docs: add EVM Policy Engine section

Reviewed-on: #24

.gitignore

@@ -1 +1,3 @@
-target/
+target/
+scripts/__pycache__/
+.DS_Store

IMPLEMENTATION.md

@@ -27,6 +27,82 @@ This document covers concrete technology choices and dependencies. For the archi
 
 ---
 
+## 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
 
 The unsealed root key must be held in a hardened memory cell resistant to dumps, page swaps, and hibernation.

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

@@ -55,6 +55,15 @@ backend = "aqua:protocolbuffers/protobuf/protoc"
 "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.python]]
+version = "3.14.3"
+backend = "core: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"}
+"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"}
+"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"}
+"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"}
+"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"
 backend = "core:rust"

mise.toml

@@ -9,3 +9,4 @@ protoc = "29.6"
 "cargo:cargo-nextest" = "0.9.126"
 "cargo:cargo-shear" = "latest"
 "cargo:cargo-insta" = "1.46.3"
+python = "3.14.3"

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 +1,38 @@
 syntax = "proto3";
 
-package arbiter;
+package arbiter.client;
 
-import "auth.proto";
+import "evm.proto";
+
+message AuthChallengeRequest {
+  bytes pubkey = 1;
+}
+
+message AuthChallenge {
+  bytes pubkey = 1;
+  int32 nonce = 2;
+}
+
+message AuthChallengeSolution {
+  bytes signature = 1;
+}
+
+message AuthOk {}
 
 message ClientRequest {
   oneof payload {
-    arbiter.auth.ClientMessage auth_message = 1;
+    AuthChallengeRequest auth_challenge_request = 1;
+    AuthChallengeSolution auth_challenge_solution = 2;
+    arbiter.evm.EvmSignTransactionRequest evm_sign_transaction = 3;
+    arbiter.evm.EvmAnalyzeTransactionRequest evm_analyze_transaction = 4;
   }
 }
 
 message ClientResponse {
   oneof payload {
-    arbiter.auth.ServerMessage auth_message = 1;
+    AuthChallenge auth_challenge = 1;
+    AuthOk auth_ok = 2;
+    arbiter.evm.EvmSignTransactionResponse evm_sign_transaction = 3;
+    arbiter.evm.EvmAnalyzeTransactionResponse evm_analyze_transaction = 4;
   }
 }

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

@@ -1,9 +1,25 @@
 syntax = "proto3";
 
-package arbiter;
+package arbiter.user_agent;
 
-import "auth.proto";
 import "google/protobuf/empty.proto";
+import "evm.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 UnsealStart {
   bytes client_pubkey = 1;
@@ -35,17 +51,29 @@ enum VaultState {
 
 message UserAgentRequest {
   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;
   }
 }
 message UserAgentResponse {
   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;
+    AuthOk auth_ok = 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;
   }
 }

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.toml

@@ -1,15 +1,17 @@
 [workspace]
 members = [
-    "crates/arbiter-client",
-    "crates/arbiter-proto",
-    "crates/arbiter-server",
-    "crates/arbiter-useragent",
+    "crates/*",
 ]
 resolver = "3"
 
 
 [workspace.dependencies]
-tonic = { version = "0.14.3", features = ["deflate", "gzip", "tls-connect-info", "zstd"] }
+tonic = { version = "0.14.3", features = [
+    "deflate",
+    "gzip",
+    "tls-connect-info",
+    "zstd",
+] }
 tracing = "0.1.44"
 tokio = { version = "1.49.0", features = ["full"] }
 ed25519-dalek = { version = "3.0.0-pre.6", features = ["rand_core"] }
@@ -23,9 +25,11 @@ async-trait = "0.1.89"
 futures = "0.3.31"
 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",

server/crates/arbiter-proto/Cargo.toml

@@ -9,6 +9,7 @@ license = "Apache-2.0"
 tonic.workspace = true
 tokio.workspace = true
 futures.workspace = true
+hex = "0.4.3"
 tonic-prost = "0.14.3"
 prost = "0.14.3"
 kameo.workspace = true
@@ -17,8 +18,9 @@ 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
 
 [build-dependencies]
 tonic-prost-build = "0.14.3"

server/crates/arbiter-proto/build.rs

@@ -11,7 +11,9 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         .compile_protos(
             &[
                 format!("{}/arbiter.proto", PROTOBUF_DIR),
-                format!("{}/auth.proto", PROTOBUF_DIR),
+                format!("{}/user_agent.proto", PROTOBUF_DIR),
+                format!("{}/client.proto", PROTOBUF_DIR),
+                format!("{}/evm.proto", PROTOBUF_DIR),
             ],
             &[PROTOBUF_DIR.to_string()],
         )

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

@@ -3,13 +3,19 @@ pub mod url;
 
 use base64::{Engine, prelude::BASE64_STANDARD};
 
-use crate::proto::auth::AuthChallenge;
-
 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 +34,7 @@ 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 +1,293 @@
-//! Transport abstraction layer for bridging gRPC bidirectional streaming with kameo actors.
+//! Transport-facing abstractions for 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 separates three concerns:
 //!
-//! - 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.
+//! - protocol/session logic wants a small duplex interface ([`Bi`])
+//! - transport adapters push concrete stream items to an underlying IO layer
+//! - transport boundaries translate between protocol-facing and transport-facing
+//!   item types via direction-specific converters
 //!
-//! 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.
+//! [`Bi`] is intentionally minimal and transport-agnostic:
+//! - [`Bi::recv`] yields inbound protocol messages
+//! - [`Bi::send`] accepts outbound protocol/domain items
 //!
-//! # Terminology
+//! # Generic Ordering Rule
 //!
-//! - **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.
+//! This module uses a single convention consistently: when a type or trait is
+//! parameterized by protocol message directions, the generic parameters are
+//! declared as `Inbound` first, then `Outbound`.
 //!
-//! # Architecture
+//! For [`Bi`], that means `Bi<Inbound, Outbound>`:
+//! - `recv() -> Option<Inbound>`
+//! - `send(Outbound)`
+//!
+//! For adapter types that are parameterized by direction-specific converters,
+//! inbound-related converter parameters are declared before outbound-related
+//! converter parameters.
+//!
+//! [`RecvConverter`] and [`SendConverter`] are infallible conversion traits used
+//! by adapters to map between protocol-facing and transport-facing item types.
+//! The traits themselves are not result-aware; adapters decide how transport
+//! errors are handled before (or instead of) conversion.
+//!
+//! [`grpc::GrpcAdapter`] combines:
+//! - a tonic inbound stream
+//! - a Tokio sender for outbound transport items
+//! - a [`RecvConverter`] for the receive path
+//! - a [`SendConverter`] for the send path
+//!
+//! [`DummyTransport`] is a no-op implementation useful for tests and local actor
+//! execution where no real network stream exists.
+//!
+//! # Component Interaction
 //!
 //! ```text
-//! gRPC Stream ──InboundMessage──▶ GrpcTransportActor ──tell(InboundMessage)──▶ BusinessActor
-//!                                 ▲                                    │
-//!                                 └─tell(Result<OutboundMessage, _>)────┘
-//!                                 │
-//!                          mpsc::Sender ──▶ Client
+//! inbound (network -> protocol)
+//! ============================
+//!
+//! tonic::Streaming<RecvTransport>
+//!     -> grpc::GrpcAdapter::recv()
+//!          |
+//!          +--> on `Ok(item)`: RecvConverter::convert(RecvTransport) -> Inbound
+//!          +--> on `Err(status)`: log error and close stream (`None`)
+//!     -> Bi::recv()
+//!     -> protocol/session actor
+//!
+//! outbound (protocol -> network)
+//! ==============================
+//!
+//! protocol/session actor
+//!     -> Bi::send(Outbound)
+//!     -> grpc::GrpcAdapter::send()
+//!          |
+//!          +--> SendConverter::convert(Outbound) -> SendTransport
+//!     -> Tokio mpsc::Sender<SendTransport>
+//!     -> tonic response stream
 //! ```
 //!
-//! # Example
+//! # Design Notes
 //!
-//! ```rust,ignore
-//! let (tx, rx) = mpsc::channel(1000);
-//! let context = server_context.clone();
-//!
-//! 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;
-//!
-//! Ok(Response::new(ReceiverStream::new(rx)))
-//! ```
+//! - `send()` returns [`Error`] only for transport delivery failures (for
+//!   example, when the outbound channel is closed).
+//! - [`grpc::GrpcAdapter`] logs tonic receive errors and treats them as stream
+//!   closure (`None`).
+//! - When protocol-facing and transport-facing types are identical, use
+//!   [`IdentityRecvConverter`] / [`IdentitySendConverter`].
 
-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,
 }
 
-/// Concrete [`Bi`] implementation backed by a tonic gRPC [`Streaming`] and an [`mpsc::Sender`].
+/// Minimal bidirectional transport abstraction used by protocol code.
 ///
-/// 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>>,
+/// `Bi<Inbound, Outbound>` models a duplex channel with:
+/// - inbound items of type `Inbound` read via [`Bi::recv`]
+/// - outbound items of type `Outbound` written via [`Bi::send`]
+#[async_trait]
+pub trait Bi<Inbound, Outbound>: Send + Sync + 'static {
+    async fn send(&mut self, item: Outbound) -> Result<(), Error>;
+
+    async fn recv(&mut self) -> Option<Inbound>;
 }
 
-impl<T, U> Stream for BiStream<T, U>
-where
-    T: Send + 'static,
-    U: Send + 'static,
-{
-    type Item = Result<T, Status>;
+/// Converts transport-facing inbound items into protocol-facing inbound items.
+pub trait RecvConverter: Send + Sync + 'static {
+    type Input;
+    type Output;
 
-    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)
-    }
+    fn convert(&self, item: Self::Input) -> Self::Output;
 }
 
-impl<T, U> Bi<T, U> for BiStream<T, U>
-where
-    T: Send + 'static,
-    U: Send + 'static,
-{
-    type Error = SendError<Result<U, Status>>;
+/// Converts protocol/domain outbound items into transport-facing outbound items.
+pub trait SendConverter: Send + Sync + 'static {
+    type Input;
+    type Output;
 
-    async fn send(&mut self, item: Result<U, Status>) -> Result<(), Self::Error> {
-        self.response_sender.send(item).await
-    }
+    fn convert(&self, item: Self::Input) -> Self::Output;
 }
 
-/// 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>>
-{
+/// A [`RecvConverter`] that forwards values unchanged.
+pub struct IdentityRecvConverter<T> {
+    _marker: PhantomData<T>,
 }
 
-/// A kameo actor that bridges a gRPC bidirectional stream with a business logic actor.
-///
-/// 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!`].
-///
-/// # Message Flow
-///
-/// - **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>,
-}
-
-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 {
+impl<T> IdentityRecvConverter<T> {
+    pub fn new() -> Self {
         Self {
-            sender,
-            receiver,
-            business_logic_actor,
-            _error: std::marker::PhantomData,
+            _marker: PhantomData,
         }
     }
 }
 
-impl<Outbound, Inbound, E> Actor for GrpcTransportActor<Outbound, Inbound, E>
+impl<T> Default for IdentityRecvConverter<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T> RecvConverter for IdentityRecvConverter<T>
 where
-    Outbound: Send + 'static,
-    Inbound: Send + 'static,
-    E: Into<tonic::Status> + Send + 'static,
+    T: Send + Sync + 'static,
 {
-    type Args = Self;
+    type Input = T;
+    type Output = T;
 
-    type Error = ();
+    fn convert(&self, item: Self::Input) -> Self::Output {
+        item
+    }
+}
 
-    async fn on_start(args: Self::Args, _: ActorRef<Self>) -> Result<Self, Self::Error> {
-        Ok(args)
+/// A [`SendConverter`] that forwards values unchanged.
+pub struct IdentitySendConverter<T> {
+    _marker: PhantomData<T>,
+}
+
+impl<T> IdentitySendConverter<T> {
+    pub fn new() -> Self {
+        Self {
+            _marker: PhantomData,
+        }
+    }
+}
+
+impl<T> Default for IdentitySendConverter<T> {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+impl<T> SendConverter for IdentitySendConverter<T>
+where
+    T: Send + Sync + 'static,
+{
+    type Input = T;
+    type Output = T;
+
+    fn convert(&self, item: Self::Input) -> Self::Output {
+        item
+    }
+}
+
+/// gRPC-specific transport adapters and helpers.
+pub mod grpc {
+    use async_trait::async_trait;
+    use futures::StreamExt;
+    use tokio::sync::mpsc;
+    use tonic::Streaming;
+
+    use super::{Bi, Error, RecvConverter, SendConverter};
+
+    /// [`Bi`] adapter backed by a tonic gRPC bidirectional stream.
+    ///
+
+    /// Tonic receive errors are logged and treated as stream closure (`None`).
+    /// The receive converter is only invoked for successful inbound transport
+    /// items.
+    pub struct GrpcAdapter<InboundConverter, OutboundConverter>
+    where
+        InboundConverter: RecvConverter,
+        OutboundConverter: SendConverter,
+    {
+        sender: mpsc::Sender<OutboundConverter::Output>,
+        receiver: Streaming<InboundConverter::Input>,
+        inbound_converter: InboundConverter,
+        outbound_converter: OutboundConverter,
     }
 
