data,
+        }) => UserAgentResponsePayload::BootstrapResult(
+            match actor
+                .ask(HandleBootstrapEncryptedKey {
+                    nonce,
+                    ciphertext,
+                    associated_data,
+                })
+                .await
+            {
+                Ok(()) => ProtoBootstrapResult::Success,
+                Err(SendError::HandlerError(BootstrapError::InvalidKey)) => {
+                    ProtoBootstrapResult::InvalidKey
+                }
+                Err(SendError::HandlerError(BootstrapError::AlreadyBootstrapped)) => {
+                    ProtoBootstrapResult::AlreadyBootstrapped
+                }
+                Err(err) => {
+                    warn!(error = ?err, "Failed to handle bootstrap request");
+                    let _ = bi
+                        .send(Err(Status::internal("Failed to bootstrap vault")))
+                        .await;
+                    return Err(());
+                }
+            }
+            .into(),
+        ),
+        UserAgentRequestPayload::QueryVaultState(_) => UserAgentResponsePayload::VaultState(
+            match actor.ask(HandleQueryVaultState {}).await {
+                Ok(KeyHolderState::Unbootstrapped) => ProtoVaultState::Unbootstrapped,
+                Ok(KeyHolderState::Sealed) => ProtoVaultState::Sealed,
+                Ok(KeyHolderState::Unsealed) => ProtoVaultState::Unsealed,
+                Err(err) => {
+                    warn!(error = ?err, "Failed to query vault state");
+                    ProtoVaultState::Error
+                }
+            }
+            .into(),
+        ),
+        UserAgentRequestPayload::EvmWalletCreate(_) => UserAgentResponsePayload::EvmWalletCreate(
+            EvmGrantOrWallet::wallet_create_response(actor.ask(HandleEvmWalletCreate {}).await),
+        ),
+        UserAgentRequestPayload::EvmWalletList(_) => UserAgentResponsePayload::EvmWalletList(
+            EvmGrantOrWallet::wallet_list_response(actor.ask(HandleEvmWalletList {}).await),
+        ),
+        UserAgentRequestPayload::EvmGrantList(_) => UserAgentResponsePayload::EvmGrantList(
+            EvmGrantOrWallet::grant_list_response(actor.ask(HandleGrantList {}).await),
+        ),
+        UserAgentRequestPayload::EvmGrantCreate(EvmGrantCreateRequest {
+            client_id,
+            shared,
+            specific,
+        }) => {
+            let (basic, grant) = match parse_grant_request(shared, specific) {
+                Ok(values) => values,
+                Err(status) => {
+                    let _ = bi.send(Err(status)).await;
+                    return Err(());
+                }
+            };
+
+            UserAgentResponsePayload::EvmGrantCreate(EvmGrantOrWallet::grant_create_response(
+                actor
+                    .ask(HandleGrantCreate {
+                        client_id,
+                        basic,
+                        grant,
+                    })
+                    .await,
+            ))
+        }
+        UserAgentRequestPayload::EvmGrantDelete(EvmGrantDeleteRequest { grant_id }) => {
+            UserAgentResponsePayload::EvmGrantDelete(EvmGrantOrWallet::grant_delete_response(
+                actor.ask(HandleGrantDelete { grant_id }).await,
+            ))
+        }
+        payload => {
+            warn!(?payload, "Unsupported post-auth user agent request");
+            let _ = bi
+                .send(Err(Status::invalid_argument(
+                    "Unsupported user-agent request",
+                )))
+                .await;
+            return Err(());
+        }
+    };
+
+    bi.send(Ok(UserAgentResponse {
+        id: Some(request_id),
+        payload: Some(payload),
+    }))
+    .await
+    .map_err(|_| ())
+}
+
+async fn send_out_of_band(
+    bi: &mut GrpcBi<UserAgentRequest, UserAgentResponse>,
+    oob: OutOfBand,
+) -> Result<(), ()> {
+    let payload = match oob {
+        // The current protobuf response payload carries only an approval boolean.
+        // Keep emitting this shape until a dedicated out-of-band request/cancel payload
+        // is reintroduced in the protocol definition.
+        OutOfBand::ClientConnectionRequest { pubkey: _ } => {
+            UserAgentResponsePayload::SdkClientConnectionResponse(
+                ProtoSdkClientConnectionResponse { approved: false },
+            )
+        }
+        OutOfBand::ClientConnectionCancel => UserAgentResponsePayload::SdkClientConnectionResponse(
+            ProtoSdkClientConnectionResponse { approved: false },
+        ),
+    };
+
+    bi.send(Ok(UserAgentResponse {
+        id: None,
+        payload: Some(payload),
+    }))
+    .await
+    .map_err(|_| ())
+}
+
+fn parse_grant_request(
+    shared: Option<ProtoSharedSettings>,
+    specific: Option<ProtoSpecificGrant>,
+) -> Result<(SharedGrantSettings, SpecificGrant), Status> {
+    let shared = shared.ok_or_else(|| Status::invalid_argument("Missing shared grant settings"))?;
+    let specific =
+        specific.ok_or_else(|| Status::invalid_argument("Missing specific grant settings"))?;
+
+    Ok((
+        shared_settings_from_proto(shared)?,
+        specific_grant_from_proto(specific)?,
+    ))
+}
+
+fn shared_settings_from_proto(shared: ProtoSharedSettings) -> Result<SharedGrantSettings, Status> {
+    Ok(SharedGrantSettings {
+        wallet_id: shared.wallet_id,
+        client_id: 0,
+        chain: shared.chain_id,
+        valid_from: shared.valid_from.map(proto_timestamp_to_utc).transpose()?,
+        valid_until: shared.valid_until.map(proto_timestamp_to_utc).transpose()?,
+        max_gas_fee_per_gas: shared
+            .max_gas_fee_per_gas
+            .as_deref()
+            .map(u256_from_proto_bytes)
+            .transpose()?,
+        max_priority_fee_per_gas: shared
+            .max_priority_fee_per_gas
+            .as_deref()
+            .map(u256_from_proto_bytes)
+            .transpose()?,
+        rate_limit: shared.rate_limit.map(|limit| TransactionRateLimit {
+            count: limit.count,
+            window: chrono::Duration::seconds(limit.window_secs),
+        }),
+    })
+}
+
+fn specific_grant_from_proto(specific: ProtoSpecificGrant) -> Result<SpecificGrant, Status> {
+    match specific.grant {
+        Some(ProtoSpecificGrantType::EtherTransfer(ProtoEtherTransferSettings {
+            targets,
+            limit,
+        })) => Ok(SpecificGrant::EtherTransfer(ether_transfer::Settings {
+            target: targets
+                .into_iter()
+                .map(address_from_bytes)
+                .collect::<Result<_, _>>()?,
+            limit: volume_rate_limit_from_proto(limit.ok_or_else(|| {
+                Status::invalid_argument("Missing ether transfer volume rate limit")
+            })?)?,
+        })),
+        Some(ProtoSpecificGrantType::TokenTransfer(ProtoTokenTransferSettings {
+            token_contract,
+            target,
+            volume_limits,
+        })) => Ok(SpecificGrant::TokenTransfer(token_transfers::Settings {
+            token_contract: address_from_bytes(token_contract)?,
+            target: target.map(address_from_bytes).transpose()?,
+            volume_limits: volume_limits
+                .into_iter()
+                .map(volume_rate_limit_from_proto)
+                .collect::<Result<_, _>>()?,
+        })),
+        None => Err(Status::invalid_argument("Missing specific grant kind")),
+    }
+}
+
+fn volume_rate_limit_from_proto(limit: ProtoVolumeRateLimit) -> Result<VolumeRateLimit, Status> {
