merge: feat-lints into main

Reviewed-on: #90

AGENTS.md

@@ -66,7 +66,7 @@ cargo insta review
 The server is actor-based using the **kameo** crate. All long-lived state lives in `GlobalActors`:
 
 - **`Bootstrapper`** — Manages the one-time bootstrap token written to `~/.arbiter/bootstrap_token` on first run.
-- **`KeyHolder`** — Holds the encrypted root key and manages the Sealed/Unsealed vault state machine. On unseal, decrypts the root key into a `memsafe` hardened memory cell.
+- **`Vault`** — Holds the encrypted root key and manages the Sealed/Unsealed vault state machine. On unseal, decrypts the root key into a `memsafe` hardened memory cell.
 - **`FlowCoordinator`** — Coordinates cross-connection flow between user agents and SDK clients.
 - **`EvmActor`** — Handles EVM transaction policy enforcement and signing.
 

CLAUDE.md

@@ -66,7 +66,7 @@ cargo insta review
 The server is actor-based using the **kameo** crate. All long-lived state lives in `GlobalActors`:
 
 - **`Bootstrapper`** — Manages the one-time bootstrap token written to `~/.arbiter/bootstrap_token` on first run.
-- **`KeyHolder`** — Holds the encrypted root key and manages the Sealed/Unsealed vault state machine. On unseal, decrypts the root key into a `memsafe` hardened memory cell.
+- **`Vault`** — Holds the encrypted root key and manages the Sealed/Unsealed vault state machine. On unseal, decrypts the root key into a `memsafe` hardened memory cell.
 - **`FlowCoordinator`** — Coordinates cross-connection flow between user agents and SDK clients.
 - **`EvmActor`** — Handles EVM transaction policy enforcement and signing.
 

IMPLEMENTATION.md

@@ -29,38 +29,23 @@ flowchart TD
     A([Client connects]) --> B[Receive AuthChallengeRequest]
     B --> C{pubkey in DB?}
 
-    C -- yes --> D[Read nonce\nIncrement nonce in DB]
-    D --> G
+    C -- yes --> G[Generate AuthChallenge]
 
     C -- no --> E[Ask all UserAgents:\nClientConnectionRequest]
     E --> F{First response}
     F -- denied --> Z([Reject connection])
     F -- approved --> F2[Cancel remaining\nUserAgent requests]
-    F2 --> F3[INSERT client\nnonce = 1]
-    F3 --> G[Send AuthChallenge\nwith nonce]
+    F2 --> F3[INSERT client]
+    F3 --> G
 
-    G --> H[Receive AuthChallengeSolution]
-    H --> I{Signature valid?}
-    I -- no --> Z
-    I -- yes --> J([Session started])
+    G --> H[Send AuthChallenge\ntimestamp + random bytes]
+    H --> I[Receive AuthChallengeSolution]
+    I --> K{Signature valid?}
+    K -- no --> Z
+    K -- yes --> J([Session started])
 ```
 
-### Known Issue: Concurrent Registration Race (TOCTOU)
-
-Two connections presenting the same previously-unknown public key can race through the approval flow simultaneously:
-
-1. Both check the DB → neither is registered.
-2. Both request approval from user agents → both receive approval.
-3. Both `INSERT` the client record → the second insert silently overwrites the first, resetting the nonce.
-
-This means the first connection's nonce is invalidated by the second, causing its challenge verification to fail. A fix requires either serialising new-client registration (e.g. an in-memory lock keyed on pubkey) or replacing the separate check + insert with an `INSERT OR IGNORE` / upsert guarded by a unique constraint on `public_key`.
-
-### Nonce Semantics
-
-The `program_client.nonce` column stores the **next usable nonce** — i.e. it is always one ahead of the nonce last issued in a challenge.
-
-- **New client:** inserted with `nonce = 1`; the first challenge is issued with `nonce = 0`.
-- **Existing client:** the current DB value is read and used as the challenge nonce, then immediately incremented within the same exclusive transaction, preventing replay.
+Auth challenges are generated from fresh random bytes plus a timestamp. They are signed as the canonical challenge payload and are not persisted in `program_client`.
 
 ---
 

mise.lock

@@ -72,6 +72,10 @@ backend = "cargo:diesel_cli"
 default-features = "false"
 features = "sqlite,sqlite-bundled"
 
+[[tools."cargo:flutter_rust_bridge_codegen"]]
+version = "2.12.0"
+backend = "cargo:flutter_rust_bridge_codegen"
+
 [[tools.flutter]]
 version = "3.38.9-stable"
 backend = "asdf:flutter"

mise.toml

@@ -4,7 +4,7 @@
 "cargo:cargo-vet" = "0.10.2"
 flutter = "3.38.9-stable"
 protoc = "29.6"
-"rust" = {version = "1.93.0", components = "clippy"}
+"rust" = {version = "1.93.0", components = "clippy,rust-analyzer"}
 "cargo:cargo-features-manager" = "0.11.1"
 "cargo:cargo-nextest" = "0.9.126"
 "cargo:cargo-shear" = "latest"
@@ -13,6 +13,7 @@ python = "3.14.3"
 ast-grep = "0.42.0"
 "cargo:cargo-edit" = "0.13.9"
 "cargo:cargo-mutants" = "27.0.0"
+"cargo:flutter_rust_bridge_codegen" = "2.12.0"
 
 [tasks.codegen]
 sources = ['protobufs/*.proto', 'protobufs/**/*.proto']

protobufs/client/auth.proto

@@ -10,8 +10,8 @@ message AuthChallengeRequest {
 }
 
 message AuthChallenge {
-  bytes pubkey = 1;
-  int32 nonce = 2;
+  uint64 timestamp_nanos = 1;
+  bytes random = 2;
 }
 
 message AuthChallengeSolution {

protobufs/user_agent/auth.proto

@@ -2,21 +2,14 @@ syntax = "proto3";
 
 package arbiter.user_agent.auth;
 
-enum KeyType {
-  KEY_TYPE_UNSPECIFIED = 0;
-  KEY_TYPE_ED25519 = 1;
-  KEY_TYPE_ECDSA_SECP256K1 = 2;
-  KEY_TYPE_RSA = 3;
-}
-
 message AuthChallengeRequest {
   bytes pubkey = 1;
   optional string bootstrap_token = 2;
-  KeyType key_type = 3;
 }
 
 message AuthChallenge {
-  int32 nonce = 1;
+  uint64 timestamp_nanos = 1;
+  bytes random = 2;
 }
 
 message AuthChallengeSolution {

server/Cargo.toml

@@ -6,31 +6,32 @@ resolver = "3"
 
 
 [workspace.dependencies]
-alloy = "1.7.3"
+alloy = "2.0.0"
 async-trait = "0.1.89"
 base64 = "0.22.1"
 chrono = { version = "0.4.44", features = ["serde"] }
 ed25519-dalek = { version = "3.0.0-pre.6", features = ["rand_core"] }
 futures = "0.3.32"
-hmac = "0.12.1"
 k256 = { version = "0.13.4", features = ["ecdsa", "pkcs8"] }
-kameo = { version = "0.20.0", git = "https://github.com/tqwewe/kameo" } # hold this until new patch version is released
+kameo = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
+kameo_actors = {git = "https://github.com/hdbg/kameo.git", rev = "805b417"}
+hmac = "0.13.0"
 miette = { version = "7.6.0", features = ["fancy", "serde"] }
 ml-dsa = { version = "0.1.0-rc.8", features = ["zeroize"] }
 mutants = "0.0.4"
 prost = "0.14.3"
 prost-types = { version = "0.14.3", features = ["chrono"] }
-rand = "0.10.0"
+rand = "0.10.1"
 rcgen = { version = "0.14.7", features = [ "aws_lc_rs",  "pem", "x509-parser", "zeroize" ], default-features = false }
 rsa = { version = "0.9", features = ["sha2"] }
 rstest = "0.26.1"
-rustls = { version = "0.23.37", features = ["aws-lc-rs", "logging", "prefer-post-quantum", "std"], default-features = false }
+rustls = { version = "0.23.38", features = ["aws-lc-rs", "logging", "prefer-post-quantum", "std"], default-features = false }
 rustls-pki-types = "1.14.0"
-sha2 = "0.10"
+sha2 = "0.11"
 smlang = "0.8.0"
-spki = "0.7"
+spki = "0.8"
 thiserror = "2.0.18"
-tokio = { version = "1.50.0", features = ["full"] }
+tokio = { version = "1.52.1", features = ["full"] }
 tokio-stream = { version = "0.1.18", features = ["full"] }
 tonic = { version = "0.14.5", features = [ "deflate", "gzip", "tls-connect-info", "zstd" ] }
 tracing = "0.1.44"
@@ -64,7 +65,6 @@ unit_bindings = "warn"
 
 # missing_docs = "warn" # ENABLE BY THE FIRST MAJOR VERSION!!
 unnameable_types = "warn"
-variant_size_differences = "warn"
 
 [workspace.lints.clippy]
 derive_partial_eq_without_eq = "allow" 
@@ -98,7 +98,6 @@ doc_include_without_cfg = "warn"
 empty_drop = "warn"
 empty_enum_variants_with_brackets = "warn"
 empty_structs_with_brackets = "warn"
-error_impl_error = "warn"
 exit = "warn"
 filetype_is_file = "warn"
 float_arithmetic = "warn"
@@ -170,3 +169,5 @@ disallowed_methods = "deny"
 
 nursery = { level = "warn", priority = -1 }
 pedantic = { level = "warn", priority = -1 }
+
+type_repetition_in_bounds = "allow"   # sometimes, it's better for readability this way

server/crates/arbiter-client/Cargo.toml

@@ -21,6 +21,7 @@ tokio.workspace = true
 tokio-stream.workspace = true
 thiserror.workspace = true
 http = "1.4.0"
-rustls-webpki = { version = "0.103.10", features = ["aws-lc-rs"] }
+rustls-webpki = { version = "0.103.12", features = ["aws-lc-rs"] }
 async-trait.workspace = true
 rand.workspace = true
+chrono.workspace = true

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

@@ -1,4 +1,8 @@
-use arbiter_crypto::authn::{CLIENT_CONTEXT, SigningKey, format_challenge};
+use crate::{
+    storage::StorageError,
+    transport::{ClientTransport, next_request_id},
+};
+use arbiter_crypto::authn::{self, CLIENT_CONTEXT, SigningKey};
 use arbiter_proto::{
     ClientMetadata,
     proto::{
@@ -16,16 +20,14 @@ use arbiter_proto::{
     },
 };
 
-use crate::{
-    storage::StorageError,
-    transport::{ClientTransport, next_request_id},
-};
+use chrono::DateTime;
 
 #[derive(Debug, thiserror::Error)]
 pub enum AuthError {
+    #[error("Server sent invalid auth challenge")]
+    InvalidChallenge,
     #[error("Client approval denied by User Agent")]
     ApprovalDenied,
-
     #[error("Auth challenge was not returned by server")]
     MissingAuthChallenge,
 
@@ -98,7 +100,15 @@ async fn send_auth_challenge_solution(
     key: &SigningKey,
     challenge: AuthChallenge,
 ) -> Result<(), AuthError> {
-    let challenge_payload = format_challenge(challenge.nonce, &challenge.pubkey);
+    let timestamp = DateTime::from_timestamp_nanos(challenge.timestamp_nanos as i64);
+    let challenge = authn::AuthChallenge {
+        nonce: *challenge
+            .random
+            .as_array()
+            .ok_or(AuthError::InvalidChallenge)?,
+        timestamp,
+    };
+    let challenge_payload: Vec<u8> = challenge.format();
     let signature = key
         .sign_message(&challenge_payload, CLIENT_CONTEXT)
         .map_err(|_| AuthError::UnexpectedAuthResponse)?

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

@@ -1,8 +1,8 @@
-use std::io::{self, Write};
-
 use arbiter_client::ArbiterClient;
 use arbiter_proto::{ClientMetadata, url::ArbiterUrl};
 
+use std::io::{self, Write};
+
 #[tokio::main]
 async fn main() {
     println!("Testing connection to Arbiter server...");

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

@@ -1,21 +1,20 @@
-use arbiter_crypto::authn::SigningKey;
-use arbiter_proto::{
-    ClientMetadata, proto::arbiter_service_client::ArbiterServiceClient, url::ArbiterUrl,
-};
-use std::sync::Arc;
-use tokio::sync::{Mutex, mpsc};
-use tokio_stream::wrappers::ReceiverStream;
-use tonic::transport::ClientTlsConfig;
-
+#[cfg(feature = "evm")]
+use crate::wallets::evm::ArbiterEvmWallet;
 use crate::{
     StorageError,
     auth::{AuthError, authenticate},
     storage::{FileSigningKeyStorage, SigningKeyStorage},
     transport::{BUFFER_LENGTH, ClientTransport},
 };
+use arbiter_crypto::authn::SigningKey;
+use arbiter_proto::{
+    ClientMetadata, proto::arbiter_service_client::ArbiterServiceClient, url::ArbiterUrl,
+};
 
-#[cfg(feature = "evm")]
-use crate::wallets::evm::ArbiterEvmWallet;
+use std::sync::Arc;
+use tokio::sync::{Mutex, mpsc};
+use tokio_stream::wrappers::ReceiverStream;
+use tonic::transport::ClientTlsConfig;
 
 #[derive(Debug, thiserror::Error)]
 pub enum ArbiterClientError {

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

@@ -1,5 +1,6 @@
 use arbiter_crypto::authn::SigningKey;
 use arbiter_proto::home_path;
+
 use std::path::{Path, PathBuf};
 
 #[derive(Debug, thiserror::Error)]

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

@@ -1,4 +1,5 @@
 use arbiter_proto::proto::client::{ClientRequest, ClientResponse};
+
 use std::sync::atomic::{AtomicI32, Ordering};
 use tokio::sync::mpsc;
 
@@ -24,10 +25,7 @@ pub struct ClientTransport {
 }
 
 impl ClientTransport {
-    pub(crate) async fn send(
-        &mut self,
-        request: ClientRequest,
-    ) -> Result<(), ClientSignError> {
+    pub(crate) async fn send(&mut self, request: ClientRequest) -> Result<(), ClientSignError> {
         self.sender
             .send(request)
             .await

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

@@ -1,13 +1,4 @@
-use alloy::{
-    consensus::SignableTransaction,
-    network::TxSigner,
-    primitives::{Address, B256, ChainId, Signature},
-    signers::{Error, Result, Signer},
-};
-use async_trait::async_trait;
-use std::sync::Arc;
-use tokio::sync::Mutex;
-
+use crate::transport::{ClientTransport, next_request_id};
 use arbiter_proto::proto::{
     client::{
         ClientRequest,
@@ -25,7 +16,15 @@ use arbiter_proto::proto::{
     shared::evm::TransactionEvalError,
 };
 
-use crate::transport::{ClientTransport, next_request_id};
+use alloy::{
+    consensus::SignableTransaction,
+    network::TxSigner,
+    primitives::{Address, B256, ChainId, Signature},
+    signers::{Error, Result, Signer},
+};
+use async_trait::async_trait;
+use std::sync::Arc;
+use tokio::sync::Mutex;
 
 /// A typed error payload returned by [`ArbiterEvmWallet`] transaction signing.
 ///

server/crates/arbiter-crypto/Cargo.toml

@@ -6,16 +6,17 @@ edition = "2024"
 [dependencies]
 ml-dsa = {workspace = true, optional = true }
 rand = {workspace = true, optional = true}
-base64 = {workspace = true, optional = true }
 memsafe = {version = "0.4.0", optional = true}
 hmac.workspace = true
 alloy.workspace = true
+x-wing = { version = "0.1.0-rc.0", features = ["zeroize"] }
 chrono.workspace = true
+thiserror.workspace = true
 
 [lints]
 workspace = true
 
 [features]
 default = ["authn", "safecell"]
-authn = ["dep:ml-dsa", "dep:rand", "dep:base64"]
+authn = ["dep:ml-dsa", "dep:rand"]
 safecell = ["dep:memsafe"]

server/crates/arbiter-crypto/src/authn/v1.rs

@@ -1,16 +1,65 @@
-use base64::{Engine as _, prelude::BASE64_STANDARD};
+use chrono::{DateTime, Utc};
 use hmac::digest::Digest;
 use ml_dsa::{
     EncodedVerifyingKey, Error, KeyGen, MlDsa87, Seed, Signature as MlDsaSignature,
     SigningKey as MlDsaSigningKey, VerifyingKey as MlDsaVerifyingKey, signature::Keypair as _,
 };
+use rand::RngExt;
 
 pub static CLIENT_CONTEXT: &[u8] = b"arbiter_client";
 pub static USERAGENT_CONTEXT: &[u8] = b"arbiter_user_agent";
 
-pub fn format_challenge(nonce: i32, pubkey: &[u8]) -> Vec<u8> {
-    let concat_form = format!("{}:{}", nonce, BASE64_STANDARD.encode(pubkey));
-    concat_form.into_bytes()
+const NONCE_SIZE: usize = 32;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq, thiserror::Error)]
+#[error("invalid length: expected {expected} bytes, got {actual} bytes")]
+pub struct InvalidLength {
+    pub expected: usize,
+    pub actual: usize,
+}
+
+#[derive(Debug, Clone)]
+pub struct AuthChallenge {
+    pub nonce: [u8; NONCE_SIZE],
+    pub timestamp: DateTime<Utc>,
+}
+
+impl AuthChallenge {
+    pub fn generate(rng: &mut impl rand::CryptoRng) -> Self {
+        let timestamp = Utc::now();
+        let nonce = {
+            let mut array = [0; NONCE_SIZE];
+            rng.fill(&mut array);
+            array
+        };
+
+        Self { nonce, timestamp }
+    }
+
+    pub fn format(&self) -> Vec<u8> {
+        {
+            let mut buffer = Vec::from(self.nonce);
+
+            let stamp = self
+                .timestamp
+                .timestamp_nanos_opt()
+                .expect("We would be long dead by the time this triggers :)");
+            buffer.extend_from_slice(stamp.to_be_bytes().as_slice());
+
+            buffer
+        }
+    }
+
+    pub fn from_parts(nonce: &[u8], timestamp: i64) -> Result<Self, InvalidLength> {
+        let random_nonce = nonce.as_array().ok_or(InvalidLength {
+            expected: NONCE_SIZE,
+            actual: nonce.len(),
+        })?;
+        Ok(Self {
+            nonce: *random_nonce,
+            timestamp: DateTime::from_timestamp_nanos(timestamp),
+        })
+    }
 }
 
 pub type KeyParams = MlDsa87;
@@ -36,12 +85,10 @@ impl PublicKey {
     }
 
     #[must_use]
-    pub fn verify(&self, nonce: i32, context: &[u8], signature: &Signature) -> bool {
-        self.0.verify_with_context(
-            &format_challenge(nonce, &self.to_bytes()),
-            context,
-            &signature.0,
-        )
+    pub fn verify(&self, challenge: &AuthChallenge, context: &[u8], signature: &Signature) -> bool {
+        let challenge = challenge.format();
+        self.0
+            .verify_with_context(&challenge, context, &signature.0)
     }
 }
 
@@ -75,11 +122,14 @@ impl SigningKey {
             .map(Into::into)
     }
 
-    pub fn sign_challenge(&self, nonce: i32, context: &[u8]) -> Result<Signature, Error> {
-        self.sign_message(
-            &format_challenge(nonce, &self.public_key().to_bytes()),
-            context,
-        )
+    pub fn sign_challenge(
+        &self,
+        challenge: &AuthChallenge,
+        context: &[u8],
+    ) -> Result<Signature, Error> {
+        let challenge = challenge.format();
+
+        self.sign_message(&challenge, context)
     }
 }
 
@@ -140,6 +190,8 @@ impl TryFrom<&'_ [u8]> for Signature {
 mod tests {
     use ml_dsa::{KeyGen, MlDsa87, signature::Keypair as _};
 
+    use crate::authn::AuthChallenge;
+
     use super::{CLIENT_CONTEXT, PublicKey, Signature, SigningKey, USERAGENT_CONTEXT};
 
     #[test]
@@ -169,13 +221,13 @@ mod tests {
     fn challenge_verification_uses_context_and_canonical_key_bytes() {
         let key = SigningKey::generate();
         let public_key = key.public_key();
-        let nonce = 17;
+        let challenge = AuthChallenge::generate(&mut rand::rng());
         let signature = key
-            .sign_challenge(nonce, CLIENT_CONTEXT)
+            .sign_challenge(&challenge, CLIENT_CONTEXT)
             .expect("signature should be created");
 
-        assert!(public_key.verify(nonce, CLIENT_CONTEXT, &signature));
-        assert!(!public_key.verify(nonce, USERAGENT_CONTEXT, &signature));
+        assert!(public_key.verify(&challenge, CLIENT_CONTEXT, &signature));
+        assert!(!public_key.verify(&challenge, USERAGENT_CONTEXT, &signature));
     }
 
     #[test]
@@ -185,10 +237,16 @@ mod tests {
 
         assert_eq!(restored.public_key(), original.public_key());
 
+        let challenge = AuthChallenge::generate(&mut rand::rng());
+
         let signature = restored
-            .sign_challenge(9, CLIENT_CONTEXT)
+            .sign_challenge(&challenge, CLIENT_CONTEXT)
             .expect("signature should be created");
 
-        assert!(restored.public_key().verify(9, CLIENT_CONTEXT, &signature));
+        assert!(
+            restored
+                .public_key()
+                .verify(&challenge, CLIENT_CONTEXT, &signature)
+        );
     }
 }

server/crates/arbiter-crypto/src/hashing.rs

@@ -1,6 +1,7 @@
-pub use hmac::digest::Digest;
 use std::collections::HashSet;
 
+pub use hmac::digest::Digest;
+
 /// Deterministically hash a value by feeding its fields into the hasher in a consistent order.
 #[diagnostic::on_unimplemented(
     note = "for local types consider adding `#[derive(arbiter_macros::Hashable)]` to your `{Self}` type",

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

@@ -3,3 +3,5 @@ pub mod authn;
 pub mod hashing;
 #[cfg(feature = "safecell")]
 pub mod safecell;
+
+pub use x_wing;

server/crates/arbiter-crypto/src/safecell.rs

@@ -1,7 +1,9 @@
-use std::ops::{Deref, DerefMut};
-use std::{any::type_name, fmt};
-
 use memsafe::MemSafe;
+use std::{
+    any::type_name,
+    fmt,
+    ops::{Deref, DerefMut},
+};
 
 pub trait SafeCellHandle<T> {
     type CellRead<'a>: Deref<Target = T>

server/crates/arbiter-macros/src/hashable.rs

@@ -1,10 +1,8 @@
+use crate::utils::{HASHABLE_TRAIT_PATH, HMAC_DIGEST_PATH};
+
 use proc_macro2::{Span, TokenStream, TokenTree};
 use quote::quote;
-use syn::parse_quote;
-use syn::spanned::Spanned;
-use syn::{DataStruct, DeriveInput, Fields, Generics, Index};
-
-use crate::utils::{HASHABLE_TRAIT_PATH, HMAC_DIGEST_PATH};
+use syn::{DataStruct, DeriveInput, Fields, Generics, Index, parse_quote, spanned::Spanned};
 
 pub(crate) fn derive(input: &DeriveInput) -> TokenStream {
     match &input.data {

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

@@ -54,10 +54,9 @@
 //!   as a closed outbound channel.
 //! - [`Bi::recv`] returns `None` when the underlying transport closes.
 //! - Message translation is intentionally out of scope for this module.
-
-use std::marker::PhantomData;
-
 use async_trait::async_trait;
+use kameo::{error::Infallible, prelude::*};
+use std::marker::PhantomData;
 
 /// Errors returned by transport adapters implementing [`Bi`].
 #[derive(thiserror::Error, Debug)]
@@ -106,6 +105,36 @@ pub trait Receiver<Inbound>: Send + Sync {
 /// any built-in correlation mechanism between inbound and outbound items.
 pub trait Bi<Inbound, Outbound>: Sender<Outbound> + Receiver<Inbound> + Send + Sync {}
 
+#[async_trait]
+impl<T, Outbound> Sender<Outbound> for &mut T
+where
+    T: Sender<Outbound> + ?Sized,
+    Outbound: Send + 'static,
+{
+    async fn send(&mut self, item: Outbound) -> Result<(), Error> {
+        (**self).send(item).await
+    }
+}
+
+#[async_trait]
+impl<T, Inbound> Receiver<Inbound> for &mut T
+where
+    T: Receiver<Inbound> + ?Sized,
+    Inbound: Send + 'static,
+{
+    async fn recv(&mut self) -> Option<Inbound> {
+        (**self).recv().await
+    }
+}
+
+impl<T, Inbound, Outbound> Bi<Inbound, Outbound> for &mut T
+where
+    T: Bi<Inbound, Outbound> + ?Sized,
+    Inbound: Send + 'static,
+    Outbound: Send + 'static,
+{
+}
+
 pub trait SplittableBi<Inbound, Outbound>: Bi<Inbound, Outbound> {
     type Sender: Sender<Outbound>;
     type Receiver: Receiver<Inbound>;
@@ -161,3 +190,29 @@ where
 }
 
 pub mod grpc;
+
+#[derive(thiserror::Error, Debug)]
+pub enum ForwardError<I> {
+    #[error("Transport error: {0}")]
+    Transport(#[from] Error),
+    #[error("Actor delivery error: {0}")]
+    Actor(SendError<I>),
+}
+
+pub async fn forward_to_actor<Transport, Inbound, Outbound, Handler>(
+    transport: &mut Transport,
+    actor: &ActorRef<Handler>,
+) -> Result<(), ForwardError<Inbound>>
+where
+    Transport: Bi<Inbound, <Outbound as Reply>::Ok>,
+    Handler: Actor + Message<Inbound, Reply = Outbound>,
+    Inbound: Send + 'static,
+    Outbound: Send + 'static + Reply<Error = Infallible>, // `Infallible` to enforce contract that `Outbound` carries handler-level error
+{
+    while let Some(request) = transport.recv().await {
+        let resp = actor.ask(request).await.map_err(ForwardError::Actor)?;
+        transport.send(resp).await?