-    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(()))
+    impl<InboundTransport, Inbound, InboundConverter, OutboundConverter>
+        GrpcAdapter<InboundConverter, OutboundConverter>
+    where
+        InboundConverter: RecvConverter<Input = InboundTransport, Output = Inbound>,
+        OutboundConverter: SendConverter,
+    {
+        pub fn new(
+            sender: mpsc::Sender<OutboundConverter::Output>,
+            receiver: Streaming<InboundTransport>,
+            inbound_converter: InboundConverter,
+            outbound_converter: OutboundConverter,
+        ) -> Self {
+            Self {
+                sender,
+                receiver,
+                inbound_converter,
+                outbound_converter,
             }
         }
     }
 
-    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_trait]
+    impl<InboundConverter, OutboundConverter> Bi<InboundConverter::Output, OutboundConverter::Input>
+        for GrpcAdapter<InboundConverter, OutboundConverter>
+    where
+        InboundConverter: RecvConverter,
+        OutboundConverter: SendConverter,
+        OutboundConverter::Input: Send + 'static,
+        OutboundConverter::Output: Send + 'static,
+    {
+        #[tracing::instrument(level = "trace", skip(self, item))]
+        async fn send(&mut self, item: OutboundConverter::Input) -> Result<(), Error> {
+            let outbound = self.outbound_converter.convert(item);
+            self.sender
+                .send(outbound)
+                .await
+                .map_err(|_| Error::ChannelClosed)
+        }
+
+        #[tracing::instrument(level = "trace", skip(self))]
+        async fn recv(&mut self) -> Option<InboundConverter::Output> {
+            match self.receiver.next().await {
+                Some(Ok(item)) => Some(self.inbound_converter.convert(item)),
+                Some(Err(error)) => {
+                    tracing::error!(error = ?error, "grpc transport recv failed; closing stream");
+                    None
                 }
+                None => None,
             }
         }
     }
 }
 
-impl<Outbound, Inbound, E> Message<Result<Outbound, E>> for GrpcTransportActor<Outbound, Inbound, E>
-where
-    Outbound: Send + 'static,
-    Inbound: Send + 'static,
-    E: Into<tonic::Status> + Send + 'static,
-{
-    type Reply = ();
+/// 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)>,
+}
 
-    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();
-            }
+impl<Inbound, Outbound> DummyTransport<Inbound, Outbound> {
+    pub fn new() -> Self {
+        Self {
+            _marker: PhantomData,
         }
     }
 }
 
-impl<Outbound, Inbound, E> TransportActor<Outbound, E> for GrpcTransportActor<Outbound, Inbound, E>
-where
-    Outbound: Send + 'static,
-    Inbound: Send + 'static,
-    E: Into<tonic::Status> + Send + 'static,
-{
+impl<Inbound, Outbound> Default for DummyTransport<Inbound, Outbound> {
+    fn default() -> Self {
+        Self::new()
+    }
 }
 
-/// 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>)
+#[async_trait]
+impl<Inbound, Outbound> Bi<Inbound, Outbound> for DummyTransport<Inbound, Outbound>
 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>),
+    Inbound: Send + Sync + 'static,
+    Outbound: Send + Sync + 'static,
 {
-    let prepared_business: PreparedActor<Business> = Spawn::prepare();
-    let prepared_transport: PreparedActor<Transport> = Spawn::prepare();
+    async fn send(&mut self, _item: Outbound) -> Result<(), Error> {
+        Ok(())
+    }
 
-    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)
+    async fn recv(&mut self) -> Option<Inbound> {
+        std::future::pending::<()>().await;
+        None
+    }
 }

server/crates/arbiter-server/Cargo.toml

@@ -42,6 +42,9 @@ argon2 = { version = "0.5.3", features = ["zeroize"] }
 restructed = "0.2.2"
 strum = { version = "0.27.2", features = ["derive"] }
 pem = "3.0.6"
+k256 = "0.13.4"
+alloy.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

@@ -56,4 +56,103 @@ 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);
+

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/mod.rs

@@ -0,0 +1,101 @@
+use arbiter_proto::proto::client::{
+    AuthChallengeRequest, AuthChallengeSolution, ClientRequest,
+    client_request::Payload as ClientRequestPayload,
+};
+use ed25519_dalek::VerifyingKey;
+use tracing::error;
+
+use crate::actors::client::{
+    ClientConnection,
+    auth::state::{AuthContext, AuthStateMachine},
+    session::ClientSession,
+};
+
+#[derive(thiserror::Error, Debug, Clone, PartialEq, Eq)]
+pub enum Error {
+    #[error("Unexpected message payload")]
+    UnexpectedMessagePayload,
+    #[error("Invalid client public key length")]
+    InvalidClientPubkeyLength,
+    #[error("Invalid client public key encoding")]
+    InvalidAuthPubkeyEncoding,
+    #[error("Database pool unavailable")]
+    DatabasePoolUnavailable,
+    #[error("Database operation failed")]
+    DatabaseOperationFailed,
+    #[error("Public key not registered")]
+    PublicKeyNotRegistered,
+    #[error("Invalid signature length")]
+    InvalidSignatureLength,
+    #[error("Invalid challenge solution")]
+    InvalidChallengeSolution,
+    #[error("Transport error")]
+    Transport,
+}
+
+mod state;
+use state::*;
+
+fn parse_auth_event(payload: ClientRequestPayload) -> Result<AuthEvents, Error> {
+    match payload {
+        ClientRequestPayload::AuthChallengeRequest(AuthChallengeRequest { pubkey }) => {
+            let pubkey_bytes = pubkey.as_array().ok_or(Error::InvalidClientPubkeyLength)?;
+            let pubkey = VerifyingKey::from_bytes(pubkey_bytes)
+                .map_err(|_| Error::InvalidAuthPubkeyEncoding)?;
+            Ok(AuthEvents::AuthRequest(ChallengeRequest {
+                pubkey: pubkey.into(),
+            }))
+        }
+        ClientRequestPayload::AuthChallengeSolution(AuthChallengeSolution { signature }) => {
+            Ok(AuthEvents::ReceivedSolution(ChallengeSolution {
+                solution: signature,
+            }))
+        }
+    }
+}
+
+pub async fn authenticate(props: &mut ClientConnection) -> Result<VerifyingKey, Error> {
+    let mut state = AuthStateMachine::new(AuthContext::new(props));
+
+    loop {
+        let transport = state.context_mut().conn.transport.as_mut();
+        let Some(ClientRequest {
+            payload: Some(payload),
+        }) = transport.recv().await
+        else {
+            return Err(Error::Transport);
+        };
+
+        let event = parse_auth_event(payload)?;
+
+        match state.process_event(event).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);
+            }
+
+            _ => (),
+        }
+    }
+}
+
+pub async fn authenticate_and_create(
+    mut props: ClientConnection,
+) -> Result<ClientSession, Error> {
+    let key = authenticate(&mut props).await?;
+    let session = ClientSession::new(props, key);
+    Ok(session)
+}

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

@@ -0,0 +1,136 @@
+use arbiter_proto::proto::client::{
+    AuthChallenge, ClientResponse,
+    client_response::Payload as ClientResponsePayload,
+};
+use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, update};
+use diesel_async::RunQueryDsl;
+use ed25519_dalek::VerifyingKey;
+use tracing::error;
+
+use super::Error;
+use crate::{actors::client::ClientConnection, db::schema};
+
+pub struct ChallengeRequest {
+    pub pubkey: VerifyingKey,
+}
+
+pub struct ChallengeContext {
+    pub challenge: AuthChallenge,
+    pub key: VerifyingKey,
+}
+
+pub struct ChallengeSolution {
+    pub solution: Vec<u8>,
+}
+
+smlang::statemachine!(
+    name: Auth,
+    custom_error: true,
+    transitions: {
+        *Init + AuthRequest(ChallengeRequest) / async prepare_challenge = SentChallenge(ChallengeContext),
+        SentChallenge(ChallengeContext) + ReceivedSolution(ChallengeSolution) [async verify_solution] / provide_key = AuthOk(VerifyingKey),
+    }
+);
+
+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::DatabasePoolUnavailable
+    })?;
+    db_conn
+        .exclusive_transaction(|conn| {
+            Box::pin(async move {
+                let current_nonce = schema::program_client::table
+                    .filter(schema::program_client::public_key.eq(pubkey_bytes.to_vec()))
+                    .select(schema::program_client::nonce)
+                    .first::<i32>(conn)
+                    .await?;
+
+                update(schema::program_client::table)
+                    .filter(schema::program_client::public_key.eq(pubkey_bytes.to_vec()))
+                    .set(schema::program_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::DatabaseOperationFailed
+        })?
+        .ok_or_else(|| {
+            error!(?pubkey_bytes, "Public key not found in database");
+            Error::PublicKeyNotRegistered
+        })
+}
+
+pub struct AuthContext<'a> {
+    pub(super) conn: &'a mut ClientConnection,
+}
+
+impl<'a> AuthContext<'a> {
+    pub fn new(conn: &'a mut ClientConnection) -> Self {
+        Self { conn }
+    }
+}
+
+impl AuthStateMachineContext for AuthContext<'_> {
+    type Error = Error;
+
+    async fn verify_solution(
+        &self,
+        ChallengeContext { challenge, key }: &ChallengeContext,
+        ChallengeSolution { solution }: &ChallengeSolution,
+    ) -> Result<bool, Self::Error> {
+        let formatted_challenge =
+            arbiter_proto::format_challenge(challenge.nonce, &challenge.pubkey);
+
+        let signature = solution.as_slice().try_into().map_err(|_| {
+            error!(?solution, "Invalid signature length");
+            Error::InvalidChallengeSolution
+        })?;
+
+        let valid = key.verify_strict(&formatted_challenge, &signature).is_ok();
+
+        Ok(valid)
+    }
+
+    async fn prepare_challenge(
+        &mut self,
+        ChallengeRequest { pubkey }: ChallengeRequest,
+    ) -> Result<ChallengeContext, Self::Error> {
+        let nonce = create_nonce(&self.conn.db, pubkey.as_bytes()).await?;
+
+        let challenge = AuthChallenge {
+            pubkey: pubkey.as_bytes().to_vec(),
+            nonce,
+        };
+
+        self.conn
+            .transport
+            .send(Ok(ClientResponse {
+                payload: Some(ClientResponsePayload::AuthChallenge(challenge.clone())),
+            }))
+            .await
+            .map_err(|e| {
+                error!(?e, "Failed to send auth challenge");
+                Error::Transport
+            })?;
+
+        Ok(ChallengeContext {
+            challenge,
+            key: pubkey,
+        })
+    }
+
+    fn provide_key(
+        &mut self,
+        state_data: &ChallengeContext,
+        _: ChallengeSolution,
+    ) -> Result<VerifyingKey, Self::Error> {
+        Ok(state_data.key)
+    }
+}

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

@@ -0,0 +1,58 @@
+use arbiter_proto::{
+    proto::client::{ClientRequest, ClientResponse},
+    transport::Bi,
+};
+use kameo::actor::Spawn;
+use tracing::{error, info};
+
+use crate::{
+    actors::{GlobalActors, client::session::ClientSession},
+    db,
+};
+
+#[derive(Debug, Clone, PartialEq, Eq, thiserror::Error)]
+pub enum ClientError {
+    #[error("Expected message with payload")]
+    MissingRequestPayload,
+    #[error("Unexpected request payload")]
+    UnexpectedRequestPayload,
+    #[error("State machine error")]
+    StateTransitionFailed,
+    #[error("Connection registration failed")]
+    ConnectionRegistrationFailed,
+    #[error(transparent)]
+    Auth(#[from] auth::Error),
+}
+
+pub type Transport = Box<dyn Bi<ClientRequest, Result<ClientResponse, ClientError>> + Send>;
+
+pub struct ClientConnection {
+    pub(crate) db: db::DatabasePool,
+    pub(crate) transport: Transport,
+    pub(crate) actors: GlobalActors,
+}
+
+impl ClientConnection {
+    pub fn new(db: db::DatabasePool, transport: Transport, actors: GlobalActors) -> Self {
+        Self {
+            db,
+            transport,
+            actors,
+        }
+    }
+}
+
+pub mod auth;
+pub mod session;
+
+pub async fn connect_client(props: ClientConnection) {
+    match auth::authenticate_and_create(props).await {
+        Ok(session) => {
+            ClientSession::spawn(session);
+            info!("Client authenticated, session started");
+        }
+        Err(err) => {
+            error!(?err, "Authentication failed, closing connection");
+        }
+    }
+}