+    Ok(VolumeRateLimit {
+        max_volume: u256_from_proto_bytes(&limit.max_volume)?,
+        window: chrono::Duration::seconds(limit.window_secs),
+    })
+}
+
+fn address_from_bytes(bytes: Vec<u8>) -> Result<Address, Status> {
+    if bytes.len() != 20 {
+        return Err(Status::invalid_argument("Invalid EVM address"));
+    }
+
+    Ok(Address::from_slice(&bytes))
+}
+
+fn u256_from_proto_bytes(bytes: &[u8]) -> Result<U256, Status> {
+    if bytes.len() > 32 {
+        return Err(Status::invalid_argument("Invalid U256 byte length"));
+    }
+
+    Ok(U256::from_be_slice(bytes))
+}
+
+fn proto_timestamp_to_utc(timestamp: ProtoTimestamp) -> Result<chrono::DateTime<Utc>, Status> {
+    Utc.timestamp_opt(timestamp.seconds, timestamp.nanos as u32)
+        .single()
+        .ok_or_else(|| Status::invalid_argument("Invalid timestamp"))
+}
+
+fn shared_settings_to_proto(shared: SharedGrantSettings) -> ProtoSharedSettings {
+    ProtoSharedSettings {
+        wallet_id: shared.wallet_id,
+        chain_id: shared.chain,
+        valid_from: shared.valid_from.map(|time| ProtoTimestamp {
+            seconds: time.timestamp(),
+            nanos: time.timestamp_subsec_nanos() as i32,
+        }),
+        valid_until: shared.valid_until.map(|time| ProtoTimestamp {
+            seconds: time.timestamp(),
+            nanos: time.timestamp_subsec_nanos() as i32,
+        }),
+        max_gas_fee_per_gas: shared
+            .max_gas_fee_per_gas
+            .map(|value| value.to_be_bytes::<32>().to_vec()),
+        max_priority_fee_per_gas: shared
+            .max_priority_fee_per_gas
+            .map(|value| value.to_be_bytes::<32>().to_vec()),
+        rate_limit: shared.rate_limit.map(|limit| ProtoTransactionRateLimit {
+            count: limit.count,
+            window_secs: limit.window.num_seconds(),
+        }),
+    }
+}
+
+fn specific_grant_to_proto(grant: SpecificGrant) -> ProtoSpecificGrant {
+    let grant = match grant {
+        SpecificGrant::EtherTransfer(settings) => {
+            ProtoSpecificGrantType::EtherTransfer(ProtoEtherTransferSettings {
+                targets: settings
+                    .target
+                    .into_iter()
+                    .map(|address| address.to_vec())
+                    .collect(),
+                limit: Some(ProtoVolumeRateLimit {
+                    max_volume: settings.limit.max_volume.to_be_bytes::<32>().to_vec(),
+                    window_secs: settings.limit.window.num_seconds(),
+                }),
+            })
+        }
+        SpecificGrant::TokenTransfer(settings) => {
+            ProtoSpecificGrantType::TokenTransfer(ProtoTokenTransferSettings {
+                token_contract: settings.token_contract.to_vec(),
+                target: settings.target.map(|address| address.to_vec()),
+                volume_limits: settings
+                    .volume_limits
+                    .into_iter()
+                    .map(|limit| ProtoVolumeRateLimit {
+                        max_volume: limit.max_volume.to_be_bytes::<32>().to_vec(),
+                        window_secs: limit.window.num_seconds(),
+                    })
+                    .collect(),
+            })
+        }
+    };
+
+    ProtoSpecificGrant { grant: Some(grant) }
+}
+
+struct EvmGrantOrWallet;
+
+impl EvmGrantOrWallet {
+    fn wallet_create_response<M>(
+        result: Result<Address, SendError<M, Error>>,
+    ) -> WalletCreateResponse {
+        let result = match result {
+            Ok(wallet) => WalletCreateResult::Wallet(WalletEntry {
+                address: wallet.to_vec(),
+            }),
+            Err(err) => {
+                warn!(error = ?err, "Failed to create EVM wallet");
+                WalletCreateResult::Error(ProtoEvmError::Internal.into())
+            }
+        };
+
+        WalletCreateResponse {
+            result: Some(result),
+        }
+    }
+
+    fn wallet_list_response<M>(
+        result: Result<Vec<Address>, SendError<M, Error>>,
+    ) -> WalletListResponse {
+        let result = match result {
+            Ok(wallets) => WalletListResult::Wallets(WalletList {
+                wallets: wallets
+                    .into_iter()
+                    .map(|wallet| WalletEntry {
+                        address: wallet.to_vec(),
+                    })
+                    .collect(),
+            }),
+            Err(err) => {
+                warn!(error = ?err, "Failed to list EVM wallets");
+                WalletListResult::Error(ProtoEvmError::Internal.into())
+            }
+        };
+
+        WalletListResponse {
+            result: Some(result),
+        }
+    }
+
+    fn grant_create_response<M>(
+        result: Result<i32, SendError<M, Error>>,
+    ) -> EvmGrantCreateResponse {
+        let result = match result {
+            Ok(grant_id) => EvmGrantCreateResult::GrantId(grant_id),
+            Err(err) => {
+                warn!(error = ?err, "Failed to create EVM grant");
+                EvmGrantCreateResult::Error(ProtoEvmError::Internal.into())
+            }
+        };
+
+        EvmGrantCreateResponse {
+            result: Some(result),
+        }
+    }
+
+    fn grant_delete_response<M>(result: Result<(), SendError<M, Error>>) -> EvmGrantDeleteResponse {
+        let result = match result {
+            Ok(()) => EvmGrantDeleteResult::Ok(ProtoEmpty {}),
+            Err(err) => {
+                warn!(error = ?err, "Failed to delete EVM grant");
+                EvmGrantDeleteResult::Error(ProtoEvmError::Internal.into())
+            }
+        };
+
+        EvmGrantDeleteResponse {
+            result: Some(result),
+        }
+    }
+
+    fn grant_list_response<M>(
+        result: Result<Vec<Grant<SpecificGrant>>, SendError<M, Error>>,
+    ) -> EvmGrantListResponse {
+        let result = match result {
+            Ok(grants) => EvmGrantListResult::Grants(EvmGrantList {
+                grants: grants
+                    .into_iter()
+                    .map(|grant| GrantEntry {
+                        id: grant.id,
+                        client_id: grant.shared.client_id,
+                        shared: Some(shared_settings_to_proto(grant.shared)),
+                        specific: Some(specific_grant_to_proto(grant.settings)),
+                    })
+                    .collect(),
+            }),
+            Err(err) => {
+                warn!(error = ?err, "Failed to list EVM grants");
+                EvmGrantListResult::Error(ProtoEvmError::Internal.into())
+            }
+        };
+
+        EvmGrantListResponse {
+            result: Some(result),
+        }
+    }
+}
+
+pub async fn start(
+    mut conn: UserAgentConnection,
+    mut bi: GrpcBi<UserAgentRequest, UserAgentResponse>,
+) {
+    let mut request_tracker = RequestTracker::default();
+    let mut response_id = None;
+
+    let pubkey = match auth::start(&mut conn, &mut bi, &mut request_tracker, &mut response_id).await
+    {
+        Ok(pubkey) => pubkey,
+        Err(e) => {
+            warn!(error = ?e, "Authentication failed");
+            return;
+        }
+    };
+
+    let (oob_sender, oob_receiver) = mpsc::channel(16);
+    let oob_adapter = OutOfBandAdapter(oob_sender);
+
+    let actor = UserAgentSession::spawn(UserAgentSession::new(conn, Box::new(oob_adapter)));
+    let actor_for_cleanup = actor.clone();
+
+    let _ = defer(move || {
+        actor_for_cleanup.kill();
+    });
+
+    info!(?pubkey, "User authenticated successfully");
+    dispatch_loop(bi, actor, oob_receiver, request_tracker).await;
+}