+    }
+
+    Err(Error::ChannelClosed.into())
+}

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

@@ -1,10 +1,10 @@
+use super::{Bi, Receiver, Sender};
+
 use async_trait::async_trait;
 use futures::StreamExt;
 use tokio::sync::mpsc;
 use tokio_stream::wrappers::ReceiverStream;
 
-use super::{Bi, Receiver, Sender};
-
 pub struct GrpcSender<Outbound> {
     tx: mpsc::Sender<Result<Outbound, tonic::Status>>,
 }

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

@@ -1,7 +1,6 @@
-use std::fmt::Display;
-
 use base64::{Engine as _, prelude::BASE64_URL_SAFE};
 use rustls_pki_types::CertificateDer;
+use std::fmt::Display;
 
 const ARBITER_URL_SCHEME: &str = "arbiter";
 const CERT_QUERY_KEY: &str = "cert";

server/crates/arbiter-server/Cargo.toml

@@ -59,9 +59,10 @@ ml-dsa.workspace = true
 ed25519-dalek.workspace = true
 x25519-dalek.workspace = true
 k256.workspace = true
+kameo_actors.workspace = true
 
 [dev-dependencies]
-insta = "1.46.3"
+insta = "1.47.2"
 proptest = "1.11.0"
 rstest.workspace = true
 test-log = { version = "0.2", default-features = false, features = ["trace"] }

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

@@ -45,13 +45,11 @@ insert into arbiter_settings (id) values (1) on conflict do nothing;
 
 create table if not exists useragent_client (
     id integer not null primary key,
-    nonce integer not null default(1), -- used for auth challenge
     public_key blob not null,
-    key_type integer not null default(1),
     created_at integer not null default(unixepoch ('now')),
     updated_at integer not null default(unixepoch ('now'))
 ) STRICT;
-create unique index if not exists uniq_useragent_client_public_key on useragent_client (public_key, key_type);
+create unique index if not exists uniq_useragent_client_public_key on useragent_client (public_key);
 
 create table if not exists client_metadata (
     id integer not null primary key,
@@ -73,7 +71,6 @@ create unique index if not exists uniq_metadata_binding_client on client_metadat
 
 create table if not exists program_client (
     id integer not null primary key,
-    nonce integer not null default(1), -- used for auth challenge
     public_key blob not null,
     metadata_id integer not null references client_metadata (id) on delete cascade,
     created_at integer not null default(unixepoch ('now')),

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

@@ -1,13 +1,13 @@
+use crate::db::{self, DatabasePool, schema};
 use arbiter_proto::{BOOTSTRAP_PATH, home_path};
+
 use diesel::QueryDsl;
 use diesel_async::RunQueryDsl;
 use kameo::{Actor, messages};
-
 use rand::{RngExt, distr::Alphanumeric, make_rng, rngs::StdRng};
 use subtle::ConstantTimeEq as _;
 use thiserror::Error;
 
-use crate::db::{self, DatabasePool, schema};
 const TOKEN_LENGTH: usize = 64;
 
 pub async fn generate_token() -> Result<String, std::io::Error> {
@@ -27,7 +27,7 @@ pub async fn generate_token() -> Result<String, std::io::Error> {
 }
 
 #[derive(Error, Debug)]
-pub enum BootstrappError {
+pub enum Error {
     #[error("Database error: {0}")]
     Database(#[from] db::PoolError),
 
@@ -44,7 +44,7 @@ pub struct Bootstrapper {
 }
 
 impl Bootstrapper {
-    pub async fn new(db: &DatabasePool) -> Result<Self, BootstrappError> {
+    pub async fn new(db: &DatabasePool) -> Result<Self, Error> {
         let row_count: i64 = {
             let mut conn = db.get().await?;
 

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

@@ -1,15 +1,5 @@
-use alloy::{
-    consensus::TxEip1559, network::TxSignerSync as _, primitives::Address, signers::Signature,
-};
-use diesel::{
-    ExpressionMethods, OptionalExtension as _, QueryDsl, SelectableHelper as _, dsl::insert_into,
-};
-use diesel_async::RunQueryDsl;
-use kameo::{Actor, actor::ActorRef, messages};
-use rand::{SeedableRng, rng, rngs::StdRng};
-
 use crate::{
-    actors::keyholder::{CreateNew, Decrypt, KeyHolder},
+    actors::vault::{CreateNew, Decrypt, Vault},
     crypto::integrity,
     db::{
         DatabaseError, DatabasePool,
@@ -26,6 +16,16 @@ use crate::{
 };
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 
+use alloy::{
+    consensus::TxEip1559, network::TxSignerSync as _, primitives::Address, signers::Signature,
+};
+use diesel::{
+    ExpressionMethods, OptionalExtension as _, QueryDsl, SelectableHelper as _, dsl::insert_into,
+};
+use diesel_async::RunQueryDsl;
+use kameo::{Actor, actor::ActorRef, messages};
+use rand::{SeedableRng, rng, rngs::StdRng};
+
 pub use crate::evm::safe_signer;
 
 #[derive(Debug, thiserror::Error)]
@@ -36,11 +36,11 @@ pub enum SignTransactionError {
     #[error("Database error: {0}")]
     Database(#[from] DatabaseError),
 
-    #[error("Keyholder error: {0}")]
-    Keyholder(#[from] crate::actors::keyholder::KeyHolderError),
+    #[error("Vault error: {0}")]
+    Vault(#[from] crate::actors::vault::Error),
 
-    #[error("Keyholder mailbox error")]
-    KeyholderSend,
+    #[error("Vault mailbox error")]
+    VaultSend,
 
     #[error("Signing error: {0}")]
     Signing(#[from] alloy::signers::Error),
@@ -50,36 +50,36 @@ pub enum SignTransactionError {
 }
 
 #[derive(Debug, thiserror::Error)]
-pub enum EvmActorError {
-    #[error("Keyholder error: {0}")]
-    Keyholder(#[from] crate::actors::keyholder::KeyHolderError),
+pub enum Error {
+    #[error("Vault error: {0}")]
+    Vault(#[from] crate::actors::vault::Error),
 
-    #[error("Keyholder mailbox error")]
-    KeyholderSend,
+    #[error("Vault mailbox error")]
+    VaultSend,
 
     #[error("Database error: {0}")]
     Database(#[from] DatabaseError),
 
     #[error("Integrity violation: {0}")]
-    Integrity(#[from] integrity::IntegrityError),
+    Integrity(#[from] integrity::Error),
 }
 
 #[derive(Actor)]
 pub struct EvmActor {
-    pub keyholder: ActorRef<KeyHolder>,
+    pub vault: ActorRef<Vault>,
     pub db: DatabasePool,
     pub rng: StdRng,
     pub engine: evm::Engine,
 }
 
 impl EvmActor {
-    pub fn new(keyholder: ActorRef<KeyHolder>, db: DatabasePool) -> Self {
+    pub fn new(vault: ActorRef<Vault>, 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(), keyholder.clone());
+        let engine = evm::Engine::new(db.clone(), vault.clone());
         Self {
-            keyholder,
+            vault,
             db,
             rng,
             engine,
@@ -90,16 +90,16 @@ impl EvmActor {
 #[messages]
 impl EvmActor {
     #[message]
-    pub async fn generate(&mut self) -> Result<(i32, Address), EvmActorError> {
+    pub async fn generate(&mut self) -> Result<(i32, Address), Error> {
         let (mut key_cell, address) = safe_signer::generate(&mut self.rng);
 
         let plaintext = key_cell.read_inline(|reader| SafeCell::new(reader.to_vec()));
 
         let aead_id: i32 = self
-            .keyholder
+            .vault
             .ask(CreateNew { plaintext })
             .await
-            .map_err(|_| EvmActorError::KeyholderSend)?;
+            .map_err(|_| Error::VaultSend)?;
 
         let mut conn = self.db.get().await.map_err(DatabaseError::from)?;
         let wallet_id = insert_into(schema::evm_wallet::table)
@@ -116,7 +116,7 @@ impl EvmActor {
     }
 
     #[message]
-    pub async fn list_wallets(&self) -> Result<Vec<(i32, Address)>, EvmActorError> {
+    pub async fn list_wallets(&self) -> Result<Vec<(i32, Address)>, Error> {
         let mut conn = self.db.get().await.map_err(DatabaseError::from)?;
         let rows: Vec<models::EvmWallet> = schema::evm_wallet::table
             .select(models::EvmWallet::as_select())
@@ -138,7 +138,7 @@ impl EvmActor {
         &mut self,
         basic: SharedGrantSettings,
         grant: SpecificGrant,
-    ) -> Result<i32, EvmActorError> {
+    ) -> Result<i32, Error> {
         match grant {
             SpecificGrant::EtherTransfer(settings) => self
                 .engine
@@ -147,7 +147,7 @@ impl EvmActor {
                     specific: settings,
                 })
                 .await
-                .map_err(EvmActorError::from),
+                .map_err(Error::from),
             SpecificGrant::TokenTransfer(settings) => self
                 .engine
                 .create_grant::<TokenTransfer>(CombinedSettings {
@@ -155,15 +155,15 @@ impl EvmActor {
                     specific: settings,
                 })
                 .await
-                .map_err(EvmActorError::from),
+                .map_err(Error::from),
         }
     }
 
     #[message]
     #[expect(clippy::unused_async, reason = "reserved for impl")]
-    pub async fn useragent_delete_grant(&mut self, _grant_id: i32) -> Result<(), EvmActorError> {
+    pub async fn useragent_delete_grant(&mut self, _grant_id: i32) -> Result<(), Error> {
         // let mut conn = self.db.get().await.map_err(DatabaseError::from)?;
-        // let keyholder = self.keyholder.clone();
+        // let vault = self.vault.clone();
 
         // diesel_async::AsyncConnection::transaction(&mut conn, |conn| {
         //     Box::pin(async move {
@@ -186,15 +186,11 @@ impl EvmActor {
     }
 
     #[message]
-    pub async fn useragent_list_grants(
-        &mut self,
-    ) -> Result<Vec<Grant<SpecificGrant>>, EvmActorError> {
+    pub async fn useragent_list_grants(&mut self) -> Result<Vec<Grant<SpecificGrant>>, Error> {
         match self.engine.list_all_grants().await {
             Ok(grants) => Ok(grants),
-            Err(ListError::Database(db_err)) => Err(EvmActorError::Database(db_err)),
-            Err(ListError::Integrity(integrity_err)) => {
-                Err(EvmActorError::Integrity(integrity_err))
-            }
+            Err(ListError::Database(db_err)) => Err(Error::Database(db_err)),
+            Err(ListError::Integrity(integrity_err)) => Err(Error::Integrity(integrity_err)),
         }
     }
 
@@ -261,12 +257,12 @@ impl EvmActor {
         drop(conn);
 
         let raw_key: SafeCell<Vec<u8>> = self
-            .keyholder
+            .vault
             .ask(Decrypt {
                 aead_id: wallet.aead_encrypted_id,
             })
             .await
-            .map_err(|_| SignTransactionError::KeyholderSend)?;
+            .map_err(|_| SignTransactionError::VaultSend)?;
 
         let signer = safe_signer::SafeSigner::from_cell(raw_key)?;
 

server/crates/arbiter-server/src/actors/flow_coordinator/client_connect_approval.rs

@@ -1,16 +1,17 @@
-use std::ops::ControlFlow;
+use crate::{
+    actors::flow_coordinator::ApprovalError,
+    peers::{
+        client::ClientProfile,
+        user_agent::{UserAgentSession, session::BeginNewClientApproval},
+    },
+};
 
 use kameo::{
     Actor, messages,
     prelude::{ActorId, ActorRef, ActorStopReason, Context, WeakActorRef},
     reply::ReplySender,
 };
-
-use crate::actors::{
-    client::ClientProfile,
-    flow_coordinator::ApprovalError,
-    user_agent::{UserAgentSession, session::BeginNewClientApproval},
-};
+use std::ops::ControlFlow;
 
 pub struct Args {
     pub client: ClientProfile,

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

@@ -1,4 +1,10 @@
-use std::{collections::HashMap, ops::ControlFlow};
+use crate::{
+    actors::{
+        flow_coordinator::client_connect_approval::ClientApprovalController,
+        useragent_registry::{GetConnected, UserAgentRegistry},
+    },
+    peers::client::{ClientProfile, session::ClientSession},
+};
 
 use kameo::{
     Actor,
@@ -7,20 +13,23 @@ use kameo::{
     prelude::{ActorStopReason, Context, WeakActorRef},
     reply::DelegatedReply,
 };
+use std::{collections::HashMap, ops::ControlFlow};
 use tracing::info;
 
-use crate::actors::{
-    client::{ClientProfile, session::ClientSession},
-    flow_coordinator::client_connect_approval::ClientApprovalController,
-    user_agent::session::UserAgentSession,
-};
-
 pub mod client_connect_approval;
 
-#[derive(Default)]
 pub struct FlowCoordinator {
-    pub user_agents: HashMap<ActorId, ActorRef<UserAgentSession>>,
     pub clients: HashMap<ActorId, ActorRef<ClientSession>>,
+    useragent_registry: ActorRef<UserAgentRegistry>,
+}
+
+impl FlowCoordinator {
+    pub fn new(useragent_registry: ActorRef<UserAgentRegistry>) -> Self {
+        Self {
+            clients: HashMap::default(),
+            useragent_registry,
+        }
+    }
 }
 
 impl Actor for FlowCoordinator {
@@ -38,13 +47,7 @@ impl Actor for FlowCoordinator {
         id: ActorId,
         _: ActorStopReason,
     ) -> Result<ControlFlow<ActorStopReason>, Self::Error> {
-        if self.user_agents.remove(&id).is_some() {
-            info!(
-                ?id,
-                actor = "FlowCoordinator",
-                event = "useragent.disconnected"
-            );
-        } else if self.clients.remove(&id).is_some() {
+        if self.clients.remove(&id).is_some() {
             info!(
                 ?id,
                 actor = "FlowCoordinator",
@@ -69,17 +72,6 @@ pub enum ApprovalError {
 
 #[messages]
 impl FlowCoordinator {
-    #[message(ctx)]
-    pub async fn register_user_agent(
-        &mut self,
-        actor: ActorRef<UserAgentSession>,
-        ctx: &mut Context<Self, ()>,
-    ) {
-        info!(id = %actor.id(), actor = "FlowCoordinator", 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,
@@ -92,7 +84,7 @@ impl FlowCoordinator {
     }
 
     #[message(ctx)]
-    pub fn request_client_approval(
+    pub async fn request_client_approval(
         &mut self,
         client: ClientProfile,
         ctx: &mut Context<Self, DelegatedReply<Result<bool, ApprovalError>>>,
@@ -101,7 +93,11 @@ impl FlowCoordinator {
             unreachable!("Expected `request_client_approval` to have callback channel");
         };
 
-        let refs: Vec<_> = self.user_agents.values().cloned().collect();
+        let Ok(refs) = self.useragent_registry.ask(GetConnected).await else {
+            reply_sender.send(Err(ApprovalError::NoUserAgentsConnected));
+            return reply;
+        };
+
         if refs.is_empty() {
             reply_sender.send(Err(ApprovalError::NoUserAgentsConnected));
             return reply;

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

@@ -1,47 +1,59 @@
-use kameo::actor::{ActorRef, Spawn};
-use thiserror::Error;
-
 use crate::{
     actors::{
         bootstrap::Bootstrapper, evm::EvmActor, flow_coordinator::FlowCoordinator,
-        keyholder::KeyHolder,
+        useragent_registry::UserAgentRegistry, vault::Vault,
     },
     db,
 };
 
+use kameo::actor::{ActorRef, Spawn};
+use kameo_actors::{DeliveryStrategy, message_bus::MessageBus};
+use thiserror::Error;
+
 pub mod bootstrap;
-pub mod client;
 pub mod evm;
 pub mod flow_coordinator;
-pub mod keyholder;
-pub mod user_agent;
+pub mod useragent_registry;
+pub mod vault;
 
 #[derive(Error, Debug)]
-pub enum GlobalActorsSpawnError {
+pub enum SpawnError {
     #[error("Failed to spawn Bootstrapper actor")]
-    Bootstrapper(#[from] bootstrap::BootstrappError),
+    Bootstrapper(#[from] bootstrap::Error),
 
-    #[error("Failed to spawn KeyHolder actor")]
-    KeyHolder(#[from] keyholder::KeyHolderError),
+    #[error("Failed to spawn Vault actor")]
+    Vault(#[from] vault::Error),
 }
 
 /// Long-lived actors that are shared across all connections and handle global state and operations
 #[derive(Clone)]
 pub struct GlobalActors {
-    pub key_holder: ActorRef<KeyHolder>,
+    pub vault: ActorRef<Vault>,
     pub bootstrapper: ActorRef<Bootstrapper>,
     pub flow_coordinator: ActorRef<FlowCoordinator>,
+    pub useragent_registry: ActorRef<UserAgentRegistry>,
     pub evm: ActorRef<EvmActor>,
+    pub events: ActorRef<MessageBus>,
 }
 
 impl GlobalActors {
-    pub async fn spawn(db: db::DatabasePool) -> Result<Self, GlobalActorsSpawnError> {
-        let key_holder = KeyHolder::spawn(KeyHolder::new(db.clone()).await?);
+    pub fn spawn_message_bus() -> ActorRef<MessageBus> {
+        MessageBus::spawn(MessageBus::new(DeliveryStrategy::Guaranteed))
+    }
+
+    pub async fn spawn(db: db::DatabasePool) -> Result<Self, SpawnError> {
+        let message_bus = Self::spawn_message_bus();
+        let key_holder = Vault::spawn(Vault::new(db.clone(), message_bus.clone()).await?);
+        let useragent_registry = UserAgentRegistry::spawn(UserAgentRegistry::default());
         Ok(Self {
             bootstrapper: Bootstrapper::spawn(Bootstrapper::new(&db).await?),
             evm: EvmActor::spawn(EvmActor::new(key_holder.clone(), db)),
-            key_holder,
-            flow_coordinator: FlowCoordinator::spawn(FlowCoordinator::default()),
+            vault: key_holder,
+            flow_coordinator: FlowCoordinator::spawn(FlowCoordinator::new(
+                useragent_registry.clone(),
+            )),
+            useragent_registry,
+            events: message_bus,
         })
     }
 }

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

@@ -1,308 +0,0 @@
-use arbiter_crypto::authn::{self, USERAGENT_CONTEXT};
-use arbiter_proto::transport::Bi;
-use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl, update};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-use kameo::actor::ActorRef;
-use tracing::error;
-
-use super::Error;
-use crate::{
-    actors::{
-        bootstrap::ConsumeToken,
-        keyholder::KeyHolder,
-        user_agent::{UserAgentConnection, UserAgentCredentials, auth::Outbound},
-    },
-    crypto::integrity,
-    db::{DatabasePool, schema::useragent_client},
-};
-
-pub struct ChallengeRequest {
-    pub pubkey: authn::PublicKey,
-}
-
-pub struct BootstrapAuthRequest {
-    pub pubkey: authn::PublicKey,
-    pub token: String,
-}
-
-pub struct ChallengeContext {
-    pub challenge_nonce: i32,
-    pub key: authn::PublicKey,
-}
-
-pub struct ChallengeSolution {
-    pub solution: Vec<u8>,
-}
-
-smlang::statemachine!(
-    name: Auth,
-    custom_error: true,
-    transitions: {
-        *Init + AuthRequest(ChallengeRequest) / async prepare_challenge = SentChallenge(ChallengeContext),
-        Init + BootstrapAuthRequest(BootstrapAuthRequest) / async verify_bootstrap_token = AuthOk(authn::PublicKey),
-        SentChallenge(ChallengeContext) + ReceivedSolution(ChallengeSolution) / async verify_solution = AuthOk(authn::PublicKey),
-    }
-);
-
-/// Returns the current nonce, ready to use for the challenge nonce.
-async fn get_current_nonce_and_id(
-    db: &DatabasePool,
-    key: &authn::PublicKey,
-) -> Result<(i32, i32), Error> {
-    let mut db_conn = db.get().await.map_err(|e| {
-        error!(error = ?e, "Database pool error");
-        Error::internal("Database unavailable")
-    })?;
-    db_conn
-        .exclusive_transaction(|conn| {
-            Box::pin(async move {
-                useragent_client::table
-                    .filter(useragent_client::public_key.eq(key.to_bytes()))
-                    .select((useragent_client::id, useragent_client::nonce))
-                    .first::<(i32, i32)>(conn)
-                    .await
-            })
-        })
-        .await
-        .optional()
-        .map_err(|e| {
-            error!(error = ?e, "Database error");
-            Error::internal("Database operation failed")
-        })?
-        .ok_or_else(|| {
-            error!(?key, "Public key not found in database");
-            Error::UnregisteredPublicKey
-        })
-}
-
-async fn verify_integrity(
-    db: &DatabasePool,
-    keyholder: &ActorRef<KeyHolder>,
-    pubkey: &authn::PublicKey,
-) -> Result<(), Error> {
-    let mut db_conn = db.get().await.map_err(|e| {
-        error!(error = ?e, "Database pool error");
-        Error::internal("Database unavailable")
-    })?;
-
-    let (id, nonce) = get_current_nonce_and_id(db, pubkey).await?;
-
-    let _result = integrity::verify_entity(
-        &mut db_conn,
-        keyholder,
-        &UserAgentCredentials {
-            pubkey: pubkey.clone(),
-            nonce,
-        },
-        id,
-    )
-    .await
-    .map_err(|e| {
-        error!(?e, "Integrity verification failed");
-        Error::internal("Integrity verification failed")
-    })?;
-
-    Ok(())
-}
-
-async fn create_nonce(
-    db: &DatabasePool,
-    keyholder: &ActorRef<KeyHolder>,
-    pubkey: &authn::PublicKey,
-) -> Result<i32, Error> {
-    let mut db_conn = db.get().await.map_err(|e| {
-        error!(error = ?e, "Database pool error");
-        Error::internal("Database unavailable")
-    })?;
-    let new_nonce = db_conn
-        .exclusive_transaction(|conn| {
-            Box::pin(async move {
-                let (id, new_nonce): (i32, i32) = update(useragent_client::table)
-                    .filter(useragent_client::public_key.eq(pubkey.to_bytes()))
-                    .set(useragent_client::nonce.eq(useragent_client::nonce + 1))
-                    .returning((useragent_client::id, useragent_client::nonce))
-                    .get_result(conn)
-                    .await
-                    .map_err(|e| {
-                        error!(error = ?e, "Database error");
-                        Error::internal("Database operation failed")
-                    })?;
-
-                integrity::sign_entity(
-                    conn,
-                    keyholder,
-                    &UserAgentCredentials {
-                        pubkey: pubkey.clone(),
-                        nonce: new_nonce,
-                    },
-                    id,
-                )
-                .await
-                .map_err(|e| {
-                    error!(?e, "Integrity signature update failed");
-                    Error::internal("Database error")
-                })?;
-
-                Result::<_, Error>::Ok(new_nonce)
-            })
-        })
-        .await?;
-    Ok(new_nonce)
-}
-
-async fn register_key(
-    db: &DatabasePool,
-    keyholder: &ActorRef<KeyHolder>,
-    pubkey: &authn::PublicKey,
-) -> Result<(), Error> {
-    let pubkey_bytes = pubkey.to_bytes();
-    let mut conn = db.get().await.map_err(|e| {
-        error!(error = ?e, "Database pool error");
-        Error::internal("Database unavailable")
-    })?;
-
-    conn.transaction(|conn| {
-        Box::pin(async move {
-            const NONCE_START: i32 = 1;
-
-            let id: i32 = diesel::insert_into(useragent_client::table)
-                .values((
-                    useragent_client::public_key.eq(pubkey_bytes),
-                    useragent_client::nonce.eq(NONCE_START),
-                ))
-                .returning(useragent_client::id)
-                .get_result(conn)
-                .await
-                .map_err(|e| {
-                    error!(error = ?e, "Database error");
-                    Error::internal("Database operation failed")
-                })?;
-
-            let entity = UserAgentCredentials {
-                pubkey: pubkey.clone(),
-                nonce: NONCE_START,
-            };
-
-            integrity::sign_entity(conn, keyholder, &entity, id)
-                .await
-                .map_err(|e| {
-                    error!(error = ?e, "Failed to sign integrity tag for new user-agent key");
-                    Error::internal("Failed to register public key")
-                })?;
-
-            Result::<_, Error>::Ok(())
-        })
-    })
-    .await?;
-
-    Ok(())
-}
-
-pub struct AuthContext<'a, T> {
-    pub(super) conn: &'a mut UserAgentConnection,
-    pub(super) transport: T,
-}
-
-impl<'a, T> AuthContext<'a, T> {
-    pub const fn new(conn: &'a mut UserAgentConnection, transport: T) -> Self {
-        Self { conn, transport }
-    }
-}
-
-impl<T> AuthStateMachineContext for AuthContext<'_, T>
-where
-    T: Bi<super::Inbound, Result<Outbound, Error>> + Send,
-{
-    type Error = Error;
-
-    async fn prepare_challenge(
-        &mut self,
-        ChallengeRequest { pubkey }: ChallengeRequest,
-    ) -> Result<ChallengeContext, Self::Error> {
-        verify_integrity(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;
-
-        let nonce = create_nonce(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;
-
-        self.transport
-            .send(Ok(Outbound::AuthChallenge { nonce }))
-            .await
-            .map_err(|e| {
-                error!(?e, "Failed to send auth challenge");
-                Error::Transport
-            })?;
-
-        Ok(ChallengeContext {
-            challenge_nonce: nonce,
-            key: pubkey,
-        })
-    }
-
-    async fn verify_bootstrap_token(
-        &mut self,
-        BootstrapAuthRequest { pubkey, token }: BootstrapAuthRequest,
-    ) -> Result<authn::PublicKey, Self::Error> {
-        let token_ok: bool = self
-            .conn
-            .actors
-            .bootstrapper
-            .ask(ConsumeToken {
-                token: token.clone(),
-            })
-            .await
-            .map_err(|e| {
-                error!(?e, "Failed to consume bootstrap token");
-                Error::internal("Failed to consume bootstrap token")
-            })?;
-
-        if !token_ok {
-            error!("Invalid bootstrap token provided");
-            return Err(Error::InvalidBootstrapToken);
-        }
-
-        if token_ok {
-            register_key(&self.conn.db, &self.conn.actors.key_holder, &pubkey).await?;
-            self.transport
-                .send(Ok(Outbound::AuthSuccess))
-                .await
-                .map_err(|_| Error::Transport)?;
-            Ok(pubkey)
-        } else {
-            error!("Invalid bootstrap token provided");
-            self.transport
-                .send(Err(Error::InvalidBootstrapToken))
-                .await
-                .map_err(|_| Error::Transport)?;
-            Err(Error::InvalidBootstrapToken)
-        }
-    }
-
-    async fn verify_solution(
-        &mut self,
-        ChallengeContext {
-            challenge_nonce,
-            key,
-        }: &ChallengeContext,
-        ChallengeSolution { solution }: ChallengeSolution,
-    ) -> Result<authn::PublicKey, Self::Error> {
-        let signature = authn::Signature::try_from(solution.as_slice()).map_err(|()| {
-            error!("Failed to decode signature in challenge solution");
-            Error::InvalidChallengeSolution
-        })?;
-
-        let valid = key.verify(*challenge_nonce, USERAGENT_CONTEXT, &signature);
-
-        if valid {
-            self.transport
-                .send(Ok(Outbound::AuthSuccess))
-                .await
-                .map_err(|_| Error::Transport)?;
-            Ok(key.clone())
-        } else {
-            self.transport
-                .send(Err(Error::InvalidChallengeSolution))
-                .await
-                .map_err(|_| Error::Transport)?;
-            Err(Error::InvalidChallengeSolution)
-        }
-    }
-}

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

@@ -1,40 +0,0 @@
-use crate::{
-    actors::{GlobalActors, client::ClientProfile},
-    crypto::integrity::Integrable,
-    db,
-};
-use arbiter_crypto::authn;
-
-#[derive(Debug, arbiter_macros::Hashable)]
-pub struct UserAgentCredentials {
-    pub pubkey: authn::PublicKey,
-    pub nonce: i32,
-}
-
-impl Integrable for UserAgentCredentials {
-    const KIND: &'static str = "useragent_credentials";
-}
-
-// Messages, sent by user agent to connection client without having a request
-#[derive(Debug)]
-pub enum OutOfBand {
-    ClientConnectionRequest { profile: ClientProfile },
-    ClientConnectionCancel { pubkey: authn::PublicKey },
-}
-
-pub struct UserAgentConnection {
-    pub(crate) db: db::DatabasePool,
-    pub(crate) actors: GlobalActors,
-}
-
-impl UserAgentConnection {
-    pub const fn new(db: db::DatabasePool, actors: GlobalActors) -> Self {
-        Self { db, actors }
-    }
-}
-
-pub mod auth;
-pub mod session;
-
-pub use auth::authenticate;
-pub use session::UserAgentSession;

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

@@ -1,534 +0,0 @@
-use std::sync::Mutex;
-
-use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
-use arbiter_crypto::{
-    authn,
-    safecell::{SafeCell, SafeCellHandle as _},
-};
-use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
-use diesel::{ExpressionMethods as _, QueryDsl as _, SelectableHelper};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-use kameo::error::SendError;
-use kameo::messages;
-use kameo::prelude::Context;
-use thiserror::Error;
-use tracing::{error, info};
-use x25519_dalek::{EphemeralSecret, PublicKey};
-
-use crate::{actors::flow_coordinator::client_connect_approval::ClientApprovalAnswer, evm::policies::SharedGrantSettings};
-use crate::actors::keyholder::KeyHolderState;
-use crate::actors::user_agent::session::UserAgentSessionError;
-use crate::actors::{
-    evm::{
-        ClientSignTransaction, Generate, ListWallets, SignTransactionError as EvmSignError,
-        UseragentCreateGrant, UseragentListGrants,
-    },
-    keyholder::{self, Bootstrap, TryUnseal},
-    user_agent::session::{
-        UserAgentSession,
-        state::{UnsealContext, UserAgentEvents, UserAgentStates},
-    },
-};
-use crate::db::models::{
-    EvmWalletAccess, NewEvmWalletAccess, ProgramClient, ProgramClientMetadata,
-};
-use crate::evm::policies::{Grant, SpecificGrant};
-
-impl UserAgentSession {
-    fn take_unseal_secret(&self) -> Result<(EphemeralSecret, PublicKey), UserAgentSessionError> {
-        let UserAgentStates::WaitingForUnsealKey(unseal_context) = self.state.state() else {
-            error!("Received encrypted key in invalid state");
-            return Err(UserAgentSessionError::internal(
-                "Invalid state for unseal encrypted key",
-            ));
-        };
-
-        let ephemeral_secret = {
-            #[allow(
-                clippy::unwrap_used,
-                reason = "Mutex poison is unrecoverable and should panic"
-            )]
-            let mut secret_lock = unseal_context.secret.lock().unwrap();
-            let secret = secret_lock.take();
-            if let Some(secret) = secret {
-                secret
-            } else {
-                drop(secret_lock);
-                error!("Ephemeral secret already taken");
-                return Err(UserAgentSessionError::internal(
-                    "Ephemeral secret already taken",
-                ));
-            }
-        };
-
-        Ok((ephemeral_secret, unseal_context.client_public_key))
-    }
-
-    fn decrypt_client_key_material(
-        ephemeral_secret: EphemeralSecret,
-        client_public_key: PublicKey,
-        nonce: &[u8],
-        ciphertext: &[u8],
-        associated_data: &[u8],
-    ) -> Result<SafeCell<Vec<u8>>, ()> {
-        let nonce = XNonce::from_slice(nonce);
-
-        let shared_secret = ephemeral_secret.diffie_hellman(&client_public_key);
-        let cipher = XChaCha20Poly1305::new(shared_secret.as_bytes().into());
-
-        let mut key_buffer = SafeCell::new(ciphertext.to_vec());
-
-        let decryption_result = key_buffer.write_inline(|write_handle| {
-            cipher.decrypt_in_place(nonce, associated_data, write_handle)
-        });
-
-        match decryption_result {
-            Ok(()) => Ok(key_buffer),
-            Err(err) => {
-                error!(?err, "Failed to decrypt encrypted key material");
-                Err(())
-            }
-        }