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

@@ -0,0 +1,98 @@
+use arbiter_proto::proto::client::{ClientRequest, ClientResponse};
+use ed25519_dalek::VerifyingKey;
+use kameo::Actor;
+use tokio::select;
+use tracing::{error, info};
+
+use crate::{actors::{
+    GlobalActors, client::{ClientError, ClientConnection}, router::RegisterClient
+}, db};
+
+pub struct ClientSession {
+    props: ClientConnection,
+    key: VerifyingKey,
+}
+
+impl ClientSession {
+    pub(crate) fn new(props: ClientConnection, key: VerifyingKey) -> Self {
+        Self { props, key }
+    }
+
+    pub async fn process_transport_inbound(&mut self, req: ClientRequest) -> Output {
+        let msg = req.payload.ok_or_else(|| {
+            error!(actor = "client", "Received message with no payload");
+            ClientError::MissingRequestPayload
+        })?;
+
+        match msg {
+            _ => Err(ClientError::UnexpectedRequestPayload),
+        }
+    }
+}
+
+type Output = Result<ClientResponse, ClientError>;
+
+impl Actor for ClientSession {
+    type Args = Self;
+
+    type Error = ClientError;
+
+    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(|_| ClientError::ConnectionRegistrationFailed)?;
+        Ok(args)
+    }
+
+    async fn next(
+        &mut self,
+        _actor_ref: kameo::prelude::WeakActorRef<Self>,
+        mailbox_rx: &mut kameo::prelude::MailboxReceiver<Self>,
+    ) -> Option<kameo::mailbox::Signal<Self>> {
+        loop {
+            select! {
+                signal = mailbox_rx.recv() => {
+                    return signal;
+                }
+                msg = self.props.transport.recv() => {
+                    match msg {
+                        Some(request) => {
+                            match self.process_transport_inbound(request).await {
+                                Ok(resp) => {
+                                    if self.props.transport.send(Ok(resp)).await.is_err() {
+                                        error!(actor = "client", reason = "channel closed", "send.failed");
+                                        return Some(kameo::mailbox::Signal::Stop);
+                                    }
+                                }
+                                Err(err) => {
+                                    let _ = self.props.transport.send(Err(err)).await;
+                                    return Some(kameo::mailbox::Signal::Stop);
+                                }
+                            }
+                        }
+                        None => {
+                            info!(actor = "client", "transport.closed");
+                            return Some(kameo::mailbox::Signal::Stop);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+impl ClientSession {
+    pub fn new_test(db: db::DatabasePool, actors: GlobalActors) -> Self {
+        use arbiter_proto::transport::DummyTransport;
+        let transport: super::Transport = Box::new(DummyTransport::new());
+        let props = ClientConnection::new(db, transport, actors);
+        let key = VerifyingKey::from_bytes(&[0u8; 32]).unwrap();
+        Self { props, key }
+    }
+}

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

@@ -0,0 +1,246 @@
+use alloy::{consensus::TxEip1559, network::TxSigner, 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 memsafe::MemSafe;
+use rand::{SeedableRng, rng, rngs::StdRng};
+
+use crate::{
+    actors::keyholder::{CreateNew, Decrypt, KeyHolder},
+    db::{self, DatabasePool, models::{self, EvmBasicGrant, SqliteTimestamp}, schema},
+    evm::{
+        self, RunKind,
+        policies::{
+            FullGrant, SharedGrantSettings, SpecificGrant, SpecificMeaning,
+            ether_transfer::EtherTransfer,
+            token_transfers::TokenTransfer,
+        },
+    },
+};
+
+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);
+
+        // Move raw key bytes into a Vec<u8> MemSafe for KeyHolder
+        let plaintext = {
+            let reader = key_cell.read().expect("MemSafe read");
+            MemSafe::new(reader.to_vec()).expect("MemSafe allocation")
+        };
+
+        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,
+        wallet_id: Option<i32>,
+    ) -> Result<Vec<EvmBasicGrant>, Error> {
+        let mut conn = self.db.get().await?;
+        let mut query = schema::evm_basic_grant::table
+            .select(EvmBasicGrant::as_select())
+            .filter(schema::evm_basic_grant::revoked_at.is_null())
+            .into_boxed();
+        if let Some(wid) = wallet_id {
+            query = query.filter(schema::evm_basic_grant::wallet_id.eq(wid));
+        }
+        Ok(query.load(&mut conn).await?)
+    }
+
+    #[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: MemSafe<Vec<u8>> = self
+            .keyholder
+            .ask(Decrypt { aead_id: wallet.aead_encrypted_id })
+            .await
+            .map_err(|_| SignTransactionError::KeyholderSend)?;
+
+        let signer = safe_signer::SafeSigner::from_memsafe(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/mod.rs

@@ -1,3 +1,4 @@
+use chrono::Utc;
 use diesel::{
     ExpressionMethods as _, OptionalExtension, QueryDsl, SelectableHelper,
     dsl::{insert_into, update},
@@ -312,7 +313,7 @@ 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)

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 +1,79 @@
+use std::{
+    collections::{HashMap},
+    ops::ControlFlow,
+};
+
+use kameo::{
+    Actor,
+    actor::{ActorId, ActorRef},
+    messages,
+    prelude::{ActorStopReason, Context, WeakActorRef},
+};
+use tracing::info;
+
+use crate::actors::{client::session::ClientSession, user_agent::session::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(()))
+    }
+}
+
+#[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);
+    }
+}

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

@@ -0,0 +1,118 @@
+use arbiter_proto::proto::user_agent::{
+    AuthChallengeRequest, AuthChallengeSolution, UserAgentRequest,
+    user_agent_request::Payload as UserAgentRequestPayload,
+};
+use ed25519_dalek::VerifyingKey;
+use tracing::error;
+
+use crate::actors::user_agent::{
+    UserAgentConnection,
+    auth::state::{AuthContext, AuthStateMachine}, session::UserAgentSession,
+};
+
+#[derive(thiserror::Error, Debug, PartialEq)]
+pub enum Error {
+    #[error("Unexpected message payload")]
+    UnexpectedMessagePayload,
+    #[error("Invalid client public key length")]
+    InvalidClientPubkeyLength,
+    #[error("Invalid client public key encoding")]
+    InvalidAuthPubkeyEncoding,
+    #[error("Database pool unavailable")]
+    DatabasePoolUnavailable,
+    #[error("Database operation failed")]
+    DatabaseOperationFailed,
+    #[error("Public key not registered")]
+    PublicKeyNotRegistered,
+    #[error("Transport error")]
+    Transport,
+    #[error("Invalid bootstrap token")]
+    InvalidBootstrapToken,
+    #[error("Bootstrapper actor unreachable")]
+    BootstrapperActorUnreachable,
+    #[error("Invalid challenge solution")]
+    InvalidChallengeSolution,
+}
+
+mod state;
+use state::*;
+
+fn parse_auth_event(payload: UserAgentRequestPayload) -> Result<AuthEvents, Error> {
+    match payload {
+        UserAgentRequestPayload::AuthChallengeRequest(AuthChallengeRequest {
+            pubkey,
+            bootstrap_token: None,
+        }) => {
+            let pubkey_bytes = pubkey.as_array().ok_or(Error::InvalidClientPubkeyLength)?;
+            let pubkey = VerifyingKey::from_bytes(pubkey_bytes)
+                .map_err(|_| Error::InvalidAuthPubkeyEncoding)?;
+            Ok(AuthEvents::AuthRequest(ChallengeRequest {
+                pubkey: pubkey.into(),
+            }))
+        }
+        UserAgentRequestPayload::AuthChallengeRequest(AuthChallengeRequest {
+            pubkey,
+            bootstrap_token: Some(token),
+        }) => {
+            let pubkey_bytes = pubkey.as_array().ok_or(Error::InvalidClientPubkeyLength)?;
+            let pubkey = VerifyingKey::from_bytes(pubkey_bytes)
+                .map_err(|_| Error::InvalidAuthPubkeyEncoding)?;
+            Ok(AuthEvents::BootstrapAuthRequest(BootstrapAuthRequest {
+                pubkey: pubkey.into(),
+                token,
+            }))
+        }
+        UserAgentRequestPayload::AuthChallengeSolution(AuthChallengeSolution { signature }) => {
+            Ok(AuthEvents::ReceivedSolution(ChallengeSolution {
+                solution: signature,
+            }))
+        }
+        _ => Err(Error::UnexpectedMessagePayload),
+    }
+}
+
+pub async fn authenticate(props: &mut UserAgentConnection) -> Result<VerifyingKey, Error> {
+    let mut state = AuthStateMachine::new(AuthContext::new(props));
+
+    loop {
+        // This is needed because `state` now holds mutable reference to `ConnectionProps`, so we can't directly access `props` here
+        let transport = state.context_mut().conn.transport.as_mut();
+        let Some(UserAgentRequest {
+            payload: Some(payload),
+        }) = transport.recv().await
+        else {
+            return Err(Error::Transport);
+        };
+
+        let event = parse_auth_event(payload)?;
+
+        match state.process_event(event).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);
+            }
+
+            _ => (),
+        }
+    }
+}
+
+
+pub async fn authenticate_and_create(mut props: UserAgentConnection) -> Result<UserAgentSession, Error> {
+    let key = authenticate(&mut props).await?;
+    let session = UserAgentSession::new(props, key.clone());
+    Ok(session)
+}

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

@@ -0,0 +1,202 @@
+use arbiter_proto::proto::user_agent::{
+    AuthChallenge, UserAgentResponse,
+    user_agent_response::Payload as UserAgentResponsePayload,
+};
+use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, update};
+use diesel_async::RunQueryDsl;
+use ed25519_dalek::VerifyingKey;
+use tracing::error;
+
+use super::Error;
+use crate::{
+    actors::{bootstrap::ConsumeToken, user_agent::UserAgentConnection},
+    db::schema,
+};
+
+pub struct ChallengeRequest {
+    pub pubkey: VerifyingKey,
+}
+
+pub struct BootstrapAuthRequest {
+    pub pubkey: VerifyingKey,
+    pub token: String,
+}
+
+pub struct ChallengeContext {
+    pub challenge: AuthChallenge,
+    pub key: VerifyingKey,
+}
+
+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] / provide_key_bootstrap = AuthOk(VerifyingKey),
+        SentChallenge(ChallengeContext) + ReceivedSolution(ChallengeSolution) [async verify_solution] / provide_key = AuthOk(VerifyingKey),
+    }
+);
+
+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::DatabasePoolUnavailable
+    })?;
+    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::DatabaseOperationFailed
+        })?
+        .ok_or_else(|| {
+            error!(?pubkey_bytes, "Public key not found in database");
+            Error::PublicKeyNotRegistered
+        })
+}
+
+async fn register_key(db: &crate::db::DatabasePool, pubkey_bytes: &[u8]) -> Result<(), Error> {
+    let mut conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::DatabasePoolUnavailable
+    })?;
+
+    diesel::insert_into(schema::useragent_client::table)
+        .values((
+            schema::useragent_client::public_key.eq(pubkey_bytes.to_vec()),
+            schema::useragent_client::nonce.eq(1),
+        ))
+        .execute(&mut conn)
+        .await
+        .map_err(|e| {
+            error!(error = ?e, "Database error");
+            Error::DatabaseOperationFailed
+        })?;
+
+    Ok(())
+}
+
+pub struct AuthContext<'a> {
+    pub(super) conn: &'a mut UserAgentConnection,
+}
+
+impl<'a> AuthContext<'a> {
+    pub fn new(conn: &'a mut UserAgentConnection) -> Self {
+        Self { conn }
+    }
+}
+
+impl AuthStateMachineContext for AuthContext<'_> {
+    type Error = Error;
+
+    async fn verify_solution(
+        &self,
+        ChallengeContext { challenge, key }: &ChallengeContext,
+        ChallengeSolution { solution }: &ChallengeSolution,
+    ) -> Result<bool, Self::Error> {
+        let formatted_challenge =
+            arbiter_proto::format_challenge(challenge.nonce, &challenge.pubkey);
+
+        let signature = solution.as_slice().try_into().map_err(|_| {
+            error!(?solution, "Invalid signature length");
+            Error::InvalidChallengeSolution
+        })?;
+
+        let valid = key.verify_strict(&formatted_challenge, &signature).is_ok();
+
+        Ok(valid)
+    }
+
+    async fn prepare_challenge(
+        &mut self,
+        ChallengeRequest { pubkey }: ChallengeRequest,
+    ) -> Result<ChallengeContext, Self::Error> {
+        let nonce = create_nonce(&self.conn.db, pubkey.as_bytes()).await?;
+
+        let challenge = AuthChallenge {
+            pubkey: pubkey.as_bytes().to_vec(),
+            nonce,
+        };
+
+        self.conn
+            .transport
+            .send(Ok(UserAgentResponse {
+                payload: Some(UserAgentResponsePayload::AuthChallenge(challenge.clone())),
+            }))
+            .await
+            .map_err(|e| {
+                error!(?e, "Failed to send auth challenge");
+                Error::Transport
+            })?;
+
+        Ok(ChallengeContext {
+            challenge,
+            key: pubkey,
+        })
+    }
+
+    #[allow(missing_docs)]
+    #[allow(clippy::result_unit_err)]
+    async fn verify_bootstrap_token(
+        &self,
+        BootstrapAuthRequest { pubkey, token }: &BootstrapAuthRequest,
+    ) -> Result<bool, Self::Error> {
+        let token_ok: bool = self
+            .conn
+            .actors
+            .bootstrapper
+            .ask(ConsumeToken {
+                token: token.clone(),
+            })
+            .await
+            .map_err(|e| {
+                error!(?pubkey, "Failed to consume bootstrap token: {e}");
+                Error::BootstrapperActorUnreachable
+            })?;
+
+        if !token_ok {
+            error!(?pubkey, "Invalid bootstrap token provided");
+            return Err(Error::InvalidBootstrapToken);
+        }
+
+        register_key(&self.conn.db, pubkey.as_bytes()).await?;
+
+        Ok(true)
+    }
+
+    fn provide_key_bootstrap(
+        &mut self,
+        event_data: BootstrapAuthRequest,
+    ) -> Result<VerifyingKey, Self::Error> {
+        Ok(event_data.pubkey)
+    }
+
+    fn provide_key(
+        &mut self,
+        state_data: &ChallengeContext,
+        _: ChallengeSolution,
+    ) -> Result<VerifyingKey, Self::Error> {
+        Ok(state_data.key)
+    }
+}