server/crates/arbiter-server/src/grpc/user_agent/auth.rs

@@ -0,0 +1,180 @@
+use arbiter_proto::{
+    proto::user_agent::{
+        AuthChallenge as ProtoAuthChallenge, AuthChallengeRequest as ProtoAuthChallengeRequest,
+        AuthChallengeSolution as ProtoAuthChallengeSolution, AuthResult as ProtoAuthResult,
+        KeyType as ProtoKeyType, UserAgentRequest, UserAgentResponse,
+        user_agent_request::Payload as UserAgentRequestPayload,
+        user_agent_response::Payload as UserAgentResponsePayload,
+    },
+    transport::{Bi, Error as TransportError, Receiver, Sender, grpc::GrpcBi},
+};
+use async_trait::async_trait;
+use tonic::Status;
+use tracing::warn;
+
+use crate::{
+    actors::user_agent::{AuthPublicKey, UserAgentConnection, auth},
+    db::models::KeyType,
+    grpc::request_tracker::RequestTracker,
+};
+
+pub struct AuthTransportAdapter<'a> {
+    bi: &'a mut GrpcBi<UserAgentRequest, UserAgentResponse>,
+    request_tracker: &'a mut RequestTracker,
+    response_id: &'a mut Option<i32>,
+}
+
+impl<'a> AuthTransportAdapter<'a> {
+    pub fn new(
+        bi: &'a mut GrpcBi<UserAgentRequest, UserAgentResponse>,
+        request_tracker: &'a mut RequestTracker,
+        response_id: &'a mut Option<i32>,
+    ) -> Self {
+        Self {
+            bi,
+            request_tracker,
+            response_id,
+        }
+    }
+
+    async fn send_user_agent_response(
+        &mut self,
+        payload: UserAgentResponsePayload,
+    ) -> Result<(), TransportError> {
+        let id = self.response_id.take();
+
+        self.bi
+            .send(Ok(UserAgentResponse {
+                id,
+                payload: Some(payload),
+            }))
+            .await
+    }
+}
+
+#[async_trait]
+impl Sender<Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {
+    async fn send(
+        &mut self,
+        item: Result<auth::Outbound, auth::Error>,
+    ) -> Result<(), TransportError> {
+        use auth::{Error, Outbound};
+        let payload = match item {
+            Ok(Outbound::AuthChallenge { nonce }) => {
+                UserAgentResponsePayload::AuthChallenge(ProtoAuthChallenge { nonce })
+            }
+            Ok(Outbound::AuthSuccess) => {
+                UserAgentResponsePayload::AuthResult(ProtoAuthResult::Success.into())
+            }
+            Err(Error::UnregisteredPublicKey) => {
+                UserAgentResponsePayload::AuthResult(ProtoAuthResult::InvalidKey.into())
+            }
+            Err(Error::InvalidChallengeSolution) => {
+                UserAgentResponsePayload::AuthResult(ProtoAuthResult::InvalidSignature.into())
+            }
+            Err(Error::InvalidBootstrapToken) => {
+                UserAgentResponsePayload::AuthResult(ProtoAuthResult::TokenInvalid.into())
+            }
+            Err(Error::Internal { details }) => return self.bi.send(Err(Status::internal(details))).await,
+            Err(Error::Transport) => {
+                return self.bi.send(Err(Status::unavailable("transport error"))).await;
+            }
+        };
+
+        self.send_user_agent_response(payload).await
+    }
+}
+
+#[async_trait]
+impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
+    async fn recv(&mut self) -> Option<auth::Inbound> {
+        let request = match self.bi.recv().await? {
+            Ok(request) => request,
+            Err(error) => {
+                warn!(error = ?error, "Failed to receive user agent auth request");
+                return None;
+            }
+        };
+
+        let request_id = match self.request_tracker.request(request.id) {
+            Ok(request_id) => request_id,
+            Err(error) => {
+                let _ = self.bi.send(Err(error)).await;
+                return None;
+            }
+        };
+        *self.response_id = Some(request_id);
+
+        let Some(payload) = request.payload else {
+            warn!(
+                event = "received request with empty payload",
+                "grpc.useragent.auth_adapter"
+            );
+            return None;
+        };
+
+        match payload {
+            UserAgentRequestPayload::AuthChallengeRequest(ProtoAuthChallengeRequest {
+                pubkey,
+                bootstrap_token,
+                key_type,
+            }) => {
+                let Ok(key_type) = ProtoKeyType::try_from(key_type) else {
+                    warn!(
+                        event = "received request with invalid key type",
+                        "grpc.useragent.auth_adapter"
+                    );
+                    return None;
+                };
+                let key_type = match key_type {
+                    ProtoKeyType::Ed25519 => KeyType::Ed25519,
+                    ProtoKeyType::EcdsaSecp256k1 => KeyType::EcdsaSecp256k1,
+                    ProtoKeyType::Rsa => KeyType::Rsa,
+                    ProtoKeyType::Unspecified => {
+                        warn!(
+                            event = "received request with unspecified key type",
+                            "grpc.useragent.auth_adapter"
+                        );
+                        return None;
+                    }
+                };
+                let Ok(pubkey) = AuthPublicKey::try_from((key_type, pubkey)) else {
+                    warn!(
+                        event = "received request with invalid public key",
+                        "grpc.useragent.auth_adapter"
+                    );
+                    return None;
+                };
+
+                Some(auth::Inbound::AuthChallengeRequest {
+                    pubkey,
+                    bootstrap_token,
+                })
+            }
+            UserAgentRequestPayload::AuthChallengeSolution(ProtoAuthChallengeSolution {
+                signature,
+            }) => Some(auth::Inbound::AuthChallengeSolution { signature }),
+            _ => {
+                let _ = self
+                    .bi
+                    .send(Err(Status::invalid_argument(
+                        "Unsupported user-agent auth request",
+                    )))
+                    .await;
+                None
+            }
+        }
+    }
+}
+
+impl Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {}
+
+pub async fn start(
+    conn: &mut UserAgentConnection,
+    bi: &mut GrpcBi<UserAgentRequest, UserAgentResponse>,
+    request_tracker: &mut RequestTracker,
+    response_id: &mut Option<i32>,
+) -> Result<AuthPublicKey, auth::Error> {
+    let transport = AuthTransportAdapter::new(bi, request_tracker, response_id);
+    auth::authenticate(conn, transport).await
+}

server/crates/arbiter-server/src/lib.rs

@@ -1,28 +1,13 @@
 #![forbid(unsafe_code)]
-use arbiter_proto::{
-    proto::{ClientRequest, ClientResponse, UserAgentRequest, UserAgentResponse},
-    transport::{BiStream, GrpcTransportActor, wire},
-};
-use async_trait::async_trait;
-use kameo::actor::PreparedActor;
-use tokio_stream::wrappers::ReceiverStream;
-
-use tokio::sync::mpsc;
-use tonic::{Request, Response, Status};
-
-use crate::{
-    actors::{
-        client::handle_client,
-        user_agent::UserAgentActor,
-    },
-    context::ServerContext,
-};
+use crate::context::ServerContext;
 
 pub mod actors;
 pub mod context;
 pub mod db;
-
-const DEFAULT_CHANNEL_SIZE: usize = 1000;
+pub mod evm;
+pub mod grpc;
+pub mod safe_cell;
+pub mod utils;
 
 pub struct Server {
     context: ServerContext,
@@ -33,51 +18,3 @@ impl Server {
         Self { context }
     }
 }
-
-#[async_trait]
-impl arbiter_proto::proto::arbiter_service_server::ArbiterService for Server {
-    type UserAgentStream = ReceiverStream<Result<UserAgentResponse, Status>>;
-    type ClientStream = ReceiverStream<Result<ClientResponse, Status>>;
-
-    async fn client(
-        &self,
-        request: Request<tonic::Streaming<ClientRequest>>,
-    ) -> Result<Response<Self::ClientStream>, Status> {
-        let req_stream = request.into_inner();
-        let (tx, rx) = mpsc::channel(DEFAULT_CHANNEL_SIZE);
-        tokio::spawn(handle_client(
-            self.context.clone(),
-            BiStream {
-                request_stream: req_stream,
-                response_sender: tx,
-            },
-        ));
-
-        Ok(Response::new(ReceiverStream::new(rx)))
-    }
-
-    async fn user_agent(
-        &self,
-        request: Request<tonic::Streaming<UserAgentRequest>>,
-    ) -> Result<Response<Self::UserAgentStream>, Status> {
-        let req_stream = request.into_inner();
-        let (tx, rx) = mpsc::channel(DEFAULT_CHANNEL_SIZE);
-        let context = self.context.clone();
-
-        wire(
-            |prepared: PreparedActor<UserAgentActor>, recipient| {
-                prepared.spawn(UserAgentActor::new(context, recipient));
-            },
-            |prepared: PreparedActor<GrpcTransportActor<_, _, _>>, business_recipient| {
-                prepared.spawn(GrpcTransportActor::new(
-                    tx,
-                    req_stream,
-                    business_recipient,
-                ));
-            },
-        )
-        .await;
-
-        Ok(Response::new(ReceiverStream::new(rx)))
-    }
-}

server/crates/arbiter-server/src/main.rs

@@ -3,6 +3,7 @@ use std::net::SocketAddr;
 use arbiter_proto::{proto::arbiter_service_server::ArbiterServiceServer, url::ArbiterUrl};
 use arbiter_server::{Server, actors::bootstrap::GetToken, context::ServerContext, db};
 use miette::miette;
+use rustls::crypto::aws_lc_rs;
 use tonic::transport::{Identity, ServerTlsConfig};
 use tracing::info;
 
@@ -10,6 +11,8 @@ const PORT: u16 = 50051;
 