-    }
-}
-
-pub struct UnsealStartResponse {
-    pub server_pubkey: PublicKey,
-}
-
-#[derive(Debug, Error)]
-pub enum UnsealError {
-    #[error("Invalid key provided for unsealing")]
-    InvalidKey,
-    #[error("Internal error during unsealing process")]
-    General(#[from] UserAgentSessionError),
-}
-
-#[derive(Debug, Error)]
-pub enum BootstrapError {
-    #[error("Invalid key provided for bootstrapping")]
-    InvalidKey,
-    #[error("Vault is already bootstrapped")]
-    AlreadyBootstrapped,
-
-    #[error("Internal error during bootstrapping process")]
-    General(#[from] UserAgentSessionError),
-}
-
-#[derive(Debug, Error)]
-pub enum SignTransactionError {
-    #[error("Policy evaluation failed")]
-    Vet(#[from] crate::evm::VetError),
-
-    #[error("Internal signing error")]
-    Internal,
-}
-
-#[derive(Debug, Error)]
-pub enum GrantMutationError {
-    #[error("Vault is sealed")]
-    VaultSealed,
-
-    #[error("Internal grant mutation error")]
-    Internal,
-}
-
-#[messages]
-impl UserAgentSession {
-    #[message]
-    pub fn handle_unseal_request(
-        &mut self,
-        client_pubkey: PublicKey,
-    ) -> Result<UnsealStartResponse, UserAgentSessionError> {
-        let secret = EphemeralSecret::random();
-        let public_key = PublicKey::from(&secret);
-
-        self.transition(UserAgentEvents::UnsealRequest(UnsealContext {
-            client_public_key: client_pubkey,
-            secret: Mutex::new(Some(secret)),
-        }))?;
-
-        Ok(UnsealStartResponse {
-            server_pubkey: public_key,
-        })
-    }
-
-    #[message]
-    pub async fn handle_unseal_encrypted_key(
-        &mut self,
-        nonce: Vec<u8>,
-        ciphertext: Vec<u8>,
-        associated_data: Vec<u8>,
-    ) -> Result<(), UnsealError> {
-        let (ephemeral_secret, client_public_key) = match self.take_unseal_secret() {
-            Ok(values) => values,
-            Err(UserAgentSessionError::State) => {
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                return Err(UnsealError::InvalidKey);
-            }
-            Err(_err) => {
-                return Err(UserAgentSessionError::internal("Failed to take unseal secret").into());
-            }
-        };
-
-        let Ok(seal_key_buffer) = Self::decrypt_client_key_material(
-            ephemeral_secret,
-            client_public_key,
-            &nonce,
-            &ciphertext,
-            &associated_data,
-        ) else {
-            self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-            return Err(UnsealError::InvalidKey);
-        };
-
-        match self
-            .props
-            .actors
-            .key_holder
-            .ask(TryUnseal {
-                seal_key_raw: seal_key_buffer,
-            })
-            .await
-        {
-            Ok(()) => {
-                info!("Successfully unsealed key with client-provided key");
-                self.transition(UserAgentEvents::ReceivedValidKey)?;
-                Ok(())
-            }
-            Err(SendError::HandlerError(keyholder::KeyHolderError::InvalidKey)) => {
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                Err(UnsealError::InvalidKey)
-            }
-            Err(SendError::HandlerError(err)) => {
-                error!(?err, "Keyholder failed to unseal key");
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                Err(UnsealError::InvalidKey)
-            }
-            Err(err) => {
-                error!(?err, "Failed to send unseal request to keyholder");
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                Err(UserAgentSessionError::internal("Vault actor error").into())
-            }
-        }
-    }
-
-    #[message]
-    pub(crate) async fn handle_bootstrap_encrypted_key(
-        &mut self,
-        nonce: Vec<u8>,
-        ciphertext: Vec<u8>,
-        associated_data: Vec<u8>,
-    ) -> Result<(), BootstrapError> {
-        let (ephemeral_secret, client_public_key) = match self.take_unseal_secret() {
-            Ok(values) => values,
-            Err(UserAgentSessionError::State) => {
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                return Err(BootstrapError::InvalidKey);
-            }
-            Err(err) => return Err(err.into()),
-        };
-
-        let Ok(seal_key_buffer) = Self::decrypt_client_key_material(
-            ephemeral_secret,
-            client_public_key,
-            &nonce,
-            &ciphertext,
-            &associated_data,
-        ) else {
-            self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-            return Err(BootstrapError::InvalidKey);
-        };
-
-        match self
-            .props
-            .actors
-            .key_holder
-            .ask(Bootstrap {
-                seal_key_raw: seal_key_buffer,
-            })
-            .await
-        {
-            Ok(()) => {
-                info!("Successfully bootstrapped vault with client-provided key");
-                self.transition(UserAgentEvents::ReceivedValidKey)?;
-                Ok(())
-            }
-            Err(SendError::HandlerError(keyholder::KeyHolderError::AlreadyBootstrapped)) => {
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                Err(BootstrapError::AlreadyBootstrapped)
-            }
-            Err(SendError::HandlerError(err)) => {
-                error!(?err, "Keyholder failed to bootstrap vault");
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                Err(BootstrapError::InvalidKey)
-            }
-            Err(err) => {
-                error!(?err, "Failed to send bootstrap request to keyholder");
-                self.transition(UserAgentEvents::ReceivedInvalidKey)?;
-                Err(BootstrapError::General(UserAgentSessionError::internal(
-                    "Vault actor error",
-                )))
-            }
-        }
-    }
-}
-
-#[messages]
-impl UserAgentSession {
-    #[message]
-    pub(crate) async fn handle_query_vault_state(
-        &mut self,
-    ) -> Result<KeyHolderState, UserAgentSessionError> {
-        use crate::actors::keyholder::GetState;
-
-        let vault_state = match self.props.actors.key_holder.ask(GetState {}).await {
-            Ok(state) => state,
-            Err(err) => {
-                error!(?err, actor = "useragent", "keyholder.query.failed");
-                return Err(UserAgentSessionError::internal("Vault is in broken state"));
-            }
-        };
-
-        Ok(vault_state)
-    }
-}
-
-#[messages]
-impl UserAgentSession {
-    #[message]
-    pub(crate) async fn handle_evm_wallet_create(
-        &mut self,
-    ) -> Result<(i32, Address), UserAgentSessionError> {
-        match self.props.actors.evm.ask(Generate {}).await {
-            Ok(address) => Ok(address),
-            Err(SendError::HandlerError(err)) => Err(UserAgentSessionError::internal(format!(
-                "EVM wallet generation failed: {err}"
-            ))),
-            Err(err) => {
-                error!(?err, "EVM actor unreachable during wallet create");
-                Err(UserAgentSessionError::internal("EVM actor unreachable"))
-            }
-        }
-    }
-
-    #[message]
-    pub(crate) async fn handle_evm_wallet_list(
-        &mut self,
-    ) -> Result<Vec<(i32, Address)>, UserAgentSessionError> {
-        match self.props.actors.evm.ask(ListWallets {}).await {
-            Ok(wallets) => Ok(wallets),
-            Err(err) => {
-                error!(?err, "EVM wallet list failed");
-                Err(UserAgentSessionError::internal(
-                    "Failed to list EVM wallets",
-                ))
-            }
-        }
-    }
-}
-
-#[messages]
-impl UserAgentSession {
-    #[message]
-    pub(crate) async fn handle_grant_list(
-        &mut self,
-    ) -> Result<Vec<Grant<SpecificGrant>>, UserAgentSessionError> {
-        match self.props.actors.evm.ask(UseragentListGrants {}).await {
-            Ok(grants) => Ok(grants),
-            Err(err) => {
-                error!(?err, "EVM grant list failed");
-                Err(UserAgentSessionError::internal("Failed to list EVM grants"))
-            }
-        }
-    }
-
-    #[message]
-    pub(crate) async fn handle_grant_create(
-        &mut self,
-        basic: SharedGrantSettings,
-        grant: SpecificGrant,
-    ) -> Result<i32, GrantMutationError> {
-        match self
-            .props
-            .actors
-            .evm
-            .ask(UseragentCreateGrant { basic, grant })
-            .await
-        {
-            Ok(grant_id) => Ok(grant_id),
-            Err(err) => {
-                error!(?err, "EVM grant create failed");
-                Err(GrantMutationError::Internal)
-            }
-        }
-    }
-
-    #[message]
-    #[expect(clippy::unused_async, reason = "false positive")]
-    pub(crate) async fn handle_grant_delete(
-        &mut self,
-        grant_id: i32,
-    ) -> Result<(), GrantMutationError> {
-        // match self
-        //     .props
-        //     .actors
-        //     .evm
-        //     .ask(UseragentDeleteGrant { grant_id })
-        //     .await
-        // {
-        //     Ok(()) => Ok(()),
-        //     Err(err) => {
-        //         error!(?err, "EVM grant delete failed");
-        //         Err(GrantMutationError::Internal)
-        //     }
-        // }
-        let _ = grant_id;
-        todo!()
-    }
-
-    #[message]
-    pub(crate) async fn handle_sign_transaction(
-        &mut self,
-        client_id: i32,
-        wallet_address: Address,
-        transaction: TxEip1559,
-    ) -> Result<Signature, SignTransactionError> {
-        match self
-            .props
-            .actors
-            .evm
-            .ask(ClientSignTransaction {
-                client_id,
-                wallet_address,
-                transaction,
-            })
-            .await
-        {
-            Ok(signature) => Ok(signature),
-            Err(SendError::HandlerError(EvmSignError::Vet(vet_error))) => {
-                Err(SignTransactionError::Vet(vet_error))
-            }
-            Err(err) => {
-                error!(?err, "EVM sign transaction failed in user-agent session");
-                Err(SignTransactionError::Internal)
-            }
-        }
-    }
-
-    #[message]
-    pub(crate) async fn handle_grant_evm_wallet_access(
-        &mut self,
-        entries: Vec<NewEvmWalletAccess>,
-    ) -> Result<(), UserAgentSessionError> {
-        let mut conn = self.props.db.get().await?;
-        conn.transaction(|conn| {
-            Box::pin(async move {
-                use crate::db::schema::evm_wallet_access;
-
-                for entry in entries {
-                    diesel::insert_into(evm_wallet_access::table)
-                        .values(&entry)
-                        .on_conflict_do_nothing()
-                        .execute(conn)
-                        .await?;
-                }
-
-                Result::<_, UserAgentSessionError>::Ok(())
-            })
-        })
-        .await?;
-        Ok(())
-    }
-
-    #[message]
-    pub(crate) async fn handle_revoke_evm_wallet_access(
-        &mut self,
-        entries: Vec<i32>,
-    ) -> Result<(), UserAgentSessionError> {
-        let mut conn = self.props.db.get().await?;
-        conn.transaction(|conn| {
-            Box::pin(async move {
-                use crate::db::schema::evm_wallet_access;
-                for entry in entries {
-                    diesel::delete(evm_wallet_access::table)
-                        .filter(evm_wallet_access::wallet_id.eq(entry))
-                        .execute(conn)
-                        .await?;
-                }
-
-                Result::<_, UserAgentSessionError>::Ok(())
-            })
-        })
-        .await?;
-        Ok(())
-    }
-
-    #[message]
-    pub(crate) async fn handle_list_wallet_access(
-        &mut self,
-    ) -> Result<Vec<EvmWalletAccess>, UserAgentSessionError> {
-        let mut conn = self.props.db.get().await?;
-        let access_entries = crate::db::schema::evm_wallet_access::table
-            .select(EvmWalletAccess::as_select())
-            .load::<_>(&mut conn)
-            .await?;
-        Ok(access_entries)
-    }
-}
-
-#[messages]
-impl UserAgentSession {
-    #[message(ctx)]
-    pub(crate) async fn handle_new_client_approve(
-        &mut self,
-        approved: bool,
-        pubkey: authn::PublicKey,
-        ctx: &Context<Self, Result<(), UserAgentSessionError>>,
-    ) -> Result<(), UserAgentSessionError> {
-        let Some(pending_approval) = self.pending_client_approvals.remove(&pubkey.to_bytes())
-        else {
-            error!("Received client connection response for unknown client");
-            return Err(UserAgentSessionError::internal(
-                "Unknown client in connection response",
-            ));
-        };
-
-        pending_approval
-            .controller
-            .tell(ClientApprovalAnswer { approved })
-            .await
-            .map_err(|err| {
-                error!(
-                    ?err,
-                    "Failed to send client approval response to controller"
-                );
-                UserAgentSessionError::internal(
-                    "Failed to send client approval response to controller",
-                )
-            })?;
-
-        ctx.actor_ref().unlink(&pending_approval.controller).await;
-
-        Ok(())
-    }
-
-    #[message]
-    pub(crate) async fn handle_sdk_client_list(
-        &mut self,
-    ) -> Result<Vec<(ProgramClient, ProgramClientMetadata)>, UserAgentSessionError> {
-        use crate::db::schema::{client_metadata, program_client};
-        let mut conn = self.props.db.get().await?;
-
-        let clients = program_client::table
-            .inner_join(client_metadata::table)
-            .select((
-                ProgramClient::as_select(),
-                ProgramClientMetadata::as_select(),
-            ))
-            .load::<(ProgramClient, ProgramClientMetadata)>(&mut conn)
-            .await?;
-
-        Ok(clients)
-    }
-}

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

@@ -1,25 +0,0 @@
-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 {
-    fn generate_temp_keypair(&mut self, event_data: UnsealContext) -> Result<UnsealContext, ()> {
-        Ok(event_data)
-    }
-}

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

@@ -0,0 +1,61 @@
+use crate::peers::user_agent::UserAgentSession;
+
+use kameo::{
+    Actor,
+    actor::{ActorId, ActorRef},
+    error::Infallible,
+    messages,
+    prelude::{ActorStopReason, Context, WeakActorRef},
+};
+use std::{collections::HashMap, ops::ControlFlow};
+use tracing::info;
+
+#[derive(Default)]
+pub struct UserAgentRegistry {
+    connected: HashMap<ActorId, ActorRef<UserAgentSession>>,
+}
+
+impl Actor for UserAgentRegistry {
+    type Args = Self;
+
+    type Error = Infallible;
+
+    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.connected.remove(&id).is_some() {
+            info!(
+                ?id,
+                actor = "UserAgentRegistry",
+                event = "useragent.disconnected"
+            );
+        }
+        Ok(ControlFlow::Continue(()))
+    }
+}
+
+#[messages]
+impl UserAgentRegistry {
+    #[message(ctx)]
+    pub async fn connect_useragent(
+        &mut self,
+        actor: ActorRef<UserAgentSession>,
+        ctx: &mut Context<Self, ()>,
+    ) {
+        info!(id = %actor.id(), actor = "UserAgentRegistry", event = "useragent.connected");
+        ctx.actor_ref().link(&actor).await;
+        self.connected.insert(actor.id(), actor);
+    }
+
+    #[message]
+    pub fn get_connected(&self) -> Vec<ActorRef<UserAgentSession>> {
+        self.connected.values().cloned().collect()
+    }
+}

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

@@ -1,47 +1,57 @@
+use crate::{
+    crypto::{
+        KeyCell, derive_key,
+        encryption::v1::{self, Nonce},
+        integrity::v1::HmacSha256,
+    },
+    db::{
+        self,
+        models::{self, RootKeyHistory},
+        schema::{self},
+    },
+};
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+
 use chrono::Utc;
 use diesel::{
     ExpressionMethods as _, OptionalExtension, QueryDsl, SelectableHelper,
     dsl::{insert_into, update},
 };
 use diesel_async::{AsyncConnection, RunQueryDsl};
-use hmac::Mac as _;
-use kameo::{Actor, Reply, messages};
+use hmac::{KeyInit as _, Mac as _};
+use kameo::{Actor, Reply, actor::ActorRef, messages};
+use kameo_actors::message_bus::{MessageBus, Publish};
 use strum::{EnumDiscriminants, IntoDiscriminant};
 use tracing::{error, info};
 
-use crate::crypto::{
-    KeyCell, derive_key,
-    encryption::v1::{self, Nonce},
-    integrity::v1::HmacSha256,
-};
-use crate::db::{
-    self,
-    models::{self, RootKeyHistory},
-    schema::{self},
-};
-use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+pub mod events {
 
-#[derive(Default, EnumDiscriminants)]
-#[strum_discriminants(derive(Reply), vis(pub), name(KeyHolderState))]
-enum State {
-    #[default]
-    Unbootstrapped,
-    Sealed {
-        root_key_history_id: i32,
-    },
-    Unsealed {
-        root_key_history_id: i32,
-        root_key: KeyCell,
-    },
+    #[derive(Clone, Copy)]
+    pub struct Bootstrapped;
+
+    #[derive(Clone, Copy)]
+    pub struct Unsealed;
+
+    #[derive(Clone, Copy)]
+    pub struct VaultResealed;
 }
 
 #[derive(Debug, thiserror::Error)]
-pub enum KeyHolderError {
-    #[error("Keyholder is already bootstrapped")]
+pub enum Error {
+    #[error("Vault is already bootstrapped")]
     AlreadyBootstrapped,
+    #[error("Vault is not bootstrapped")]
+    NotBootstrapped,
+    #[error("Vault is sealed")]
+    Sealed,
+    #[error("Invalid key provided")]
+    InvalidKey,
 
-    #[error("Broken database")]
-    BrokenDatabase,
+    #[error("Requested aead entry not found")]
+    NotFound,
+
+    #[error("Encryption error: {0}")]
+    Encryption(#[from] chacha20poly1305::aead::Error),
 
     #[error("Database error: {0}")]
     DatabaseConnection(#[from] db::PoolError),
@@ -49,17 +59,24 @@ pub enum KeyHolderError {
     #[error("Database transaction error: {0}")]
     DatabaseTransaction(#[from] diesel::result::Error),
 
-    #[error("Encryption error: {0}")]
-    Encryption(#[from] chacha20poly1305::aead::Error),
+    #[error("Broken database")]
+    BrokenDatabase,
+}
 
-    #[error("Invalid key provided")]
-    InvalidKey,
+struct Unsealed {
+    root_key_history_id: i32,
+    root_key: KeyCell,
+}
 
-    #[error("Keyholder is not bootstrapped")]
-    NotBootstrapped,
-
-    #[error("Requested aead entry not found")]
-    NotFound,
+#[derive(Default, EnumDiscriminants)]
+#[strum_discriminants(derive(Reply), vis(pub), name(VaultState))]
+enum State {
+    #[default]
+    Unbootstrapped,
+    Sealed {
+        root_key_history_id: i32,
+    },
+    Unsealed(Unsealed),
 }
 
 /// Manages vault root key and tracks current state of the vault (bootstrapped/unbootstrapped, sealed/unsealed).
@@ -67,14 +84,15 @@ pub enum KeyHolderError {
 /// Provides API for encrypting and decrypting data using the vault root key.
 /// Abstraction over database to make sure nonces are never reused and encryption keys are never exposed in plaintext outside of this actor.
 #[derive(Actor)]
-pub struct KeyHolder {
+pub struct Vault {
     db: db::DatabasePool,
     state: State,
+    events: ActorRef<MessageBus>,
 }
 
 #[messages]
-impl KeyHolder {
-    pub async fn new(db: db::DatabasePool) -> Result<Self, KeyHolderError> {
+impl Vault {
+    pub async fn new(db: db::DatabasePool, events: ActorRef<MessageBus>) -> Result<Self, Error> {
         let state = {
             let mut conn = db.get().await?;
 
@@ -92,15 +110,12 @@ impl KeyHolder {
             }
         };
 
-        Ok(Self { db, state })
+        Ok(Self { db, state, events })
     }
 
-    // Exclusive transaction to avoid race condtions if multiple keyholders write
+    // Exclusive transaction to avoid race condtions if multiple vaults write
     // additional layer of protection against nonce-reuse
-    async fn get_new_nonce(
-        pool: &db::DatabasePool,
-        root_key_id: i32,
-    ) -> Result<Nonce, KeyHolderError> {
+    async fn get_new_nonce(pool: &db::DatabasePool, root_key_id: i32) -> Result<Nonce, Error> {
         let mut conn = pool.get().await?;
 
         let nonce = conn
@@ -117,7 +132,7 @@ impl KeyHolder {
                             "Broken database: invalid nonce for root key history id={}",
                             root_key_id
                         );
-                        KeyHolderError::BrokenDatabase
+                        Error::BrokenDatabase
                     })?;
                     nonce.increment();
 
@@ -127,7 +142,7 @@ impl KeyHolder {
                         .execute(conn)
                         .await?;
 
-                    Result::<_, KeyHolderError>::Ok(nonce)
+                    Result::<_, Error>::Ok(nonce)
                 })
             })
             .await?;
@@ -135,13 +150,18 @@ impl KeyHolder {
         Ok(nonce)
     }
 
+    const fn expect_unsealed(state: &mut State) -> Result<&mut Unsealed, Error> {
+        match state {
+            State::Unsealed(unsealed) => Ok(unsealed),
+            State::Unbootstrapped => Err(Error::NotBootstrapped),
+            State::Sealed { .. } => Err(Error::Sealed),
+        }
+    }
+
     #[message]
-    pub async fn bootstrap(
-        &mut self,
-        seal_key_raw: SafeCell<Vec<u8>>,
-    ) -> Result<(), KeyHolderError> {
+    pub async fn bootstrap(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
         if !matches!(self.state, State::Unbootstrapped) {
-            return Err(KeyHolderError::AlreadyBootstrapped);
+            return Err(Error::AlreadyBootstrapped);
         }
         let salt = v1::generate_salt();
         let mut seal_key = derive_key(seal_key_raw, &salt);
@@ -157,7 +177,7 @@ impl KeyHolder {
                 .encrypt(&root_key_nonce, v1::ROOT_KEY_TAG, root_key_reader)
                 .map_err(|err| {
                     error!(?err, "Fatal bootstrap error");
-                    KeyHolderError::Encryption(err)
+                    Error::Encryption(err)
                 })
         })?;
 
@@ -190,26 +210,24 @@ impl KeyHolder {
             })
             .await?;
 
-        self.state = State::Unsealed {
+        self.state = State::Unsealed(Unsealed {
             root_key,
             root_key_history_id,
-        };
+        });
 
-        info!("Keyholder bootstrapped successfully");
+        info!("Vault bootstrapped successfully");
+        let _ = self.events.tell(Publish(events::Bootstrapped)).await;
 
         Ok(())
     }
 
     #[message]
-    pub async fn try_unseal(
-        &mut self,
-        seal_key_raw: SafeCell<Vec<u8>>,
-    ) -> Result<(), KeyHolderError> {
+    pub async fn try_unseal(&mut self, seal_key_raw: SafeCell<Vec<u8>>) -> Result<(), Error> {
         let State::Sealed {
             root_key_history_id,
         } = &self.state
         else {
-            return Err(KeyHolderError::NotBootstrapped);
+            return Err(Error::NotBootstrapped);
         };
 
         // We don't want to hold connection while doing expensive KDF work
@@ -225,44 +243,42 @@ impl KeyHolder {
         let salt = &current_key.salt;
         let salt = v1::Salt::try_from(salt.as_slice()).map_err(|_| {
             error!("Broken database: invalid salt for root key");
-            KeyHolderError::BrokenDatabase
+            Error::BrokenDatabase
         })?;
         let mut seal_key = derive_key(seal_key_raw, &salt);
 
         let mut root_key = SafeCell::new(current_key.ciphertext.clone());
 
-        let nonce = Nonce::try_from(current_key.root_key_encryption_nonce.as_slice()).map_err(
-            |()| {
+        let nonce =
+            Nonce::try_from(current_key.root_key_encryption_nonce.as_slice()).map_err(|()| {
                 error!("Broken database: invalid nonce for root key");
-                KeyHolderError::BrokenDatabase
-            },
-        )?;
+                Error::BrokenDatabase
+            })?;
 
         seal_key
             .decrypt_in_place(&nonce, v1::ROOT_KEY_TAG, &mut root_key)
             .map_err(|err| {
                 error!(?err, "Failed to unseal root key: invalid seal key");
-                KeyHolderError::InvalidKey
+                Error::InvalidKey
             })?;
 
-        self.state = State::Unsealed {
+        self.state = State::Unsealed(Unsealed {
             root_key_history_id: current_key.id,
             root_key: KeyCell::try_from(root_key).map_err(|err| {
                 error!(?err, "Broken database: invalid encryption key size");
-                KeyHolderError::BrokenDatabase
+                Error::BrokenDatabase
             })?,
-        };
+        });
 
-        info!("Keyholder unsealed successfully");
+        info!("Vault unsealed successfully");
+        let _ = self.events.tell(Publish(events::Unsealed)).await;
 
         Ok(())
     }
 
     #[message]
-    pub async fn decrypt(&mut self, aead_id: i32) -> Result<SafeCell<Vec<u8>>, KeyHolderError> {
-        let State::Unsealed { root_key, .. } = &mut self.state else {
-            return Err(KeyHolderError::NotBootstrapped);
-        };
+    pub async fn decrypt(&mut self, aead_id: i32) -> Result<SafeCell<Vec<u8>>, Error> {
+        let Unsealed { root_key, .. } = Self::expect_unsealed(&mut self.state)?;
 
         let row: models::AeadEncrypted = {
             let mut conn = self.db.get().await?;
@@ -272,7 +288,7 @@ impl KeyHolder {
                 .first(&mut conn)
                 .await
                 .optional()?
-                .ok_or(KeyHolderError::NotFound)?
+                .ok_or(Error::NotFound)?
         };
 
         let nonce = Nonce::try_from(row.current_nonce.as_slice()).map_err(|()| {
@@ -280,7 +296,7 @@ impl KeyHolder {
                 "Broken database: invalid nonce for aead_encrypted id={}",
                 aead_id
             );
-            KeyHolderError::BrokenDatabase
+            Error::BrokenDatabase
         })?;
         let mut output = SafeCell::new(row.ciphertext);
         root_key.decrypt_in_place(&nonce, v1::TAG, &mut output)?;
@@ -289,18 +305,11 @@ impl KeyHolder {
 
     // Creates new `aead_encrypted` entry in the database and returns it's ID
     #[message]
-    pub async fn create_new(
-        &mut self,
-        mut plaintext: SafeCell<Vec<u8>>,
-    ) -> Result<i32, KeyHolderError> {
-        let State::Unsealed {
+    pub async fn create_new(&mut self, mut plaintext: SafeCell<Vec<u8>>) -> Result<i32, Error> {
+        let Unsealed {
             root_key,
             root_key_history_id,
-            ..
-        } = &mut self.state
-        else {
-            return Err(KeyHolderError::NotBootstrapped);
-        };
+        } = Self::expect_unsealed(&mut self.state)?;
 
         // Order matters here - `get_new_nonce` acquires connection, so we need to call it before next acquire
         // Borrow checker note: &mut borrow a few lines above is disjoint from this field
@@ -330,23 +339,22 @@ impl KeyHolder {
     }
 
     #[message]
-    pub fn get_state(&self) -> KeyHolderState {
+    pub fn get_state(&self) -> VaultState {
         self.state.discriminant()
     }
 
     #[message]
-    pub fn sign_integrity(&mut self, mac_input: Vec<u8>) -> Result<(i32, Vec<u8>), KeyHolderError> {
-        let State::Unsealed {
+    pub fn sign_integrity(&mut self, mac_input: Vec<u8>) -> Result<(i32, Vec<u8>), Error> {
+        let Unsealed {
             root_key,
             root_key_history_id,
-        } = &mut self.state
-        else {
-            return Err(KeyHolderError::NotBootstrapped);
-        };
+        } = Self::expect_unsealed(&mut self.state)?;
 
-        let mut hmac = root_key.0.read_inline(|k| {
-            HmacSha256::new_from_slice(k)
-                .unwrap_or_else(|_| unreachable!("HMAC accepts keys of any size"))
+        let mut hmac = root_key
+            .0
+            .read_inline(|k| match HmacSha256::new_from_slice(k) {
+                Ok(v) => v,
+                Err(_) => unreachable!("HMAC accepts keys of any size"),
             });
         hmac.update(&root_key_history_id.to_be_bytes());
         hmac.update(&mac_input);
@@ -361,22 +369,21 @@ impl KeyHolder {
         mac_input: Vec<u8>,
         expected_mac: Vec<u8>,
         key_version: i32,
-    ) -> Result<bool, KeyHolderError> {
-        let State::Unsealed {
+    ) -> Result<bool, Error> {
+        let Unsealed {
             root_key,
             root_key_history_id,
-        } = &mut self.state
-        else {
-            return Err(KeyHolderError::NotBootstrapped);
-        };
+        } = Self::expect_unsealed(&mut self.state)?;
 
         if *root_key_history_id != key_version {
             return Ok(false);
         }
 
-        let mut hmac = root_key.0.read_inline(|k| {
-            HmacSha256::new_from_slice(k)
-                .unwrap_or_else(|_| unreachable!("HMAC accepts keys of any size"))
+        let mut hmac = root_key
+            .0
+            .read_inline(|k| match HmacSha256::new_from_slice(k) {
+                Ok(v) => v,
+                Err(_) => unreachable!("HMAC accepts keys of any size"),
             });
         hmac.update(&key_version.to_be_bytes());
         hmac.update(&mac_input);
@@ -385,29 +392,31 @@ impl KeyHolder {
     }
 
     #[message]
-    pub fn seal(&mut self) -> Result<(), KeyHolderError> {
-        let State::Unsealed {
+    pub async fn seal(&mut self) -> Result<(), Error> {
+        let Unsealed {
             root_key_history_id,
             ..
-        } = &self.state
-        else {
-            return Err(KeyHolderError::NotBootstrapped);
-        };
+        } = Self::expect_unsealed(&mut self.state)?;
+
         self.state = State::Sealed {
             root_key_history_id: *root_key_history_id,
         };
+        let _ = self.events.tell(Publish(events::VaultResealed)).await;
         Ok(())
     }
 }
 
 #[cfg(test)]
 mod tests {
+    use crate::actors::GlobalActors;
     use arbiter_crypto::safecell::SafeCellHandle as _;
 
     use super::*;
 
-    async fn bootstrapped_actor(db: &db::DatabasePool) -> KeyHolder {
-        let mut actor = KeyHolder::new(db.clone()).await.unwrap();
+    async fn bootstrapped_actor(db: &db::DatabasePool) -> Vault {
+        let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
+            .await
+            .unwrap();
         let seal_key = SafeCell::new(b"test-seal-key".to_vec());
         actor.bootstrap(seal_key).await.unwrap();
         actor
@@ -418,25 +427,25 @@ mod tests {
     async fn nonce_monotonic_even_when_nonce_allocation_interleaves() {
         let db = db::create_test_pool().await;
         let mut actor = bootstrapped_actor(&db).await;
-        let State::Unsealed {
+        let root_key_history_id = match actor.state {
+            State::Unsealed(Unsealed {
                 root_key_history_id,
                 ..