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 +1,65 @@
-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 arbiter_proto::{
+    proto::user_agent::{UserAgentRequest, UserAgentResponse},
+    transport::Bi,
 };
-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 kameo::actor::Spawn as _;
 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, user_agent::session::UserAgentSession},
+    db::{self},
 };
 
-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>>,
+#[derive(Debug, thiserror::Error, PartialEq)]
+pub enum UserAgentError {
+    #[error("Expected message with payload")]
+    MissingRequestPayload,
+    #[error("Unexpected request payload")]
+    UnexpectedRequestPayload,
+    #[error("Invalid state for unseal encrypted key")]
+    InvalidStateForUnsealEncryptedKey,
+    #[error("client_pubkey must be 32 bytes")]
+    InvalidClientPubkeyLength,
+    #[error("State machine error")]
+    StateTransitionFailed,
+    #[error("Vault is not available")]
+    KeyHolderActorUnreachable,
+    #[error(transparent)]
+    Auth(#[from] auth::Error),
+    #[error("Failed registering connection")]
+    ConnectionRegistrationFailed,
 }
 
-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 type Transport =
+    Box<dyn Bi<UserAgentRequest, Result<UserAgentResponse, UserAgentError>> + Send>;
 
-    pub fn new_manual(
-        db: db::DatabasePool,
-        actors: GlobalActors,
-        transport: Recipient<Result<UserAgentResponse, UserAgentError>>,
-    ) -> Self {
+pub struct UserAgentConnection {
+    db: db::DatabasePool,
+    actors: GlobalActors,
+    transport: Transport,
+}
+
+impl UserAgentConnection {
+    pub fn new(db: db::DatabasePool, actors: GlobalActors, transport: Transport) -> 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>;
+pub mod auth;
+pub mod session;
 
-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(),
-                )))
-            }
+pub async fn connect_user_agent(props: UserAgentConnection) {
+    match auth::authenticate_and_create(props).await {
+        Ok(session) => {
+            UserAgentSession::spawn(session);
+            info!("User authenticated, session started");
         }
-    }
-
-    #[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)
-        }
-    }
-}
-
-impl Message<UserAgentRequest> for UserAgentActor {
-    type Reply = ();
-
-    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);
+        Err(err) => {
+            error!(?err, "Authentication failed, closing connection");
         }
     }
 }

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

@@ -0,0 +1,320 @@
+use std::{ops::DerefMut, sync::Mutex};
+
+use arbiter_proto::proto::{
+    evm as evm_proto,
+    user_agent::{
+        UnsealEncryptedKey, UnsealResult, UnsealStart, UnsealStartResponse, UserAgentRequest,
+        UserAgentResponse, user_agent_request::Payload as UserAgentRequestPayload,
+        user_agent_response::Payload as UserAgentResponsePayload,
+    },
+};
+use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
+use ed25519_dalek::VerifyingKey;
+use kameo::{
+    Actor,
+    error::SendError,
+};
+use memsafe::MemSafe;
+use tokio::select;
+use tracing::{error, info};
+use x25519_dalek::{EphemeralSecret, PublicKey};
+
+use crate::actors::{
+    evm::{Generate, ListWallets},
+    keyholder::{self, TryUnseal},
+    router::RegisterUserAgent,
+    user_agent::{UserAgentConnection, UserAgentError},
+};
+
+mod state;
+use state::{DummyContext, UnsealContext, UserAgentEvents, UserAgentStateMachine, UserAgentStates};
+
+pub struct UserAgentSession {
+    props: UserAgentConnection,
+    key: VerifyingKey,
+    state: UserAgentStateMachine<DummyContext>,
+}
+
+impl UserAgentSession {
+    pub(crate) fn new(props: UserAgentConnection, key: VerifyingKey) -> Self {
+        Self {
+            props,
+            key,
+            state: UserAgentStateMachine::new(DummyContext),
+        }
+    }
+
+    fn transition(&mut self, event: UserAgentEvents) -> Result<(), UserAgentError> {
+        self.state.process_event(event).map_err(|e| {
+            error!(?e, "State transition failed");
+            UserAgentError::StateTransitionFailed
+        })?;
+        Ok(())
+    }
+
+    pub async fn process_transport_inbound(&mut self, req: UserAgentRequest) -> Output {
+        let msg = req.payload.ok_or_else(|| {
+            error!(actor = "useragent", "Received message with no payload");
+            UserAgentError::MissingRequestPayload
+        })?;
+
+        match msg {
+            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
+            }
+            UserAgentRequestPayload::EvmWalletCreate(_) => self.handle_evm_wallet_create().await,
+            UserAgentRequestPayload::EvmWalletList(_) => self.handle_evm_wallet_list().await,
+            _ => Err(UserAgentError::UnexpectedRequestPayload),
+        }
+    }
+}
+
+type Output = Result<UserAgentResponse, UserAgentError>;
+
+fn response(payload: UserAgentResponsePayload) -> UserAgentResponse {
+    UserAgentResponse {
+        payload: Some(payload),
+    }
+}
+
+impl UserAgentSession {
+    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::InvalidClientPubkeyLength)?;
+
+        let client_public_key = PublicKey::from(client_pubkey_bytes);
+
+        self.transition(UserAgentEvents::UnsealRequest(UnsealContext {
+            secret: Mutex::new(Some(secret)),
+            client_public_key,
+        }))?;
+
+        Ok(response(UserAgentResponsePayload::UnsealStartResponse(
+            UnsealStartResponse {
+                server_pubkey: public_key.as_bytes().to_vec(),
+            },
+        )))
+    }
+
+    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::InvalidStateForUnsealEncryptedKey);
+        };
+        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(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
+                    .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(response(UserAgentResponsePayload::UnsealResult(
+                            UnsealResult::Success.into(),
+                        )))
+                    }
+                    Err(SendError::HandlerError(keyholder::Error::InvalidKey)) => {
+                        self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                        Ok(response(UserAgentResponsePayload::UnsealResult(
+                            UnsealResult::InvalidKey.into(),
+                        )))
+                    }
+                    Err(SendError::HandlerError(err)) => {
+                        error!(?err, "Keyholder failed to unseal key");
+                        self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                        Ok(response(UserAgentResponsePayload::UnsealResult(
+                            UnsealResult::InvalidKey.into(),
+                        )))
+                    }
+                    Err(err) => {
+                        error!(?err, "Failed to send unseal request to keyholder");
+                        self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                        Err(UserAgentError::KeyHolderActorUnreachable)
+                    }
+                }
+            }
+            Err(err) => {
+                error!(?err, "Failed to decrypt unseal key");
+                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
+                Ok(response(UserAgentResponsePayload::UnsealResult(
+                    UnsealResult::InvalidKey.into(),
+                )))
+            }
+        }
+    }
+}
+
+impl UserAgentSession {
+    async fn handle_evm_wallet_create(&mut self) -> Output {
+        use evm_proto::wallet_create_response::Result as CreateResult;
+
+        let result = match self.props.actors.evm.ask(Generate {}).await {
+            Ok(address) => CreateResult::Wallet(evm_proto::WalletEntry {
+                address: address.as_slice().to_vec(),
+            }),
+            Err(err) => CreateResult::Error(map_evm_error("wallet create", err).into()),
+        };
+
+        Ok(response(UserAgentResponsePayload::EvmWalletCreate(
+            evm_proto::WalletCreateResponse {
+                result: Some(result),
+            },
+        )))
+    }
+
+    async fn handle_evm_wallet_list(&mut self) -> Output {
+        use evm_proto::wallet_list_response::Result as ListResult;
+
+        let result = match self.props.actors.evm.ask(ListWallets {}).await {
+            Ok(wallets) => ListResult::Wallets(evm_proto::WalletList {
+                wallets: wallets
+                    .into_iter()
+                    .map(|addr| evm_proto::WalletEntry {
+                        address: addr.as_slice().to_vec(),
+                    })
+                    .collect(),
+            }),
+            Err(err) => ListResult::Error(map_evm_error("wallet list", err).into()),
+        };
+
+        Ok(response(UserAgentResponsePayload::EvmWalletList(
+            evm_proto::WalletListResponse {
+                result: Some(result),
+            },
+        )))
+    }
+}
+
+fn map_evm_error<M>(op: &str, err: SendError<M, crate::actors::evm::Error>) -> evm_proto::EvmError {
+    use crate::actors::{evm::Error as EvmError, keyholder::Error as KhError};
+    match err {
+        SendError::HandlerError(EvmError::Keyholder(KhError::NotBootstrapped)) => {
+            evm_proto::EvmError::VaultSealed
+        }
+        SendError::HandlerError(err) => {
+            error!(?err, "EVM {op} failed");
+            evm_proto::EvmError::Internal
+        }
+        _ => {
+            error!("EVM actor unreachable during {op}");
+            evm_proto::EvmError::Internal
+        }
+    }
+}
+
+impl Actor for UserAgentSession {
+    type Args = Self;
+
+    type Error = UserAgentError;
+
+    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");
+                UserAgentError::ConnectionRegistrationFailed
+            })?;
+        Ok(args)
+    }
+
+    async fn next(
+        &mut self,
+        _actor_ref: kameo::prelude::WeakActorRef<Self>,
+        mailbox_rx: &mut kameo::prelude::MailboxReceiver<Self>,
+    ) -> Option<kameo::mailbox::Signal<Self>> {
+        loop {
+            select! {
+                signal = mailbox_rx.recv() => {
+                    return signal;
+                }
+                msg = self.props.transport.recv() => {
+                    match msg {
+                        Some(request) => {
+                            match self.process_transport_inbound(request).await {
+                                Ok(response) => {
+                                    if self.props.transport.send(Ok(response)).await.is_err() {
+                                        error!(actor = "useragent", reason = "channel closed", "send.failed");
+                                        return Some(kameo::mailbox::Signal::Stop);
+                                    }
+                                }
+                                Err(err) => {
+                                    let _ = self.props.transport.send(Err(err)).await;
+                                    return Some(kameo::mailbox::Signal::Stop);
+                                }
+                            }
+                        }
+                        None => {
+                            info!(actor = "useragent", "transport.closed");
+                            return Some(kameo::mailbox::Signal::Stop);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+impl UserAgentSession {
+    pub fn new_test(db: crate::db::DatabasePool, actors: crate::actors::GlobalActors) -> Self {
+        use arbiter_proto::transport::DummyTransport;
+        let transport: super::Transport = Box::new(DummyTransport::new());
+        let props = UserAgentConnection::new(db, actors, transport);
+        let key = VerifyingKey::from_bytes(&[0u8; 32]).unwrap();
+        Self {
+            props,
+            key,
+            state: UserAgentStateMachine::new(DummyContext),
+        }
+    }
+}