 #[tokio::main]
 async fn main() -> miette::Result<()> {
+    aws_lc_rs::default_provider().install_default().unwrap();
+
     tracing_subscriber::fmt()
         .with_env_filter(
             tracing_subscriber::EnvFilter::try_from_default_env()

server/crates/arbiter-server/src/safe_cell.rs

@@ -0,0 +1,111 @@
+use std::ops::{Deref, DerefMut};
+use std::{any::type_name, fmt};
+
+use memsafe::MemSafe;
+
+pub trait SafeCellHandle<T> {
+    type CellRead<'a>: Deref<Target = T>
+    where
+        Self: 'a,
+        T: 'a;
+    type CellWrite<'a>: Deref<Target = T> + DerefMut<Target = T>
+    where
+        Self: 'a,
+        T: 'a;
+
+    fn new(value: T) -> Self
+    where
+        Self: Sized;
+
+    fn read(&mut self) -> Self::CellRead<'_>;
+    fn write(&mut self) -> Self::CellWrite<'_>;
+
+    fn new_inline<F>(f: F) -> Self
+    where
+        Self: Sized,
+        T: Default,
+        F: for<'a> FnOnce(&'a mut T),
+    {
+        let mut cell = Self::new(T::default());
+        {
+            let mut handle = cell.write();
+            f(handle.deref_mut());
+        }
+        cell
+    }
+
+    #[inline(always)]
+    fn read_inline<F, R>(&mut self, f: F) -> R
+    where
+        F: FnOnce(&T) -> R,
+    {
+        f(&*self.read())
+    }
+
+    #[inline(always)]
+    fn write_inline<F, R>(&mut self, f: F) -> R
+    where
+        F: FnOnce(&mut T) -> R,
+    {
+        f(&mut *self.write())
+    }
+}
+
+pub struct MemSafeCell<T>(MemSafe<T>);
+
+impl<T> fmt::Debug for MemSafeCell<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("MemSafeCell")
+            .field("inner", &format_args!("<protected {}>", type_name::<T>()))
+            .finish()
+    }
+}
+
+impl<T> SafeCellHandle<T> for MemSafeCell<T> {
+    type CellRead<'a>
+        = memsafe::MemSafeRead<'a, T>
+    where
+        Self: 'a,
+        T: 'a;
+    type CellWrite<'a>
+        = memsafe::MemSafeWrite<'a, T>
+    where
+        Self: 'a,
+        T: 'a;
+
+    fn new(value: T) -> Self {
+        match MemSafe::new(value) {
+            Ok(inner) => Self(inner),
+            Err(err) => {
+                // If protected memory cannot be allocated, process integrity is compromised.
+                abort_memory_breach("safe cell allocation", &err)
+            }
+        }
+    }
+
+    #[inline(always)]
+    fn read(&mut self) -> Self::CellRead<'_> {
+        match self.0.read() {
+            Ok(inner) => inner,
+            Err(err) => abort_memory_breach("safe cell read", &err),
+        }
+    }
+
+    #[inline(always)]
+    fn write(&mut self) -> Self::CellWrite<'_> {
+        match self.0.write() {
+            Ok(inner) => inner,
+            Err(err) => {
+                // If protected memory becomes unwritable here, treat it as a fatal memory breach.
+                abort_memory_breach("safe cell write", &err)
+            }
+        }
+    }
+}
+
+fn abort_memory_breach(action: &str, err: &memsafe::error::MemoryError) -> ! {
+    eprintln!("fatal {action}: {err}");
+    std::process::abort();
+}
+
+pub type SafeCell<T> = MemSafeCell<T>;

server/crates/arbiter-server/src/utils.rs

@@ -0,0 +1,16 @@
+struct DeferClosure<F: FnOnce()> {
+    f: Option<F>,
+}
+
+impl<F: FnOnce()> Drop for DeferClosure<F> {
+    fn drop(&mut self) {
+        if let Some(f) = self.f.take() {
+            f();
+        }
+    }
+}
+
+// Run some code when a scope is exited, similar to Go's defer statement
+pub fn defer<F: FnOnce()>(f: F) -> impl Drop + Sized {
+    DeferClosure { f: Some(f) }
+}

server/crates/arbiter-server/tests/client.rs

@@ -0,0 +1,4 @@
+mod common;
+
+#[path = "client/auth.rs"]
+mod auth;

server/crates/arbiter-server/tests/client/auth.rs

@@ -0,0 +1,108 @@
+use arbiter_proto::transport::{Receiver, Sender};
+use arbiter_server::actors::GlobalActors;
+use arbiter_server::{
+    actors::client::{ClientConnection, auth, connect_client},
+    db::{self, schema},
+};
+use diesel::{ExpressionMethods as _, insert_into};
+use diesel_async::RunQueryDsl;
+use ed25519_dalek::Signer as _;
+
+use super::common::ChannelTransport;
+
+#[tokio::test]
+#[test_log::test]
+pub async fn test_unregistered_pubkey_rejected() {
+    let db = db::create_test_pool().await;
+
+    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    let props = ClientConnection::new(db.clone(), actors);
+    let task = tokio::spawn(async move {
+        let mut server_transport = server_transport;
+        connect_client(props, &mut server_transport).await;
+    });
+
+    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
+
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: new_key.verifying_key(),
+        })
+        .await
+        .unwrap();
+
+    // Auth fails, connect_client returns, transport drops
+    task.await.unwrap();
+}
+
+#[tokio::test]
+#[test_log::test]
+pub async fn test_challenge_auth() {
+    let db = db::create_test_pool().await;
+
+    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
+    let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
+
+    {
+        let mut conn = db.get().await.unwrap();
+        insert_into(schema::program_client::table)
+            .values(schema::program_client::public_key.eq(pubkey_bytes.clone()))
+            .execute(&mut conn)
+            .await
+            .unwrap();
+    }
+
+    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+
+    let props = ClientConnection::new(db.clone(), actors);
+    let task = tokio::spawn(async move {
+        let mut server_transport = server_transport;
+        connect_client(props, &mut server_transport).await;
+    });
+
+    // Send challenge request
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: new_key.verifying_key(),
+        })
+        .await
+        .unwrap();
+
+    // Read the challenge response
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(resp) => match resp {
+            auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
+            other => panic!("Expected AuthChallenge, got {other:?}"),
+        },
+        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
+    };
+
+    // Sign the challenge and send solution
+    let formatted_challenge = arbiter_proto::format_challenge(challenge.1, challenge.0.as_bytes());
+    let signature = new_key.sign(&formatted_challenge);
+
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution { signature })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive auth success");
+    match response {
+        Ok(auth::Outbound::AuthSuccess) => {}
+        Ok(other) => panic!("Expected AuthSuccess, got {other:?}"),
+        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
+    }
+
+    // Auth completes, session spawned
+    task.await.unwrap();
+}
+

server/crates/arbiter-server/tests/common/mod.rs

@@ -1,16 +1,19 @@
+use arbiter_proto::transport::{Bi, Error, Receiver, Sender};
 use arbiter_server::{
     actors::keyholder::KeyHolder,
     db::{self, schema},
+    safe_cell::{SafeCell, SafeCellHandle as _},
 };
+use async_trait::async_trait;
 use diesel::QueryDsl;
 use diesel_async::RunQueryDsl;
-use memsafe::MemSafe;
+use tokio::sync::mpsc;
 
 #[allow(dead_code)]
 pub async fn bootstrapped_keyholder(db: &db::DatabasePool) -> KeyHolder {
     let mut actor = KeyHolder::new(db.clone()).await.unwrap();
     actor
-        .bootstrap(MemSafe::new(b"test-seal-key".to_vec()).unwrap())
+        .bootstrap(SafeCell::new(b"test-seal-key".to_vec()))
         .await
         .unwrap();
     actor
@@ -26,3 +29,59 @@ pub async fn root_key_history_id(db: &db::DatabasePool) -> i32 {
         .unwrap();
     id.expect("root_key_id should be set after bootstrap")
 }
+
+#[allow(dead_code)]
+pub struct ChannelTransport<T, Y> {
+    receiver: mpsc::Receiver<T>,
+    sender: mpsc::Sender<Y>,
+}
+
+impl<T, Y> ChannelTransport<T, Y> {
+    #[allow(dead_code)]
+    pub fn new() -> (Self, ChannelTransport<Y, T>) {
+        let (tx1, rx1) = mpsc::channel(10);
+        let (tx2, rx2) = mpsc::channel(10);
+        (
+            Self {
+                receiver: rx1,
+                sender: tx2,
+            },
+            ChannelTransport {
+                receiver: rx2,
+                sender: tx1,
+            },
+        )
+    }
+}
+
+#[async_trait]
+impl<T, Y> Sender<Y> for ChannelTransport<T, Y>
+where
+    T: Send + Sync + 'static,
+    Y: Send + Sync + 'static,
+{
+    async fn send(&mut self, item: Y) -> Result<(), Error> {
+        self.sender
+            .send(item)
+            .await
+            .map_err(|_| Error::ChannelClosed)
+    }
+}
+
+#[async_trait]
+impl<T, Y> Receiver<T> for ChannelTransport<T, Y>
+where
+    T: Send + Sync + 'static,
+    Y: Send + Sync + 'static,
+{
+    async fn recv(&mut self) -> Option<T> {
+        self.receiver.recv().await
+    }
+}
+
+impl<T, Y> Bi<T, Y> for ChannelTransport<T, Y>
+where
+    T: Send + Sync + 'static,
+    Y: Send + Sync + 'static,
+{
+}