-        } = actor.state
-        else {
-            panic!("expected unsealed state");
+            }) => root_key_history_id,
+            _ => panic!("expected unsealed state"),
         };
 
-        let n1 = KeyHolder::get_new_nonce(&db, root_key_history_id)
+        let n1 = Vault::get_new_nonce(&db, root_key_history_id)
             .await
             .unwrap();
-        let n2 = KeyHolder::get_new_nonce(&db, root_key_history_id)
+        let n2 = Vault::get_new_nonce(&db, root_key_history_id)
             .await
             .unwrap();
         assert!(n2.to_vec() > n1.to_vec(), "nonce must increase");
 
         let mut conn = db.get().await.unwrap();
-        let root_row = schema::root_key_history::table
-            .select(RootKeyHistory::as_select())
+        let root_row: models::RootKeyHistory = schema::root_key_history::table
+            .select(models::RootKeyHistory::as_select())
             .first(&mut conn)
             .await
             .unwrap();

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

@@ -1,13 +1,12 @@
-use std::sync::Arc;
-
-use thiserror::Error;
-
 use crate::{
     actors::GlobalActors,
     context::tls::TlsManager,
     db::{self},
 };
 
+use std::sync::Arc;
+use thiserror::Error;
+
 pub mod tls;
 
 #[derive(Error, Debug)]
@@ -25,7 +24,7 @@ pub enum InitError {
     Tls(#[from] tls::InitError),
 
     #[error("Actor spawn failed: {0}")]
-    ActorSpawn(#[from] crate::actors::GlobalActorsSpawnError),
+    ActorSpawn(#[from] crate::actors::SpawnError),
 
     #[error("I/O Error: {0}")]
     Io(#[from] std::io::Error),

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

@@ -1,17 +1,3 @@
-use std::{net::Ipv4Addr, string::FromUtf8Error};
-
-use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper as _};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-
-use pem::Pem;
-use rcgen::{
-    BasicConstraints, Certificate, CertificateParams, CertifiedIssuer, DistinguishedName, DnType,
-    IsCa, Issuer, KeyPair, KeyUsagePurpose, SanType,
-};
-use rustls::pki_types::pem::PemObject;
-use thiserror::Error;
-use tonic::transport::CertificateDer;
-
 use crate::db::{
     self,
     models::{NewTlsHistory, TlsHistory},
@@ -21,6 +7,18 @@ use crate::db::{
     },
 };
 
+use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper as _};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use pem::Pem;
+use rcgen::{
+    BasicConstraints, Certificate, CertificateParams, CertifiedIssuer, DistinguishedName, DnType,
+    IsCa, Issuer, KeyPair, KeyUsagePurpose, SanType,
+};
+use rustls::pki_types::pem::PemObject;
+use std::{net::Ipv4Addr, string::FromUtf8Error};
+use thiserror::Error;
+use tonic::transport::CertificateDer;
+
 const ENCODE_CONFIG: pem::EncodeConfig = {
     let line_ending = if cfg!(target_family = "windows") {
         pem::LineEnding::CRLF

server/crates/arbiter-server/src/crypto/encryption/v1.rs

@@ -1,5 +1,4 @@
 use argon2::password_hash::Salt as ArgonSalt;
-
 use rand::{
     Rng as _, SeedableRng,
     rngs::{StdRng, SysRng},
@@ -60,7 +59,7 @@ mod tests {
     use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 
     #[test]
-    pub fn derive_seal_key_deterministic() {
+    fn derive_seal_key_deterministic() {
         static PASSWORD: &[u8] = b"password";
         let password = SafeCell::new(PASSWORD.to_vec());
         let password2 = SafeCell::new(PASSWORD.to_vec());
@@ -76,7 +75,7 @@ mod tests {
     }
 
     #[test]
-    pub fn successful_derive() {
+    fn successful_derive() {
         static PASSWORD: &[u8] = b"password";
         let password = SafeCell::new(PASSWORD.to_vec());
         let salt = generate_salt();

server/crates/arbiter-server/src/crypto/integrity/v1.rs

@@ -1,32 +1,29 @@
-use crate::actors::keyholder;
-use arbiter_crypto::hashing::Hashable;
-use hmac::Hmac;
-use sha2::Sha256;
-
-use diesel::{ExpressionMethods as _, QueryDsl, dsl::insert_into, sqlite::Sqlite};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-use kameo::{actor::ActorRef, error::SendError};
-use sha2::Digest as _;
-
 use crate::{
-    actors::keyholder::{KeyHolder, SignIntegrity, VerifyIntegrity},
+    actors::vault::{self, GetState, SignIntegrity, Vault, VerifyIntegrity},
     db::{
         self,
         models::{IntegrityEnvelope, NewIntegrityEnvelope},
         schema::integrity_envelope,
     },
 };
+use arbiter_crypto::hashing::Hashable;
+
+use diesel::{ExpressionMethods as _, QueryDsl, dsl::insert_into, sqlite::Sqlite};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use hmac::Hmac;
+use kameo::{actor::ActorRef, error::SendError};
+use sha2::{Digest as _, Sha256};
 
 #[derive(Debug, thiserror::Error)]
-pub enum IntegrityError {
+pub enum Error {
     #[error("Database error: {0}")]
     Database(#[from] db::DatabaseError),
 
-    #[error("KeyHolder error: {0}")]
-    Keyholder(#[from] keyholder::KeyHolderError),
+    #[error("Vault error: {0}")]
+    Vault(#[from] vault::Error),
 
-    #[error("KeyHolder mailbox error")]
-    KeyholderSend,
+    #[error("Vault mailbox error")]
+    VaultSend,
 
     #[error("Integrity envelope is missing for entity {entity_kind}")]
     MissingEnvelope { entity_kind: &'static str },
@@ -108,22 +105,23 @@ impl IntoId for &'_ [u8] {
 
 pub async fn sign_entity<E: Integrable>(
     conn: &mut impl AsyncConnection<Backend = Sqlite>,
-    keyholder: &ActorRef<KeyHolder>,
+    vault: &ActorRef<Vault>,
     entity: &E,
     entity_id: impl IntoId,
-) -> Result<(), IntegrityError> {
+) -> Result<(), Error> {
     let payload_hash = payload_hash(&entity);
 
     let entity_id = entity_id.into_id();
 
     let mac_input = build_mac_input(E::KIND, &entity_id, E::VERSION, &payload_hash);
 
-    let (key_version, mac) = keyholder
+    let (key_version, mac) =
+        vault
             .ask(SignIntegrity { mac_input })
             .await
             .map_err(|err| match err {
-            SendError::HandlerError(inner) => IntegrityError::Keyholder(inner),
-            _ => IntegrityError::KeyholderSend,
+                SendError::HandlerError(inner) => Error::Vault(inner),
+                _ => Error::VaultSend,
             })?;
 
     insert_into(integrity_envelope::table)
@@ -153,10 +151,10 @@ pub async fn sign_entity<E: Integrable>(
 
 pub async fn verify_entity<E: Integrable>(
     conn: &mut impl AsyncConnection<Backend = Sqlite>,
-    keyholder: &ActorRef<KeyHolder>,
+    vault: &ActorRef<Vault>,
     entity: &E,
     entity_id: impl IntoId,
-) -> Result<AttestationStatus, IntegrityError> {
+) -> Result<AttestationStatus, Error> {
     let entity_id = entity_id.into_id();
     let envelope: IntegrityEnvelope = integrity_envelope::table
         .filter(integrity_envelope::entity_kind.eq(E::KIND))
@@ -164,14 +162,14 @@ pub async fn verify_entity<E: Integrable>(
         .first(conn)
         .await
         .map_err(|err| match err {
-            diesel::result::Error::NotFound => IntegrityError::MissingEnvelope {
+            diesel::result::Error::NotFound => Error::MissingEnvelope {
                 entity_kind: E::KIND,
             },
-            other => IntegrityError::Database(db::DatabaseError::from(other)),
+            other => Error::Database(db::DatabaseError::from(other)),
         })?;
 
     if envelope.payload_version != E::VERSION {
-        return Err(IntegrityError::PayloadVersionMismatch {
+        return Err(Error::PayloadVersionMismatch {
             entity_kind: E::KIND,
             expected: E::VERSION,
             found: envelope.payload_version,
@@ -181,7 +179,7 @@ pub async fn verify_entity<E: Integrable>(
     let payload_hash = payload_hash(&entity);
     let mac_input = build_mac_input(E::KIND, &entity_id, envelope.payload_version, &payload_hash);
 
-    let result = keyholder
+    let result = vault
         .ask(VerifyIntegrity {
             mac_input,
             expected_mac: envelope.mac,
@@ -191,16 +189,19 @@ pub async fn verify_entity<E: Integrable>(
 
     match result {
         Ok(true) => Ok(AttestationStatus::Attested),
-        Ok(false) => Err(IntegrityError::MacMismatch {
+        Ok(false) => Err(Error::MacMismatch {
             entity_kind: E::KIND,
         }),
-        Err(SendError::HandlerError(keyholder::KeyHolderError::NotBootstrapped)) => {
-            Ok(AttestationStatus::Unavailable)
-        }
-        Err(_) => Err(IntegrityError::KeyholderSend),
+        Err(SendError::HandlerError(vault::Error::Sealed)) => Ok(AttestationStatus::Unavailable),
+        Err(_) => Err(Error::VaultSend),
     }
 }
 
+pub async fn is_signing_available(vault: &ActorRef<Vault>) -> Result<bool, Error> {
+    let state = vault.ask(GetState).await.map_err(|_| Error::VaultSend)?;
+    Ok(matches!(state, vault::VaultState::Unsealed))
+}
+
 #[cfg(test)]
 mod tests {
     use diesel::{ExpressionMethods as _, QueryDsl};
@@ -208,12 +209,15 @@ mod tests {
     use kameo::{actor::ActorRef, prelude::Spawn};
 
     use crate::{
-        actors::keyholder::{Bootstrap, KeyHolder},
+        actors::{
+            GlobalActors,
+            vault::{Bootstrap, Vault},
+        },
         db::{self, schema},
     };
     use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 
-    use super::{Integrable, IntegrityError, sign_entity, verify_entity};
+    use super::{Error, Integrable, sign_entity, verify_entity};
     #[derive(Clone, arbiter_macros::Hashable)]
     struct DummyEntity {
         payload_version: i32,
@@ -223,8 +227,12 @@ mod tests {
         const KIND: &'static str = "dummy_entity";
     }
 
-    async fn bootstrapped_keyholder(db: &db::DatabasePool) -> ActorRef<KeyHolder> {
-        let actor = KeyHolder::spawn(KeyHolder::new(db.clone()).await.unwrap());
+    async fn bootstrapped_vault(db: &db::DatabasePool) -> ActorRef<Vault> {
+        let actor = Vault::spawn(
+            Vault::new(db.clone(), GlobalActors::spawn_message_bus())
+                .await
+                .unwrap(),
+        );
         actor
             .ask(Bootstrap {
                 seal_key_raw: SafeCell::new(b"integrity-test-seal-key".to_vec()),
@@ -239,7 +247,7 @@ mod tests {
         const ENTITY_ID: &[u8] = b"entity-id-7";
 
         let db = db::create_test_pool().await;
-        let keyholder = bootstrapped_keyholder(&db).await;
+        let vault = bootstrapped_vault(&db).await;
         let mut conn = db.get().await.unwrap();
 
         let entity = DummyEntity {
@@ -247,7 +255,7 @@ mod tests {
             payload: b"payload-v1".to_vec(),
         };
 
-        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+        sign_entity(&mut conn, &vault, &entity, ENTITY_ID)
             .await
             .unwrap();
 
@@ -260,7 +268,7 @@ mod tests {
             .unwrap();
 
         assert_eq!(count, 1, "envelope row must be created exactly once");
-        verify_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+        verify_entity(&mut conn, &vault, &entity, ENTITY_ID)
             .await
             .unwrap();
     }
@@ -270,7 +278,7 @@ mod tests {
         const ENTITY_ID: &[u8] = b"entity-id-11";
 
         let db = db::create_test_pool().await;
-        let keyholder = bootstrapped_keyholder(&db).await;
+        let vault = bootstrapped_vault(&db).await;
         let mut conn = db.get().await.unwrap();
 
         let entity = DummyEntity {
@@ -278,7 +286,7 @@ mod tests {
             payload: b"payload-v1".to_vec(),
         };
 
-        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+        sign_entity(&mut conn, &vault, &entity, ENTITY_ID)
             .await
             .unwrap();
 
@@ -290,10 +298,10 @@ mod tests {
             .await
             .unwrap();
 
-        let err = verify_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+        let err = verify_entity(&mut conn, &vault, &entity, ENTITY_ID)
             .await
             .unwrap_err();
-        assert!(matches!(err, IntegrityError::MacMismatch { .. }));
+        assert!(matches!(err, Error::MacMismatch { .. }));
     }
 
     #[tokio::test]
@@ -301,7 +309,7 @@ mod tests {
         const ENTITY_ID: &[u8] = b"entity-id-21";
 
         let db = db::create_test_pool().await;
-        let keyholder = bootstrapped_keyholder(&db).await;
+        let vault = bootstrapped_vault(&db).await;
         let mut conn = db.get().await.unwrap();
 
         let entity = DummyEntity {
@@ -309,7 +317,7 @@ mod tests {
             payload: b"payload-v1".to_vec(),
         };
 
-        sign_entity(&mut conn, &keyholder, &entity, ENTITY_ID)
+        sign_entity(&mut conn, &vault, &entity, ENTITY_ID)
             .await
             .unwrap();
 
@@ -318,9 +326,9 @@ mod tests {
             ..entity
         };
 
-        let err = verify_entity(&mut conn, &keyholder, &tampered, ENTITY_ID)
+        let err = verify_entity(&mut conn, &vault, &tampered, ENTITY_ID)
             .await
             .unwrap_err();
-        assert!(matches!(err, IntegrityError::MacMismatch { .. }));
+        assert!(matches!(err, Error::MacMismatch { .. }));
     }
 }

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

@@ -1,3 +1,6 @@
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use encryption::v1::{Nonce, Salt};
+
 use argon2::{Algorithm, Argon2};
 use chacha20poly1305::{
     AeadInPlace, Key, KeyInit as _, XChaCha20Poly1305, XNonce,
@@ -8,13 +11,9 @@ use rand::{
     rngs::{StdRng, SysRng},
 };
 
-use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
-
 pub mod encryption;
 pub mod integrity;
 
-use encryption::v1::{Nonce, Salt};
-
 pub struct KeyCell(pub SafeCell<Key>);
 impl From<SafeCell<Key>> for KeyCell {
     fn from(value: SafeCell<Key>) -> Self {
@@ -131,7 +130,7 @@ mod tests {
     use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 
     #[test]
-    pub fn encrypt_decrypt() {
+    fn encrypt_decrypt() {
         static PASSWORD: &[u8] = b"password";
         let password = SafeCell::new(PASSWORD.to_vec());
         let salt = generate_salt();

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

@@ -5,7 +5,6 @@ use diesel_async::{
     sync_connection_wrapper::SyncConnectionWrapper,
 };
 use diesel_migrations::{EmbeddedMigrations, MigrationHarness, embed_migrations};
-
 use thiserror::Error;
 use tracing::info;
 

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

@@ -2,13 +2,13 @@
     clippy::duplicated_attributes,
     reason = "restructed's #[view] causes false positives"
 )]
-
 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,
     integrity_envelope, root_key_history, tls_history,
 };
+
 use diesel::{prelude::*, sqlite::Sqlite};
 use restructed::Models;
 
@@ -241,7 +241,6 @@ pub struct ProgramClientMetadataHistory {
 #[diesel(table_name = schema::program_client, check_for_backend(Sqlite))]
 pub struct ProgramClient {
     pub id: i32,
-    pub nonce: i32,
     pub public_key: Vec<u8>,
     pub metadata_id: i32,
     pub created_at: SqliteTimestamp,
@@ -252,7 +251,6 @@ pub struct ProgramClient {
 #[diesel(table_name = schema::useragent_client, check_for_backend(Sqlite))]
 pub struct UseragentClient {
     pub id: i32,
-    pub nonce: i32,
     pub public_key: Vec<u8>,
     pub created_at: SqliteTimestamp,
     pub updated_at: SqliteTimestamp,

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

@@ -155,7 +155,6 @@ diesel::table! {
 diesel::table! {
     program_client (id) {
         id -> Integer,
-        nonce -> Integer,
         public_key -> Binary,
         metadata_id -> Integer,
         created_at -> Integer,
@@ -189,9 +188,7 @@ diesel::table! {
 diesel::table! {
     useragent_client (id) {
         id -> Integer,
-        nonce -> Integer,
         public_key -> Binary,
-        key_type -> Integer,
         created_at -> Integer,
         updated_at -> Integer,
     }

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

@@ -1,17 +1,5 @@
-pub mod abi;
-pub mod safe_signer;
-
-use alloy::{
-    consensus::TxEip1559,
-    primitives::{TxKind, U256},
-};
-use chrono::Utc;
-use diesel::{ExpressionMethods as _, QueryDsl as _, QueryResult, insert_into, sqlite::Sqlite};
-use diesel_async::{AsyncConnection, RunQueryDsl};
-use kameo::actor::ActorRef;
-
 use crate::{
-    actors::keyholder::KeyHolder,
+    actors::vault::Vault,
     crypto::integrity,
     db::{
         self, DatabaseError,
@@ -27,6 +15,18 @@ use crate::{
     },
 };
 
+use alloy::{
+    consensus::TxEip1559,
+    primitives::{TxKind, U256},
+};
+use chrono::Utc;
+use diesel::{ExpressionMethods as _, QueryDsl as _, QueryResult, insert_into, sqlite::Sqlite};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use kameo::actor::ActorRef;
+
+pub mod abi;
+pub mod safe_signer;
+
 pub mod policies;
 mod utils;
 
@@ -41,7 +41,7 @@ pub enum PolicyError {
     NoMatchingGrant,
 
     #[error("Integrity error: {0}")]
-    Integrity(#[from] integrity::IntegrityError),
+    Integrity(#[from] integrity::Error),
 }
 
 #[derive(Debug, thiserror::Error)]
@@ -69,7 +69,7 @@ pub enum ListError {
     Database(#[from] DatabaseError),
 
     #[error("Integrity verification failed for grant")]
-    Integrity(#[from] integrity::IntegrityError),
+    Integrity(#[from] integrity::Error),
 }
 
 /// Controls whether a transaction should be executed or only validated
@@ -138,7 +138,7 @@ async fn check_shared_constraints(
 // 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,
-    keyholder: ActorRef<KeyHolder>,
+    vault: ActorRef<Vault>,
 }
 
 impl Engine {
@@ -158,7 +158,7 @@ impl Engine {
             .map_err(DatabaseError::from)?
             .ok_or(PolicyError::NoMatchingGrant)?;
 
-        integrity::verify_entity(&mut conn, &self.keyholder, &grant.settings, grant.id).await?;
+        integrity::verify_entity(&mut conn, &self.vault, &grant.settings, grant.id).await?;
 
         let mut violations = check_shared_constraints(
             &context,
@@ -207,8 +207,8 @@ impl Engine {
 }
 
 impl Engine {
-    pub const fn new(db: db::DatabasePool, keyholder: ActorRef<KeyHolder>) -> Self {
-        Self { db, keyholder }
+    pub const fn new(db: db::DatabasePool, vault: ActorRef<Vault>) -> Self {
+        Self { db, vault }
     }
 
     pub async fn create_grant<P: Policy>(
@@ -219,7 +219,7 @@ impl Engine {
         P::Settings: Clone,
     {
         let mut conn = self.db.get().await?;
-        let keyholder = self.keyholder.clone();
+        let vault = self.vault.clone();
 
         let id = conn
             .transaction(|conn| {
@@ -264,7 +264,7 @@ impl Engine {
 
                     P::create_grant(&basic_grant, &full_grant.specific, conn).await?;
 
-                    integrity::sign_entity(conn, &keyholder, &full_grant, basic_grant.id)
+                    integrity::sign_entity(conn, &vault, &full_grant, basic_grant.id)
                         .await
                         .map_err(|_| diesel::result::Error::RollbackTransaction)?;
 
@@ -289,7 +289,7 @@ impl Engine {
 
         // Verify integrity of all grants before returning any results
         for grant in &all_grants {
-            integrity::verify_entity(conn, &self.keyholder, &grant.settings, grant.id).await?;
+            integrity::verify_entity(conn, &self.vault, &grant.settings, grant.id).await?;
         }
 
         Ok(all_grants.into_iter().map(|g| Grant {

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

@@ -1,4 +1,8 @@
-use std::fmt::Display;
+use crate::{
+    crypto::integrity::v1::Integrable,
+    db::models::{EvmBasicGrant, EvmWalletAccess},
+    evm::utils,
+};
 
 use alloy::primitives::{Address, Bytes, ChainId, U256};
 use chrono::{DateTime, Duration, Utc};
@@ -6,15 +10,9 @@ use diesel::{
     ExpressionMethods as _, QueryDsl, SelectableHelper, result::QueryResult, sqlite::Sqlite,
 };
 use diesel_async::{AsyncConnection, RunQueryDsl};
-
+use std::fmt::Display;
 use thiserror::Error;
 
-use crate::{
-    crypto::integrity::v1::Integrable,
-    db::models::{EvmBasicGrant, EvmWalletAccess},
-    evm::utils,
-};
-
 pub mod ether_transfer;
 pub mod token_transfers;
 

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

@@ -1,30 +1,32 @@
-use std::collections::HashMap;
-use std::fmt::Display;
-
-use alloy::primitives::{Address, U256};
-use chrono::{DateTime, Duration, Utc};
-use diesel::dsl::{auto_type, insert_into};
-use diesel::prelude::*;
-use diesel::sqlite::Sqlite;
-use diesel_async::{AsyncConnection, RunQueryDsl};
-
-use crate::crypto::integrity::v1::Integrable;
-use crate::db::models::{
+use super::{DatabaseID, EvalContext, EvalViolation};
+use crate::{
+    crypto::integrity::v1::Integrable,
+    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::{
-    CombinedSettings, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
-};
-use crate::{
+    },
+    db::schema::{evm_basic_grant, evm_ether_transfer_limit, evm_transaction_log},
     db::{
         models::{NewEvmEtherTransferGrant, NewEvmEtherTransferGrantTarget},
         schema::{evm_ether_transfer_grant, evm_ether_transfer_grant_target},
     },
+    evm::policies::{
+        CombinedSettings, Grant, SharedGrantSettings, SpecificGrant, SpecificMeaning,
+        VolumeRateLimit,
+    },
     evm::{policies::Policy, utils},
 };
 
+use alloy::primitives::{Address, U256};
+use chrono::{DateTime, Duration, Utc};
+use diesel::{
+    dsl::{auto_type, insert_into},
+    prelude::*,
+    sqlite::Sqlite,
+};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use std::{collections::HashMap, fmt::Display};
+
 #[auto_type]
 fn grant_join() -> _ {
     evm_ether_transfer_grant::table.inner_join(
@@ -32,8 +34,6 @@ fn grant_join() -> _ {
     )
 }
 
-use super::{DatabaseID, EvalContext, EvalViolation};
-
 // Plain ether transfer
 #[derive(Clone, Debug, PartialEq, Eq, Hash)]
 pub struct Meaning {

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

@@ -1,24 +1,25 @@
-use alloy::primitives::{Address, Bytes, U256, address};
-use chrono::{Duration, Utc};
-use diesel::{SelectableHelper, insert_into};
-use diesel_async::RunQueryDsl;
-
-use crate::db::{
+use super::{EtherTransfer, Settings};
+use crate::{
+    db::{
         self, DatabaseConnection,
         models::{
             EvmBasicGrant, EvmWalletAccess, NewEvmBasicGrant, NewEvmTransactionLog, SqliteTimestamp,
         },
         schema::{evm_basic_grant, evm_transaction_log},
-};
-use crate::evm::{
+    },
+    evm::{
         policies::{
             CombinedSettings, EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings,
             VolumeRateLimit,
         },
         utils,
+    },
 };
 
-use super::{EtherTransfer, Settings};
+use alloy::primitives::{Address, Bytes, U256, address};
+use chrono::{Duration, Utc};
+use diesel::{SelectableHelper, insert_into};
+use diesel_async::RunQueryDsl;
 
 const WALLET_ACCESS_ID: i32 = 1;
 const CHAIN_ID: alloy::primitives::ChainId = 1;

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

@@ -1,16 +1,4 @@
-use std::collections::HashMap;
-
-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};
 use crate::{
     crypto::integrity::Integrable,
     db::models::{
@@ -18,20 +6,33 @@ use crate::{
         NewEvmTokenTransferGrant, NewEvmTokenTransferLog, NewEvmTokenTransferVolumeLimit,
         SqliteTimestamp,
     },
+    db::schema::{
+        evm_basic_grant, evm_token_transfer_grant, evm_token_transfer_log,
+        evm_token_transfer_volume_limit,
+    },
     evm::policies::CombinedSettings,
+    evm::{
+        abi::IERC20::transferCall,
+        policies::{
+            Grant, Policy, SharedGrantSettings, SpecificGrant, SpecificMeaning, VolumeRateLimit,
+        },
+        utils,
+    },
 };
+use arbiter_tokens_registry::evm::nonfungible::{self, TokenInfo};
+
 use alloy::{
     primitives::{Address, U256},
     sol_types::SolCall,
 };
-use arbiter_tokens_registry::evm::nonfungible::{self, TokenInfo};
 use chrono::{DateTime, Duration, Utc};
-use diesel::dsl::{auto_type, insert_into};
-use diesel::prelude::*;
-use diesel::sqlite::Sqlite;
+use diesel::{
+    dsl::{auto_type, insert_into},
+    prelude::*,
+    sqlite::Sqlite,
+};
 use diesel_async::{AsyncConnection, RunQueryDsl};
-
-use super::{DatabaseID, EvalContext, EvalViolation};
+use std::collections::HashMap;
 
 #[auto_type]
 fn grant_join() -> _ {

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

@@ -1,24 +1,27 @@
-use alloy::primitives::{Address, Bytes, U256, address};
-use alloy::sol_types::SolCall;
-use chrono::{Duration, Utc};
-use diesel::{SelectableHelper, insert_into};
-use diesel_async::RunQueryDsl;
-
-use crate::db::{
+use super::{Settings, TokenTransfer};
+use crate::{
+    db::{
         self, DatabaseConnection,
         models::{EvmBasicGrant, EvmWalletAccess, NewEvmBasicGrant, SqliteTimestamp},
         schema::evm_basic_grant,
-};
-use crate::evm::{
+    },
+    evm::{
         abi::IERC20::transferCall,
         policies::{
             CombinedSettings, EvalContext, EvalViolation, Grant, Policy, SharedGrantSettings,
             VolumeRateLimit,
         },
         utils,
+    },
 };
 
-use super::{Settings, TokenTransfer};
+use alloy::{
+    primitives::{Address, Bytes, U256, address},
+    sol_types::SolCall,
+};
+use chrono::{Duration, Utc};
+use diesel::{SelectableHelper, insert_into};
+use diesel_async::RunQueryDsl;
 
 // DAI on Ethereum mainnet — present in the static token registry
 const CHAIN_ID: u64 = 1;

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

@@ -1,4 +1,4 @@
-use std::sync::Mutex;
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 
 use alloy::{
     consensus::SignableTransaction,
@@ -6,9 +6,9 @@ use alloy::{
     primitives::{Address, B256, ChainId, Signature},
     signers::{Error, Result, Signer, SignerSync, utils::secret_key_to_address},
 };
-use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use async_trait::async_trait;
 use k256::ecdsa::{self, RecoveryId, SigningKey, signature::hazmat::PrehashSigner};
+use std::sync::Mutex;
 
 /// An Ethereum signer that stores its secp256k1 secret key inside a
 /// hardware-protected [`MemSafe`] cell.

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

@@ -2,20 +2,20 @@ 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(super) struct LengthError {
+    pub(super) expected: usize,
+    pub(super) actual: usize,
 }
 
 pub const fn u256_to_bytes(value: U256) -> [u8; 32] {
     value.to_le_bytes()
 }
-pub fn bytes_to_u256(bytes: &[u8]) -> Option<U256> {
+pub(super) 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> {
+pub(super) 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,

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

@@ -1,3 +1,7 @@
+use crate::{
+    grpc::request_tracker::RequestTracker,
+    peers::client::{ClientConnection, session::ClientSession},
+};
 use arbiter_proto::{
     proto::client::{
         ClientRequest, ClientResponse, client_request::Payload as ClientRequestPayload,
@@ -5,15 +9,11 @@ use arbiter_proto::{
     },
     transport::{Receiver, Sender, grpc::GrpcBi},
 };
+
 use kameo::actor::{ActorRef, Spawn as _};
 use tonic::Status;
 use tracing::{info, warn};
 
-use crate::{
-    actors::client::{ClientConnection, session::ClientSession},
-    grpc::request_tracker::RequestTracker,
-};
-
 mod auth;
 mod evm;
 mod inbound;

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

@@ -1,3 +1,7 @@
+use crate::{
+    grpc::{Convert, request_tracker::RequestTracker},
+    peers::client::{ClientConnection, auth},
+};
 use arbiter_crypto::authn;
 use arbiter_proto::{
     ClientMetadata,
@@ -5,7 +9,8 @@ use arbiter_proto::{
         client::{
             ClientRequest, ClientResponse,
             auth::{
-                self as proto_auth, AuthChallengeRequest as ProtoAuthChallengeRequest,
+                self as proto_auth, AuthChallenge as ProtoAuthChallenge,
+                AuthChallengeRequest as ProtoAuthChallengeRequest,
                 AuthChallengeSolution as ProtoAuthChallengeSolution, AuthResult as ProtoAuthResult,
                 request::Payload as AuthRequestPayload, response::Payload as AuthResponsePayload,
             },
@@ -16,22 +21,18 @@ use arbiter_proto::{
     },
     transport::{Bi, Error as TransportError, Receiver, Sender, grpc::GrpcBi},
 };
+
 use async_trait::async_trait;
 use tonic::Status;
 use tracing::warn;
 
-use crate::{
-    actors::client::{ClientConnection, auth},
-    grpc::request_tracker::RequestTracker,
-};
-
-pub struct AuthTransportAdapter<'a> {
+pub(super) struct AuthTransportAdapter<'a> {
     bi: &'a mut GrpcBi<ClientRequest, ClientResponse>,
     request_tracker: &'a mut RequestTracker,
 }
 
 impl<'a> AuthTransportAdapter<'a> {
-    pub const fn new(
+    pub(super) const fn new(
         bi: &'a mut GrpcBi<ClientRequest, ClientResponse>,
         request_tracker: &'a mut RequestTracker,
     ) -> Self {
@@ -62,14 +63,14 @@ impl<'a> AuthTransportAdapter<'a> {
 }
 
 #[async_trait]
-impl Sender<Result<auth::Outbound, auth::ClientAuthError>> for AuthTransportAdapter<'_> {
+impl Sender<Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {
     async fn send(
         &mut self,
-        item: Result<auth::Outbound, auth::ClientAuthError>,
+        item: Result<auth::Outbound, auth::Error>,
     ) -> Result<(), TransportError> {
         let payload = match item {
-            Ok(message) => message.into(),
-            Err(err) => AuthResponsePayload::Result(ProtoAuthResult::from(err).into()),
+            Ok(message) => message.convert(),
+            Err(err) => err.convert(),
         };
 
         self.send_client_response(payload).await
@@ -132,7 +133,7 @@ impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
                 };
                 Some(auth::Inbound::AuthChallengeRequest {
                     pubkey,
-                    metadata: client_metadata_from_proto(client_info),
+                    metadata: client_info.convert(),
                 })
             }
             AuthRequestPayload::ChallengeSolution(ProtoAuthChallengeSolution { signature }) => {
@@ -148,21 +149,71 @@ impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
     }
 }
 
-impl Bi<auth::Inbound, Result<auth::Outbound, auth::ClientAuthError>> for AuthTransportAdapter<'_> {}
+impl Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {}
 
-fn client_metadata_from_proto(metadata: ProtoClientInfo) -> ClientMetadata {
+impl Convert for ProtoClientInfo {
+    type Output = ClientMetadata;
+
+    fn convert(self) -> Self::Output {
         ClientMetadata {
-        name: metadata.name,
-        description: metadata.description,
-        version: metadata.version,
+            name: self.name,
+            description: self.description,
+            version: self.version,
+        }
     }
 }
 
-pub async fn start(
+impl Convert for auth::Error {
+    type Output = AuthResponsePayload;
+
+    fn convert(self) -> Self::Output {
+        use auth::Error::{
+            ApproveError, DatabaseOperationFailed, DatabasePoolUnavailable, IntegrityCheckFailed,
+            InvalidChallengeSolution, Transport,
+        };
+        AuthResponsePayload::Result(
+            match self {
+                InvalidChallengeSolution => ProtoAuthResult::InvalidSignature,
+                ApproveError(auth::ApproveError::Denied) => ProtoAuthResult::ApprovalDenied,
+                ApproveError(auth::ApproveError::Upstream(
+                    crate::actors::flow_coordinator::ApprovalError::NoUserAgentsConnected,
+                )) => ProtoAuthResult::NoUserAgentsOnline,
+                ApproveError(auth::ApproveError::Internal)
+                | DatabasePoolUnavailable
+                | DatabaseOperationFailed
+                | IntegrityCheckFailed
+                | Transport => ProtoAuthResult::Internal,
+            }
+            .into(),
+        )
+    }
+}
+
+impl Convert for auth::Outbound {
+    type Output = AuthResponsePayload;
+
+    fn convert(self) -> Self::Output {
+        match self {
+            Self::AuthChallenge { challenge } => {
+                AuthResponsePayload::Challenge(ProtoAuthChallenge {
+                    timestamp_nanos: challenge
+                        .timestamp
+                        .timestamp_nanos_opt()
+                        .expect("timestamp within range")
+                        as u64,
+                    random: challenge.nonce.to_vec(),
+                })
+            }
+            Self::AuthSuccess => AuthResponsePayload::Result(ProtoAuthResult::Success.into()),
+        }
+    }
+}
+
+pub(super) async fn start(
     conn: &mut ClientConnection,
     bi: &mut GrpcBi<ClientRequest, ClientResponse>,
     request_tracker: &mut RequestTracker,
-) -> Result<i32, auth::ClientAuthError> {
+) -> Result<i32, auth::Error> {
     let mut transport = AuthTransportAdapter::new(bi, request_tracker);
     auth::authenticate(conn, &mut transport).await
 }

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

@@ -1,3 +1,10 @@
+use crate::{
+    grpc::{
+        Convert, TryConvert,
+        common::inbound::{RawEvmAddress, RawEvmTransaction},
+    },
+    peers::client::session::{ClientSession, HandleSignTransaction, SignTransactionRpcError},
+};
 use arbiter_proto::proto::{
     client::{
         client_response::Payload as ClientResponsePayload,
@@ -11,18 +18,11 @@ use arbiter_proto::proto::{
         evm_sign_transaction_response::Result as EvmSignTransactionResult,
     },
 };
+
 use kameo::actor::ActorRef;
 use tonic::Status;
 use tracing::warn;
 
-use crate::{
-    actors::client::session::{ClientSession, HandleSignTransaction, SignTransactionRpcError},
-    grpc::{
-        Convert, TryConvert,
-        common::inbound::{RawEvmAddress, RawEvmTransaction},
-    },
-};
-
 const fn wrap_response(payload: EvmResponsePayload) -> ClientResponsePayload {
     ClientResponsePayload::Evm(proto_evm::Response {
         payload: Some(payload),

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

@@ -1,3 +1,7 @@
+use crate::{
+    actors::vault::VaultState,
+    peers::client::session::{ClientSession, Error, HandleQueryVaultState},
+};
 use arbiter_proto::proto::{
     client::{
         client_response::Payload as ClientResponsePayload,
@@ -8,15 +12,11 @@ use arbiter_proto::proto::{
     },
     shared::VaultState as ProtoVaultState,
 };
+
 use kameo::{actor::ActorRef, error::SendError};
 use tonic::Status;
 use tracing::warn;
 
-use crate::actors::{
-    client::session::{ClientSession, ClientSessionError, HandleQueryVaultState},
-    keyholder::KeyHolderState,
-};
-
 pub(super) async fn dispatch(
     actor: &ActorRef<ClientSession>,
     req: proto_vault::Request,
@@ -30,12 +30,10 @@ pub(super) async fn dispatch(
     match payload {
         VaultRequestPayload::QueryState(()) => {
             let state = match actor.ask(HandleQueryVaultState {}).await {
-                Ok(KeyHolderState::Unbootstrapped) => ProtoVaultState::Unbootstrapped,
-                Ok(KeyHolderState::Sealed) => ProtoVaultState::Sealed,
-                Ok(KeyHolderState::Unsealed) => ProtoVaultState::Unsealed,
-                Err(SendError::HandlerError(ClientSessionError::Internal)) => {
-                    ProtoVaultState::Error
-                }
+                Ok(VaultState::Unbootstrapped) => ProtoVaultState::Unbootstrapped,
+                Ok(VaultState::Sealed) => ProtoVaultState::Sealed,
+                Ok(VaultState::Unsealed) => ProtoVaultState::Unsealed,
+                Err(SendError::HandlerError(Error::Internal)) => ProtoVaultState::Error,
                 Err(err) => {
                     warn!(error = ?err, "Failed to query vault state");
                     ProtoVaultState::Error

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

@@ -1,2 +1,2 @@
-pub mod inbound;
-pub mod outbound;
+pub(super) mod inbound;
+pub(super) mod outbound;

server/crates/arbiter-server/src/grpc/common/inbound.rs

@@ -1,8 +1,8 @@
-use alloy::{consensus::TxEip1559, primitives::Address, rlp::Decodable as _};
-
 use crate::grpc::TryConvert;
 
-pub struct RawEvmAddress(pub Vec<u8>);
+use alloy::{consensus::TxEip1559, primitives::Address, rlp::Decodable as _};
+
+pub(in crate::grpc) struct RawEvmAddress(pub(in crate::grpc) Vec<u8>);
 impl TryConvert for RawEvmAddress {
     type Output = Address;
 
@@ -21,7 +21,7 @@ impl TryConvert for RawEvmAddress {
     }
 }
 
-pub struct RawEvmTransaction(pub Vec<u8>);
+pub(in crate::grpc) struct RawEvmTransaction(pub(in crate::grpc) Vec<u8>);
 impl TryConvert for RawEvmTransaction {
     type Output = TxEip1559;
 

server/crates/arbiter-server/src/grpc/common/outbound.rs

@@ -1,4 +1,10 @@
-use alloy::primitives::U256;
+use crate::{
+    evm::{
+        PolicyError, VetError,
+        policies::{EvalViolation, SpecificMeaning},
+    },
+    grpc::Convert,
+};
 use arbiter_proto::proto::{
     evm::{
         EvmError as ProtoEvmError,
@@ -14,13 +20,7 @@ use arbiter_proto::proto::{
     },
 };
 
-use crate::{
-    evm::{
-        PolicyError, VetError,
-        policies::{EvalViolation, SpecificMeaning},
-    },
-    grpc::Convert,
-};
+use alloy::primitives::U256;
 
 fn u256_to_proto_bytes(value: U256) -> Vec<u8> {
     value.to_be_bytes::<32>().to_vec()

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

@@ -1,3 +1,4 @@
+use crate::peers::{client::ClientConnection, user_agent::UserAgentConnection};
 use arbiter_proto::{
     proto::{
         client::{ClientRequest, ClientResponse},
@@ -5,15 +6,11 @@ use arbiter_proto::{
     },
     transport::grpc::GrpcBi,
 };
+
 use tokio_stream::wrappers::ReceiverStream;
 use tonic::{Request, Response, Status, async_trait};
 use tracing::info;
 
-use crate::{
-    actors::{client::ClientConnection, user_agent::UserAgentConnection},
-    grpc::user_agent::start,
-};
-
 mod request_tracker;
 
 pub mod client;
@@ -63,7 +60,7 @@ impl arbiter_proto::proto::arbiter_service_server::ArbiterService for super::Ser
 
         let (bi, rx) = GrpcBi::from_bi_stream(req_stream);
 
-        tokio::spawn(start(
+        tokio::spawn(user_agent::start(
             UserAgentConnection {
                 db: self.context.db.clone(),
                 actors: self.context.actors.clone(),

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

@@ -1,12 +1,12 @@
 use tonic::Status;
 
 #[derive(Default)]
-pub struct RequestTracker {
+pub(super) struct RequestTracker {
     next_request_id: i32,
 }
 
 impl RequestTracker {
-    pub fn request(&mut self, id: i32) -> Result<i32, Status> {
+    pub(super) fn request(&mut self, id: i32) -> Result<i32, Status> {
         if id < self.next_request_id {
             return Err(Status::invalid_argument("Duplicate request id"));
         }
@@ -20,7 +20,7 @@ impl RequestTracker {
 
     // This is used to set the response id for auth responses, which need to match the request id of the auth challenge request.