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/db/models.rs

@@ -1,14 +1,78 @@
 #![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 std::os::unix;
+
     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)]
+    #[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 Into<chrono::DateTime<Utc>> for SqliteTimestamp {
+        fn into(self) -> chrono::DateTime<Utc> {
+            self.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::Integer) = bytes.value_type() else {
+                return Err(format!(
+                    "Expected Integer type for SqliteTimestamp, got {:?}",
+                    bytes.value_type()
+                )
+                .into());
+            };
+
+            let unix_timestamp = bytes.read_integer();
+            let datetime = DateTime::from_timestamp(unix_timestamp as i64, 0)
+                .ok_or("Timestamp is out of bounds")?;
+
+            Ok(SqliteTimestamp(datetime))
+        }
+    }
 }
+pub use types::*;
 
 #[derive(Models, Queryable, Debug, Insertable, Selectable)]
 #[view(
@@ -25,7 +89,7 @@ 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 +122,9 @@ 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 +132,173 @@ 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(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)]
 #[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,
+}
+
+#[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,
@@ -66,10 +159,29 @@ diesel::table! {
 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 +1,331 @@
+pub mod abi;
+pub mod safe_signer;
+
+use alloy::{consensus::TxEip1559, primitives::{TxKind, U256}};
+use chrono::Utc;
+use diesel::{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.map_or(false, |t| now < t)
+        || shared.valid_until.map_or(false, |t| now > t)
+    {
+        violations.push(EvalViolation::InvalidTime);
+    }
+
+    // Gas fee caps
+    let fee_exceeded = shared
+        .max_gas_fee_per_gas
+        .map_or(false, |cap| U256::from(context.max_fee_per_gas) > cap);
+    let priority_exceeded = shared
+        .max_priority_fee_per_gas
+        .map_or(false, |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: 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(Grant::from),
+        );
+        grants.extend(
+            TokenTransfer::find_all_grants(&mut conn)
+                .await?
+                .into_iter()
+                .map(Grant::from),
+        );
+
+        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 +1,220 @@
+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;
+
+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;
+
+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 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,
+            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)
+    }
+}
+
+pub enum SpecificGrant {
+    EtherTransfer(ether_transfer::Settings),
+    TokenTransfer(token_transfers::Settings),
+}
+
+/// Blanket conversion from a typed `Grant<S>` into `Grant<SpecificGrant>`.
+/// Lets the engine collect across all policies into one `Vec<Grant<SpecificGrant>>`.
+impl<S: Into<SpecificGrant>> From<Grant<S>> for Grant<SpecificGrant> {
+    fn from(g: Grant<S>) -> Self {
+        Grant {
+            id: g.id,
+            shared_grant_id: g.shared_grant_id,
+            shared: g.shared,
+            settings: g.settings.into(),
+        }
+    }
+}
+
+pub struct FullGrant<PolicyGrant> {
+    pub basic: SharedGrantSettings,
+    pub specific: PolicyGrant,
+}

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

@@ -0,0 +1,338 @@
+use std::collections::HashMap;
+use std::fmt::Display;
+
+use alloy::primitives::{Address, U256};
+use chrono::{DateTime, Duration, Utc};
+use diesel::dsl::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},
+};
+
+#[diesel::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.to_string()
+        )
+    }
+}
+impl Into<SpecificMeaning> for Meaning {
+    fn into(self) -> SpecificMeaning {
+        SpecificMeaning::EtherTransfer(self)
+    }
+}
+
+// A grant for ether transfers, which can be scoped to specific target addresses and volume limits
+pub struct Settings {
+    target: Vec<Address>,
+    limit: VolumeRateLimit,
+}
+
+impl Into<SpecificGrant> for Settings {
+    fn into(self) -> SpecificGrant {
+        SpecificGrant::EtherTransfer(self)
+    }
+}
+
+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)> = grant_join()
+            .filter(evm_basic_grant::wallet_id.eq(context.wallet_id))
+            .filter(evm_basic_grant::client_id.eq(context.client_id))
+            .filter(evm_ether_transfer_grant_target::address.eq(&target_bytes))
+            .filter(evm_basic_grant::revoked_at.is_null())
+            .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()
+    }
+}

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

@@ -0,0 +1,382 @@
+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::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};
+
+#[diesel::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 Into<SpecificMeaning> for Meaning {
+    fn into(self) -> SpecificMeaning {
+        SpecificMeaning::TokenTransfer(self)
+    }
+}
+
+// A grant for token transfers, which can be scoped to specific target addresses and volume limits
+pub struct Settings {
+    token_contract: Address,
+    target: Option<Address>,
+    volume_limits: Vec<VolumeRateLimit>,
+}
+impl Into<SpecificGrant> for Settings {
+    fn into(self) -> SpecificGrant {
+        SpecificGrant::TokenTransfer(self)
+    }
+}
+
+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 {
+            if 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()
+    }
+}

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

@@ -0,0 +1,196 @@
+use std::sync::Mutex;
+
+use alloy::{
+    consensus::SignableTransaction,
+    network::{TxSigner, TxSignerSync},
+    primitives::{Address, ChainId, Signature, B256},
+    signers::{Error, Result, Signer, SignerSync, utils::secret_key_to_address},
+};
+use async_trait::async_trait;
+use k256::ecdsa::{self, signature::hazmat::PrehashSigner, RecoveryId, SigningKey};
+use memsafe::MemSafe;
+
+/// 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<MemSafe<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) -> (MemSafe<[u8; 32]>, Address) {
+    loop {
+        let mut cell = MemSafe::new([0u8; 32]).expect("MemSafe allocation");
+        {
+            let mut w = cell.write().expect("MemSafe write");
+            rng.fill_bytes(w.as_mut());
+        }
+        let reader = cell.read().expect("MemSafe 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_memsafe(mut cell: MemSafe<Vec<u8>>) -> Result<Self> {
+        let reader = cell.read().map_err(Error::other)?;
+        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 = MemSafe::new(key).map_err(Error::other)?;
+        Ok(Self {
+            key: Mutex::new(cell),
+            address,
+            chain_id: None,
+        })
+    }
+
+    fn sign_hash_inner(&self, hash: &B256) -> Result<Signature> {
+        let mut cell = self.key.lock().expect("SafeSigner mutex poisoned");
+        let reader = cell.read().map_err(Error::other)?;
+        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 {
+            if !tx.set_chain_id_checked(chain_id) {
+                return Err(Error::TransactionChainIdMismatch {
+                    signer: chain_id,
+                    tx: tx.chain_id().unwrap(),
+                });
+            }
+        }
+        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/lib.rs

@@ -1,19 +1,22 @@
 #![forbid(unsafe_code)]
 use arbiter_proto::{
-    proto::{ClientRequest, ClientResponse, UserAgentRequest, UserAgentResponse},
-    transport::{BiStream, GrpcTransportActor, wire},
+    proto::{
+        client::{ClientRequest, ClientResponse},
+        user_agent::{UserAgentRequest, UserAgentResponse},
+    },
+    transport::{IdentityRecvConverter, SendConverter, grpc},
 };
 use async_trait::async_trait;
-use kameo::actor::PreparedActor;
 use tokio_stream::wrappers::ReceiverStream;
 
 use tokio::sync::mpsc;
 use tonic::{Request, Response, Status};
+use tracing::info;
 
 use crate::{
     actors::{
-        client::handle_client,
-        user_agent::UserAgentActor,
+        client::{self, ClientError, ClientConnection as ClientConnectionProps, connect_client},
+        user_agent::{self, UserAgentConnection, UserAgentError, connect_user_agent},
     },
     context::ServerContext,
 };
@@ -21,9 +24,112 @@ use crate::{
 pub mod actors;
 pub mod context;
 pub mod db;
+pub mod evm;
 
 const DEFAULT_CHANNEL_SIZE: usize = 1000;
 
+struct UserAgentGrpcSender;
+
+impl SendConverter for UserAgentGrpcSender {
+    type Input = Result<UserAgentResponse, UserAgentError>;
+    type Output = Result<UserAgentResponse, Status>;
+
+    fn convert(&self, item: Self::Input) -> Self::Output {
+        match item {
+            Ok(message) => Ok(message),
+            Err(err) => Err(user_agent_error_status(err)),
+        }
+    }
+}
+
+struct ClientGrpcSender;
+
+impl SendConverter for ClientGrpcSender {
+    type Input = Result<ClientResponse, ClientError>;
+    type Output = Result<ClientResponse, Status>;
+
+    fn convert(&self, item: Self::Input) -> Self::Output {
+        match item {
+            Ok(message) => Ok(message),
+            Err(err) => Err(client_error_status(err)),
+        }
+    }
+}
+
+fn client_error_status(value: ClientError) -> Status {
+    match value {
+        ClientError::MissingRequestPayload | ClientError::UnexpectedRequestPayload => {
+            Status::invalid_argument("Expected message with payload")
+        }
+        ClientError::StateTransitionFailed => Status::internal("State machine error"),
+        ClientError::Auth(ref err) => client_auth_error_status(err),
+        ClientError::ConnectionRegistrationFailed => {
+            Status::internal("Connection registration failed")
+        }
+    }
+}
+
+fn client_auth_error_status(value: &client::auth::Error) -> Status {
+    use client::auth::Error;
+    match value {
+        Error::UnexpectedMessagePayload | Error::InvalidClientPubkeyLength => {
+            Status::invalid_argument(value.to_string())
+        }
+        Error::InvalidAuthPubkeyEncoding => {
+            Status::invalid_argument("Failed to convert pubkey to VerifyingKey")
+        }
+        Error::InvalidSignatureLength => Status::invalid_argument("Invalid signature length"),
+        Error::PublicKeyNotRegistered | Error::InvalidChallengeSolution => {
+            Status::unauthenticated(value.to_string())
+        }
+        Error::Transport => Status::internal("Transport error"),
+        Error::DatabasePoolUnavailable => Status::internal("Database pool error"),
+        Error::DatabaseOperationFailed => Status::internal("Database error"),
+    }
+}
+
+fn user_agent_error_status(value: UserAgentError) -> Status {
+    match value {
+        UserAgentError::MissingRequestPayload | UserAgentError::UnexpectedRequestPayload => {
+            Status::invalid_argument("Expected message with payload")
+        }
+        UserAgentError::InvalidStateForUnsealEncryptedKey => {
+            Status::failed_precondition("Invalid state for unseal encrypted key")
+        }
+        UserAgentError::InvalidClientPubkeyLength => {
+            Status::invalid_argument("client_pubkey must be 32 bytes")
+        }
+        UserAgentError::StateTransitionFailed => Status::internal("State machine error"),
+        UserAgentError::KeyHolderActorUnreachable => Status::internal("Vault is not available"),
+        UserAgentError::Auth(ref err) => auth_error_status(err),
+        UserAgentError::ConnectionRegistrationFailed => {
+            Status::internal("Failed registering connection")
+        }
+    }
+}
+
+fn auth_error_status(value: &user_agent::auth::Error) -> Status {
+    use user_agent::auth::Error;
+    match value {
+        Error::UnexpectedMessagePayload | Error::InvalidClientPubkeyLength => {
+            Status::invalid_argument(value.to_string())
+        }
+        Error::InvalidAuthPubkeyEncoding => {
+            Status::invalid_argument("Failed to convert pubkey to VerifyingKey")
+        }
+        Error::PublicKeyNotRegistered | Error::InvalidChallengeSolution => {
+            Status::unauthenticated(value.to_string())
+        }
+        Error::InvalidBootstrapToken => Status::invalid_argument("Invalid bootstrap token"),
+        Error::Transport => Status::internal("Transport error"),
+        Error::BootstrapperActorUnreachable => {
+            Status::internal("Bootstrap token consumption failed")
+        }
+        Error::DatabasePoolUnavailable => Status::internal("Database pool error"),
+        Error::DatabaseOperationFailed => Status::internal("Database error"),
+    }
+}
+
 pub struct Server {
     context: ServerContext,
 }
@@ -39,44 +145,54 @@ impl arbiter_proto::proto::arbiter_service_server::ArbiterService for 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 (tx, rx) = mpsc::channel(DEFAULT_CHANNEL_SIZE);
-        tokio::spawn(handle_client(
-            self.context.clone(),
-            BiStream {
-                request_stream: req_stream,
-                response_sender: tx,
-            },
-        ));
+
+        let transport = grpc::GrpcAdapter::new(
+            tx,
+            req_stream,
+            IdentityRecvConverter::<ClientRequest>::new(),
+            ClientGrpcSender,
+        );
+        let props = ClientConnectionProps::new(
+            self.context.db.clone(),
+            Box::new(transport),
+            self.context.actors.clone(),
+        );
+        tokio::spawn(connect_client(props));
+
+        info!(event = "connection established", "grpc.client");
 
         Ok(Response::new(ReceiverStream::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 (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;
+        let transport = grpc::GrpcAdapter::new(
+            tx,
+            req_stream,
+            IdentityRecvConverter::<UserAgentRequest>::new(),
+            UserAgentGrpcSender,
+        );
+        let props = UserAgentConnection::new(
+            self.context.db.clone(),
+            self.context.actors.clone(),
+            Box::new(transport),
+        );
+        tokio::spawn(connect_user_agent(props));
+
+        info!(event = "connection established", "grpc.user_agent");
 