server/crates/arbiter-server/tests/keyholder/concurrency.rs

@@ -3,11 +3,11 @@ use std::collections::{HashMap, HashSet};
 use arbiter_server::{
     actors::keyholder::{CreateNew, Error, KeyHolder},
     db::{self, models, schema},
+    safe_cell::{SafeCell, SafeCellHandle as _},
 };
 use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper, dsl::sql_query};
 use diesel_async::RunQueryDsl;
 use kameo::actor::{ActorRef, Spawn as _};
-use memsafe::MemSafe;
 use tokio::task::JoinSet;
 
 use crate::common;
@@ -24,7 +24,7 @@ async fn write_concurrently(
             let plaintext = format!("{prefix}-{i}").into_bytes();
             let id = actor
                 .ask(CreateNew {
-                    plaintext: MemSafe::new(plaintext.clone()).unwrap(),
+                    plaintext: SafeCell::new(plaintext.clone()),
                 })
                 .await
                 .unwrap();
@@ -118,7 +118,7 @@ async fn insert_failure_does_not_create_partial_row() {
     drop(conn);
 
     let err = actor
-        .create_new(MemSafe::new(b"should fail".to_vec()).unwrap())
+        .create_new(SafeCell::new(b"should fail".to_vec()))
         .await
         .unwrap_err();
     assert!(matches!(err, Error::DatabaseTransaction(_)));
@@ -162,12 +162,12 @@ async fn decrypt_roundtrip_after_high_concurrency() {
 
     let mut decryptor = KeyHolder::new(db.clone()).await.unwrap();
     decryptor
-        .try_unseal(MemSafe::new(b"test-seal-key".to_vec()).unwrap())
+        .try_unseal(SafeCell::new(b"test-seal-key".to_vec()))
         .await
         .unwrap();
 
     for (id, plaintext) in expected {
         let mut decrypted = decryptor.decrypt(id).await.unwrap();
-        assert_eq!(*decrypted.read().unwrap(), plaintext);
+        assert_eq!(*decrypted.read(), plaintext);
     }
 }

server/crates/arbiter-server/tests/keyholder/lifecycle.rs

@@ -1,10 +1,10 @@
 use arbiter_server::{
     actors::keyholder::{Error, KeyHolder},
     db::{self, models, schema},
+    safe_cell::{SafeCell, SafeCellHandle as _},
 };
 use diesel::{QueryDsl, SelectableHelper};
 use diesel_async::RunQueryDsl;
-use memsafe::MemSafe;
 
 use crate::common;
 
@@ -14,7 +14,7 @@ async fn test_bootstrap() {
     let db = db::create_test_pool().await;
     let mut actor = KeyHolder::new(db.clone()).await.unwrap();
 
-    let seal_key = MemSafe::new(b"test-seal-key".to_vec()).unwrap();
+    let seal_key = SafeCell::new(b"test-seal-key".to_vec());
     actor.bootstrap(seal_key).await.unwrap();
 
     let mut conn = db.get().await.unwrap();
@@ -43,7 +43,7 @@ async fn test_bootstrap_rejects_double() {
     let db = db::create_test_pool().await;
     let mut actor = common::bootstrapped_keyholder(&db).await;
 
-    let seal_key2 = MemSafe::new(b"test-seal-key".to_vec()).unwrap();
+    let seal_key2 = SafeCell::new(b"test-seal-key".to_vec());
     let err = actor.bootstrap(seal_key2).await.unwrap_err();
     assert!(matches!(err, Error::AlreadyBootstrapped));
 }
@@ -55,7 +55,7 @@ async fn test_create_new_before_bootstrap_fails() {
     let mut actor = KeyHolder::new(db).await.unwrap();
 
     let err = actor
-        .create_new(MemSafe::new(b"data".to_vec()).unwrap())
+        .create_new(SafeCell::new(b"data".to_vec()))
         .await
         .unwrap_err();
     assert!(matches!(err, Error::NotBootstrapped));
@@ -91,17 +91,17 @@ async fn test_unseal_correct_password() {
 
     let plaintext = b"survive a restart";
     let aead_id = actor
-        .create_new(MemSafe::new(plaintext.to_vec()).unwrap())
+        .create_new(SafeCell::new(plaintext.to_vec()))
         .await
         .unwrap();
     drop(actor);
 
     let mut actor = KeyHolder::new(db.clone()).await.unwrap();
-    let seal_key = MemSafe::new(b"test-seal-key".to_vec()).unwrap();
+    let seal_key = SafeCell::new(b"test-seal-key".to_vec());
     actor.try_unseal(seal_key).await.unwrap();
 
     let mut decrypted = actor.decrypt(aead_id).await.unwrap();
-    assert_eq!(*decrypted.read().unwrap(), plaintext);
+    assert_eq!(*decrypted.read(), plaintext);
 }
 
 #[tokio::test]
@@ -112,20 +112,20 @@ async fn test_unseal_wrong_then_correct_password() {
 
     let plaintext = b"important data";
     let aead_id = actor
-        .create_new(MemSafe::new(plaintext.to_vec()).unwrap())
+        .create_new(SafeCell::new(plaintext.to_vec()))
         .await
         .unwrap();
     drop(actor);
 
     let mut actor = KeyHolder::new(db.clone()).await.unwrap();
 
-    let bad_key = MemSafe::new(b"wrong-password".to_vec()).unwrap();
+    let bad_key = SafeCell::new(b"wrong-password".to_vec());
     let err = actor.try_unseal(bad_key).await.unwrap_err();
     assert!(matches!(err, Error::InvalidKey));
 
-    let good_key = MemSafe::new(b"test-seal-key".to_vec()).unwrap();
+    let good_key = SafeCell::new(b"test-seal-key".to_vec());
     actor.try_unseal(good_key).await.unwrap();
 
     let mut decrypted = actor.decrypt(aead_id).await.unwrap();
-    assert_eq!(*decrypted.read().unwrap(), plaintext);
+    assert_eq!(*decrypted.read(), plaintext);
 }

server/crates/arbiter-server/tests/keyholder/storage.rs

@@ -3,10 +3,10 @@ use std::collections::HashSet;
 use arbiter_server::{
     actors::keyholder::{Error, encryption::v1},
     db::{self, models, schema},
+    safe_cell::{SafeCell, SafeCellHandle as _},
 };
 use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper, dsl::update};
 use diesel_async::RunQueryDsl;
-use memsafe::MemSafe;
 
 use crate::common;
 
@@ -18,12 +18,12 @@ async fn test_create_decrypt_roundtrip() {
 
     let plaintext = b"hello arbiter";
     let aead_id = actor
-        .create_new(MemSafe::new(plaintext.to_vec()).unwrap())
+        .create_new(SafeCell::new(plaintext.to_vec()))
         .await
         .unwrap();
 
     let mut decrypted = actor.decrypt(aead_id).await.unwrap();
-    assert_eq!(*decrypted.read().unwrap(), plaintext);
+    assert_eq!(*decrypted.read(), plaintext);
 }
 
 #[tokio::test]
@@ -44,11 +44,11 @@ async fn test_ciphertext_differs_across_entries() {
 
     let plaintext = b"same content";
     let id1 = actor
-        .create_new(MemSafe::new(plaintext.to_vec()).unwrap())
+        .create_new(SafeCell::new(plaintext.to_vec()))
         .await
         .unwrap();
     let id2 = actor
-        .create_new(MemSafe::new(plaintext.to_vec()).unwrap())
+        .create_new(SafeCell::new(plaintext.to_vec()))
         .await
         .unwrap();
 