     // -1 offset is needed because request() increments the next_request_id after returning the current request id.
-    pub const fn current_request_id(&self) -> i32 {
+    pub(super) const fn current_request_id(&self) -> i32 {
         self.next_request_id - 1
     }
 }

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

@@ -1,5 +1,7 @@
-use tokio::sync::mpsc;
-
+use crate::{
+    grpc::request_tracker::RequestTracker,
+    peers::user_agent::{OutOfBand, UserAgentConnection, UserAgentSession},
+};
 use arbiter_proto::{
     proto::user_agent::{
         UserAgentRequest, UserAgentResponse,
@@ -8,22 +10,20 @@ use arbiter_proto::{
     },
     transport::{Error as TransportError, Receiver, Sender, grpc::GrpcBi},
 };
+
 use async_trait::async_trait;
-use kameo::actor::{ActorRef, Spawn as _};
+use kameo::actor::ActorRef;
+use tokio::sync::mpsc;
 use tonic::Status;
 use tracing::{error, info, warn};
 
-use crate::{
-    actors::user_agent::{OutOfBand, UserAgentConnection, UserAgentSession},
-    grpc::request_tracker::RequestTracker,
-};
-
 mod auth;
 mod evm;
 mod inbound;
 mod outbound;
 mod sdk_client;
 mod vault;
+mod vault_gate;
 
 pub struct OutOfBandAdapter(mpsc::Sender<OutOfBand>);
 
@@ -124,21 +124,22 @@ pub async fn start(
 ) {
     let mut request_tracker = RequestTracker::default();
 
-    let pubkey = match auth::start(&mut conn, &mut bi, &mut request_tracker).await {
-        Ok(pubkey) => pubkey,
-        Err(e) => {
-            warn!(error = ?e, "Authentication failed");
-            return;
-        }
-    };
-
     let (oob_sender, oob_receiver) = mpsc::channel(16);
     let oob_adapter = OutOfBandAdapter(oob_sender);
 
-    let actor = UserAgentSession::spawn(UserAgentSession::new(conn, Box::new(oob_adapter)));
-    let actor_for_cleanup = actor.clone();
+    let actor = {
+        let transport = auth::AuthTransportAdapter::new(&mut bi, &mut request_tracker);
+        match crate::peers::user_agent::start(&mut conn, transport, Box::new(oob_adapter)).await {
+            Ok(actor) => actor,
+            Err(e) => {
+                warn!(error = ?e, "User agent connection failed");
+                return;
+            }
+        }
+    };
 
-    info!(?pubkey, "User authenticated successfully");
-    dispatch_loop(bi, actor, oob_receiver, request_tracker).await;
-    actor_for_cleanup.kill();
+    info!("User agent session established");
+
+    dispatch_loop(bi, actor.clone(), oob_receiver, request_tracker).await;
+    actor.kill();
 }

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

@@ -1,3 +1,4 @@
+use crate::{grpc::request_tracker::RequestTracker, peers::user_agent::auth};
 use arbiter_crypto::authn;
 use arbiter_proto::{
     proto::user_agent::{
@@ -13,22 +14,18 @@ use arbiter_proto::{
     },
     transport::{Bi, Error as TransportError, Receiver, Sender, grpc::GrpcBi},
 };
+
 use async_trait::async_trait;
 use tonic::Status;
 use tracing::warn;
 
-use crate::{
-    actors::user_agent::{UserAgentConnection, auth},
-    grpc::request_tracker::RequestTracker,
-};
-
-pub struct AuthTransportAdapter<'a> {
-    bi: &'a mut GrpcBi<UserAgentRequest, UserAgentResponse>,
-    request_tracker: &'a mut RequestTracker,
+pub(super) struct AuthTransportAdapter<'a> {
+    pub(super) bi: &'a mut GrpcBi<UserAgentRequest, UserAgentResponse>,
+    pub(super) request_tracker: &'a mut RequestTracker,
 }
 
 impl<'a> AuthTransportAdapter<'a> {
-    pub const fn new(
+    pub(super) const fn new(
         bi: &'a mut GrpcBi<UserAgentRequest, UserAgentResponse>,
         request_tracker: &'a mut RequestTracker,
     ) -> Self {
@@ -38,16 +35,32 @@ impl<'a> AuthTransportAdapter<'a> {
         }
     }
 
-    async fn send_user_agent_response(
+    pub(super) const fn bi_mut(&mut self) -> &mut GrpcBi<UserAgentRequest, UserAgentResponse> {
+        self.bi
+    }
+
+    pub(super) const fn tracker_mut(&mut self) -> &mut RequestTracker {
+        self.request_tracker
+    }
+
+    pub(super) async fn send_response_payload(
         &mut self,
-        payload: AuthResponsePayload,
+        payload: UserAgentResponsePayload,
     ) -> Result<(), TransportError> {
         self.bi
             .send(Ok(UserAgentResponse {
                 id: Some(self.request_tracker.current_request_id()),
-                payload: Some(UserAgentResponsePayload::Auth(proto_auth::Response {
                 payload: Some(payload),
-                })),
+            }))
+            .await
+    }
+
+    async fn send_user_agent_response(
+        &mut self,
+        payload: AuthResponsePayload,
+    ) -> Result<(), TransportError> {
+        self.send_response_payload(UserAgentResponsePayload::Auth(proto_auth::Response {
+            payload: Some(payload),
         }))
         .await
     }
@@ -61,8 +74,15 @@ impl Sender<Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {
     ) -> Result<(), TransportError> {
         use auth::{Error, Outbound};
         let payload = match item {
-            Ok(Outbound::AuthChallenge { nonce }) => {
-                AuthResponsePayload::Challenge(ProtoAuthChallenge { nonce })
+            Ok(Outbound::AuthChallenge { challenge }) => {
+                AuthResponsePayload::Challenge(ProtoAuthChallenge {
+                    timestamp_nanos: challenge
+                        .timestamp
+                        .timestamp_nanos_opt()
+                        .expect("timestamp within range")
+                        as u64,
+                    random: challenge.nonce.to_vec(),
+                })
             }
             Ok(Outbound::AuthSuccess) => {
                 AuthResponsePayload::Result(ProtoAuthResult::Success.into())
@@ -140,7 +160,6 @@ impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
             AuthRequestPayload::ChallengeRequest(ProtoAuthChallengeRequest {
                 pubkey,
                 bootstrap_token,
-                ..
             }) => {
                 let Ok(pubkey) = authn::PublicKey::try_from(pubkey.as_slice()) else {
                     warn!(
@@ -163,12 +182,3 @@ impl Receiver<auth::Inbound> for AuthTransportAdapter<'_> {
 }
 
 impl Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> for AuthTransportAdapter<'_> {}
-
-pub async fn start(
-    conn: &mut UserAgentConnection,
-    bi: &mut GrpcBi<UserAgentRequest, UserAgentResponse>,
-    request_tracker: &mut RequestTracker,
-) -> Result<authn::PublicKey, auth::Error> {
-    let transport = AuthTransportAdapter::new(bi, request_tracker);
-    auth::authenticate(conn, transport).await
-}

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

@@ -1,3 +1,17 @@
+use crate::{
+    grpc::{
+        Convert, TryConvert,
+        common::inbound::{RawEvmAddress, RawEvmTransaction},
+    },
+    peers::user_agent::{
+        UserAgentSession,
+        session::handlers::{
+            GrantMutationError, HandleEvmWalletCreate, HandleEvmWalletList, HandleGrantCreate,
+            HandleGrantDelete, HandleGrantList, HandleSignTransaction,
+            SignTransactionError as SessionSignTransactionError,
+        },
+    },
+};
 use arbiter_proto::proto::{
     evm::{
         EvmError as ProtoEvmError, EvmGrantCreateRequest, EvmGrantCreateResponse,
@@ -18,25 +32,11 @@ use arbiter_proto::proto::{
         user_agent_response::Payload as UserAgentResponsePayload,
     },
 };
+
 use kameo::actor::ActorRef;
 use tonic::Status;
 use tracing::warn;
 
-use crate::{
-    actors::user_agent::{
-        UserAgentSession,
-        session::connection::{
-            GrantMutationError, HandleEvmWalletCreate, HandleEvmWalletList, HandleGrantCreate,
-            HandleGrantDelete, HandleGrantList, HandleSignTransaction,
-            SignTransactionError as SessionSignTransactionError,
-        },
-    },
-    grpc::{
-        Convert, TryConvert,
-        common::inbound::{RawEvmAddress, RawEvmTransaction},
-    },
-};
-
 const fn wrap_evm_response(payload: EvmResponsePayload) -> UserAgentResponsePayload {
     UserAgentResponsePayload::Evm(proto_evm::Response {
         payload: Some(payload),

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

@@ -1,26 +1,26 @@
-use alloy::primitives::{Address, U256};
-use arbiter_proto::proto::evm::{
-    EtherTransferSettings as ProtoEtherTransferSettings, SharedSettings as ProtoSharedSettings,
-    SpecificGrant as ProtoSpecificGrant, TokenTransferSettings as ProtoTokenTransferSettings,
-    TransactionRateLimit as ProtoTransactionRateLimit, VolumeRateLimit as ProtoVolumeRateLimit,
-    specific_grant::Grant as ProtoSpecificGrantType,
-};
-use arbiter_proto::proto::user_agent::sdk_client::{
-    WalletAccess, WalletAccessEntry as SdkClientWalletAccess,
-};
-use chrono::{DateTime, TimeZone, Utc};
-use prost_types::Timestamp as ProtoTimestamp;
-use tonic::Status;
-
-use crate::db::models::{CoreEvmWalletAccess, NewEvmWalletAccess};
-use crate::grpc::Convert;
 use crate::{
+    db::models::{CoreEvmWalletAccess, NewEvmWalletAccess},
     evm::policies::{
         SharedGrantSettings, SpecificGrant, TransactionRateLimit, VolumeRateLimit, ether_transfer,
         token_transfers,
     },
+    grpc::Convert,
     grpc::TryConvert,
 };
+use arbiter_proto::{
+    proto::evm::{
+        EtherTransferSettings as ProtoEtherTransferSettings, SharedSettings as ProtoSharedSettings,
+        SpecificGrant as ProtoSpecificGrant, TokenTransferSettings as ProtoTokenTransferSettings,
+        TransactionRateLimit as ProtoTransactionRateLimit, VolumeRateLimit as ProtoVolumeRateLimit,
+        specific_grant::Grant as ProtoSpecificGrantType,
+    },
+    proto::user_agent::sdk_client::{WalletAccess, WalletAccessEntry as SdkClientWalletAccess},
+};
+
+use alloy::primitives::{Address, U256};
+use chrono::{DateTime, TimeZone, Utc};
+use prost_types::Timestamp as ProtoTimestamp;
+use tonic::Status;
 
 fn address_from_bytes(bytes: &[u8]) -> Result<Address, Status> {
     if bytes.len() != 20 {

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

@@ -1,3 +1,8 @@
+use crate::{
+    db::models::EvmWalletAccess,
+    evm::policies::{SharedGrantSettings, SpecificGrant, TransactionRateLimit, VolumeRateLimit},
+    grpc::Convert,
+};
 use arbiter_proto::proto::{
     evm::{
         EtherTransferSettings as ProtoEtherTransferSettings, SharedSettings as ProtoSharedSettings,
@@ -7,15 +12,10 @@ use arbiter_proto::proto::{
     },
     user_agent::sdk_client::{WalletAccess, WalletAccessEntry as ProtoSdkClientWalletAccess},
 };
+
 use chrono::{DateTime, Utc};
 use prost_types::Timestamp as ProtoTimestamp;
 
-use crate::{
-    db::models::EvmWalletAccess,
-    evm::policies::{SharedGrantSettings, SpecificGrant, TransactionRateLimit, VolumeRateLimit},
-    grpc::Convert,
-};
-
 impl Convert for DateTime<Utc> {
     type Output = ProtoTimestamp;
 

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

@@ -1,3 +1,14 @@
+use crate::{
+    db::models::NewEvmWalletAccess,
+    grpc::Convert,
+    peers::user_agent::{
+        OutOfBand, UserAgentSession,
+        session::handlers::{
+            HandleGrantEvmWalletAccess, HandleListWalletAccess, HandleNewClientApprove,
+            HandleRevokeEvmWalletAccess, HandleSdkClientList,
+        },
+    },
+};
 use arbiter_crypto::authn;
 use arbiter_proto::proto::{
     shared::ClientInfo as ProtoClientMetadata,
@@ -16,22 +27,11 @@ use arbiter_proto::proto::{
         user_agent_response::Payload as UserAgentResponsePayload,
     },
 };
+
 use kameo::actor::ActorRef;
 use tonic::Status;
 use tracing::{info, warn};
 
-use crate::{
-    actors::user_agent::{
-        OutOfBand, UserAgentSession,
-        session::connection::{
-            HandleGrantEvmWalletAccess, HandleListWalletAccess, HandleNewClientApprove,
-            HandleRevokeEvmWalletAccess, HandleSdkClientList,
-        },
-    },
-    db::models::NewEvmWalletAccess,
-    grpc::Convert,
-};
-
 const fn wrap_sdk_client_response(payload: SdkClientResponsePayload) -> UserAgentResponsePayload {
     UserAgentResponsePayload::SdkClient(proto_sdk_client::Response {
         payload: Some(payload),

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

@@ -1,54 +1,28 @@
-use arbiter_proto::proto::shared::VaultState as ProtoVaultState;
-use arbiter_proto::proto::user_agent::{
+use crate::{
+    actors::vault::VaultState,
+    peers::user_agent::{UserAgentSession, session::handlers::HandleQueryVaultState},
+};
+use arbiter_proto::{
+    proto::shared::VaultState as ProtoVaultState,
+    proto::user_agent::{
         user_agent_response::Payload as UserAgentResponsePayload,
         vault::{
-        self as proto_vault,
-        bootstrap::{
-            self as proto_bootstrap, BootstrapEncryptedKey as ProtoBootstrapEncryptedKey,
-            BootstrapResult as ProtoBootstrapResult,
-        },
-        request::Payload as VaultRequestPayload,
+            self as proto_vault, request::Payload as VaultRequestPayload,
             response::Payload as VaultResponsePayload,
-        unseal::{
-            self as proto_unseal, UnsealEncryptedKey as ProtoUnsealEncryptedKey,
-            UnsealResult as ProtoUnsealResult, UnsealStart,
-            request::Payload as UnsealRequestPayload, response::Payload as UnsealResponsePayload,
         },
     },
 };
-use kameo::{actor::ActorRef, error::SendError};
+
+use kameo::actor::ActorRef;
 use tonic::Status;
 use tracing::warn;
 
-use crate::actors::{
-    keyholder::KeyHolderState,
-    user_agent::{
-        UserAgentSession,
-        session::connection::{
-            BootstrapError, HandleBootstrapEncryptedKey, HandleQueryVaultState,
-            HandleUnsealEncryptedKey, HandleUnsealRequest, UnsealError,
-        },
-    },
-};
-
 const fn wrap_vault_response(payload: VaultResponsePayload) -> UserAgentResponsePayload {
     UserAgentResponsePayload::Vault(proto_vault::Response {
         payload: Some(payload),
     })
 }
 
-const fn wrap_unseal_response(payload: UnsealResponsePayload) -> UserAgentResponsePayload {
-    wrap_vault_response(VaultResponsePayload::Unseal(proto_unseal::Response {
-        payload: Some(payload),
-    }))
-}
-
-fn wrap_bootstrap_response(result: ProtoBootstrapResult) -> UserAgentResponsePayload {
-    wrap_vault_response(VaultResponsePayload::Bootstrap(proto_bootstrap::Response {
-        result: result.into(),
-    }))
-}
-
 pub(super) async fn dispatch(
     actor: &ActorRef<UserAgentSession>,
     req: proto_vault::Request,
@@ -59,116 +33,21 @@ pub(super) async fn dispatch(
 
     match payload {
         VaultRequestPayload::QueryState(()) => handle_query_vault_state(actor).await,
-        VaultRequestPayload::Unseal(req) => dispatch_unseal_request(actor, req).await,
-        VaultRequestPayload::Bootstrap(req) => handle_bootstrap_request(actor, req).await,
+        VaultRequestPayload::Unseal(_) | VaultRequestPayload::Bootstrap(_) => {
+            Err(Status::permission_denied(
+                "Vault is already unsealed; unseal/bootstrap not permitted in session",
+            ))
         }
-}
-
-async fn dispatch_unseal_request(
-    actor: &ActorRef<UserAgentSession>,
-    req: proto_unseal::Request,
-) -> Result<Option<UserAgentResponsePayload>, Status> {
-    let Some(payload) = req.payload else {
-        return Err(Status::invalid_argument("Missing unseal request payload"));
-    };
-
-    match payload {
-        UnsealRequestPayload::Start(req) => handle_unseal_start(actor, req).await,
-        UnsealRequestPayload::EncryptedKey(req) => handle_unseal_encrypted_key(actor, req).await,
     }
 }
 
-async fn handle_unseal_start(
-    actor: &ActorRef<UserAgentSession>,
-    req: UnsealStart,
-) -> Result<Option<UserAgentResponsePayload>, Status> {
-    let client_pubkey = <[u8; 32]>::try_from(req.client_pubkey)
-        .map(x25519_dalek::PublicKey::from)
-        .map_err(|_| Status::invalid_argument("Invalid X25519 public key"))?;
-
-    let response = actor
-        .ask(HandleUnsealRequest { client_pubkey })
-        .await
-        .map_err(|err| {
-            warn!(error = ?err, "Failed to handle unseal start request");
-            Status::internal("Failed to start unseal flow")
-        })?;
-
-    Ok(Some(wrap_unseal_response(UnsealResponsePayload::Start(
-        proto_unseal::UnsealStartResponse {
-            server_pubkey: response.server_pubkey.as_bytes().to_vec(),
-        },
-    ))))
-}
-
-async fn handle_unseal_encrypted_key(
-    actor: &ActorRef<UserAgentSession>,
-    req: ProtoUnsealEncryptedKey,
-) -> Result<Option<UserAgentResponsePayload>, Status> {
-    let result = match actor
-        .ask(HandleUnsealEncryptedKey {
-            nonce: req.nonce,
-            ciphertext: req.ciphertext,
-            associated_data: req.associated_data,
-        })
-        .await
-    {
-        Ok(()) => ProtoUnsealResult::Success,
-        Err(SendError::HandlerError(UnsealError::InvalidKey)) => ProtoUnsealResult::InvalidKey,
-        Err(err) => {
-            warn!(error = ?err, "Failed to handle unseal request");
-            return Err(Status::internal("Failed to unseal vault"));
-        }
-    };
-    Ok(Some(wrap_unseal_response(UnsealResponsePayload::Result(
-        result.into(),
-    ))))
-}
-
-async fn handle_bootstrap_request(
-    actor: &ActorRef<UserAgentSession>,
-    req: proto_bootstrap::Request,
-) -> Result<Option<UserAgentResponsePayload>, Status> {
-    let encrypted_key = req
-        .encrypted_key
-        .ok_or_else(|| Status::invalid_argument("Missing bootstrap encrypted key"))?;
-    handle_bootstrap_encrypted_key(actor, encrypted_key).await
-}
-
-async fn handle_bootstrap_encrypted_key(
-    actor: &ActorRef<UserAgentSession>,
-    req: ProtoBootstrapEncryptedKey,
-) -> Result<Option<UserAgentResponsePayload>, Status> {
-    let result = match actor
-        .ask(HandleBootstrapEncryptedKey {
-            nonce: req.nonce,
-            ciphertext: req.ciphertext,
-            associated_data: req.associated_data,
-        })
-        .await
-    {
-        Ok(()) => ProtoBootstrapResult::Success,
-        Err(SendError::HandlerError(BootstrapError::InvalidKey)) => {
-            ProtoBootstrapResult::InvalidKey
-        }
-        Err(SendError::HandlerError(BootstrapError::AlreadyBootstrapped)) => {
-            ProtoBootstrapResult::AlreadyBootstrapped
-        }
-        Err(err) => {
-            warn!(error = ?err, "Failed to handle bootstrap request");
-            return Err(Status::internal("Failed to bootstrap vault"));
-        }
-    };
-    Ok(Some(wrap_bootstrap_response(result)))
-}
-
 async fn handle_query_vault_state(
     actor: &ActorRef<UserAgentSession>,
 ) -> Result<Option<UserAgentResponsePayload>, Status> {
     let state = match actor.ask(HandleQueryVaultState {}).await {
-        Ok(KeyHolderState::Unbootstrapped) => ProtoVaultState::Unbootstrapped,
-        Ok(KeyHolderState::Sealed) => ProtoVaultState::Sealed,
-        Ok(KeyHolderState::Unsealed) => ProtoVaultState::Unsealed,
+        Ok(VaultState::Unbootstrapped) => ProtoVaultState::Unbootstrapped,
+        Ok(VaultState::Sealed) => ProtoVaultState::Sealed,
+        Ok(VaultState::Unsealed) => ProtoVaultState::Unsealed,
         Err(err) => {
             warn!(error = ?err, "Failed to query vault state");
             ProtoVaultState::Error

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

@@ -0,0 +1,79 @@
+use super::auth::AuthTransportAdapter;
+use crate::{
+    grpc::TryConvert,
+    peers::user_agent::vault_gate::{self as vault_gate},
+};
+use arbiter_proto::transport::{Bi, Error as TransportError, Receiver, Sender};
+
+use async_trait::async_trait;
+use tonic::Status;
+use tracing::warn;
+
+mod inbound;
+mod outbound;
+
+#[async_trait]
+impl Receiver<vault_gate::Inbound> for AuthTransportAdapter<'_> {
+    async fn recv(&mut self) -> Option<vault_gate::Inbound> {
+        let request = match self.bi_mut().recv().await? {
+            Ok(request) => request,
+            Err(error) => {
+                warn!(
+                    ?error,
+                    "Failed to receive user agent request during vault gate"
+                );
+                return None;
+            }
+        };
+
+        if let Err(err) = self.tracker_mut().request(request.id) {
+            let _ = self.bi_mut().send(Err(err)).await;
+            return None;
+        }
+
+        let Some(payload) = request.payload else {
+            let _ = self
+                .bi_mut()
+                .send(Err(Status::invalid_argument("Missing request payload")))
+                .await;
+            return None;
+        };
+
+        match payload.try_convert() {
+            Ok(inbound) => Some(inbound),
+            Err(status) => {
+                let _ = self.bi_mut().send(Err(status)).await;
+                None
+            }
+        }
+    }
+}
+
+#[async_trait]
+impl Sender<Result<vault_gate::Outbound, vault_gate::Error>> for AuthTransportAdapter<'_> {
+    async fn send(
+        &mut self,
+        item: Result<vault_gate::Outbound, vault_gate::Error>,
+    ) -> Result<(), TransportError> {
+        let outbound = match item {
+            Ok(outbound) => outbound,
+            Err(err) => {
+                warn!(?err, "vault gate produced transport-level error");
+                return self
+                    .bi_mut()
+                    .send(Err(Status::internal(err.to_string())))
+                    .await;
+            }
+        };
+
+        match outbound.try_convert() {
+            Ok(payload) => self.send_response_payload(payload).await,
+            Err(status) => self.bi_mut().send(Err(status)).await,
+        }
+    }
+}
+
+impl Bi<vault_gate::Inbound, Result<vault_gate::Outbound, vault_gate::Error>>
+    for AuthTransportAdapter<'_>
+{
+}

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

@@ -0,0 +1,129 @@
+use crate::{
+    grpc::{Convert, TryConvert},
+    peers::user_agent::vault_gate::{
+        self as vault_gate, HandleBootstrapEncryptedKey, HandleHandshake, HandleUnsealEncryptedKey,
+    },
+};
+use arbiter_proto::proto::user_agent::{
+    user_agent_request::Payload as UserAgentRequestPayload,
+    vault::{
+        self as proto_vault,
+        bootstrap::{self as proto_bootstrap},
+        request::Payload as VaultRequestPayload,
+        unseal::{self as proto_unseal, request::Payload as UnsealRequestPayload},
+    },
+};
+
+use tonic::Status;
+
+impl TryConvert for UserAgentRequestPayload {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        match self {
+            Self::Vault(req) => req.try_convert(),
+            _ => Err(Status::permission_denied(
+                "Only vault operations are permitted before unsealing",
+            )),
+        }
+    }
+}
+
+impl TryConvert for proto_vault::Request {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        self.payload
+            .ok_or_else(|| Status::invalid_argument("Missing vault request payload"))?
+            .try_convert()
+    }
+}
+
+impl TryConvert for VaultRequestPayload {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        match self {
+            Self::QueryState(()) => Ok(vault_gate::Inbound::HandleVaultState),
+            Self::Unseal(req) => req.try_convert(),
+            Self::Bootstrap(req) => req.try_convert(),
+        }
+    }
+}
+
+impl TryConvert for proto_unseal::Request {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        self.payload
+            .ok_or_else(|| Status::invalid_argument("Missing unseal request payload"))?
+            .try_convert()
+    }
+}
+
+impl TryConvert for UnsealRequestPayload {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        match self {
+            Self::Start(start) => start.try_convert(),
+            Self::EncryptedKey(key) => Ok(key.convert()),
+        }
+    }
+}
+
+impl TryConvert for proto_unseal::UnsealStart {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        let bytes = <[u8; 32]>::try_from(self.client_pubkey)
+            .map_err(|_| Status::invalid_argument("Invalid X25519 public key"))?;
+        Ok(vault_gate::Inbound::HandleHandshake(HandleHandshake {
+            client_pubkey: x25519_dalek::PublicKey::from(bytes),
+        }))
+    }
+}
+
+impl Convert for proto_unseal::UnsealEncryptedKey {
+    type Output = vault_gate::Inbound;
+
+    fn convert(self) -> vault_gate::Inbound {
+        vault_gate::Inbound::HandleUnsealEncryptedKey(HandleUnsealEncryptedKey {
+            nonce: self.nonce,
+            ciphertext: self.ciphertext,
+            associated_data: self.associated_data,
+        })
+    }
+}
+
+impl TryConvert for proto_bootstrap::Request {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        self.encrypted_key
+            .ok_or_else(|| Status::invalid_argument("Missing bootstrap encrypted key"))?