         Ok(Response::new(ReceiverStream::new(rx)))
     }

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 +1,111 @@
+use arbiter_proto::proto::client::{
+    AuthChallengeRequest, AuthChallengeSolution, ClientRequest,
+    client_request::Payload as ClientRequestPayload,
+    client_response::Payload as ClientResponsePayload,
+};
+use arbiter_proto::transport::Bi;
+use arbiter_server::actors::GlobalActors;
+use arbiter_server::{
+    actors::client::{ClientConnection, 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(), Box::new(server_transport), actors);
+    let task = tokio::spawn(connect_client(props));
+
+    let new_key = ed25519_dalek::SigningKey::generate(&mut rand::rng());
+    let pubkey_bytes = new_key.verifying_key().to_bytes().to_vec();
+
+    test_transport
+        .send(ClientRequest {
+            payload: Some(ClientRequestPayload::AuthChallengeRequest(
+                AuthChallengeRequest {
+                    pubkey: pubkey_bytes,
+                },
+            )),
+        })
+        .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(), Box::new(server_transport), actors);
+    let task = tokio::spawn(connect_client(props));
+
+    // Send challenge request
+    test_transport
+        .send(ClientRequest {
+            payload: Some(ClientRequestPayload::AuthChallengeRequest(
+                AuthChallengeRequest {
+                    pubkey: pubkey_bytes,
+                },
+            )),
+        })
+        .await
+        .unwrap();
+
+    // Read the challenge response
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(resp) => match resp.payload {
+            Some(ClientResponsePayload::AuthChallenge(c)) => c,
+            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.nonce, &challenge.pubkey);
+    let signature = new_key.sign(&formatted_challenge);
+
+    test_transport
+        .send(ClientRequest {
+            payload: Some(ClientRequestPayload::AuthChallengeSolution(
+                AuthChallengeSolution {
+                    signature: signature.to_bytes().to_vec(),
+                },
+            )),
+        })
+        .await
+        .unwrap();
+
+    // Auth completes, session spawned
+    task.await.unwrap();
+}

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

@@ -1,10 +1,14 @@
+use arbiter_proto::transport::{Bi, Error};
 use arbiter_server::{
     actors::keyholder::KeyHolder,
     db::{self, schema},
 };
+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 {
@@ -26,3 +30,46 @@ pub async fn root_key_history_id(db: &db::DatabasePool) -> i32 {
         .unwrap();
     id.expect("root_key_id should be set after bootstrap")
 }
+
+
+pub struct ChannelTransport<T, Y> {
+    receiver: mpsc::Receiver<T>,
+    sender: mpsc::Sender<Y>,
+}
+
+impl<T, Y> ChannelTransport<T, Y> {
+    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> Bi<T, Y> for ChannelTransport<T, Y>
+where
+    T: Send + 'static,
+    Y: Send + 'static,
+{
+    async fn send(&mut self, item: Y) -> Result<(), Error> {
+        self.sender
+            .send(item)
+            .await
+            .map_err(|_| Error::ChannelClosed)
+    }
+
+    async fn recv(&mut self) -> Option<T> {
+        self.receiver.recv().await
+    }
+}

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 +1,50 @@
-use arbiter_proto::proto::{
-    UserAgentResponse,
-    auth::{self, AuthChallengeRequest, AuthOk},
+use arbiter_proto::proto::user_agent::{
+    AuthChallengeRequest, AuthChallengeSolution, UserAgentRequest,
+    user_agent_request::Payload as UserAgentRequestPayload,
     user_agent_response::Payload as UserAgentResponsePayload,
 };
+use arbiter_proto::transport::Bi;
 use arbiter_server::{
     actors::{
         GlobalActors,
         bootstrap::GetToken,
-        user_agent::{HandleAuthChallengeRequest, HandleAuthChallengeSolution, UserAgentActor},
+        user_agent::{UserAgentConnection, connect_user_agent},
     },
     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 props = UserAgentConnection::new(db.clone(), actors, Box::new(server_transport));
+    let task = tokio::spawn(connect_user_agent(props));
 
     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),
-            },
-        })
-        .await
-        .expect("Shouldn't fail to send message");
-
-    assert_eq!(
-        result,
-        UserAgentResponse {
-            payload: Some(UserAgentResponsePayload::AuthMessage(
-                arbiter_proto::proto::auth::ServerMessage {
-                    payload: Some(arbiter_proto::proto::auth::server_message::Payload::AuthOk(
-                        AuthOk {},
-                    )),
+    test_transport
+        .send(UserAgentRequest {
+            payload: Some(UserAgentRequestPayload::AuthChallengeRequest(
+                AuthChallengeRequest {
+                    pubkey: pubkey_bytes,
+                    bootstrap_token: Some(token),
                 },
             )),
-        }
-    );
+        })
+        .await
+        .unwrap();
+
+    task.await.unwrap();
 
     let mut conn = db.get().await.unwrap();
     let stored_pubkey: Vec<u8> = schema::useragent_client::table
@@ -66,49 +59,45 @@ 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 props = UserAgentConnection::new(db.clone(), actors, Box::new(server_transport));
+    let task = tokio::spawn(connect_user_agent(props));
 
     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(UserAgentRequest {
+            payload: Some(UserAgentRequestPayload::AuthChallengeRequest(
+                AuthChallengeRequest {
+                    pubkey: pubkey_bytes,
+                    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");
-        }
-    }
+    // Auth fails, connect_user_agent returns, transport drops
+    task.await.unwrap();
+
+    // 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();
@@ -122,50 +111,51 @@ pub async fn test_challenge_auth() {
             .unwrap();
     }
 
-    let result = user_agent_ref
-        .ask(HandleAuthChallengeRequest {
-            req: AuthChallengeRequest {
-                pubkey: pubkey_bytes,
-                bootstrap_token: None,
-            },
-        })
-        .await
-        .expect("Shouldn't fail to send message");
+    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let props = UserAgentConnection::new(db.clone(), actors, Box::new(server_transport));
+    let task = tokio::spawn(connect_user_agent(props));
 
-    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:?}");
-    };
-
-    let formatted_challenge = arbiter_proto::format_challenge(&challenge);
-    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,
-            },
-        })
-        .await
-        .expect("Shouldn't fail to send message");
-
-    assert_eq!(
-        result,
-        UserAgentResponse {
-            payload: Some(UserAgentResponsePayload::AuthMessage(
-                arbiter_proto::proto::auth::ServerMessage {
-                    payload: Some(arbiter_proto::proto::auth::server_message::Payload::AuthOk(
-                        AuthOk {},
-                    )),
+    // Send challenge request
+    test_transport
+        .send(UserAgentRequest {
+            payload: Some(UserAgentRequestPayload::AuthChallengeRequest(
+                AuthChallengeRequest {
+                    pubkey: pubkey_bytes,
+                    bootstrap_token: None,
                 },
             )),
-        }
-    );
+        })
+        .await
+        .unwrap();
+
+    // Read the challenge response
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(resp) => match resp.payload {
+            Some(UserAgentResponsePayload::AuthChallenge(c)) => c,
+            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.nonce, &challenge.pubkey);
+    let signature = new_key.sign(&formatted_challenge);
+
+    test_transport
+        .send(UserAgentRequest {
+            payload: Some(UserAgentRequestPayload::AuthChallengeSolution(
+                AuthChallengeSolution {
+                    signature: signature.to_bytes().to_vec(),
+                },
+            )),
+        })
+        .await
+        .unwrap();
+
+    // Auth completes, session spawned
+    task.await.unwrap();
 }

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

@@ -1,30 +1,26 @@
-use arbiter_proto::proto::{
-    UnsealEncryptedKey, UnsealResult, UnsealStart, auth::AuthChallengeRequest,
+use arbiter_proto::proto::user_agent::{
+    UnsealEncryptedKey, UnsealResult, UnsealStart, UserAgentRequest,
+    user_agent_request::Payload as UserAgentRequestPayload,
     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::UserAgentSession,
     },
     db,
 };
 use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
-use kameo::actor::{ActorRef, Spawn};
 use memsafe::MemSafe;
 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, UserAgentSession) {
     let db = db::create_test_pool().await;
-
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+
     actors
         .key_holder
         .ask(Bootstrap {
@@ -34,37 +30,23 @@ async fn setup_authenticated_user_agent(
         .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::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: &mut UserAgentSession,
     key_to_send: &[u8],
 ) -> UnsealEncryptedKey {
     let client_secret = EphemeralSecret::random();
     let client_public = PublicKey::from(&client_secret);
 
-    let response = user_agent_ref
-        .ask(HandleUnsealRequest {
-            req: UnsealStart {
+    let response = user_agent
+        .process_transport_inbound(UserAgentRequest {
+            payload: Some(UserAgentRequestPayload::UnsealStart(UnsealStart {
                 client_pubkey: client_public.as_bytes().to_vec(),
-            },
+            })),
         })
         .await
         .unwrap();
@@ -91,16 +73,22 @@ async fn client_dh_encrypt(
     }
 }
 
+fn unseal_key_request(req: UnsealEncryptedKey) -> UserAgentRequest {
+    UserAgentRequest {
+        payload: Some(UserAgentRequestPayload::UnsealEncryptedKey(req)),
+    }
+}
+
 #[tokio::test]
 #[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, mut 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(&mut user_agent, seal_key).await;
 
-    let response = user_agent_ref
-        .ask(HandleUnsealEncryptedKey { req: encrypted_key })
+    let response = user_agent
+        .process_transport_inbound(unseal_key_request(encrypted_key))
         .await
         .unwrap();
 
@@ -113,12 +101,12 @@ pub async fn test_unseal_success() {
 #[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, mut 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(&mut user_agent, b"wrong-key").await;
 
-    let response = user_agent_ref
-        .ask(HandleUnsealEncryptedKey { req: encrypted_key })
+    let response = user_agent
+        .process_transport_inbound(unseal_key_request(encrypted_key))
         .await
         .unwrap();
 
@@ -131,28 +119,26 @@ pub async fn test_unseal_wrong_seal_key() {
 #[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, mut 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
-        .ask(HandleUnsealRequest {
-            req: UnsealStart {
+    user_agent
+        .process_transport_inbound(UserAgentRequest {
+            payload: Some(UserAgentRequestPayload::UnsealStart(UnsealStart {
                 client_pubkey: client_public.as_bytes().to_vec(),
-            },
+            })),
         })
         .await
         .unwrap();
 
-    let response = user_agent_ref
-        .ask(HandleUnsealEncryptedKey {
-            req: UnsealEncryptedKey {
-                nonce: vec![0u8; 24],
-                ciphertext: vec![0u8; 32],
-                associated_data: vec![],
-            },
-        })
+    let response = user_agent
+        .process_transport_inbound(unseal_key_request(UnsealEncryptedKey {
+            nonce: vec![0u8; 24],
+            ciphertext: vec![0u8; 32],
+            associated_data: vec![],
+        }))
         .await
         .unwrap();
 
@@ -162,49 +148,17 @@ pub async fn test_unseal_corrupted_ciphertext() {
     );
 }
 
-#[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(),
-            },
-        })
-        .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:?}"),
-    }
-}
-
 #[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, mut 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(&mut user_agent, b"wrong-key").await;
 
-        let response = user_agent_ref
-            .ask(HandleUnsealEncryptedKey { req: encrypted_key })
+        let response = user_agent
+            .process_transport_inbound(unseal_key_request(encrypted_key))
             .await
             .unwrap();
 
@@ -215,10 +169,10 @@ pub async fn test_unseal_retry_after_invalid_key() {
     }
 
     {
-        let encrypted_key = client_dh_encrypt(&user_agent_ref, seal_key).await;
+        let encrypted_key = client_dh_encrypt(&mut user_agent, seal_key).await;
 
-        let response = user_agent_ref
-            .ask(HandleUnsealEncryptedKey { req: encrypted_key })
+        let response = user_agent
+            .process_transport_inbound(unseal_key_request(encrypted_key))
             .await
             .unwrap();
 

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

@@ -9,7 +9,13 @@ arbiter-proto.path = "../arbiter-proto"
 kameo.workspace = true
 tokio = {workspace = true, features = ["net"]}
 tonic.workspace = true
+tonic.features = ["tls-aws-lc"]
 tracing.workspace = true
 ed25519-dalek.workspace = true
 smlang.workspace = true
 x25519-dalek.workspace = true
+thiserror.workspace = true
+tokio-stream.workspace = true
+http = "1.4.0"
+rustls-webpki = { version = "0.103.9", features = ["aws-lc-rs"] }
+async-trait.workspace = true