@@ -70,8 +70,8 @@ async fn test_ciphertext_differs_across_entries() {
 
     let mut d1 = actor.decrypt(id1).await.unwrap();
     let mut d2 = actor.decrypt(id2).await.unwrap();
-    assert_eq!(*d1.read().unwrap(), plaintext);
-    assert_eq!(*d2.read().unwrap(), plaintext);
+    assert_eq!(*d1.read(), plaintext);
+    assert_eq!(*d2.read(), plaintext);
 }
 
 #[tokio::test]
@@ -83,7 +83,7 @@ async fn test_nonce_never_reused() {
     let n = 5;
     for i in 0..n {
         actor
-            .create_new(MemSafe::new(format!("secret {i}").into_bytes()).unwrap())
+            .create_new(SafeCell::new(format!("secret {i}").into_bytes()))
             .await
             .unwrap();
     }
@@ -137,7 +137,7 @@ async fn broken_db_nonce_format_fails_closed() {
     drop(conn);
 
     let err = actor
-        .create_new(MemSafe::new(b"must fail".to_vec()).unwrap())
+        .create_new(SafeCell::new(b"must fail".to_vec()))
         .await
         .unwrap_err();
     assert!(matches!(err, Error::BrokenDatabase));
@@ -145,7 +145,7 @@ async fn broken_db_nonce_format_fails_closed() {
     let db = db::create_test_pool().await;
     let mut actor = common::bootstrapped_keyholder(&db).await;
     let id = actor
-        .create_new(MemSafe::new(b"decrypt target".to_vec()).unwrap())
+        .create_new(SafeCell::new(b"decrypt target".to_vec()))
         .await
         .unwrap();
     let mut conn = db.get().await.unwrap();

server/crates/arbiter-server/tests/user_agent.rs

@@ -1,30 +1,5 @@
 mod common;
 
-use arbiter_proto::proto::UserAgentResponse;
-use arbiter_server::actors::user_agent::UserAgentError;
-use kameo::{Actor, actor::Recipient, actor::Spawn, prelude::Message};
-
-/// A no-op actor that discards any messages it receives.
-#[derive(Actor)]
-struct NullSink;
-
-impl Message<Result<UserAgentResponse, UserAgentError>> for NullSink {
-    type Reply = ();
-
-    async fn handle(
-        &mut self,
-        _msg: Result<UserAgentResponse, UserAgentError>,
-        _ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
-    ) -> Self::Reply {
-    }
-}
-
-/// Creates a `Recipient` that silently discards all messages.
-fn null_recipient() -> Recipient<Result<UserAgentResponse, UserAgentError>> {
-    let actor_ref = NullSink::spawn(NullSink);
-    actor_ref.recipient()
-}
-
 #[path = "user_agent/auth.rs"]
 mod auth;
 #[path = "user_agent/unseal.rs"]

server/crates/arbiter-server/tests/user_agent/auth.rs

@@ -1,57 +1,51 @@
-use arbiter_proto::proto::{
-    UserAgentResponse,
-    auth::{self, AuthChallengeRequest, AuthOk},
-    user_agent_response::Payload as UserAgentResponsePayload,
-};
+use arbiter_proto::transport::{Receiver, Sender};
 use arbiter_server::{
     actors::{
         GlobalActors,
         bootstrap::GetToken,
-        user_agent::{HandleAuthChallengeRequest, HandleAuthChallengeSolution, UserAgentActor},
+        user_agent::{AuthPublicKey, UserAgentConnection, auth},
     },
     db::{self, schema},
 };
 use diesel::{ExpressionMethods as _, QueryDsl, insert_into};
 use diesel_async::RunQueryDsl;
 use ed25519_dalek::Signer as _;
-use kameo::actor::Spawn;
+
+use super::common::ChannelTransport;
 
 #[tokio::test]
 #[test_log::test]
 pub async fn test_bootstrap_token_auth() {
-    let db =db::create_test_pool().await;
-
+    let db = db::create_test_pool().await;
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
     let token = actors.bootstrapper.ask(GetToken).await.unwrap().unwrap();
-    let user_agent =
-        UserAgentActor::new_manual(db.clone(), actors, super::null_recipient());
-    let user_agent_ref = UserAgentActor::spawn(user_agent);
+
+    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let db_for_task = db.clone();
+    let task = tokio::spawn(async move {
+        let mut props = UserAgentConnection::new(db_for_task, actors);
+        auth::authenticate(&mut props, server_transport).await
+    });
 
     let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-    let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
-
-    let result = user_agent_ref
-        .ask(HandleAuthChallengeRequest {
-            req: AuthChallengeRequest {
-                pubkey: pubkey_bytes,
-                bootstrap_token: Some(token),
-            },
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+            bootstrap_token: Some(token),
         })
         .await
-        .expect("Shouldn't fail to send message");
+        .unwrap();
 
-    assert_eq!(
-        result,
-        UserAgentResponse {
-            payload: Some(UserAgentResponsePayload::AuthMessage(
-                arbiter_proto::proto::auth::ServerMessage {
-                    payload: Some(arbiter_proto::proto::auth::server_message::Payload::AuthOk(
-                        AuthOk {},
-                    )),
-                },
-            )),
-        }
-    );
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive auth result");
+    match response {
+        Ok(auth::Outbound::AuthSuccess) => {}
+        other => panic!("Expected AuthSuccess, got {other:?}"),
+    }
+
+    task.await.unwrap().unwrap();
 
     let mut conn = db.get().await.unwrap();
     let stored_pubkey: Vec<u8> = schema::useragent_client::table
@@ -66,106 +60,108 @@ pub async fn test_bootstrap_token_auth() {
 #[test_log::test]
 pub async fn test_bootstrap_invalid_token_auth() {
     let db = db::create_test_pool().await;
-
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
-    let user_agent =
-        UserAgentActor::new_manual(db.clone(), actors, super::null_recipient());
-    let user_agent_ref = UserAgentActor::spawn(user_agent);
+
+    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let db_for_task = db.clone();
+    let task = tokio::spawn(async move {
+        let mut props = UserAgentConnection::new(db_for_task, actors);
+        auth::authenticate(&mut props, server_transport).await
+    });
 
     let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-    let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
-
-    let result = user_agent_ref
-        .ask(HandleAuthChallengeRequest {
-            req: AuthChallengeRequest {
-                pubkey: pubkey_bytes,
-                bootstrap_token: Some("invalid_token".to_string()),
-            },
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+            bootstrap_token: Some("invalid_token".to_string()),
         })
-        .await;
+        .await
+        .unwrap();
 
-    match result {
-        Err(kameo::error::SendError::HandlerError(err)) => {
-            assert!(
-                matches!(err, arbiter_server::actors::user_agent::UserAgentError::InvalidBootstrapToken),
-                "Expected InvalidBootstrapToken, got {err:?}"
-            );
-        }
-        Err(other) => {
-            panic!("Expected SendError::HandlerError, got {other:?}");
-        }
-        Ok(_) => {
-            panic!("Expected error due to invalid bootstrap token, but got success");
-        }
-    }
+    assert!(matches!(
+        task.await.unwrap(),
+        Err(auth::Error::InvalidBootstrapToken)
+    ));
+
+    // Verify no key was registered
+    let mut conn = db.get().await.unwrap();
+    let count: i64 = schema::useragent_client::table
+        .count()
+        .get_result::<i64>(&mut conn)
+        .await
+        .unwrap();
+    assert_eq!(count, 0);
 }
 
 #[tokio::test]
 #[test_log::test]
 pub async fn test_challenge_auth() {
     let db = db::create_test_pool().await;
-
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
-    let user_agent =
-        UserAgentActor::new_manual(db.clone(), actors, super::null_recipient());
-    let user_agent_ref = UserAgentActor::spawn(user_agent);
 
     let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
     let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
 
+    // Pre-register key with key_type
     {
         let mut conn = db.get().await.unwrap();
         insert_into(schema::useragent_client::table)
-            .values(schema::useragent_client::public_key.eq(pubkey_bytes.clone()))
+            .values((
+                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
+                schema::useragent_client::key_type.eq(1i32),
+            ))
             .execute(&mut conn)
             .await
             .unwrap();
     }
 
-    let result = user_agent_ref
-        .ask(HandleAuthChallengeRequest {
-            req: AuthChallengeRequest {
-                pubkey: pubkey_bytes,
-                bootstrap_token: None,
-            },
+    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let db_for_task = db.clone();
+    let task = tokio::spawn(async move {
+        let mut props = UserAgentConnection::new(db_for_task, actors);
+        auth::authenticate(&mut props, server_transport).await
+    });
+
+    // Send challenge request
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: AuthPublicKey::Ed25519(new_key.verifying_key()),
+            bootstrap_token: None,
         })
         .await
-        .expect("Shouldn't fail to send message");
+        .unwrap();
 