+            .try_convert()
+    }
+}
+
+impl TryConvert for proto_bootstrap::BootstrapEncryptedKey {
+    type Output = vault_gate::Inbound;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<vault_gate::Inbound, Status> {
+        Ok(vault_gate::Inbound::HandleBootstrapEncryptedKey(
+            HandleBootstrapEncryptedKey {
+                nonce: self.nonce,
+                ciphertext: self.ciphertext,
+                associated_data: self.associated_data,
+            },
+        ))
+    }
+}

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

@@ -0,0 +1,115 @@
+use crate::{
+    actors::vault::VaultState,
+    grpc::{Convert, TryConvert},
+    peers::user_agent::vault_gate::{self as vault_gate},
+};
+use arbiter_proto::proto::{
+    shared::VaultState as ProtoVaultState,
+    user_agent::{
+        user_agent_response::Payload as UserAgentResponsePayload,
+        vault::{
+            self as proto_vault,
+            bootstrap::{self as proto_bootstrap, BootstrapResult as ProtoBootstrapResult},
+            response::Payload as VaultResponsePayload,
+            unseal::{
+                self as proto_unseal, UnsealResult as ProtoUnsealResult,
+                response::Payload as UnsealResponsePayload,
+            },
+        },
+    },
+};
+
+use tonic::Status;
+use tracing::warn;
+
+const fn wrap_vault_response(payload: VaultResponsePayload) -> UserAgentResponsePayload {
+    UserAgentResponsePayload::Vault(proto_vault::Response {
+        payload: Some(payload),
+    })
+}
+
+const fn wrap_unseal_response(payload: UnsealResponsePayload) -> UserAgentResponsePayload {
+    wrap_vault_response(VaultResponsePayload::Unseal(proto_unseal::Response {
+        payload: Some(payload),
+    }))
+}
+
+fn wrap_bootstrap_response(result: ProtoBootstrapResult) -> UserAgentResponsePayload {
+    wrap_vault_response(VaultResponsePayload::Bootstrap(proto_bootstrap::Response {
+        result: result.into(),
+    }))
+}
+
+impl Convert for VaultState {
+    type Output = UserAgentResponsePayload;
+
+    fn convert(self) -> UserAgentResponsePayload {
+        let proto_state = match self {
+            Self::Unbootstrapped => ProtoVaultState::Unbootstrapped,
+            Self::Sealed => ProtoVaultState::Sealed,
+            Self::Unsealed => ProtoVaultState::Unsealed,
+        };
+        wrap_vault_response(VaultResponsePayload::State(proto_state.into()))
+    }
+}
+
+impl Convert for vault_gate::HandshakeResponse {
+    type Output = UserAgentResponsePayload;
+
+    fn convert(self) -> UserAgentResponsePayload {
+        wrap_unseal_response(UnsealResponsePayload::Start(
+            proto_unseal::UnsealStartResponse {
+                server_pubkey: self.server_pubkey.as_bytes().to_vec(),
+            },
+        ))
+    }
+}
+
+impl TryConvert for vault_gate::Outbound {
+    type Output = UserAgentResponsePayload;
+    type Error = Status;
+
+    fn try_convert(self) -> Result<UserAgentResponsePayload, Status> {
+        match self {
+            Self::HandleVaultState(result) => result
+                .map_err(|err| {
+                    warn!(?err, "vault state query failed");
+                    Status::internal("Failed to query vault state")
+                })
+                .map(VaultState::convert),
+            Self::HandleHandshake(result) => result
+                .map_err(|err| {
+                    warn!(?err, "handshake failed");
+                    Status::internal("Failed to start unseal flow")
+                })
+                .map(vault_gate::HandshakeResponse::convert),
+            Self::HandleUnsealEncryptedKey(result) => {
+                let proto_result = match result {
+                    Ok(()) => ProtoUnsealResult::Success,
+                    Err(vault_gate::Error::InvalidKey) => ProtoUnsealResult::InvalidKey,
+                    Err(err) => {
+                        warn!(?err, "unseal failed");
+                        return Err(Status::internal("Failed to unseal vault"));
+                    }
+                };
+                Ok(wrap_unseal_response(UnsealResponsePayload::Result(
+                    proto_result.into(),
+                )))
+            }
+            Self::HandleBootstrapEncryptedKey(result) => {
+                let proto_result = match result {
+                    Ok(()) => ProtoBootstrapResult::Success,
+                    Err(vault_gate::Error::InvalidKey) => ProtoBootstrapResult::InvalidKey,
+                    Err(vault_gate::Error::AlreadyBootstrapped) => {
+                        ProtoBootstrapResult::AlreadyBootstrapped
+                    }
+                    Err(err) => {
+                        warn!(?err, "bootstrap failed");
+                        return Err(Status::internal("Failed to bootstrap vault"));
+                    }
+                };
+                Ok(wrap_bootstrap_response(proto_result))
+            }
+        }
+    }
+}

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

@@ -6,6 +6,7 @@ pub mod crypto;
 pub mod db;
 pub mod evm;
 pub mod grpc;
+pub mod peers;
 pub mod utils;
 
 pub struct Server {

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

@@ -1,9 +1,9 @@
-use std::net::SocketAddr;
-
-use anyhow::anyhow;
 use arbiter_proto::{proto::arbiter_service_server::ArbiterServiceServer, url::ArbiterUrl};
 use arbiter_server::{Server, actors::bootstrap::GetToken, context::ServerContext, db};
+
+use anyhow::anyhow;
 use rustls::crypto::aws_lc_rs;
+use std::net::SocketAddr;
 use tonic::transport::{Identity, ServerTlsConfig};
 use tracing::info;
 

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

@@ -1,9 +1,23 @@
-use arbiter_crypto::authn::{self, CLIENT_CONTEXT};
+use super::{ClientConnection, ClientCredentials, ClientProfile};
+use crate::{
+    actors::{
+        GlobalActors,
+        flow_coordinator::{self, RequestClientApproval},
+        vault::Vault,
+    },
+    crypto::integrity::{self, AttestationStatus},
+    db::{
+        self,
+        models::{ProgramClientMetadata, SqliteTimestamp},
+        schema::program_client,
+    },
+};
+use arbiter_crypto::authn::{self, AuthChallenge, CLIENT_CONTEXT};
 use arbiter_proto::{
     ClientMetadata,
-    proto::client::auth::{AuthChallenge as ProtoAuthChallenge, AuthResult as ProtoAuthResult},
     transport::{Bi, expect_message},
 };
+
 use chrono::Utc;
 use diesel::{
     ExpressionMethods as _, OptionalExtension as _, QueryDsl as _, SelectableHelper as _,
@@ -13,75 +27,35 @@ use diesel_async::RunQueryDsl as _;
 use kameo::{actor::ActorRef, error::SendError};
 use tracing::error;
 
-use crate::{
-    actors::{
-        client::{ClientConnection, ClientCredentials, ClientProfile},
-        flow_coordinator::{self, RequestClientApproval},
-        keyholder::KeyHolder,
-    },
-    crypto::integrity::{self, AttestationStatus},
-    db::{
-        self,
-        models::{ProgramClientMetadata, SqliteTimestamp},
-        schema::program_client,
-    },
-};
-
 #[derive(thiserror::Error, Debug, Clone, PartialEq, Eq)]
-pub enum ClientAuthError {
-    #[error("Client approval request failed")]
-    ApproveError(#[from] ApproveError),
-
-    #[error("Database operation failed")]
-    DatabaseOperationFailed,
-
+pub enum Error {
     #[error("Database pool unavailable")]
     DatabasePoolUnavailable,
-
+    #[error("Database operation failed")]
+    DatabaseOperationFailed,
     #[error("Integrity check failed")]
     IntegrityCheckFailed,
-
     #[error("Invalid challenge solution")]
     InvalidChallengeSolution,
-
+    #[error("Client approval request failed")]
+    ApproveError(#[from] ApproveError),
     #[error("Transport error")]
     Transport,
 }
 
-impl From<diesel::result::Error> for ClientAuthError {
+impl From<diesel::result::Error> for Error {
     fn from(e: diesel::result::Error) -> Self {
         error!(?e, "Database error");
         Self::DatabaseOperationFailed
     }
 }
 
-impl From<ClientAuthError> for arbiter_proto::proto::client::auth::AuthResult {
-    fn from(value: ClientAuthError) -> Self {
-        match value {
-            ClientAuthError::ApproveError(e) => match e {
-                ApproveError::Denied => Self::ApprovalDenied,
-                ApproveError::Internal => Self::Internal,
-                ApproveError::Upstream(flow_coordinator::ApprovalError::NoUserAgentsConnected) => {
-                    Self::NoUserAgentsOnline
-                } // ApproveError::Upstream(_) => Self::Internal,
-            },
-            ClientAuthError::DatabaseOperationFailed
-            | ClientAuthError::DatabasePoolUnavailable
-            | ClientAuthError::IntegrityCheckFailed
-            | ClientAuthError::Transport => Self::Internal,
-            ClientAuthError::InvalidChallengeSolution => Self::InvalidSignature,
-        }
-    }
-}
-
 #[derive(thiserror::Error, Debug, Clone, PartialEq, Eq)]
 pub enum ApproveError {
-    #[error("Client connection denied by user agents")]
-    Denied,
-
     #[error("Internal error")]
     Internal,
-
+    #[error("Client connection denied by user agents")]
+    Denied,
     #[error("Upstream error: {0}")]
     Upstream(flow_coordinator::ApprovalError),
 }
@@ -99,137 +73,69 @@ pub enum Inbound {
 
 #[derive(Debug, Clone)]
 pub enum Outbound {
-    AuthChallenge {
-        pubkey: authn::PublicKey,
-        nonce: i32,
-    },
+    AuthChallenge { challenge: AuthChallenge },
     AuthSuccess,
 }
 
-impl From<Outbound> for arbiter_proto::proto::client::auth::response::Payload {
-    fn from(value: Outbound) -> Self {
-        match value {
-            Outbound::AuthChallenge { pubkey, nonce } => Self::Challenge(ProtoAuthChallenge {
-                pubkey: pubkey.to_bytes(),
-                nonce,
-            }),
-            Outbound::AuthSuccess => Self::Result(ProtoAuthResult::Success.into()),
-        }
-    }
-}
-
-/// Returns the current nonce and client ID for a registered client.
-/// Returns `None` if the pubkey is not registered.
-async fn get_current_nonce_and_id(
+async fn get_client_id(
     db: &db::DatabasePool,
     pubkey: &authn::PublicKey,
-) -> Result<Option<(i32, i32)>, ClientAuthError> {
+) -> Result<Option<i32>, Error> {
     let pubkey_bytes = pubkey.to_bytes();
     let mut conn = db.get().await.map_err(|e| {
         error!(error = ?e, "Database pool error");
-        ClientAuthError::DatabasePoolUnavailable
+        Error::DatabasePoolUnavailable
     })?;
     program_client::table
         .filter(program_client::public_key.eq(&pubkey_bytes))
-        .select((program_client::id, program_client::nonce))
-        .first::<(i32, i32)>(&mut conn)
+        .select(program_client::id)
+        .first::<i32>(&mut conn)
         .await
         .optional()
         .map_err(|e| {
             error!(error = ?e, "Database error");
-            ClientAuthError::DatabaseOperationFailed
+            Error::DatabaseOperationFailed
         })
 }
 
 async fn verify_integrity(
     db: &db::DatabasePool,
-    keyholder: &ActorRef<KeyHolder>,
+    vault: &ActorRef<Vault>,
     pubkey: &authn::PublicKey,
-) -> Result<(), ClientAuthError> {
+) -> Result<(), Error> {
     let mut db_conn = db.get().await.map_err(|e| {
         error!(error = ?e, "Database pool error");
-        ClientAuthError::DatabasePoolUnavailable
+        Error::DatabasePoolUnavailable
     })?;
 
-    let (id, nonce) = get_current_nonce_and_id(db, pubkey).await?.ok_or_else(|| {
+    let id = get_client_id(db, pubkey).await?.ok_or_else(|| {
         error!("Client not found during integrity verification");
-        ClientAuthError::DatabaseOperationFailed
+        Error::DatabaseOperationFailed
     })?;
 
     let attestation = integrity::verify_entity(
         &mut db_conn,
-        keyholder,
+        vault,
         &ClientCredentials {
             pubkey: pubkey.clone(),
-            nonce,
         },
         id,
     )
     .await
     .map_err(|e| {
         error!(?e, "Integrity verification failed");
-        ClientAuthError::IntegrityCheckFailed
+        Error::IntegrityCheckFailed
     })?;
 
     if attestation != AttestationStatus::Attested {
         error!("Integrity attestation unavailable for client {id}");
-        return Err(ClientAuthError::IntegrityCheckFailed);
+        return Err(Error::IntegrityCheckFailed);
     }
 
     Ok(())
 }
 
-/// Atomically increments the nonce and re-signs the integrity envelope.
-/// Returns the new nonce, which is used as the challenge nonce.
-async fn create_nonce(
-    db: &db::DatabasePool,
-    keyholder: &ActorRef<KeyHolder>,
-    pubkey: &authn::PublicKey,
-) -> Result<i32, ClientAuthError> {
-    let pubkey_bytes = pubkey.to_bytes();
-    let pubkey = pubkey.clone();
-
-    let mut conn = db.get().await.map_err(|e| {
-        error!(error = ?e, "Database pool error");
-        ClientAuthError::DatabasePoolUnavailable
-    })?;
-
-    conn.exclusive_transaction(|conn| {
-        let keyholder = keyholder.clone();
-        let pubkey = pubkey.clone();
-        Box::pin(async move {
-            let (id, new_nonce): (i32, i32) = update(program_client::table)
-                .filter(program_client::public_key.eq(&pubkey_bytes))
-                .set(program_client::nonce.eq(program_client::nonce + 1))
-                .returning((program_client::id, program_client::nonce))
-                .get_result(conn)
-                .await?;
-
-            integrity::sign_entity(
-                conn,
-                &keyholder,
-                &ClientCredentials {
-                    pubkey: pubkey.clone(),
-                    nonce: new_nonce,
-                },
-                id,
-            )
-            .await
-            .map_err(|e| {
-                error!(?e, "Integrity sign failed after nonce update");
-                ClientAuthError::DatabaseOperationFailed
-            })?;
-
-            Ok(new_nonce)
-        })
-    })
-    .await
-}
-
-async fn approve_new_client(
-    actors: &crate::actors::GlobalActors,
-    profile: ClientProfile,
-) -> Result<(), ClientAuthError> {
+async fn approve_new_client(actors: &GlobalActors, profile: ClientProfile) -> Result<(), Error> {
     let result = actors
         .flow_coordinator
         .ask(RequestClientApproval { client: profile })
@@ -237,39 +143,38 @@ async fn approve_new_client(
 
     match result {
         Ok(true) => Ok(()),
-        Ok(false) => Err(ClientAuthError::ApproveError(ApproveError::Denied)),
+        Ok(false) => Err(Error::ApproveError(ApproveError::Denied)),
         Err(SendError::HandlerError(e)) => {
             error!(error = ?e, "Approval upstream error");
-            Err(ClientAuthError::ApproveError(ApproveError::Upstream(e)))
+            Err(Error::ApproveError(ApproveError::Upstream(e)))
         }
         Err(e) => {
             error!(error = ?e, "Approval request to flow coordinator failed");
-            Err(ClientAuthError::ApproveError(ApproveError::Internal))
+            Err(Error::ApproveError(ApproveError::Internal))
         }
     }
 }
 
 async fn insert_client(
     db: &db::DatabasePool,
-    keyholder: &ActorRef<KeyHolder>,
+    vault: &ActorRef<Vault>,
     pubkey: &authn::PublicKey,
     metadata: &ClientMetadata,
-) -> Result<i32, ClientAuthError> {
+) -> Result<i32, Error> {
     use crate::db::schema::client_metadata;
+
     let pubkey = pubkey.clone();
     let metadata = metadata.clone();
 
     let mut conn = db.get().await.map_err(|e| {
         error!(error = ?e, "Database pool error");
-        ClientAuthError::DatabasePoolUnavailable
+        Error::DatabasePoolUnavailable
     })?;
 
     conn.exclusive_transaction(|conn| {
-        let keyholder = keyholder.clone();
+        let vault = vault.clone();
         let pubkey = pubkey.clone();
         Box::pin(async move {
-            const NONCE_START: i32 = 1;
-
             let metadata_id = insert_into(client_metadata::table)
                 .values((
                     client_metadata::name.eq(&metadata.name),
@@ -284,7 +189,6 @@ async fn insert_client(
                 .values((
                     program_client::public_key.eq(pubkey.to_bytes()),
                     program_client::metadata_id.eq(metadata_id),
-                    program_client::nonce.eq(NONCE_START),
                 ))
                 .on_conflict_do_nothing()
                 .returning(program_client::id)
@@ -293,17 +197,16 @@ async fn insert_client(
 
             integrity::sign_entity(
                 conn,
-                &keyholder,
+                &vault,
                 &ClientCredentials {
                     pubkey: pubkey.clone(),
-                    nonce: NONCE_START,
                 },
                 client_id,
             )
             .await
             .map_err(|e| {
                 error!(error = ?e, "Failed to sign integrity tag for new client key");
-                ClientAuthError::DatabaseOperationFailed
+                Error::DatabaseOperationFailed
             })?;
 
             Ok(client_id)
@@ -316,14 +219,14 @@ async fn sync_client_metadata(
     db: &db::DatabasePool,
     client_id: i32,
     metadata: &ClientMetadata,
-) -> Result<(), ClientAuthError> {
+) -> Result<(), Error> {
     use crate::db::schema::{client_metadata, client_metadata_history};
 
     let now = SqliteTimestamp(Utc::now());
 
     let mut conn = db.get().await.map_err(|e| {
         error!(error = ?e, "Database pool error");
-        ClientAuthError::DatabasePoolUnavailable
+        Error::DatabasePoolUnavailable
     })?;
 
     conn.exclusive_transaction(|conn| {
@@ -379,60 +282,56 @@ async fn sync_client_metadata(
     .await
     .map_err(|e| {
         error!(error = ?e, "Database error");
-        ClientAuthError::DatabaseOperationFailed
+        Error::DatabaseOperationFailed
     })
 }
 
 async fn challenge_client<T>(
     transport: &mut T,
     pubkey: authn::PublicKey,
-    nonce: i32,
-) -> Result<(), ClientAuthError>
+    challenge: AuthChallenge,
+) -> Result<(), Error>
 where
-    T: Bi<Inbound, Result<Outbound, ClientAuthError>> + ?Sized,
+    T: Bi<Inbound, Result<Outbound, Error>> + ?Sized,
 {
     transport
         .send(Ok(Outbound::AuthChallenge {
-            pubkey: pubkey.clone(),
-            nonce,
+            challenge: challenge.clone(),
         }))
         .await
         .map_err(|e| {
             error!(error = ?e, "Failed to send auth challenge");
-            ClientAuthError::Transport
+            Error::Transport
         })?;
 
     let signature = expect_message(transport, |req: Inbound| match req {
         Inbound::AuthChallengeSolution { signature } => Some(signature),
-        Inbound::AuthChallengeRequest { .. } => None,
+        _ => None,
     })
     .await
     .map_err(|e| {
         error!(error = ?e, "Failed to receive challenge solution");
-        ClientAuthError::Transport
+        Error::Transport
     })?;
 
-    if !pubkey.verify(nonce, CLIENT_CONTEXT, &signature) {
+    if !pubkey.verify(&challenge, CLIENT_CONTEXT, &signature) {
         error!("Challenge solution verification failed");
-        return Err(ClientAuthError::InvalidChallengeSolution);
+        return Err(Error::InvalidChallengeSolution);
     }
 
     Ok(())
 }
 
-pub async fn authenticate<T>(
-    props: &mut ClientConnection,
-    transport: &mut T,
-) -> Result<i32, ClientAuthError>
+pub async fn authenticate<T>(props: &mut ClientConnection, transport: &mut T) -> Result<i32, Error>
 where
-    T: Bi<Inbound, Result<Outbound, ClientAuthError>> + Send + ?Sized,
+    T: Bi<Inbound, Result<Outbound, Error>> + Send + ?Sized,
 {
     let Some(Inbound::AuthChallengeRequest { pubkey, metadata }) = transport.recv().await else {
-        return Err(ClientAuthError::Transport);
+        return Err(Error::Transport);
     };
 
-    let client_id = if let Some((id, _)) = get_current_nonce_and_id(&props.db, &pubkey).await? {
-        verify_integrity(&props.db, &props.actors.key_holder, &pubkey).await?;
+    let client_id = if let Some(id) = get_client_id(&props.db, &pubkey).await? {
+        verify_integrity(&props.db, &props.actors.vault, &pubkey).await?;
         id
     } else {
         approve_new_client(
@@ -443,19 +342,20 @@ where
             },
         )
         .await?;
-        insert_client(&props.db, &props.actors.key_holder, &pubkey, &metadata).await?
+        insert_client(&props.db, &props.actors.vault, &pubkey, &metadata).await?
     };
 
     sync_client_metadata(&props.db, client_id, &metadata).await?;
-    let challenge_nonce = create_nonce(&props.db, &props.actors.key_holder, &pubkey).await?;
-    challenge_client(transport, pubkey, challenge_nonce).await?;
+
+    let challenge = AuthChallenge::generate(&mut rand::rng());
+    challenge_client(transport, pubkey, challenge).await?;
 
     transport
         .send(Ok(Outbound::AuthSuccess))
         .await
         .map_err(|e| {
             error!(error = ?e, "Failed to send auth success");
-            ClientAuthError::Transport
+            Error::Transport
         })?;
 
     Ok(client_id)

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

@@ -1,24 +1,22 @@
+use crate::{
+    actors::GlobalActors, crypto::integrity::Integrable, db, peers::client::session::ClientSession,
+};
 use arbiter_crypto::authn;
+use arbiter_macros::Hashable;
 use arbiter_proto::{ClientMetadata, transport::Bi};
+
 use kameo::actor::Spawn;
 use tracing::{error, info};
 
-use crate::{
-    actors::{GlobalActors, client::session::ClientSession},
-    crypto::integrity::Integrable,
-    db,
-};
-
 #[derive(Debug, Clone)]
 pub struct ClientProfile {
     pub pubkey: authn::PublicKey,
     pub metadata: ClientMetadata,
 }
 
-#[derive(arbiter_macros::Hashable)]
+#[derive(Hashable)]
 pub struct ClientCredentials {
     pub pubkey: authn::PublicKey,
-    pub nonce: i32,
 }
 
 impl Integrable for ClientCredentials {
@@ -41,7 +39,7 @@ pub mod session;
 
 pub async fn connect_client<T>(mut props: ClientConnection, transport: &mut T)
 where
-    T: Bi<auth::Inbound, Result<auth::Outbound, auth::ClientAuthError>> + Send + ?Sized,
+    T: Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> + Send + ?Sized,
 {
     let fut = auth::authenticate(&mut props, transport);
     println!("authenticate future size: {}", size_of_val(&fut));

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

@@ -1,20 +1,19 @@
-use kameo::{Actor, messages};
-use tracing::error;
-
-use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
-
+use super::ClientConnection;
 use crate::{
     actors::{
         GlobalActors,
-        client::ClientConnection,
         evm::{ClientSignTransaction, SignTransactionError},
         flow_coordinator::RegisterClient,
-        keyholder::KeyHolderState,
+        vault::VaultState,
     },
     db,
     evm::VetError,
 };
 
+use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
+use kameo::{Actor, messages};
+use tracing::error;
+
 pub struct ClientSession {
     props: ClientConnection,
     client_id: i32,
@@ -29,16 +28,14 @@ impl ClientSession {
 #[messages]
 impl ClientSession {
     #[message]
-    pub(crate) async fn handle_query_vault_state(
-        &mut self,
-    ) -> Result<KeyHolderState, ClientSessionError> {
-        use crate::actors::keyholder::GetState;
+    pub(crate) async fn handle_query_vault_state(&mut self) -> Result<VaultState, Error> {
+        use crate::actors::vault::GetState;
 
-        let vault_state = match self.props.actors.key_holder.ask(GetState {}).await {
+        let vault_state = match self.props.actors.vault.ask(GetState {}).await {
             Ok(state) => state,
             Err(err) => {
-                error!(?err, actor = "client", "keyholder.query.failed");
-                return Err(ClientSessionError::Internal);
+                error!(?err, actor = "client", "vault.query.failed");
+                return Err(Error::Internal);
             }
         };
 
@@ -77,7 +74,7 @@ impl ClientSession {
 impl Actor for ClientSession {
     type Args = Self;
 
-    type Error = ClientSessionError;
+    type Error = Error;
 
     async fn on_start(
         args: Self::Args,
@@ -88,7 +85,7 @@ impl Actor for ClientSession {
             .flow_coordinator
             .ask(RegisterClient { actor: this })
             .await
-            .map_err(|_| ClientSessionError::ConnectionRegistrationFailed)?;
+            .map_err(|_| Error::ConnectionRegistrationFailed)?;
         Ok(args)
     }
 }
@@ -104,7 +101,7 @@ impl ClientSession {
 }
 
 #[derive(Debug, thiserror::Error)]
-pub enum ClientSessionError {
+pub enum Error {
     #[error("Connection registration failed")]
     ConnectionRegistrationFailed,
     #[error("Internal error")]
@@ -113,9 +110,9 @@ pub enum ClientSessionError {
 
 #[derive(Debug, thiserror::Error)]
 pub enum SignTransactionRpcError {
-    #[error("Internal error")]
-    Internal,
-
     #[error("Policy evaluation failed")]
     Vet(#[from] VetError),
+
+    #[error("Internal error")]
+    Internal,
 }

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

@@ -0,0 +1,2 @@
+pub mod client;
+pub mod user_agent;

server/crates/arbiter-server/src/peers/user_agent/auth/mod.rs

@@ -1,15 +1,14 @@
-use arbiter_crypto::authn;
+use super::{Credentials, UserAgentConnection};
+use arbiter_crypto::authn::{self, AuthChallenge};
 use arbiter_proto::transport::Bi;
+
+use state::{
+    AuthContext, AuthError, AuthEvents, AuthStateMachine, AuthStates, ChallengeRequest,
+    ChallengeSolution,
+};
 use tracing::error;
 
-use crate::actors::user_agent::{
-    UserAgentConnection,
-    auth::state::{AuthContext, AuthStateMachine},
-};
 mod state;
-use state::{
-    AuthError, AuthEvents, AuthStates, BootstrapAuthRequest, ChallengeRequest, ChallengeSolution,
-};
 
 #[derive(Debug, Clone)]
 pub enum Inbound {
@@ -48,7 +47,7 @@ impl From<diesel::result::Error> for Error {
 
 #[derive(Debug, Clone)]
 pub enum Outbound {
-    AuthChallenge { nonce: i32 },
+    AuthChallenge { challenge: AuthChallenge },
     AuthSuccess,
 }
 
@@ -56,12 +55,11 @@ fn parse_auth_event(payload: Inbound) -> AuthEvents {
     match payload {
         Inbound::AuthChallengeRequest {
             pubkey,
-            bootstrap_token: None,
-        } => AuthEvents::AuthRequest(ChallengeRequest { pubkey }),
-        Inbound::AuthChallengeRequest {
+            bootstrap_token,
+        } => AuthEvents::AuthRequest(ChallengeRequest {
             pubkey,
-            bootstrap_token: Some(token),
-        } => AuthEvents::BootstrapAuthRequest(BootstrapAuthRequest { pubkey, token }),
+            bootstrap_token,
+        }),
         Inbound::AuthChallengeSolution { signature } => {
             AuthEvents::ReceivedSolution(ChallengeSolution {
                 solution: signature,
@@ -72,21 +70,20 @@ fn parse_auth_event(payload: Inbound) -> AuthEvents {
 
 pub async fn authenticate<T>(
     props: &mut UserAgentConnection,
-    transport: T,
-) -> Result<authn::PublicKey, Error>
+    transport: &mut T,
+) -> Result<Credentials, Error>
 where
-    T: Bi<Inbound, Result<Outbound, Error>> + Send,
+    T: Bi<Inbound, Result<Outbound, Error>> + Send + ?Sized,
 {
     let mut state = AuthStateMachine::new(AuthContext::new(props, transport));
 
     loop {
-        // `state` holds a mutable reference to `props` so we can't access it directly here
         let Some(payload) = state.context_mut().transport.recv().await else {
             return Err(Error::Transport);
         };
 
         match state.process_event(parse_auth_event(payload)).await {
-            Ok(AuthStates::AuthOk(key)) => return Ok(key.clone()),
+            Ok(AuthStates::AuthOk(result)) => return Ok(result.clone()),
             Err(AuthError::ActionFailed(err)) => {
                 error!(?err, "State machine action failed");
                 return Err(err);

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

@@ -0,0 +1,198 @@
+use super::{
+    super::{Credentials, UserAgentConnection},
+    Error,
+};
+use crate::{
+    actors::bootstrap::ConsumeToken,
+    db::{DatabasePool, schema::useragent_client},
+    peers::user_agent::auth::Outbound,
+};
+use arbiter_crypto::authn::{self, AuthChallenge, USERAGENT_CONTEXT};
+use arbiter_proto::transport::Bi;
+
+use diesel::{ExpressionMethods as _, OptionalExtension as _, QueryDsl};
+use diesel_async::RunQueryDsl;
+use tracing::error;
+
+pub(super) struct ChallengeRequest {
+    pub(super) pubkey: authn::PublicKey,
+    pub(super) bootstrap_token: Option<String>,
+}
+
+pub(super) struct ChallengeContext {
+    pub(super) challenge: AuthChallenge,
+    pub(super) pubkey: authn::PublicKey,
+    pub(super) bootstrap_token: Option<String>,
+}
+
+pub(super) struct ChallengeSolution {
+    pub(super) 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 = AuthOk(Credentials),
+    }
+);
+
+async fn get_client_id(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<Option<i32>, Error> {
+    let mut conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::internal("Database unavailable")
+    })?;
+
+    useragent_client::table
+        .filter(useragent_client::public_key.eq(pubkey.to_bytes()))
+        .select(useragent_client::id)
+        .first::<i32>(&mut conn)
+        .await
+        .optional()
+        .map_err(|e| {
+            error!(error = ?e, "Database error");
+            Error::internal("Database operation failed")
+        })
+}
+
+async fn register_key(db: &DatabasePool, pubkey: &authn::PublicKey) -> Result<i32, Error> {
+    let pubkey_bytes = pubkey.to_bytes();
+    let mut conn = db.get().await.map_err(|e| {
+        error!(error = ?e, "Database pool error");
+        Error::internal("Database unavailable")
+    })?;
+
+    let id: i32 = diesel::insert_into(useragent_client::table)
+        .values((useragent_client::public_key.eq(pubkey_bytes),))
+        .returning(useragent_client::id)
+        .get_result(&mut conn)
+        .await
+        .map_err(|e| {
+            error!(error = ?e, "Database error");
+            Error::internal("Database operation failed")
+        })?;
+
+    Ok(id)
+}
+
+pub(super) struct AuthContext<'a, T: ?Sized> {
+    pub(super) conn: &'a mut UserAgentConnection,
+    pub(super) transport: &'a mut T,
+}
+
+impl<'a, T: ?Sized> AuthContext<'a, T> {
+    pub(super) const fn new(conn: &'a mut UserAgentConnection, transport: &'a mut T) -> Self {
+        Self { conn, transport }
+    }
+}
+
+impl<T> AuthStateMachineContext for AuthContext<'_, T>
+where
+    T: Bi<super::Inbound, Result<Outbound, Error>> + Send + ?Sized,
+{
+    type Error = Error;
+
+    async fn prepare_challenge(
+        &mut self,
+        ChallengeRequest {
+            pubkey,
+            bootstrap_token,
+        }: ChallengeRequest,
+    ) -> Result<ChallengeContext, Self::Error> {
+        // Verify pubkey is registered (unless bootstrapping)
+        if bootstrap_token.is_none() {
+            let id = get_client_id(&self.conn.db, &pubkey).await?;
+            if id.is_none() {
+                return Err(Error::UnregisteredPublicKey);
+            }
+        }
+
+        let challenge = AuthChallenge::generate(&mut rand::rng());
+
+        self.transport
+            .send(Ok(Outbound::AuthChallenge {
+                challenge: challenge.clone(),
+            }))
+            .await
+            .map_err(|e| {
+                error!(?e, "Failed to send auth challenge");
+                Error::Transport
+            })?;
+
+        Ok(ChallengeContext {
+            challenge,
+            pubkey,
+            bootstrap_token,
+        })
+    }
+
+    #[allow(missing_docs)]
+    #[allow(clippy::unused_unit)]
+    async fn verify_solution(
+        &mut self,
+        ChallengeContext {
+            challenge,
+            pubkey,
+            bootstrap_token,
+        }: &ChallengeContext,
+        ChallengeSolution { solution }: ChallengeSolution,
+    ) -> Result<Credentials, Self::Error> {
+        let signature = authn::Signature::try_from(solution.as_slice()).map_err(|()| {
+            error!("Failed to decode signature in challenge solution");
+            Error::InvalidChallengeSolution
+        })?;
+
+        let valid = pubkey.verify(challenge, USERAGENT_CONTEXT, &signature);
+
+        if !valid {
+            self.transport
+                .send(Err(Error::InvalidChallengeSolution))
+                .await
+                .map_err(|_| Error::Transport)?;
+            return Err(Error::InvalidChallengeSolution);
+        }
+
+        // Resolve client id: bootstrap (consume token + register) or lookup
+        let id = match bootstrap_token {
+            Some(token) => {
+                let token_ok: bool = self
+                    .conn
+                    .actors
+                    .bootstrapper
+                    .ask(ConsumeToken {
+                        token: token.clone(),
+                    })
+                    .await
+                    .map_err(|e| {
+                        error!(?e, "Failed to consume bootstrap token");
+                        Error::internal("Failed to consume bootstrap token")
+                    })?;
+
+                if !token_ok {
+                    error!("Invalid bootstrap token provided");
+                    self.transport
+                        .send(Err(Error::InvalidBootstrapToken))
+                        .await
+                        .map_err(|_| Error::Transport)?;
+                    return Err(Error::InvalidBootstrapToken);
+                }
+
+                register_key(&self.conn.db, pubkey).await?
+            }
+            None => get_client_id(&self.conn.db, pubkey)
+                .await?