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

@@ -0,0 +1,72 @@
+use arbiter_proto::{
+    proto::{
+        user_agent::{UserAgentRequest, UserAgentResponse},
+        arbiter_service_client::ArbiterServiceClient,
+    },
+    transport::{IdentityRecvConverter, IdentitySendConverter, grpc},
+    url::ArbiterUrl,
+};
+use ed25519_dalek::SigningKey;
+use kameo::actor::{ActorRef, Spawn};
+
+use tokio::sync::mpsc;
+use tokio_stream::wrappers::ReceiverStream;
+
+use tonic::transport::ClientTlsConfig;
+
+
+#[derive(Debug, thiserror::Error)]
+pub enum ConnectError {
+    #[error("Could establish connection")]
+    Connection(#[from] tonic::transport::Error),
+
+    #[error("Invalid server URI")]
+    InvalidUri(#[from] http::uri::InvalidUri),
+
+    #[error("Invalid CA certificate")]
+    InvalidCaCert(#[from] webpki::Error),
+
+    #[error("gRPC error")]
+    Grpc(#[from] tonic::Status),
+}
+
+    use super::UserAgentActor;
+
+pub type UserAgentGrpc = ActorRef<
+    UserAgentActor<
+        grpc::GrpcAdapter<
+            IdentityRecvConverter<UserAgentResponse>,
+            IdentitySendConverter<UserAgentRequest>,
+        >,
+    >,
+>;
+pub async fn connect_grpc(
+    url: ArbiterUrl,
+    key: SigningKey,
+) -> Result<UserAgentGrpc, ConnectError> {
+    let bootstrap_token = url.bootstrap_token.clone();
+    let anchor = webpki::anchor_from_trusted_cert(&url.ca_cert)?.to_owned();
+    let tls = ClientTlsConfig::new().trust_anchor(anchor);
+
+    // TODO: if `host` is localhost, we need to verify server's process authenticity
+    let channel = tonic::transport::Channel::from_shared(format!("{}:{}", url.host, url.port))?
+        .tls_config(tls)?
+        .connect()
+        .await?;
+
+    let mut client = ArbiterServiceClient::new(channel);
+    let (tx, rx) = mpsc::channel(16);
+    let bistream = client.user_agent(ReceiverStream::new(rx)).await?;
+    let bistream = bistream.into_inner();
+
+    let adapter = grpc::GrpcAdapter::new(
+        tx,
+        bistream,
+        IdentityRecvConverter::new(),
+        IdentitySendConverter::new(),
+    );
+
+    let actor = UserAgentActor::spawn(UserAgentActor::new(key, bootstrap_token, adapter));
+
+    Ok(actor)
+}

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

@@ -1,66 +1,195 @@
-use arbiter_proto::{proto::UserAgentRequest, transport::TransportActor};
-use ed25519_dalek::SigningKey;
-use kameo::{
-    Actor, Reply,
-    actor::{ActorRef, WeakActorRef},
-    prelude::Message,
+use arbiter_proto::{
+    format_challenge,
+    proto::user_agent::{
+        AuthChallengeRequest, AuthChallengeSolution, AuthOk,
+        UserAgentRequest, UserAgentResponse,
+        user_agent_request::Payload as UserAgentRequestPayload,
+        user_agent_response::Payload as UserAgentResponsePayload,
+    },
+    transport::Bi,
 };
+use ed25519_dalek::{Signer, SigningKey};
+use kameo::{Actor, actor::ActorRef};
 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),
-}
+use tokio::select;
+use tracing::{error, info};
 
 statemachine! {
-    name: UserAgentStateMachine,
+    name: UserAgent,
     custom_error: false,
     transitions: {
-        *Init + SendAuthChallenge = WaitingForAuthSolution
+        *Init + SentAuthChallengeRequest = WaitingForServerAuth,
+        WaitingForServerAuth + ReceivedAuthChallenge = WaitingForAuthOk,
+        WaitingForServerAuth + ReceivedAuthOk = Authenticated,
+        WaitingForAuthOk + ReceivedAuthOk = Authenticated,
     }
 }
 
+pub struct DummyContext;
+impl UserAgentStateMachineContext for DummyContext {}
 
+#[derive(Debug, thiserror::Error)]
+pub enum InboundError {
+    #[error("Invalid user agent response")]
+    InvalidResponse,
+    #[error("Expected response payload")]
+    MissingResponsePayload,
+    #[error("Unexpected response payload")]
+    UnexpectedResponsePayload,
+    #[error("Invalid state for auth challenge")]
+    InvalidStateForAuthChallenge,
+    #[error("Invalid state for auth ok")]
+    InvalidStateForAuthOk,
+    #[error("State machine error")]
+    StateTransitionFailed,
+    #[error("Transport send failed")]
+    TransportSendFailed,
+}
 
-pub struct UserAgentActor<A: TransportActor<UserAgentRequest>> {
+pub struct UserAgentActor<Transport>
+where
+    Transport: Bi<UserAgentResponse, UserAgentRequest>,
+{
     key: SigningKey,
-    server_ca_cert: CertificateDer<'static>,
-    sender: ActorRef<A>,
+    bootstrap_token: Option<String>,
+    state: UserAgentStateMachine<DummyContext>,
+    transport: Transport,
 }
-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!()
+impl<Transport> UserAgentActor<Transport>
+where
+    Transport: Bi<UserAgentResponse, UserAgentRequest>,
+{
+    pub fn new(key: SigningKey, bootstrap_token: Option<String>, transport: Transport) -> Self {
+        Self {
+            key,
+            bootstrap_token,
+            state: UserAgentStateMachine::new(DummyContext),
+            transport,
+        }
     }
 
-    async fn on_link_died(
+    fn transition(&mut self, event: UserAgentEvents) -> Result<(), InboundError> {
+        self.state.process_event(event).map_err(|e| {
+            error!(?e, "useragent state transition failed");
+            InboundError::StateTransitionFailed
+        })?;
+        Ok(())
+    }
+
+    async fn send_auth_challenge_request(&mut self) -> Result<(), InboundError> {
+        let req = AuthChallengeRequest {
+            pubkey: self.key.verifying_key().to_bytes().to_vec(),
+            bootstrap_token: self.bootstrap_token.take(),
+        };
+
+        self.transition(UserAgentEvents::SentAuthChallengeRequest)?;
+
+        self.transport
+            .send(UserAgentRequest {
+                payload: Some(UserAgentRequestPayload::AuthChallengeRequest(req)),
+            })
+            .await
+            .map_err(|_| InboundError::TransportSendFailed)?;
+
+        info!(actor = "useragent", "auth.request.sent");
+        Ok(())
+    }
+
+    async fn handle_auth_challenge(
         &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(()))
+        challenge: arbiter_proto::proto::user_agent::AuthChallenge,
+    ) -> Result<(), InboundError> {
+        self.transition(UserAgentEvents::ReceivedAuthChallenge)?;
+
+        let formatted = format_challenge(challenge.nonce, &challenge.pubkey);
+        let signature = self.key.sign(&formatted);
+        let solution = AuthChallengeSolution {
+            signature: signature.to_bytes().to_vec(),
+        };
+
+        self.transport
+            .send(UserAgentRequest {
+                payload: Some(UserAgentRequestPayload::AuthChallengeSolution(solution)),
+            })
+            .await
+            .map_err(|_| InboundError::TransportSendFailed)?;
+
+        info!(actor = "useragent", "auth.solution.sent");
+        Ok(())
+    }
+
+    fn handle_auth_ok(&mut self, _ok: AuthOk) -> Result<(), InboundError> {
+        self.transition(UserAgentEvents::ReceivedAuthOk)?;
+        info!(actor = "useragent", "auth.ok");
+        Ok(())
+    }
+
+    pub async fn process_inbound_transport(
+        &mut self,
+        inbound: UserAgentResponse
+    ) -> Result<(), InboundError> {
+        let payload = inbound
+            .payload
+            .ok_or(InboundError::MissingResponsePayload)?;
+
+        match payload {
+            UserAgentResponsePayload::AuthChallenge(challenge) => {
+                self.handle_auth_challenge(challenge).await
+            }
+            UserAgentResponsePayload::AuthOk(ok) => self.handle_auth_ok(ok),
+            _ => Err(InboundError::UnexpectedResponsePayload),
         }
     }
 }
+
+impl<Transport> Actor for UserAgentActor<Transport>
+where
+    Transport: Bi<UserAgentResponse, UserAgentRequest>,
+{
+    type Args = Self;
+
+    type Error = ();
+
+    async fn on_start(
+        mut args: Self::Args,
+        _actor_ref: ActorRef<Self>,
+    ) -> Result<Self, Self::Error> {
+        if let Err(err) = args.send_auth_challenge_request().await {
+            error!(?err, actor = "useragent", "auth.start.failed");
+            return Err(());
+        }
+        Ok(args)
+    }
+
+    async fn next(
+        &mut self,
+        _actor_ref: kameo::prelude::WeakActorRef<Self>,
+        mailbox_rx: &mut kameo::prelude::MailboxReceiver<Self>,
+    ) -> Option<kameo::mailbox::Signal<Self>> {
+        loop {
+            select! {
+                signal = mailbox_rx.recv() => {
+                    return signal;
+                }
+                inbound = self.transport.recv() => {
+                    match inbound {
+                        Some(inbound) => {
+                            if let Err(err) = self.process_inbound_transport(inbound).await {
+                                error!(?err, actor = "useragent", "transport.inbound.failed");
+                                return Some(kameo::mailbox::Signal::Stop);
+                            }
+                        }
+                        None => {
+                            info!(actor = "useragent", "transport.closed");
+                            return Some(kameo::mailbox::Signal::Stop);
+                        }
+                    }
+                }
+            }
+        }
+    }
+}
+
+mod grpc;
+pub use grpc::{connect_grpc, ConnectError};

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

@@ -0,0 +1,141 @@
+use arbiter_proto::{
+    format_challenge,
+    proto::user_agent::{
+        AuthChallenge, AuthOk,
+        UserAgentRequest, UserAgentResponse,
+        user_agent_request::Payload as UserAgentRequestPayload,
+        user_agent_response::Payload as UserAgentResponsePayload,
+    },
+    transport::Bi,
+};
+use arbiter_useragent::UserAgentActor;
+use ed25519_dalek::SigningKey;
+use kameo::actor::Spawn;
+use tokio::sync::mpsc;
+use tokio::time::{Duration, timeout};
+use async_trait::async_trait;
+
+struct TestTransport {
+    inbound_rx: mpsc::Receiver<UserAgentResponse>,
+    outbound_tx: mpsc::Sender<UserAgentRequest>,
+}
+
+#[async_trait]
+impl Bi<UserAgentResponse, UserAgentRequest> for TestTransport {
+    async fn send(&mut self, item: UserAgentRequest) -> Result<(), arbiter_proto::transport::Error> {
+        self.outbound_tx
+            .send(item)
+            .await
+            .map_err(|_| arbiter_proto::transport::Error::ChannelClosed)
+    }
+
+    async fn recv(&mut self) -> Option<UserAgentResponse> {
+        self.inbound_rx.recv().await
+    }
+}
+
+fn make_transport() -> (
+    TestTransport,
+    mpsc::Sender<UserAgentResponse>,
+    mpsc::Receiver<UserAgentRequest>,
+) {
+    let (inbound_tx, inbound_rx) = mpsc::channel(8);
+    let (outbound_tx, outbound_rx) = mpsc::channel(8);
+    (
+        TestTransport {
+            inbound_rx,
+            outbound_tx,
+        },
+        inbound_tx,
+        outbound_rx,
+    )
+}
+
+fn test_key() -> SigningKey {
+    SigningKey::from_bytes(&[7u8; 32])
+}
+
+#[tokio::test]
+async fn sends_auth_request_on_start_with_bootstrap_token() {
+    let key = test_key();
+    let pubkey = key.verifying_key().to_bytes().to_vec();
+    let bootstrap_token = Some("bootstrap-123".to_string());
+    let (transport, inbound_tx, mut outbound_rx) = make_transport();
+
+    let actor = UserAgentActor::spawn(UserAgentActor::new(key, bootstrap_token.clone(), transport));
+
+    let outbound = timeout(Duration::from_secs(1), outbound_rx.recv())
+        .await
+        .expect("timed out waiting for auth request")
+        .expect("channel closed before auth request");
+
+    let UserAgentRequest {
+        payload: Some(UserAgentRequestPayload::AuthChallengeRequest(req)),
+    } = outbound
+    else {
+        panic!("expected auth challenge request");
+    };
+
+    assert_eq!(req.pubkey, pubkey);
+    assert_eq!(req.bootstrap_token, bootstrap_token);
+
+    drop(inbound_tx);
+    drop(actor);
+}
+
+#[tokio::test]
+async fn challenge_flow_sends_solution_from_transport_inbound() {
+    let key = test_key();
+    let verify_key = key.verifying_key();
+    let (transport, inbound_tx, mut outbound_rx) = make_transport();
+
+    let actor = UserAgentActor::spawn(UserAgentActor::new(key, None, transport));
+
+    let _initial_auth_request = timeout(Duration::from_secs(1), outbound_rx.recv())
+        .await
+        .expect("timed out waiting for initial auth request")
+        .expect("missing initial auth request");
+
+    let challenge = AuthChallenge {
+        pubkey: verify_key.to_bytes().to_vec(),
+        nonce: 42,
+    };
+    inbound_tx
+        .send(UserAgentResponse {
+            payload: Some(UserAgentResponsePayload::AuthChallenge(challenge.clone())),
+        })
+        .await
+        .unwrap();
+
+    let outbound = timeout(Duration::from_secs(1), outbound_rx.recv())
+        .await
+        .expect("timed out waiting for challenge solution")
+        .expect("missing challenge solution");
+
+    let UserAgentRequest {
+        payload: Some(UserAgentRequestPayload::AuthChallengeSolution(solution)),
+    } = outbound
+    else {
+        panic!("expected auth challenge solution");
+    };
+
+    let formatted = format_challenge(challenge.nonce, &challenge.pubkey);
+    let sig: ed25519_dalek::Signature = solution
+        .signature
+        .as_slice()
+        .try_into()
+        .expect("signature bytes length");
+    verify_key
+        .verify_strict(&formatted, &sig)
+        .expect("solution signature should verify");
+
+    inbound_tx
+        .send(UserAgentResponse {
+            payload: Some(UserAgentResponsePayload::AuthOk(AuthOk {})),
+        })
+        .await
+        .unwrap();
+
+    drop(inbound_tx);
+    drop(actor);
+}

useragent/.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.