-    let UserAgentResponse {
-        payload:
-            Some(UserAgentResponsePayload::AuthMessage(arbiter_proto::proto::auth::ServerMessage {
-                payload:
-                    Some(arbiter_proto::proto::auth::server_message::Payload::AuthChallenge(challenge)),
-            })),
-    } = result
-    else {
-        panic!("Expected auth challenge response, got {result:?}");
+    // Read the challenge response
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(resp) => match resp {
+            auth::Outbound::AuthChallenge { nonce } => nonce,
+            other => panic!("Expected AuthChallenge, got {other:?}"),
+        },
+        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
     };
 
-    let formatted_challenge = arbiter_proto::format_challenge(&challenge);
+    let formatted_challenge = arbiter_proto::format_challenge(challenge, &pubkey_bytes);
     let signature = new_key.sign(&formatted_challenge);
-    let serialized_signature = signature.to_bytes().to_vec();
 
-    let result = user_agent_ref
-        .ask(HandleAuthChallengeSolution {
-            solution: auth::AuthChallengeSolution {
-                signature: serialized_signature,
-            },
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes().to_vec(),
         })
         .await
-        .expect("Shouldn't fail to send message");
+        .unwrap();
 
-    assert_eq!(
-        result,
-        UserAgentResponse {
-            payload: Some(UserAgentResponsePayload::AuthMessage(
-                arbiter_proto::proto::auth::ServerMessage {
-                    payload: Some(arbiter_proto::proto::auth::server_message::Payload::AuthOk(
-                        AuthOk {},
-                    )),
-                },
-            )),
-        }
-    );
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive auth result");
+    match response {
+        Ok(auth::Outbound::AuthSuccess) => {}
+        other => panic!("Expected AuthSuccess, got {other:?}"),
+    }
+
+    task.await.unwrap().unwrap();
 }

server/crates/arbiter-server/tests/user_agent/unseal.rs

@@ -1,81 +1,55 @@
-use arbiter_proto::proto::{
-    UnsealEncryptedKey, UnsealResult, UnsealStart, auth::AuthChallengeRequest,
-    user_agent_response::Payload as UserAgentResponsePayload,
-};
 use arbiter_server::{
     actors::{
         GlobalActors,
-        bootstrap::GetToken,
         keyholder::{Bootstrap, Seal},
-        user_agent::{
-            HandleAuthChallengeRequest, HandleUnsealEncryptedKey, HandleUnsealRequest,
-            UserAgentActor,
+        user_agent::session::{
+            HandleUnsealEncryptedKey, HandleUnsealRequest, UnsealError, UserAgentSession,
         },
     },
     db,
+    safe_cell::{SafeCell, SafeCellHandle as _},
 };
 use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
-use kameo::actor::{ActorRef, Spawn};
-use memsafe::MemSafe;
+use kameo::actor::Spawn as _;
 use x25519_dalek::{EphemeralSecret, PublicKey};
 
-async fn setup_authenticated_user_agent(
+async fn setup_sealed_user_agent(
     seal_key: &[u8],
-) -> (arbiter_server::db::DatabasePool, ActorRef<UserAgentActor>) {
+) -> (db::DatabasePool, kameo::actor::ActorRef<UserAgentSession>) {
     let db = db::create_test_pool().await;
-
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+
     actors
         .key_holder
         .ask(Bootstrap {
-            seal_key_raw: MemSafe::new(seal_key.to_vec()).unwrap(),
+            seal_key_raw: SafeCell::new(seal_key.to_vec()),
         })
         .await
         .unwrap();
     actors.key_holder.ask(Seal).await.unwrap();
 
-    let user_agent =
-        UserAgentActor::new_manual(db.clone(), actors.clone(), super::null_recipient());
-    let user_agent_ref = UserAgentActor::spawn(user_agent);
+    let session = UserAgentSession::spawn(UserAgentSession::new_test(db.clone(), actors));
 
-    let token = actors.bootstrapper.ask(GetToken).await.unwrap().unwrap();
-    let auth_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
-    user_agent_ref
-        .ask(HandleAuthChallengeRequest {
-            req: AuthChallengeRequest {
-                pubkey: auth_key.verifying_key().to_bytes().to_vec(),
-                bootstrap_token: Some(token),
-            },
-        })
-        .await
-        .unwrap();
-
-    (db, user_agent_ref)
+    (db, session)
 }
 
 async fn client_dh_encrypt(
-    user_agent_ref: &ActorRef<UserAgentActor>,
+    user_agent: &kameo::actor::ActorRef<UserAgentSession>,
     key_to_send: &[u8],
-) -> UnsealEncryptedKey {
+) -> HandleUnsealEncryptedKey {
     let client_secret = EphemeralSecret::random();
     let client_public = PublicKey::from(&client_secret);
 
-    let response = user_agent_ref
+    let response = user_agent
         .ask(HandleUnsealRequest {
-            req: UnsealStart {
-                client_pubkey: client_public.as_bytes().to_vec(),
-            },
+            client_pubkey: client_public,
         })
         .await
         .unwrap();
 
-    let server_pubkey = match response.payload.unwrap() {
-        UserAgentResponsePayload::UnsealStartResponse(resp) => resp.server_pubkey,
-        other => panic!("Expected UnsealStartResponse, got {other:?}"),
-    };
-    let server_public = PublicKey::from(<[u8; 32]>::try_from(server_pubkey.as_slice()).unwrap());
+    let server_pubkey = response.server_pubkey;
 
-    let shared_secret = client_secret.diffie_hellman(&server_public);
+    let shared_secret = client_secret.diffie_hellman(&server_pubkey);
     let cipher = XChaCha20Poly1305::new(shared_secret.as_bytes().into());
     let nonce = XNonce::from([0u8; 24]);
     let associated_data = b"unseal";
@@ -84,7 +58,7 @@ async fn client_dh_encrypt(
         .encrypt_in_place(&nonce, associated_data, &mut ciphertext)
         .unwrap();
 
-    UnsealEncryptedKey {
+    HandleUnsealEncryptedKey {
         nonce: nonce.to_vec(),
         ciphertext,
         associated_data: associated_data.to_vec(),
@@ -95,136 +69,83 @@ async fn client_dh_encrypt(
 #[test_log::test]
 pub async fn test_unseal_success() {
     let seal_key = b"test-seal-key";
-    let (_db, user_agent_ref) = setup_authenticated_user_agent(seal_key).await;
+    let (_db, user_agent) = setup_sealed_user_agent(seal_key).await;
 
-    let encrypted_key = client_dh_encrypt(&user_agent_ref, seal_key).await;
+    let encrypted_key = client_dh_encrypt(&user_agent, seal_key).await;
 
-    let response = user_agent_ref
-        .ask(HandleUnsealEncryptedKey { req: encrypted_key })
-        .await
-        .unwrap();
-
-    assert_eq!(
-        response.payload.unwrap(),
-        UserAgentResponsePayload::UnsealResult(UnsealResult::Success.into()),
-    );
+    let response = user_agent.ask(encrypted_key).await;
+    assert!(matches!(response, Ok(())));
 }
 
 #[tokio::test]
 #[test_log::test]
 pub async fn test_unseal_wrong_seal_key() {
-    let (_db, user_agent_ref) = setup_authenticated_user_agent(b"correct-key").await;
+    let (_db, user_agent) = setup_sealed_user_agent(b"correct-key").await;
 
-    let encrypted_key = client_dh_encrypt(&user_agent_ref, b"wrong-key").await;
+    let encrypted_key = client_dh_encrypt(&user_agent, b"wrong-key").await;
 
-    let response = user_agent_ref
-        .ask(HandleUnsealEncryptedKey { req: encrypted_key })
-        .await
-        .unwrap();
-
-    assert_eq!(
-        response.payload.unwrap(),
-        UserAgentResponsePayload::UnsealResult(UnsealResult::InvalidKey.into()),
-    );
+    let response = user_agent.ask(encrypted_key).await;
+    assert!(matches!(
+        response,
+        Err(kameo::error::SendError::HandlerError(
+            UnsealError::InvalidKey
+        ))
+    ));
 }
 