+                .ok_or(Error::UnregisteredPublicKey)?,
+        };
+
+        self.transport
+            .send(Ok(Outbound::AuthSuccess))
+            .await
+            .map_err(|_| Error::Transport)?;
+
+        Ok(Credentials {
+            id,
+            pubkey: pubkey.clone(),
+        })
+    }
+}

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

@@ -0,0 +1,185 @@
+use crate::{
+    actors::{
+        GlobalActors,
+        vault::{GetState, Vault},
+    },
+    crypto::integrity::{self, AttestationStatus, Integrable},
+    db::{DatabaseError, DatabasePool},
+    peers::client::ClientProfile,
+};
+use arbiter_crypto::authn;
+use arbiter_macros::Hashable;
+use arbiter_proto::transport::{Bi, Sender};
+use vault_gate::VaultGate;
+
+use kameo::actor::{ActorRef, Spawn as _};
+use tokio::sync::oneshot;
+use tracing::{error, warn};
+
+pub use auth::authenticate;
+pub use session::UserAgentSession;
+
+pub mod auth;
+pub mod session;
+pub mod vault_gate;
+
+#[derive(Debug, Clone, Hashable)]
+pub struct Credentials {
+    pub id: i32,
+    pub pubkey: authn::PublicKey,
+}
+
+impl Integrable for Credentials {
+    const KIND: &'static str = "useragent_credentials";
+}
+
+// Messages, sent by user agent to connection client without having a request
+#[derive(Debug)]
+pub enum OutOfBand {
+    ClientConnectionRequest { profile: ClientProfile },
+    ClientConnectionCancel { pubkey: authn::PublicKey },
+}
+
+#[derive(Clone)]
+pub struct UserAgentConnection {
+    pub(crate) db: DatabasePool,
+    pub(crate) actors: GlobalActors,
+}
+
+impl UserAgentConnection {
+    pub const fn new(db: DatabasePool, actors: GlobalActors) -> Self {
+        Self { db, actors }
+    }
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("authentication failed: {0:?}")]
+    Auth(auth::Error),
+    #[error("vault gate failed: {0}")]
+    VaultGate(#[from] vault_gate::Error),
+    #[error("transport closed unexpectedly")]
+    Transport,
+    #[error("database error: {0}")]
+    Database(DatabaseError),
+    #[error("internal: {0}")]
+    Internal(String),
+}
+
+impl From<auth::Error> for Error {
+    fn from(err: auth::Error) -> Self {
+        Self::Auth(err)
+    }
+}
+
+async fn verify_integrity(
+    db: &DatabasePool,
+    vault: &ActorRef<Vault>,
+    credentials: &Credentials,
+) -> Result<(), Error> {
+    let mut conn = db
+        .get()
+        .await
+        .map_err(|_| Error::Internal("DB unavailable".into()))?;
+    match integrity::verify_entity(&mut conn, vault, credentials, credentials.id).await {
+        Ok(AttestationStatus::Attested) => Ok(()),
+        Ok(AttestationStatus::Unavailable) => {
+            Err(Error::Internal("Vault sealed during promotion".into()))
+        }
+        Err(e) => {
+            error!(?e, "Integrity verification failed during unseal promotion");
+            Err(Error::Internal("Integrity check failed".into()))
+        }
+    }
+}
+
+async fn should_run_gate(vault: &ActorRef<Vault>) -> Result<bool, Error> {
+    let vault_state = vault
+        .ask(GetState {})
+        .await
+        .map_err(|_| Error::Internal("Failed to contact the vault".into()))?;
+
+    Ok(!matches!(
+        vault_state,
+        crate::actors::vault::VaultState::Unsealed
+    ))
+}
+
+async fn run_vault_gate<T>(
+    props: &UserAgentConnection,
+    transport: &mut T,
+    auth_creds: Credentials,
+) -> Result<(), Error>
+where
+    T: Bi<vault_gate::Inbound, Result<vault_gate::Outbound, vault_gate::Error>> + Send + ?Sized,
+{
+    let (promotion_tx, mut promotion_rx) = oneshot::channel();
+    let gate = VaultGate::spawn(VaultGate::new(
+        auth_creds,
+        props.actors.clone(),
+        props.db.clone(),
+        promotion_tx,
+    ));
+
+    let result = loop {
+        tokio::select! {
+            promotion = &mut promotion_rx => {
+                break match promotion {
+                    Ok(Ok(creds)) => Ok(creds),
+                    Ok(Err(err)) => Err(Error::VaultGate(err)),
+                    Err(_) => Err(Error::Internal(
+                        "vault gate promotion channel closed".into(),
+                    )),
+                };
+            }
+
+            inbound = transport.recv() => {
+                let Some(inbound) = inbound else {
+                    break Err(Error::Transport);
+                };
+
+                match gate.ask(inbound).await {
+                    Ok(outbound) => {
+                        if transport.send(Ok(outbound)).await.is_err() {
+                            break Err(Error::Transport);
+                        }
+                    }
+                    Err(err) => {
+                        warn!(?err, "VaultGate failed to handle message");
+                        break Err(Error::Internal(format!(
+                            "vault gate ask failed: {err:?}"
+                        )));
+                    }
+                }
+            }
+        }
+    };
+
+    gate.kill();
+    result
+}
+
+pub async fn start<T>(
+    props: &mut UserAgentConnection,
+    mut transport: T,
+    oob_sender: Box<dyn Sender<OutOfBand>>,
+) -> Result<ActorRef<UserAgentSession>, Error>
+where
+    T: Bi<auth::Inbound, Result<auth::Outbound, auth::Error>> + Send,
+    T: Bi<vault_gate::Inbound, Result<vault_gate::Outbound, vault_gate::Error>> + Send,
+{
+    let creds = authenticate(props, &mut transport).await?;
+
+    // should run vault gate only if sealed / unbootstrapped
+    if should_run_gate(&props.actors.vault).await? {
+        run_vault_gate(props, &mut transport, creds.clone()).await?;
+    }
+
+    // checking the integrity
+    verify_integrity(&props.db, &props.actors.vault, &creds).await?;
+
+    Ok(UserAgentSession::spawn(UserAgentSession::new(
+        props.clone(),
+        oob_sender,
+    )))
+}

server/crates/arbiter-server/src/peers/user_agent/session/handlers.rs

@@ -0,0 +1,278 @@
+use super::{Error, UserAgentSession};
+use crate::{
+    actors::evm::{
+        ClientSignTransaction, Generate, ListWallets, SignTransactionError as EvmSignError,
+        UseragentCreateGrant, UseragentListGrants,
+    },
+    actors::flow_coordinator::client_connect_approval::ClientApprovalAnswer,
+    actors::vault::VaultState,
+    db::models::{EvmWalletAccess, NewEvmWalletAccess, ProgramClient, ProgramClientMetadata},
+    evm::policies::{Grant, SpecificGrant},
+};
+use arbiter_crypto::authn;
+
+use alloy::{consensus::TxEip1559, primitives::Address, signers::Signature};
+use diesel::{ExpressionMethods as _, QueryDsl as _, SelectableHelper};
+use diesel_async::{AsyncConnection, RunQueryDsl};
+use kameo::{error::SendError, messages, prelude::Context};
+use tracing::error;
+
+#[derive(Debug, Error)]
+pub enum SignTransactionError {
+    #[error("Policy evaluation failed")]
+    Vet(#[from] crate::evm::VetError),
+
+    #[error("Internal signing error")]
+    Internal,
+}
+
+#[derive(Debug, Error)]
+pub enum GrantMutationError {
+    #[error("Vault is sealed")]
+    VaultSealed,
+
+    #[error("Internal grant mutation error")]
+    Internal,
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message]
+    pub(crate) async fn handle_query_vault_state(&mut self) -> Result<VaultState, Error> {
+        use crate::actors::vault::GetState;
+
+        let vault_state = match self.props.actors.vault.ask(GetState {}).await {
+            Ok(state) => state,
+            Err(err) => {
+                error!(?err, actor = "useragent", "vault.query.failed");
+                return Err(Error::internal("Vault is in broken state"));
+            }
+        };
+
+        Ok(vault_state)
+    }
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message]
+    pub(crate) async fn handle_evm_wallet_create(&mut self) -> Result<(i32, Address), Error> {
+        match self.props.actors.evm.ask(Generate {}).await {
+            Ok(address) => Ok(address),
+            Err(SendError::HandlerError(err)) => Err(Error::internal(format!(
+                "EVM wallet generation failed: {err}"
+            ))),
+            Err(err) => {
+                error!(?err, "EVM actor unreachable during wallet create");
+                Err(Error::internal("EVM actor unreachable"))
+            }
+        }
+    }
+
+    #[message]
+    pub(crate) async fn handle_evm_wallet_list(&mut self) -> Result<Vec<(i32, Address)>, Error> {
+        match self.props.actors.evm.ask(ListWallets {}).await {
+            Ok(wallets) => Ok(wallets),
+            Err(err) => {
+                error!(?err, "EVM wallet list failed");
+                Err(Error::internal("Failed to list EVM wallets"))
+            }
+        }
+    }
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message]
+    pub(crate) async fn handle_grant_list(&mut self) -> Result<Vec<Grant<SpecificGrant>>, Error> {
+        match self.props.actors.evm.ask(UseragentListGrants {}).await {
+            Ok(grants) => Ok(grants),
+            Err(err) => {
+                error!(?err, "EVM grant list failed");
+                Err(Error::internal("Failed to list EVM grants"))
+            }
+        }
+    }
+
+    #[message]
+    pub(crate) async fn handle_grant_create(
+        &mut self,
+        basic: crate::evm::policies::SharedGrantSettings,
+        grant: SpecificGrant,
+    ) -> Result<i32, GrantMutationError> {
+        match self
+            .props
+            .actors
+            .evm
+            .ask(UseragentCreateGrant { basic, grant })
+            .await
+        {
+            Ok(grant_id) => Ok(grant_id),
+            Err(err) => {
+                error!(?err, "EVM grant create failed");
+                Err(GrantMutationError::Internal)
+            }
+        }
+    }
+
+    #[message]
+    pub(crate) fn handle_grant_delete(&mut self, grant_id: i32) -> Result<(), GrantMutationError> {
+        // match self
+        //     .props
+        //     .actors
+        //     .evm
+        //     .ask(UseragentDeleteGrant { grant_id })
+        //     .await
+        // {
+        //     Ok(()) => Ok(()),
+        //     Err(err) => {
+        //         error!(?err, "EVM grant delete failed");
+        //         Err(GrantMutationError::Internal)
+        //     }
+        // }
+        let _ = grant_id;
+        todo!()
+    }
+
+    #[message]
+    pub(crate) async fn handle_sign_transaction(
+        &mut self,
+        client_id: i32,
+        wallet_address: Address,
+        transaction: TxEip1559,
+    ) -> Result<Signature, SignTransactionError> {
+        match self
+            .props
+            .actors
+            .evm
+            .ask(ClientSignTransaction {
+                client_id,
+                wallet_address,
+                transaction,
+            })
+            .await
+        {
+            Ok(signature) => Ok(signature),
+            Err(SendError::HandlerError(EvmSignError::Vet(vet_error))) => {
+                Err(SignTransactionError::Vet(vet_error))
+            }
+            Err(err) => {
+                error!(?err, "EVM sign transaction failed in user-agent session");
+                Err(SignTransactionError::Internal)
+            }
+        }
+    }
+
+    #[message]
+    pub(crate) async fn handle_grant_evm_wallet_access(
+        &mut self,
+        entries: Vec<NewEvmWalletAccess>,
+    ) -> Result<(), Error> {
+        let mut conn = self.props.db.get().await?;
+        conn.transaction(|conn| {
+            Box::pin(async move {
+                use crate::db::schema::evm_wallet_access;
+
+                for entry in entries {
+                    diesel::insert_into(evm_wallet_access::table)
+                        .values(&entry)
+                        .on_conflict_do_nothing()
+                        .execute(conn)
+                        .await?;
+                }
+
+                Result::<_, Error>::Ok(())
+            })
+        })
+        .await?;
+        Ok(())
+    }
+
+    #[message]
+    pub(crate) async fn handle_revoke_evm_wallet_access(
+        &mut self,
+        entries: Vec<i32>,
+    ) -> Result<(), Error> {
+        let mut conn = self.props.db.get().await?;
+        conn.transaction(|conn| {
+            Box::pin(async move {
+                use crate::db::schema::evm_wallet_access;
+                for entry in entries {
+                    diesel::delete(evm_wallet_access::table)
+                        .filter(evm_wallet_access::wallet_id.eq(entry))
+                        .execute(conn)
+                        .await?;
+                }
+
+                Result::<_, Error>::Ok(())
+            })
+        })
+        .await?;
+        Ok(())
+    }
+
+    #[message]
+    pub(crate) async fn handle_list_wallet_access(
+        &mut self,
+    ) -> Result<Vec<EvmWalletAccess>, Error> {
+        let mut conn = self.props.db.get().await?;
+        use crate::db::schema::evm_wallet_access;
+        let access_entries = evm_wallet_access::table
+            .select(EvmWalletAccess::as_select())
+            .load::<_>(&mut conn)
+            .await?;
+        Ok(access_entries)
+    }
+}
+
+#[messages]
+impl UserAgentSession {
+    #[message(ctx)]
+    pub(crate) async fn handle_new_client_approve(
+        &mut self,
+        approved: bool,
+        pubkey: authn::PublicKey,
+        ctx: &mut Context<Self, Result<(), Error>>,
+    ) -> Result<(), Error> {
+        let Some(pending_approval) = self.pending_client_approvals.remove(&pubkey.to_bytes())
+        else {
+            error!("Received client connection response for unknown client");
+            return Err(Error::internal("Unknown client in connection response"));
+        };
+
+        pending_approval
+            .controller
+            .tell(ClientApprovalAnswer { approved })
+            .await
+            .map_err(|err| {
+                error!(
+                    ?err,
+                    "Failed to send client approval response to controller"
+                );
+                Error::internal("Failed to send client approval response to controller")
+            })?;
+
+        ctx.actor_ref().unlink(&pending_approval.controller).await;
+
+        Ok(())
+    }
+
+    #[message]
+    pub(crate) async fn handle_sdk_client_list(
+        &mut self,
+    ) -> Result<Vec<(ProgramClient, ProgramClientMetadata)>, Error> {
+        use crate::db::schema::{client_metadata, program_client};
+        let mut conn = self.props.db.get().await?;
+
+        let clients = program_client::table
+            .inner_join(client_metadata::table)
+            .select((
+                ProgramClient::as_select(),
+                ProgramClientMetadata::as_select(),
+            ))
+            .load::<(ProgramClient, ProgramClientMetadata)>(&mut conn)
+            .await?;
+
+        Ok(clients)
+    }
+}

server/crates/arbiter-server/src/peers/user_agent/session/mod.rs

@@ -1,44 +1,42 @@
+use super::{OutOfBand, UserAgentConnection};
+use crate::{
+    actors::{
+        flow_coordinator::client_connect_approval::ClientApprovalController,
+        useragent_registry::ConnectUseragent,
+    },
+    peers::client::ClientProfile,
+};
 use arbiter_crypto::authn;
-
-use std::{borrow::Cow, collections::HashMap};
-
 use arbiter_proto::transport::Sender;
-use async_trait::async_trait;
+
 use kameo::{Actor, actor::ActorRef, messages};
+use std::{borrow::Cow, collections::HashMap};
 use thiserror::Error;
 use tracing::error;
 
-use crate::actors::{
-    client::ClientProfile,
-    flow_coordinator::{RegisterUserAgent, client_connect_approval::ClientApprovalController},
-    user_agent::{OutOfBand, UserAgentConnection},
-};
-mod state;
-use state::{DummyContext, UserAgentEvents, UserAgentStateMachine};
-
 #[derive(Debug, Error)]
-pub enum UserAgentSessionError {
-    #[error("Internal error: {message}")]
-    Internal { message: Cow<'static, str> },
-
+pub enum Error {
     #[error("State transition failed")]
     State,
+
+    #[error("Internal error: {message}")]
+    Internal { message: Cow<'static, str> },
 }
 
-impl From<crate::db::PoolError> for UserAgentSessionError {
+impl From<crate::db::PoolError> for Error {
     fn from(err: crate::db::PoolError) -> Self {
         error!(?err, "Database pool error");
         Self::internal("Database pool error")
     }
 }
-impl From<diesel::result::Error> for UserAgentSessionError {
+impl From<diesel::result::Error> for Error {
     fn from(err: diesel::result::Error) -> Self {
         error!(?err, "Database error");
         Self::internal("Database error")
     }
 }
 
-impl UserAgentSessionError {
+impl Error {
     pub fn internal(message: impl Into<Cow<'static, str>>) -> Self {
         Self::Internal {
             message: message.into(),
@@ -53,47 +51,21 @@ pub struct PendingClientApproval {
 
 pub struct UserAgentSession {
     props: UserAgentConnection,
-    state: UserAgentStateMachine<DummyContext>,
     sender: Box<dyn Sender<OutOfBand>>,
 
     pending_client_approvals: HashMap<Vec<u8>, PendingClientApproval>,
 }
 
-pub mod connection;
+pub mod handlers;
 
 impl UserAgentSession {
     pub(crate) fn new(props: UserAgentConnection, sender: Box<dyn Sender<OutOfBand>>) -> Self {
         Self {
             props,
-            state: UserAgentStateMachine::new(DummyContext),
             sender,
-            pending_client_approvals: HashMap::default(),
+            pending_client_approvals: Default::default(),
         }
     }
-
-    pub fn new_test(db: crate::db::DatabasePool, actors: crate::actors::GlobalActors) -> Self {
-        struct DummySender;
-
-        #[async_trait]
-        impl Sender<OutOfBand> for DummySender {
-            async fn send(
-                &mut self,
-                _item: OutOfBand,
-            ) -> Result<(), arbiter_proto::transport::Error> {
-                Ok(())
-            }
-        }
-
-        Self::new(UserAgentConnection::new(db, actors), Box::new(DummySender))
-    }
-
-    fn transition(&mut self, event: UserAgentEvents) -> Result<(), UserAgentSessionError> {
-        self.state.process_event(event).map_err(|e| {
-            error!(?e, "State transition failed");
-            UserAgentSessionError::State
-        })?;
-        Ok(())
-    }
 }
 
 #[messages]
@@ -132,27 +104,22 @@ impl UserAgentSession {
 impl Actor for UserAgentSession {
     type Args = Self;
 
-    type Error = UserAgentSessionError;
+    type Error = Error;
 
-    async fn on_start(
-        args: Self::Args,
-        this: ActorRef<Self>,
-    ) -> Result<Self, Self::Error> {
+    async fn on_start(args: Self::Args, this: ActorRef<Self>) -> Result<Self, Self::Error> {
         args.props
             .actors
-            .flow_coordinator
-            .ask(RegisterUserAgent {
+            .useragent_registry
+            .ask(ConnectUseragent {
                 actor: this.clone(),
             })
             .await
             .map_err(|err| {
                 error!(
                     ?err,
-                    "Failed to register user agent connection with flow coordinator"
+                    "Failed to register user agent connection with user agent registry"
                 );
-                UserAgentSessionError::internal(
-                    "Failed to register user agent connection with flow coordinator",
-                )
+                Error::internal("Failed to register user agent connection with user agent registry")
             })?;
         Ok(args)
     }

server/crates/arbiter-server/src/peers/user_agent/vault_gate/mod.rs

@@ -0,0 +1,288 @@
+use super::Credentials;
+use crate::{
+    actors::{
+        GlobalActors,
+        vault::{self, Bootstrap, GetState, TryUnseal, VaultState, events},
+    },
+    crypto::integrity::{self},
+    db::DatabasePool,
+};
+use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use state::State;
+
+use chacha20poly1305::{AeadInPlace, KeyInit as _, XChaCha20Poly1305, XNonce};
+use kameo::{Actor, error::SendError, messages, prelude::Message};
+use kameo_actors::message_bus::Register;
+use tokio::sync::oneshot;
+use tracing::{error, info};
+use x25519_dalek::{EphemeralSecret, PublicKey, SharedSecret};
+
+pub mod state;
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("Vault is already bootstrapped")]
+    AlreadyBootstrapped,
+    #[error("Invalid key provided")]
+    InvalidKey,
+
+    #[error("State transition failed")]
+    State,
+
+    #[error("Internal error: {0}")]
+    Internal(String),
+}
+impl Error {
+    fn internal(message: impl Into<String>) -> Self {
+        Self::Internal(message.into())
+    }
+}
+
+pub struct HandshakeResponse {
+    pub server_pubkey: PublicKey,
+}
+
+pub struct VaultGate {
+    pub auth_creds: Credentials,
+    pub promotion_tx: Option<oneshot::Sender<Result<(), Error>>>,
+    pub state: State,
+    pub actors: GlobalActors,
+    pub db: DatabasePool,
+}
+
+impl VaultGate {
+    pub fn new(
+        auth_creds: Credentials,
+        actors: GlobalActors,
+        db: DatabasePool,
+        promotion_tx: oneshot::Sender<Result<(), Error>>,
+    ) -> Self {
+        Self {
+            auth_creds,
+            state: State::default(),
+            actors,
+            db,
+            promotion_tx: Some(promotion_tx),
+        }
+    }
+}
+
+impl Actor for VaultGate {
+    type Args = Self;
+
+    type Error = ();
+
+    async fn on_start(
+        args: Self::Args,
+        actor_ref: kameo::prelude::ActorRef<Self>,
+    ) -> Result<Self, Self::Error> {
+        let _ = args
+            .actors
+            .events
+            .tell(Register(
+                actor_ref.clone().recipient::<events::Bootstrapped>(),
+            ))
+            .await;
+        let _ = args
+            .actors
+            .events
+            .tell(Register(actor_ref.recipient::<events::Unsealed>()))
+            .await;
+        Ok(args)
+    }
+}
+
+impl VaultGate {
+    fn decrypt_key(
+        secret: &SharedSecret,
+        nonce: &[u8],
+        ciphertext: &[u8],
+        associated_data: &[u8],
+    ) -> Result<SafeCell<Vec<u8>>, ()> {
+        let nonce = XNonce::from_slice(nonce);
+
+        let cipher = XChaCha20Poly1305::new(secret.as_bytes().into());
+
+        let mut key_buffer = SafeCell::new(ciphertext.to_vec());
+
+        let decryption_result = key_buffer.write_inline(|write_handle| {
+            cipher.decrypt_in_place(nonce, associated_data, write_handle)
+        });
+
+        match decryption_result {
+            Ok(()) => Ok(key_buffer),
+            Err(err) => {
+                error!(?err, "Failed to decrypt encrypted key material");
+                Err(())
+            }
+        }
+    }
+}
+
+#[messages(messages = Inbound, replies = Outbound)]
+impl VaultGate {
+    #[message]
+    pub fn handle_handshake(
+        &mut self,
+        client_pubkey: PublicKey,
+    ) -> Result<HandshakeResponse, Error> {
+        let ephemeral_secret = EphemeralSecret::random();
+        let public_key = PublicKey::from(&ephemeral_secret);
+
+        let secret = ephemeral_secret.diffie_hellman(&client_pubkey);
+
+        self.state = State::ReadyForExchange {
+            server_key: public_key,
+            secret,
+        };
+
+        Ok(HandshakeResponse {
+            server_pubkey: public_key,
+        })
+    }
+
+    #[message]
+    pub async fn handle_unseal_encrypted_key(
+        &mut self,
+        nonce: Vec<u8>,
+        ciphertext: Vec<u8>,
+        associated_data: Vec<u8>,
+    ) -> Result<(), Error> {
+        let State::ReadyForExchange { secret, .. } = &self.state else {
+            return Err(Error::State);
+        };
+
+        let Ok(seal_key_buffer) = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
+        else {
+            return Err(Error::InvalidKey);
+        };
+
+        match self
+            .actors
+            .vault
+            .ask(TryUnseal {
+                seal_key_raw: seal_key_buffer,
+            })
+            .await
+        {
+            Ok(()) => {
+                info!("Successfully unsealed key with client-provided key");
+                Ok(())
+            }
+            Err(SendError::HandlerError(vault::Error::InvalidKey)) => Err(Error::InvalidKey),
+            Err(SendError::HandlerError(err)) => {
+                error!(?err, "Vault failed to unseal key");
+                Err(Error::InvalidKey)
+            }
+            Err(err) => {
+                error!(?err, "Failed to send unseal request to vault");
+                Err(Error::internal("Vault actor error"))
+            }
+        }
+    }
+
+    #[message]
+    pub async fn handle_bootstrap_encrypted_key(
+        &mut self,
+        nonce: Vec<u8>,
+        ciphertext: Vec<u8>,
+        associated_data: Vec<u8>,
+    ) -> Result<(), Error> {
+        let State::ReadyForExchange { secret, .. } = &self.state else {
+            return Err(Error::State);
+        };
+
+        let Ok(seal_key_buffer) = Self::decrypt_key(secret, &nonce, &ciphertext, &associated_data)
+        else {
+            return Err(Error::InvalidKey);
+        };
+
+        match self
+            .actors
+            .vault
+            .ask(Bootstrap {
+                seal_key_raw: seal_key_buffer,
+            })
+            .await
+        {
+            Ok(()) => {
+                info!("Successfully bootstrapped vault with client-provided key");
+                Ok(())
+            }
+            Err(SendError::HandlerError(vault::Error::AlreadyBootstrapped)) => {
+                Err(Error::AlreadyBootstrapped)
+            }
+            Err(SendError::HandlerError(err)) => {
+                error!(?err, "Vault failed to bootstrap vault");
+                Err(Error::InvalidKey)
+            }
+            Err(err) => {
+                error!(?err, "Failed to send bootstrap request to vault");
+                Err(Error::internal("Vault error"))
+            }
+        }
+    }
+
+    #[message]
+    pub async fn handle_vault_state(&mut self) -> Result<VaultState, Error> {
+        let answer = self
+            .actors
+            .vault
+            .ask(GetState {})
+            .await
+            .map_err(|_| Error::internal("failed to query vault"))?;
+
+        Ok(answer)
+    }
+}
+
+impl Message<events::Bootstrapped> for VaultGate {
+    type Reply = ();
+
+    async fn handle(
+        &mut self,
+        _: events::Bootstrapped,
+        ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
+    ) -> Self::Reply {
+        let result = async {
+            let mut conn = self
+                .db
+                .get()
+                .await
+                .map_err(|_| Error::internal("DB unavailable"))?;
+            integrity::sign_entity(
+                &mut conn,
+                &self.actors.vault,
+                &self.auth_creds,
+                self.auth_creds.id,
+            )
+            .await
+            .map_err(|e| {
+                error!(?e, "Failed to sign integrity envelope on bootstrap");
+                Error::internal("Integrity sign failed")
+            })?;
+            Ok(())
+        }
+        .await;
+
+        if let Some(tx) = self.promotion_tx.take() {
+            let _ = tx.send(result);
+        }
+        ctx.stop();
+    }
+}
+
+impl Message<events::Unsealed> for VaultGate {
+    type Reply = ();
+
+    async fn handle(
+        &mut self,
+        _: events::Unsealed,
+        ctx: &mut kameo::prelude::Context<Self, Self::Reply>,
+    ) -> Self::Reply {
+        if let Some(tx) = self.promotion_tx.take() {
+            let _ = tx.send(Ok(()));
+        }
+        ctx.stop();
+    }
+}

server/crates/arbiter-server/src/peers/user_agent/vault_gate/state.rs

@@ -0,0 +1,11 @@
+use x25519_dalek::{PublicKey, SharedSecret};
+
+#[derive(Default)]
+pub enum State {
+    #[default]
+    Idle,
+    ReadyForExchange {
+        server_key: PublicKey,
+        secret: SharedSecret,
+    },
+}

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

@@ -1,24 +1,23 @@
+use super::common::ChannelTransport;
 use arbiter_crypto::{
-    authn::{self, CLIENT_CONTEXT, format_challenge},
+    authn::{self, AuthChallenge, CLIENT_CONTEXT},
     safecell::{SafeCell, SafeCellHandle as _},
 };
-use arbiter_proto::ClientMetadata;
-use arbiter_proto::transport::{Receiver, Sender};
+use arbiter_proto::{
+    ClientMetadata,
+    transport::{Receiver, Sender},
+};
 use arbiter_server::{
-    actors::{
-        GlobalActors,
-        client::{ClientConnection, ClientCredentials, auth, connect_client},
-        keyholder::Bootstrap,
-    },
+    actors::{GlobalActors, vault::Bootstrap},
     crypto::integrity,
     db::{self, schema},
+    peers::client::{ClientConnection, ClientCredentials, auth, connect_client},
 };
+
 use diesel::{ExpressionMethods as _, NullableExpressionMethods as _, QueryDsl as _, insert_into};
 use diesel_async::RunQueryDsl;
 use ml_dsa::{KeyGen, MlDsa87, SigningKey, VerifyingKey, signature::Keypair};
 
-use super::common::ChannelTransport;
-
 fn metadata(name: &str, description: Option<&str>, version: Option<&str>) -> ClientMetadata {
     ClientMetadata {
         name: name.to_owned(),
@@ -62,10 +61,9 @@ async fn insert_registered_client(
 
     integrity::sign_entity(
         &mut conn,
-        &actors.key_holder,
+        &actors.vault,
         &ClientCredentials {
             pubkey: pubkey.into(),
-            nonce: 1,
         },
         client_id,
     )
@@ -73,12 +71,8 @@ async fn insert_registered_client(
     .unwrap();
 }
 
-fn sign_client_challenge(
-    key: &SigningKey<MlDsa87>,
-    nonce: i32,
-    pubkey: &authn::PublicKey,
-) -> authn::Signature {
-    let challenge = format_challenge(nonce, &pubkey.to_bytes());
+fn sign_client_challenge(key: &SigningKey<MlDsa87>, challenge: &AuthChallenge) -> authn::Signature {
+    let challenge = challenge.format();
     key.signing_key()
         .sign_deterministic(&challenge, CLIENT_CONTEXT)
         .unwrap()
@@ -93,10 +87,7 @@ async fn insert_bootstrap_sentinel_useragent(db: &db::DatabasePool) {
         .to_vec();
 
     insert_into(schema::useragent_client::table)
-        .values((
-            schema::useragent_client::public_key.eq(sentinel_key),
-            schema::useragent_client::key_type.eq(1i32),
-        ))
+        .values((schema::useragent_client::public_key.eq(sentinel_key),))
         .execute(&mut conn)
         .await
         .unwrap();
@@ -107,7 +98,7 @@ async fn spawn_test_actors(db: &db::DatabasePool) -> GlobalActors {
 
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
     actors
-        .key_holder
+        .vault
         .ask(Bootstrap {
             seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
         })
@@ -182,14 +173,14 @@ pub async fn challenge_auth() {
         .expect("should receive challenge");
     let challenge = match response {
         Ok(resp) => match resp {
-            auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
+            auth::Outbound::AuthChallenge { challenge } => challenge,
             other @ auth::Outbound::AuthSuccess => panic!("Expected AuthChallenge, got {other:?}"),
         },
         Err(err) => panic!("Expected Ok response, got Err({err:?})"),
     };
 
     // Sign the challenge and send solution
-    let signature = sign_client_challenge(&new_key, challenge.1, &challenge.0);
+    let signature = sign_client_challenge(&new_key, &challenge);
 
     test_transport
         .send(auth::Inbound::AuthChallengeSolution { signature })
@@ -243,11 +234,11 @@ pub async fn metadata_unchanged_does_not_append_history() {
         .unwrap();
 
     let response = test_transport.recv().await.unwrap().unwrap();
-    let (pubkey, nonce) = match response {
-        auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
+    let challenge = match response {
+        auth::Outbound::AuthChallenge { challenge } => challenge,
         auth::Outbound::AuthSuccess => panic!("Expected AuthChallenge, got AuthSuccess"),
     };