useragent/.dart_tool/extension_discovery/vs_code.json

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

useragent/.dart_tool/package_config.json

@@ -0,0 +1,172 @@
+{
+  "configVersion": 2,
+  "packages": [
+    {
+      "name": "async",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/async-2.13.0",
+      "packageUri": "lib/",
+      "languageVersion": "3.4"
+    },
+    {
+      "name": "boolean_selector",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/boolean_selector-2.1.2",
+      "packageUri": "lib/",
+      "languageVersion": "3.1"
+    },
+    {
+      "name": "characters",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/characters-1.4.0",
+      "packageUri": "lib/",
+      "languageVersion": "3.4"
+    },
+    {
+      "name": "clock",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/clock-1.1.2",
+      "packageUri": "lib/",
+      "languageVersion": "3.4"
+    },
+    {
+      "name": "collection",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/collection-1.19.1",
+      "packageUri": "lib/",
+      "languageVersion": "3.4"
+    },
+    {
+      "name": "fake_async",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/fake_async-1.3.3",
+      "packageUri": "lib/",
+      "languageVersion": "3.3"
+    },
+    {
+      "name": "flutter",
+      "rootUri": "file:///Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable/packages/flutter",
+      "packageUri": "lib/",
+      "languageVersion": "3.8"
+    },
+    {
+      "name": "flutter_lints",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/flutter_lints-6.0.0",
+      "packageUri": "lib/",
+      "languageVersion": "3.8"
+    },
+    {
+      "name": "flutter_test",
+      "rootUri": "file:///Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable/packages/flutter_test",
+      "packageUri": "lib/",
+      "languageVersion": "3.8"
+    },
+    {
+      "name": "leak_tracker",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/leak_tracker-11.0.2",
+      "packageUri": "lib/",
+      "languageVersion": "3.2"
+    },
+    {
+      "name": "leak_tracker_flutter_testing",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/leak_tracker_flutter_testing-3.0.10",
+      "packageUri": "lib/",
+      "languageVersion": "3.2"
+    },
+    {
+      "name": "leak_tracker_testing",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/leak_tracker_testing-3.0.2",
+      "packageUri": "lib/",
+      "languageVersion": "3.2"
+    },
+    {
+      "name": "lints",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/lints-6.1.0",
+      "packageUri": "lib/",
+      "languageVersion": "3.8"
+    },
+    {
+      "name": "matcher",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/matcher-0.12.17",
+      "packageUri": "lib/",
+      "languageVersion": "3.4"
+    },
+    {
+      "name": "material_color_utilities",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/material_color_utilities-0.11.1",
+      "packageUri": "lib/",
+      "languageVersion": "2.17"
+    },
+    {
+      "name": "meta",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/meta-1.17.0",
+      "packageUri": "lib/",
+      "languageVersion": "3.5"
+    },
+    {
+      "name": "path",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/path-1.9.1",
+      "packageUri": "lib/",
+      "languageVersion": "3.4"
+    },
+    {
+      "name": "sky_engine",
+      "rootUri": "file:///Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable/bin/cache/pkg/sky_engine",
+      "packageUri": "lib/",
+      "languageVersion": "3.8"
+    },
+    {
+      "name": "source_span",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/source_span-1.10.2",
+      "packageUri": "lib/",
+      "languageVersion": "3.1"
+    },
+    {
+      "name": "stack_trace",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/stack_trace-1.12.1",
+      "packageUri": "lib/",
+      "languageVersion": "3.4"
+    },
+    {
+      "name": "stream_channel",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/stream_channel-2.1.4",
+      "packageUri": "lib/",
+      "languageVersion": "3.3"
+    },
+    {
+      "name": "string_scanner",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/string_scanner-1.4.1",
+      "packageUri": "lib/",
+      "languageVersion": "3.1"
+    },
+    {
+      "name": "term_glyph",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/term_glyph-1.2.2",
+      "packageUri": "lib/",
+      "languageVersion": "3.1"
+    },
+    {
+      "name": "test_api",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/test_api-0.7.7",
+      "packageUri": "lib/",
+      "languageVersion": "3.5"
+    },
+    {
+      "name": "vector_math",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/vector_math-2.2.0",
+      "packageUri": "lib/",
+      "languageVersion": "3.1"
+    },
+    {
+      "name": "vm_service",
+      "rootUri": "file:///Users/kaska/.pub-cache/hosted/pub.dev/vm_service-15.0.2",
+      "packageUri": "lib/",
+      "languageVersion": "3.5"
+    },
+    {
+      "name": "arbiter",
+      "rootUri": "../",
+      "packageUri": "lib/",
+      "languageVersion": "3.10"
+    }
+  ],
+  "generator": "pub",
+  "generatorVersion": "3.10.8",
+  "flutterRoot": "file:///Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable",
+  "flutterVersion": "3.38.9",
+  "pubCache": "file:///Users/kaska/.pub-cache"
+}

useragent/.dart_tool/package_graph.json

@@ -0,0 +1,224 @@
+{
+  "roots": [
+    "arbiter"
+  ],
+  "packages": [
+    {
+      "name": "arbiter",
+      "version": "0.1.0",
+      "dependencies": [
+        "flutter"
+      ],
+      "devDependencies": [
+        "flutter_lints",
+        "flutter_test"
+      ]
+    },
+    {
+      "name": "flutter_lints",
+      "version": "6.0.0",
+      "dependencies": [
+        "lints"
+      ]
+    },
+    {
+      "name": "flutter_test",
+      "version": "0.0.0",
+      "dependencies": [
+        "clock",
+        "collection",
+        "fake_async",
+        "flutter",
+        "leak_tracker_flutter_testing",
+        "matcher",
+        "meta",
+        "path",
+        "stack_trace",
+        "stream_channel",
+        "test_api",
+        "vector_math"
+      ]
+    },
+    {
+      "name": "flutter",
+      "version": "0.0.0",
+      "dependencies": [
+        "characters",
+        "collection",
+        "material_color_utilities",
+        "meta",
+        "sky_engine",
+        "vector_math"
+      ]
+    },
+    {
+      "name": "lints",
+      "version": "6.1.0",
+      "dependencies": []
+    },
+    {
+      "name": "stream_channel",
+      "version": "2.1.4",
+      "dependencies": [
+        "async"
+      ]
+    },
+    {
+      "name": "meta",
+      "version": "1.17.0",
+      "dependencies": []
+    },
+    {
+      "name": "collection",
+      "version": "1.19.1",
+      "dependencies": []
+    },
+    {
+      "name": "leak_tracker_flutter_testing",
+      "version": "3.0.10",
+      "dependencies": [
+        "flutter",
+        "leak_tracker",
+        "leak_tracker_testing",
+        "matcher",
+        "meta"
+      ]
+    },
+    {
+      "name": "vector_math",
+      "version": "2.2.0",
+      "dependencies": []
+    },
+    {
+      "name": "stack_trace",
+      "version": "1.12.1",
+      "dependencies": [
+        "path"
+      ]
+    },
+    {
+      "name": "clock",
+      "version": "1.1.2",
+      "dependencies": []
+    },
+    {
+      "name": "fake_async",
+      "version": "1.3.3",
+      "dependencies": [
+        "clock",
+        "collection"
+      ]
+    },
+    {
+      "name": "path",
+      "version": "1.9.1",
+      "dependencies": []
+    },
+    {
+      "name": "matcher",
+      "version": "0.12.17",
+      "dependencies": [
+        "async",
+        "meta",
+        "stack_trace",
+        "term_glyph",
+        "test_api"
+      ]
+    },
+    {
+      "name": "test_api",
+      "version": "0.7.7",
+      "dependencies": [
+        "async",
+        "boolean_selector",
+        "collection",
+        "meta",
+        "source_span",
+        "stack_trace",
+        "stream_channel",
+        "string_scanner",
+        "term_glyph"
+      ]
+    },
+    {
+      "name": "sky_engine",
+      "version": "0.0.0",
+      "dependencies": []
+    },
+    {
+      "name": "material_color_utilities",
+      "version": "0.11.1",
+      "dependencies": [
+        "collection"
+      ]
+    },
+    {
+      "name": "characters",
+      "version": "1.4.0",
+      "dependencies": []
+    },
+    {
+      "name": "async",
+      "version": "2.13.0",
+      "dependencies": [
+        "collection",
+        "meta"
+      ]
+    },
+    {
+      "name": "leak_tracker_testing",
+      "version": "3.0.2",
+      "dependencies": [
+        "leak_tracker",
+        "matcher",
+        "meta"
+      ]
+    },
+    {
+      "name": "leak_tracker",
+      "version": "11.0.2",
+      "dependencies": [
+        "clock",
+        "collection",
+        "meta",
+        "path",
+        "vm_service"
+      ]
+    },
+    {
+      "name": "term_glyph",
+      "version": "1.2.2",
+      "dependencies": []
+    },
+    {
+      "name": "string_scanner",
+      "version": "1.4.1",
+      "dependencies": [
+        "source_span"
+      ]
+    },
+    {
+      "name": "source_span",
+      "version": "1.10.2",
+      "dependencies": [
+        "collection",
+        "path",
+        "term_glyph"
+      ]
+    },
+    {
+      "name": "boolean_selector",
+      "version": "2.1.2",
+      "dependencies": [
+        "source_span",
+        "string_scanner"
+      ]
+    },
+    {
+      "name": "vm_service",
+      "version": "15.0.2",
+      "dependencies": []
+    }
+  ],
+  "configVersion": 1
+}

useragent/.dart_tool/version

@@ -0,0 +1 @@
+3.38.9

useragent/macos/Flutter/ephemeral/Flutter-Generated.xcconfig

@@ -0,0 +1,11 @@
+// This is a generated file; do not edit or check into version control.
+FLUTTER_ROOT=/Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable
+FLUTTER_APPLICATION_PATH=/Users/kaska/Documents/Projects/Major/arbiter/useragent
+COCOAPODS_PARALLEL_CODE_SIGN=true
+FLUTTER_BUILD_DIR=build
+FLUTTER_BUILD_NAME=0.1.0
+FLUTTER_BUILD_NUMBER=0.1.0
+DART_OBFUSCATION=false
+TRACK_WIDGET_CREATION=true
+TREE_SHAKE_ICONS=false
+PACKAGE_CONFIG=.dart_tool/package_config.json

useragent/macos/Flutter/ephemeral/flutter_export_environment.sh

@@ -0,0 +1,12 @@
+#!/bin/sh
+# This is a generated file; do not edit or check into version control.
+export "FLUTTER_ROOT=/Users/kaska/.local/share/mise/installs/flutter/3.38.9-stable"
+export "FLUTTER_APPLICATION_PATH=/Users/kaska/Documents/Projects/Major/arbiter/useragent"
+export "COCOAPODS_PARALLEL_CODE_SIGN=true"
+export "FLUTTER_BUILD_DIR=build"
+export "FLUTTER_BUILD_NAME=0.1.0"
+export "FLUTTER_BUILD_NUMBER=0.1.0"
+export "DART_OBFUSCATION=false"
+export "TRACK_WIDGET_CREATION=true"
+export "TREE_SHAKE_ICONS=false"
+export "PACKAGE_CONFIG=.dart_tool/package_config.json"