 #[tokio::test]
 #[test_log::test]
 pub async fn test_unseal_corrupted_ciphertext() {
-    let (_db, user_agent_ref) = setup_authenticated_user_agent(b"test-key").await;
+    let (_db, user_agent) = setup_sealed_user_agent(b"test-key").await;
 
     let client_secret = EphemeralSecret::random();
     let client_public = PublicKey::from(&client_secret);
 
-    user_agent_ref
+    user_agent
         .ask(HandleUnsealRequest {
-            req: UnsealStart {
-                client_pubkey: client_public.as_bytes().to_vec(),
-            },
+            client_pubkey: client_public,
         })
         .await
         .unwrap();
 
-    let response = user_agent_ref
+    let response = user_agent
         .ask(HandleUnsealEncryptedKey {
-            req: UnsealEncryptedKey {
-                nonce: vec![0u8; 24],
-                ciphertext: vec![0u8; 32],
-                associated_data: vec![],
-            },
-        })
-        .await
-        .unwrap();
-
-    assert_eq!(
-        response.payload.unwrap(),
-        UserAgentResponsePayload::UnsealResult(UnsealResult::InvalidKey.into()),
-    );
-}
-
-#[tokio::test]
-#[test_log::test]
-pub async fn test_unseal_start_without_auth_fails() {
-    let db = db::create_test_pool().await;
-
-    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
-    let user_agent =
-        UserAgentActor::new_manual(db.clone(), actors, super::null_recipient());
-    let user_agent_ref = UserAgentActor::spawn(user_agent);
-
-    let client_secret = EphemeralSecret::random();
-    let client_public = PublicKey::from(&client_secret);
-
-    let result = user_agent_ref
-        .ask(HandleUnsealRequest {
-            req: UnsealStart {
-                client_pubkey: client_public.as_bytes().to_vec(),
-            },
+            nonce: vec![0u8; 24],
+            ciphertext: vec![0u8; 32],
+            associated_data: vec![],
         })
         .await;
 
-    match result {
-        Err(kameo::error::SendError::HandlerError(err)) => {
-            assert!(
-                matches!(err, arbiter_server::actors::user_agent::UserAgentError::InvalidState),
-                "Expected InvalidState, got {err:?}"
-            );
-        }
-        other => panic!("Expected state machine error, got {other:?}"),
-    }
+    assert!(matches!(
+        response,
+        Err(kameo::error::SendError::HandlerError(
+            UnsealError::InvalidKey
+        ))
+    ));
 }
 
 #[tokio::test]
 #[test_log::test]
 pub async fn test_unseal_retry_after_invalid_key() {
     let seal_key = b"real-seal-key";
-    let (_db, user_agent_ref) = setup_authenticated_user_agent(seal_key).await;
+    let (_db, user_agent) = setup_sealed_user_agent(seal_key).await;
 
     {
-        let encrypted_key = client_dh_encrypt(&user_agent_ref, b"wrong-key").await;
+        let encrypted_key = client_dh_encrypt(&user_agent, b"wrong-key").await;
 
-        let response = user_agent_ref
-            .ask(HandleUnsealEncryptedKey { req: encrypted_key })
-            .await
-            .unwrap();
-
-        assert_eq!(
-            response.payload.unwrap(),
-            UserAgentResponsePayload::UnsealResult(UnsealResult::InvalidKey.into()),
-        );
+        let response = user_agent.ask(encrypted_key).await;
+        assert!(matches!(
+            response,
+            Err(kameo::error::SendError::HandlerError(
+                UnsealError::InvalidKey
+            ))
+        ));
     }
 
     {
-        let encrypted_key = client_dh_encrypt(&user_agent_ref, seal_key).await;
+        let encrypted_key = client_dh_encrypt(&user_agent, seal_key).await;
 
-        let response = user_agent_ref
-            .ask(HandleUnsealEncryptedKey { req: encrypted_key })
-            .await
-            .unwrap();
-
-        assert_eq!(
-            response.payload.unwrap(),
-            UserAgentResponsePayload::UnsealResult(UnsealResult::Success.into()),
-        );
+        let response = user_agent.ask(encrypted_key).await;
+        assert!(matches!(response, Ok(())));
     }
 }

server/crates/arbiter-tokens-registry/Cargo.toml

@@ -0,0 +1,7 @@
+[package]
+name = "arbiter-tokens-registry"
+version = "0.1.0"
+edition = "2024"
+
+[dependencies]
+alloy.workspace = true

server/crates/arbiter-tokens-registry/src/evm/mod.rs

@@ -0,0 +1 @@
+pub mod nonfungible;

server/crates/arbiter-tokens-registry/src/evm/nonfungible.rs

@@ -0,0 +1,13 @@
+use alloy::primitives::{Address, ChainId, address};
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct TokenInfo {
+    pub name: &'static str,
+    pub symbol: &'static str,
+    pub decimals: u32,
+    pub contract: Address,
+    pub chain: ChainId,
+    pub logo_uri: Option<&'static str>,
+}
+
+include!("tokens.rs");

server/crates/arbiter-tokens-registry/src/lib.rs

@@ -0,0 +1 @@
+pub mod evm;

server/crates/arbiter-useragent/Cargo.toml

@@ -1,15 +0,0 @@
-[package]
-name = "arbiter-useragent"
-version = "0.1.0"
-edition = "2024"
-license = "Apache-2.0"
-
-[dependencies]
-arbiter-proto.path = "../arbiter-proto"
-kameo.workspace = true
-tokio = {workspace = true, features = ["net"]}
-tonic.workspace = true
-tracing.workspace = true
-ed25519-dalek.workspace = true
-smlang.workspace = true
-x25519-dalek.workspace = true

server/crates/arbiter-useragent/src/lib.rs

@@ -1,66 +0,0 @@
-use arbiter_proto::{proto::UserAgentRequest, transport::TransportActor};
-use ed25519_dalek::SigningKey;
-use kameo::{
-    Actor, Reply,
-    actor::{ActorRef, WeakActorRef},
-    prelude::Message,
-};
-use smlang::statemachine;
-use tonic::transport::CertificateDer;
-use tracing::{debug, error};
-
-struct Storage {
-    pub identity: SigningKey,
-    pub server_ca_cert: CertificateDer<'static>,
-}
-
-#[derive(Debug)]
-pub enum InitError {
-    StorageError,
-    Other(String),
-}
-
-statemachine! {
-    name: UserAgentStateMachine,
-    custom_error: false,
-    transitions: {
-        *Init + SendAuthChallenge = WaitingForAuthSolution
-    }
-}
-
-
-
-pub struct UserAgentActor<A: TransportActor<UserAgentRequest>> {
-    key: SigningKey,
-    server_ca_cert: CertificateDer<'static>,
-    sender: ActorRef<A>,
-}
-impl<A: TransportActor<UserAgentRequest>> Actor for UserAgentActor<A> {
-    type Args = Self;
-
-    type Error = InitError;
-
-    async fn on_start(args: Self::Args, actor_ref: ActorRef<Self>) -> Result<Self, Self::Error> {
-        todo!()
-    }
-
-    async fn on_link_died(
-        &mut self,
-        _: WeakActorRef<Self>,
-        id: kameo::prelude::ActorId,
-        _: kameo::prelude::ActorStopReason,
-    ) -> Result<std::ops::ControlFlow<kameo::prelude::ActorStopReason>, Self::Error> {
-        if id == self.sender.id() {
-            error!("Transport actor died, stopping UserAgentActor");
-            Ok(std::ops::ControlFlow::Break(
-                kameo::prelude::ActorStopReason::Normal,
-            ))
-        } else {
-            debug!(
-                "Linked actor {} died, but it's not the transport actor, ignoring",
-                id
-            );
-            Ok(std::ops::ControlFlow::Continue(()))
-        }
-    }
-}

server/rules/safecell/new-inline.yaml

@@ -0,0 +1,10 @@
+id: safecell-new-inline
+language: Rust
+rule:
+  pattern: $CELL.write_inline(|$W| $BODY);
+  follows:
+    pattern: let mut $CELL = SafeCell::new($INIT);
+fix: 
+  template: let mut $CELL = SafeCell::new_inline(|$W| $BODY);
+  expandStart:
+    pattern: let mut $CELL = SafeCell::new($INIT)

server/rules/safecell/read-inline.yaml

@@ -0,0 +1,17 @@
+id: safecell-read-inline
+language: Rust
+rule:
+  pattern: 
+    context: |
+      {
+          let $READ = $CELL.read();
+          $$$BODY
+      }
+    selector: block
+  inside:
+    kind: block
+fix: 
+  template: | 
+    $CELL.read_inline(|$READ| { 
+      $$$BODY 
+    });