-    let signature = sign_client_challenge(&new_key, nonce, &pubkey);
+    let signature = sign_client_challenge(&new_key, &challenge);
     test_transport
         .send(auth::Inbound::AuthChallengeSolution { signature })
         .await
@@ -305,11 +296,11 @@ pub async fn metadata_change_appends_history_and_repoints_binding() {
         .unwrap();
 
     let response = test_transport.recv().await.unwrap().unwrap();
-    let (pubkey, nonce) = match response {
-        auth::Outbound::AuthChallenge { pubkey, nonce } => (pubkey, nonce),
+    let challenge = match response {
+        auth::Outbound::AuthChallenge { challenge } => challenge,
         auth::Outbound::AuthSuccess => panic!("Expected AuthChallenge, got AuthSuccess"),
     };
-    let signature = sign_client_challenge(&new_key, nonce, &pubkey);
+    let signature = sign_client_challenge(&new_key, &challenge);
     test_transport
         .send(auth::Inbound::AuthChallengeSolution { signature })
         .await
@@ -411,10 +402,7 @@ pub async fn challenge_auth_rejects_integrity_tag_mismatch() {
         .recv()
         .await
         .expect("should receive auth rejection");
-    assert!(matches!(
-        response,
-        Err(auth::ClientAuthError::IntegrityCheckFailed)
-    ));
+    assert!(matches!(response, Err(auth::Error::IntegrityCheckFailed)));
 
     task.await.unwrap();
 }

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

@@ -1,8 +1,11 @@
-#![allow(dead_code, reason = "Common test utilities that may not be used in every test")]
+#![allow(
+    dead_code,
+    reason = "Common test utilities that may not be used in every test"
+)]
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_proto::transport::{Bi, Error, Receiver, Sender};
 use arbiter_server::{
-    actors::keyholder::KeyHolder,
+    actors::{GlobalActors, vault::Vault},
     db::{self, schema},
 };
 
@@ -11,8 +14,10 @@ use diesel::QueryDsl;
 use diesel_async::RunQueryDsl;
 use tokio::sync::mpsc;
 
-pub async fn bootstrapped_keyholder(db: &db::DatabasePool) -> KeyHolder {
-    let mut actor = KeyHolder::new(db.clone()).await.unwrap();
+pub(crate) async fn bootstrapped_vault(db: &db::DatabasePool) -> Vault {
+    let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
+        .await
+        .unwrap();
     actor
         .bootstrap(SafeCell::new(b"test-seal-key".to_vec()))
         .await
@@ -20,7 +25,7 @@ pub async fn bootstrapped_keyholder(db: &db::DatabasePool) -> KeyHolder {
     actor
 }
 
-pub async fn root_key_history_id(db: &db::DatabasePool) -> i32 {
+pub(crate) async fn root_key_history_id(db: &db::DatabasePool) -> i32 {
     let mut conn = db.get().await.unwrap();
     let id = schema::arbiter_settings::table
         .select(schema::arbiter_settings::root_key_id)
@@ -30,13 +35,13 @@ pub async fn root_key_history_id(db: &db::DatabasePool) -> i32 {
     id.expect("root_key_id should be set after bootstrap")
 }
 
-pub struct ChannelTransport<T, Y> {
+pub(crate) 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>) {
+    pub(crate) fn new() -> (Self, ChannelTransport<Y, T>) {
         let (tx1, rx1) = mpsc::channel(10);
         let (tx2, rx2) = mpsc::channel(10);
         (

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

@@ -1,8 +0,0 @@
-mod common;
-
-#[path = "keyholder/concurrency.rs"]
-mod concurrency;
-#[path = "keyholder/lifecycle.rs"]
-mod lifecycle;
-#[path = "keyholder/storage.rs"]
-mod storage;

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

@@ -1,24 +1,21 @@
+use super::common::ChannelTransport;
 use arbiter_crypto::{
-    authn::{self, USERAGENT_CONTEXT, format_challenge},
+    authn::{self, AuthChallenge, USERAGENT_CONTEXT},
     safecell::{SafeCell, SafeCellHandle as _},
 };
-
-use arbiter_proto::transport::{Receiver, Sender};
+use arbiter_proto::transport::{Error as TransportError, Receiver, Sender};
 use arbiter_server::{
-    actors::{
-        GlobalActors,
-        bootstrap::GetToken,
-        keyholder::Bootstrap,
-        user_agent::{UserAgentConnection, UserAgentCredentials, auth},
-    },
+    actors::{GlobalActors, bootstrap::GetToken, vault::Bootstrap},
     crypto::integrity,
     db::{self, schema},
+    peers::user_agent::{self, Credentials, UserAgentConnection, auth, vault_gate},
 };
+
+use async_trait::async_trait;
 use diesel::{ExpressionMethods as _, QueryDsl, insert_into};
 use diesel_async::RunQueryDsl;
 use ml_dsa::{KeyGen, MlDsa87, SigningKey, VerifyingKey, signature::Keypair};
-
-use super::common::ChannelTransport;
+use tokio::sync::mpsc;
 
 fn verifying_key(key: &SigningKey<MlDsa87>) -> VerifyingKey<MlDsa87> {
     <SigningKey<MlDsa87> as Keypair>::verifying_key(key)
@@ -26,23 +23,139 @@ fn verifying_key(key: &SigningKey<MlDsa87>) -> VerifyingKey<MlDsa87> {
 
 fn sign_useragent_challenge(
     key: &SigningKey<MlDsa87>,
-    nonce: i32,
-    pubkey_bytes: &[u8],
+    challenge: &AuthChallenge,
 ) -> authn::Signature {
-    let challenge = format_challenge(nonce, pubkey_bytes);
+    let challenge = challenge.format();
     key.signing_key()
         .sign_deterministic(&challenge, USERAGENT_CONTEXT)
         .unwrap()
         .into()
 }
 
+fn tamper_challenge(challenge: &AuthChallenge) -> AuthChallenge {
+    let mut challenge = challenge.clone();
+    challenge.nonce[0] ^= 1;
+    challenge
+}
+
+struct NullOobSender;
+
+#[async_trait]
+impl Sender<user_agent::OutOfBand> for NullOobSender {
+    async fn send(&mut self, _item: user_agent::OutOfBand) -> Result<(), TransportError> {
+        Ok(())
+    }
+}
+
+struct StartServerTransport {
+    auth_rx: mpsc::Receiver<auth::Inbound>,
+    auth_tx: mpsc::Sender<Result<auth::Outbound, auth::Error>>,
+    vault_rx: mpsc::Receiver<vault_gate::Inbound>,
+    vault_tx: mpsc::Sender<Result<vault_gate::Outbound, vault_gate::Error>>,
+}
+
+struct StartTestTransport {
+    auth_rx: mpsc::Receiver<Result<auth::Outbound, auth::Error>>,
+    auth_tx: mpsc::Sender<auth::Inbound>,
+}
+
+fn start_transport_pair() -> (StartServerTransport, StartTestTransport) {
+    let (auth_in_tx, auth_in_rx) = mpsc::channel(10);
+    let (auth_out_tx, auth_out_rx) = mpsc::channel(10);
+    let (_vault_in_tx, vault_in_rx) = mpsc::channel(10);
+    let (vault_out_tx, _vault_out_rx) = mpsc::channel(10);
+
+    (
+        StartServerTransport {
+            auth_rx: auth_in_rx,
+            auth_tx: auth_out_tx,
+            vault_rx: vault_in_rx,
+            vault_tx: vault_out_tx,
+        },
+        StartTestTransport {
+            auth_rx: auth_out_rx,
+            auth_tx: auth_in_tx,
+        },
+    )
+}
+
+#[async_trait]
+impl Receiver<auth::Inbound> for StartServerTransport {
+    async fn recv(&mut self) -> Option<auth::Inbound> {
+        self.auth_rx.recv().await
+    }
+}
+
+#[async_trait]
+impl Sender<Result<auth::Outbound, auth::Error>> for StartServerTransport {
+    async fn send(
+        &mut self,
+        item: Result<auth::Outbound, auth::Error>,
+    ) -> Result<(), TransportError> {
+        self.auth_tx
+            .send(item)
+            .await
+            .map_err(|_| TransportError::ChannelClosed)
+    }
+}
+
+impl arbiter_proto::transport::Bi<auth::Inbound, Result<auth::Outbound, auth::Error>>
+    for StartServerTransport
+{
+}
+
+#[async_trait]
+impl Receiver<vault_gate::Inbound> for StartServerTransport {
+    async fn recv(&mut self) -> Option<vault_gate::Inbound> {
+        self.vault_rx.recv().await
+    }
+}
+
+#[async_trait]
+impl Sender<Result<vault_gate::Outbound, vault_gate::Error>> for StartServerTransport {
+    async fn send(
+        &mut self,
+        item: Result<vault_gate::Outbound, vault_gate::Error>,
+    ) -> Result<(), TransportError> {
+        self.vault_tx
+            .send(item)
+            .await
+            .map_err(|_| TransportError::ChannelClosed)
+    }
+}
+
+impl
+    arbiter_proto::transport::Bi<
+        vault_gate::Inbound,
+        Result<vault_gate::Outbound, vault_gate::Error>,
+    > for StartServerTransport
+{
+}
+
+#[async_trait]
+impl Receiver<Result<auth::Outbound, auth::Error>> for StartTestTransport {
+    async fn recv(&mut self) -> Option<Result<auth::Outbound, auth::Error>> {
+        self.auth_rx.recv().await
+    }
+}
+
+#[async_trait]
+impl Sender<auth::Inbound> for StartTestTransport {
+    async fn send(&mut self, item: auth::Inbound) -> Result<(), TransportError> {
+        self.auth_tx
+            .send(item)
+            .await
+            .map_err(|_| TransportError::ChannelClosed)
+    }
+}
+
 #[tokio::test]
 #[test_log::test]
 pub async fn bootstrap_token_auth() {
     let db = db::create_test_pool().await;
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
     actors
-        .key_holder
+        .vault
         .ask(Bootstrap {
             seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
         })
@@ -50,11 +163,11 @@ pub async fn bootstrap_token_auth() {
         .unwrap();
     let token = actors.bootstrapper.ask(GetToken).await.unwrap().unwrap();
 
-    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let (mut server_transport, mut test_transport) = ChannelTransport::new();
     let db_for_task = db.clone();
     let task = tokio::spawn(async move {
         let mut props = UserAgentConnection::new(db_for_task, actors);
-        auth::authenticate(&mut props, server_transport).await
+        auth::authenticate(&mut props, &mut server_transport).await
     });
 
     let new_key = MlDsa87::key_gen(&mut rand::rng());
@@ -66,14 +179,29 @@ pub async fn bootstrap_token_auth() {
         .await
         .unwrap();
 
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(auth::Outbound::AuthChallenge { challenge }) => challenge,
+        other => panic!("Expected AuthChallenge, got {other:?}"),
+    };
+
+    let signature = sign_useragent_challenge(&new_key, &challenge);
+
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes(),
+        })
+        .await
+        .unwrap();
+
     let response = test_transport
         .recv()
         .await
         .expect("should receive auth result");
-    match response {
-        Ok(auth::Outbound::AuthSuccess) => {}
-        other => panic!("Expected AuthSuccess, got {other:?}"),
-    }
+    assert!(matches!(response, Ok(auth::Outbound::AuthSuccess)));
 
     task.await.unwrap().unwrap();
 
@@ -92,11 +220,11 @@ pub async fn bootstrap_invalid_token_auth() {
     let db = db::create_test_pool().await;
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
 
-    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let (mut server_transport, mut test_transport) = ChannelTransport::new();
     let db_for_task = db.clone();
     let task = tokio::spawn(async move {
         let mut props = UserAgentConnection::new(db_for_task, actors);
-        auth::authenticate(&mut props, server_transport).await
+        auth::authenticate(&mut props, &mut server_transport).await
     });
 
     let new_key = MlDsa87::key_gen(&mut rand::rng());
@@ -108,6 +236,23 @@ pub async fn bootstrap_invalid_token_auth() {
         .await
         .unwrap();
 
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(auth::Outbound::AuthChallenge { challenge }) => challenge,
+        other => panic!("Expected AuthChallenge, got {other:?}"),
+    };
+
+    let signature = sign_useragent_challenge(&new_key, &challenge);
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes(),
+        })
+        .await
+        .unwrap();
+
     assert!(matches!(
         task.await.unwrap(),
         Err(auth::Error::InvalidBootstrapToken)
@@ -128,7 +273,7 @@ pub async fn challenge_auth() {
     let db = db::create_test_pool().await;
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
     actors
-        .key_holder
+        .vault
         .ask(Bootstrap {
             seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
         })
@@ -141,20 +286,17 @@ pub async fn challenge_auth() {
     {
         let mut conn = db.get().await.unwrap();
         let id: i32 = insert_into(schema::useragent_client::table)
-            .values((
-                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
-                schema::useragent_client::key_type.eq(1i32),
-            ))
+            .values((schema::useragent_client::public_key.eq(pubkey_bytes.clone()),))
             .returning(schema::useragent_client::id)
             .get_result(&mut conn)
             .await
             .unwrap();
         integrity::sign_entity(
             &mut conn,
-            &actors.key_holder,
-            &UserAgentCredentials {
+            &actors.vault,
+            &Credentials {
+                id,
                 pubkey: verifying_key(&new_key).into(),
-                nonce: 1,
             },
             id,
         )
@@ -162,11 +304,11 @@ pub async fn challenge_auth() {
         .unwrap();
     }
 
-    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let (mut server_transport, mut test_transport) = ChannelTransport::new();
     let db_for_task = db.clone();
     let task = tokio::spawn(async move {
         let mut props = UserAgentConnection::new(db_for_task, actors);
-        auth::authenticate(&mut props, server_transport).await
+        auth::authenticate(&mut props, &mut server_transport).await
     });
 
     test_transport
@@ -183,13 +325,13 @@ pub async fn challenge_auth() {
         .expect("should receive challenge");
     let challenge = match response {
         Ok(resp) => match resp {
-            auth::Outbound::AuthChallenge { nonce } => nonce,
+            auth::Outbound::AuthChallenge { challenge } => challenge,
             auth::Outbound::AuthSuccess => panic!("Expected AuthChallenge, got AuthSuccess"),
         },
         Err(err) => panic!("Expected Ok response, got Err({err:?})"),
     };
 
-    let signature = sign_useragent_challenge(&new_key, challenge, &pubkey_bytes);
+    let signature = sign_useragent_challenge(&new_key, &challenge);
 
     test_transport
         .send(auth::Inbound::AuthChallengeSolution {
@@ -217,7 +359,7 @@ pub async fn challenge_auth_rejects_integrity_tag_mismatch_when_unsealed() {
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
 
     actors
-        .key_holder
+        .vault
         .ask(Bootstrap {
             seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
         })
@@ -230,81 +372,17 @@ pub async fn challenge_auth_rejects_integrity_tag_mismatch_when_unsealed() {
     {
         let mut conn = db.get().await.unwrap();
         insert_into(schema::useragent_client::table)
-            .values((
-                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
-                schema::useragent_client::key_type.eq(1i32),
-            ))
+            .values((schema::useragent_client::public_key.eq(pubkey_bytes.clone()),))
             .execute(&mut conn)
             .await
             .unwrap();
     }
 
-    let (server_transport, mut test_transport) = ChannelTransport::new();
+    let (server_transport, mut test_transport) = start_transport_pair();
     let db_for_task = db.clone();
     let task = tokio::spawn(async move {
         let mut props = UserAgentConnection::new(db_for_task, actors);
-        auth::authenticate(&mut props, server_transport).await
-    });
-
-    test_transport
-        .send(auth::Inbound::AuthChallengeRequest {
-            pubkey: verifying_key(&new_key).into(),
-            bootstrap_token: None,
-        })
-        .await
-        .unwrap();
-
-    assert!(matches!(
-        task.await.unwrap(),
-        Err(auth::Error::Internal { .. })
-    ));
-}
-
-#[tokio::test]
-#[test_log::test]
-pub async fn challenge_auth_rejects_invalid_signature() {
-    let db = db::create_test_pool().await;
-    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
-    actors
-        .key_holder
-        .ask(Bootstrap {
-            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
-        })
-        .await
-        .unwrap();
-
-    let new_key = MlDsa87::key_gen(&mut rand::rng());
-    let pubkey_bytes = authn::PublicKey::from(verifying_key(&new_key)).to_bytes();
-
-    {
-        let mut conn = db.get().await.unwrap();
-        let id: i32 = insert_into(schema::useragent_client::table)
-            .values((
-                schema::useragent_client::public_key.eq(pubkey_bytes.clone()),
-                schema::useragent_client::key_type.eq(1i32),
-            ))
-            .returning(schema::useragent_client::id)
-            .get_result(&mut conn)
-            .await
-            .unwrap();
-        integrity::sign_entity(
-            &mut conn,
-            &actors.key_holder,
-            &UserAgentCredentials {
-                pubkey: verifying_key(&new_key).into(),
-                nonce: 1,
-            },
-            id,
-        )
-        .await
-        .unwrap();
-    }
-
-    let (server_transport, mut test_transport) = ChannelTransport::new();
-    let db_for_task = db.clone();
-    let task = tokio::spawn(async move {
-        let mut props = UserAgentConnection::new(db_for_task, actors);
-        auth::authenticate(&mut props, server_transport).await
+        user_agent::start(&mut props, server_transport, Box::new(NullOobSender)).await
     });
 
     test_transport
@@ -321,13 +399,98 @@ pub async fn challenge_auth_rejects_invalid_signature() {
         .expect("should receive challenge");
     let challenge = match response {
         Ok(resp) => match resp {
-            auth::Outbound::AuthChallenge { nonce } => nonce,
+            auth::Outbound::AuthChallenge { challenge } => challenge,
+            other => panic!("Expected AuthChallenge, got {other:?}"),
+        },
+        Err(err) => panic!("Expected Ok response, got Err({err:?})"),
+    };
+
+    let signature = sign_useragent_challenge(&new_key, &challenge);
+
+    test_transport
+        .send(auth::Inbound::AuthChallengeSolution {
+            signature: signature.to_bytes(),
+        })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive auth result");
+    assert!(matches!(response, Ok(auth::Outbound::AuthSuccess)));
+
+    assert!(matches!(
+        task.await.unwrap(),
+        Err(user_agent::Error::Internal(_))
+    ));
+}
+
+#[tokio::test]
+#[test_log::test]
+pub async fn challenge_auth_rejects_invalid_signature() {
+    let db = db::create_test_pool().await;
+    let actors = GlobalActors::spawn(db.clone()).await.unwrap();
+    actors
+        .vault
+        .ask(Bootstrap {
+            seal_key_raw: SafeCell::new(b"test-seal-key".to_vec()),
+        })
+        .await
+        .unwrap();
+
+    let new_key = MlDsa87::key_gen(&mut rand::rng());
+    let pubkey_bytes = authn::PublicKey::from(verifying_key(&new_key)).to_bytes();
+
+    {
+        let mut conn = db.get().await.unwrap();
+        let id: i32 = insert_into(schema::useragent_client::table)
+            .values((schema::useragent_client::public_key.eq(pubkey_bytes.clone()),))
+            .returning(schema::useragent_client::id)
+            .get_result(&mut conn)
+            .await
+            .unwrap();
+        integrity::sign_entity(
+            &mut conn,
+            &actors.vault,
+            &Credentials {
+                id,
+                pubkey: verifying_key(&new_key).into(),
+            },
+            id,
+        )
+        .await
+        .unwrap();
+    }
+
+    let (mut server_transport, mut test_transport) = ChannelTransport::new();
+    let db_for_task = db.clone();
+    let task = tokio::spawn(async move {
+        let mut props = UserAgentConnection::new(db_for_task, actors);
+        auth::authenticate(&mut props, &mut server_transport).await
+    });
+
+    test_transport
+        .send(auth::Inbound::AuthChallengeRequest {
+            pubkey: verifying_key(&new_key).into(),
+            bootstrap_token: None,
+        })
+        .await
+        .unwrap();
+
+    let response = test_transport
+        .recv()
+        .await
+        .expect("should receive challenge");
+    let challenge = match response {
+        Ok(resp) => match resp {
+            auth::Outbound::AuthChallenge { challenge } => challenge,
             auth::Outbound::AuthSuccess => panic!("Expected AuthChallenge, got AuthSuccess"),
         },
         Err(err) => panic!("Expected Ok response, got Err({err:?})"),
     };
 
-    let signature = sign_useragent_challenge(&new_key, challenge + 1, &pubkey_bytes);
+    let signature = sign_useragent_challenge(&new_key, &tamper_challenge(&challenge));
 
     test_transport
         .send(auth::Inbound::AuthChallengeSolution {

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

@@ -1,49 +1,62 @@
-use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
+use arbiter_crypto::{
+    authn,
+    safecell::{SafeCell, SafeCellHandle as _},
+};
 use arbiter_server::{
     actors::{
         GlobalActors,
-        keyholder::{Bootstrap, Seal},
-        user_agent::{
-            UserAgentSession,
-            session::connection::{HandleUnsealEncryptedKey, HandleUnsealRequest, UnsealError},
-        },
+        vault::{Bootstrap, Seal},
     },
     db,
+    peers::user_agent::{
+        Credentials,
+        vault_gate::{
+            Error as VaultGateError, HandleHandshake, HandleUnsealEncryptedKey, VaultGate,
+        },
+    },
 };
 
 use chacha20poly1305::{AeadInPlace, XChaCha20Poly1305, XNonce, aead::KeyInit};
 use kameo::actor::Spawn as _;
+use tokio::sync::oneshot;
 use x25519_dalek::{EphemeralSecret, PublicKey};
 
-async fn setup_sealed_user_agent(
+async fn setup_sealed_gate(
     seal_key: &[u8],
-) -> (db::DatabasePool, kameo::actor::ActorRef<UserAgentSession>) {
+) -> (
+    db::DatabasePool,
+    kameo::actor::ActorRef<VaultGate>,
+    oneshot::Receiver<Result<(), VaultGateError>>,
+) {
     let db = db::create_test_pool().await;
     let actors = GlobalActors::spawn(db.clone()).await.unwrap();
 
     actors
-        .key_holder
+        .vault
         .ask(Bootstrap {
             seal_key_raw: SafeCell::new(seal_key.to_vec()),
         })
         .await
         .unwrap();
-    actors.key_holder.ask(Seal).await.unwrap();
+    actors.vault.ask(Seal).await.unwrap();
 
-    let session = UserAgentSession::spawn(UserAgentSession::new_test(db.clone(), actors));
+    let (promotion_tx, promotion_rx) = oneshot::channel();
+    let pubkey = authn::SigningKey::generate().public_key();
+    let auth_creds = Credentials { id: 1, pubkey };
+    let gate = VaultGate::spawn(VaultGate::new(auth_creds, actors, db.clone(), promotion_tx));
 
-    (db, session)
+    (db, gate, promotion_rx)
 }
 
 async fn client_dh_encrypt(
-    user_agent: &kameo::actor::ActorRef<UserAgentSession>,
+    gate: &kameo::actor::ActorRef<VaultGate>,
     key_to_send: &[u8],
 ) -> HandleUnsealEncryptedKey {
     let client_secret = EphemeralSecret::random();
     let client_public = PublicKey::from(&client_secret);
 
-    let response = user_agent
-        .ask(HandleUnsealRequest {
+    let response = gate
+        .ask(HandleHandshake {
             client_pubkey: client_public,
         })
         .await
@@ -71,26 +84,27 @@ async fn client_dh_encrypt(
 #[test_log::test]
 pub async fn unseal_success() {
     let seal_key = b"test-seal-key";
-    let (_db, user_agent) = setup_sealed_user_agent(seal_key).await;
+    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;
 
-    let encrypted_key = client_dh_encrypt(&user_agent, seal_key).await;
+    let encrypted_key = client_dh_encrypt(&gate, seal_key).await;
 
-    let response = user_agent.ask(encrypted_key).await;
+    let response = gate.ask(encrypted_key).await;
     assert!(matches!(response, Ok(())));
 }
 
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_wrong_seal_key() {
-    let (_db, user_agent) = setup_sealed_user_agent(b"correct-key").await;
+    let seal_key = b"test-seal-key";
+    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;
 
-    let encrypted_key = client_dh_encrypt(&user_agent, b"wrong-key").await;
+    let encrypted_key = client_dh_encrypt(&gate, b"wrong-key").await;
 
-    let response = user_agent.ask(encrypted_key).await;
+    let response = gate.ask(encrypted_key).await;
     assert!(matches!(
         response,
         Err(kameo::error::SendError::HandlerError(
-            UnsealError::InvalidKey
+            VaultGateError::InvalidKey
         ))
     ));
 }
@@ -98,19 +112,19 @@ pub async fn unseal_wrong_seal_key() {
 #[tokio::test]
 #[test_log::test]
 pub async fn unseal_corrupted_ciphertext() {
-    let (_db, user_agent) = setup_sealed_user_agent(b"test-key").await;
+    let seal_key = b"test-seal-key";
+    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;
 
     let client_secret = EphemeralSecret::random();
     let client_public = PublicKey::from(&client_secret);
 
-    user_agent
-        .ask(HandleUnsealRequest {
+    gate.ask(HandleHandshake {
         client_pubkey: client_public,
     })
     .await
     .unwrap();
 
-    let response = user_agent
+    let response = gate
         .ask(HandleUnsealEncryptedKey {
             nonce: vec![0u8; 24],
             ciphertext: vec![0u8; 32],
@@ -121,7 +135,7 @@ pub async fn unseal_corrupted_ciphertext() {
     assert!(matches!(
         response,
         Err(kameo::error::SendError::HandlerError(
-            UnsealError::InvalidKey
+            VaultGateError::InvalidKey
         ))
     ));
 }
@@ -130,24 +144,24 @@ pub async fn unseal_corrupted_ciphertext() {
 #[test_log::test]
 pub async fn unseal_retry_after_invalid_key() {
     let seal_key = b"real-seal-key";
-    let (_db, user_agent) = setup_sealed_user_agent(seal_key).await;
+    let (_db, gate, _promotion_rx) = setup_sealed_gate(seal_key).await;
 
     {
-        let encrypted_key = client_dh_encrypt(&user_agent, b"wrong-key").await;
+        let encrypted_key = client_dh_encrypt(&gate, b"wrong-key").await;
 
-        let response = user_agent.ask(encrypted_key).await;
+        let response = gate.ask(encrypted_key).await;
         assert!(matches!(
             response,
             Err(kameo::error::SendError::HandlerError(
-                UnsealError::InvalidKey
+                VaultGateError::InvalidKey
             ))
         ));
     }
 
     {
-        let encrypted_key = client_dh_encrypt(&user_agent, seal_key).await;
+        let encrypted_key = client_dh_encrypt(&gate, seal_key).await;
 
-        let response = user_agent.ask(encrypted_key).await;
+        let response = gate.ask(encrypted_key).await;
         assert!(matches!(response, Ok(())));
     }
 }

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

@@ -0,0 +1,8 @@
+mod common;
+
+#[path = "vault/concurrency.rs"]
+mod concurrency;
+#[path = "vault/lifecycle.rs"]
+mod lifecycle;
+#[path = "vault/storage.rs"]
+mod storage;

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

@@ -1,20 +1,21 @@
-use std::collections::{HashMap, HashSet};
-
+use crate::common;
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
-    actors::keyholder::{CreateNew, KeyHolder, KeyHolderError},
+    actors::{
+        GlobalActors,
+        vault::{CreateNew, Error, Vault},
+    },
     db::{self, models, schema},
 };
 
 use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper, dsl::sql_query};
 use diesel_async::RunQueryDsl;
 use kameo::actor::{ActorRef, Spawn as _};
+use std::collections::{HashMap, HashSet};
 use tokio::task::JoinSet;
 
-use crate::common;
-
 async fn write_concurrently(
-    actor: ActorRef<KeyHolder>,
+    actor: ActorRef<Vault>,
     prefix: &'static str,
     count: usize,
 ) -> Vec<(i32, Vec<u8>)> {
@@ -44,7 +45,7 @@ async fn write_concurrently(
 #[test_log::test]
 async fn concurrent_create_new_no_duplicate_nonces_() {
     let db = db::create_test_pool().await;
-    let actor = KeyHolder::spawn(common::bootstrapped_keyholder(&db).await);
+    let actor = Vault::spawn(common::bootstrapped_vault(&db).await);
 
     let writes = write_concurrently(actor, "nonce-unique", 32).await;
     assert_eq!(writes.len(), 32);
@@ -66,7 +67,7 @@ async fn concurrent_create_new_no_duplicate_nonces_() {
 #[test_log::test]
 async fn concurrent_create_new_root_nonce_never_moves_backward() {
     let db = db::create_test_pool().await;
-    let actor = KeyHolder::spawn(common::bootstrapped_keyholder(&db).await);
+    let actor = Vault::spawn(common::bootstrapped_vault(&db).await);
 
     write_concurrently(actor, "root-max", 24).await;
 
@@ -94,7 +95,7 @@ async fn concurrent_create_new_root_nonce_never_moves_backward() {
 #[test_log::test]
 async fn insert_failure_does_not_create_partial_row() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
     let root_key_history_id = common::root_key_history_id(&db).await;
 
     let mut conn = db.get().await.unwrap();
@@ -122,7 +123,7 @@ async fn insert_failure_does_not_create_partial_row() {
         .create_new(SafeCell::new(b"should fail".to_vec()))
         .await
         .unwrap_err();
-    assert!(matches!(err, KeyHolderError::DatabaseTransaction(_)));
+    assert!(matches!(err, Error::DatabaseTransaction(_)));
 
     let mut conn = db.get().await.unwrap();
     sql_query("DROP TRIGGER fail_aead_insert;")
@@ -156,12 +157,14 @@ async fn insert_failure_does_not_create_partial_row() {
 #[test_log::test]
 async fn decrypt_roundtrip_after_high_concurrency() {
     let db = db::create_test_pool().await;
-    let actor = KeyHolder::spawn(common::bootstrapped_keyholder(&db).await);
+    let actor = Vault::spawn(common::bootstrapped_vault(&db).await);
 
     let writes = write_concurrently(actor, "roundtrip", 40).await;
     let expected: HashMap<i32, Vec<u8>> = writes.into_iter().collect();
 
-    let mut decryptor = KeyHolder::new(db.clone()).await.unwrap();
+    let mut decryptor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
+        .await
+        .unwrap();
     decryptor
         .try_unseal(SafeCell::new(b"test-seal-key".to_vec()))
         .await

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

@@ -1,6 +1,10 @@
+use crate::common;
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
-    actors::keyholder::{KeyHolder, KeyHolderError},
+    actors::{
+        GlobalActors,
+        vault::{Error, Vault},
+    },
     crypto::encryption::v1::{Nonce, ROOT_KEY_TAG},
     db::{self, models, schema},
 };
@@ -8,13 +12,13 @@ use arbiter_server::{
 use diesel::{QueryDsl, SelectableHelper};
 use diesel_async::RunQueryDsl;
 
-use crate::common;
-
 #[tokio::test]
 #[test_log::test]
-async fn bootstrap() {
+async fn test_bootstrap() {
     let db = db::create_test_pool().await;
-    let mut actor = KeyHolder::new(db.clone()).await.unwrap();
+    let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
+        .await
+        .unwrap();
 
     let seal_key = SafeCell::new(b"test-seal-key".to_vec());
     actor.bootstrap(seal_key).await.unwrap();
@@ -35,55 +39,61 @@ async fn bootstrap() {
 
 #[tokio::test]
 #[test_log::test]
-async fn bootstrap_rejects_double() {
+async fn test_bootstrap_rejects_double() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
 
     let seal_key2 = SafeCell::new(b"test-seal-key".to_vec());
     let err = actor.bootstrap(seal_key2).await.unwrap_err();
-    assert!(matches!(err, KeyHolderError::AlreadyBootstrapped));
+    assert!(matches!(err, Error::AlreadyBootstrapped));
 }
 
 #[tokio::test]
 #[test_log::test]
-async fn create_new_before_bootstrap_fails() {
+async fn test_create_new_before_bootstrap_fails() {
     let db = db::create_test_pool().await;
-    let mut actor = KeyHolder::new(db).await.unwrap();
+    let mut actor = Vault::new(db, GlobalActors::spawn_message_bus())
+        .await
+        .unwrap();
 
     let err = actor
         .create_new(SafeCell::new(b"data".to_vec()))
         .await
         .unwrap_err();
-    assert!(matches!(err, KeyHolderError::NotBootstrapped));
+    assert!(matches!(err, Error::NotBootstrapped));
 }
 
 #[tokio::test]
 #[test_log::test]
-async fn decrypt_before_bootstrap_fails() {
+async fn test_decrypt_before_bootstrap_fails() {
     let db = db::create_test_pool().await;
-    let mut actor = KeyHolder::new(db).await.unwrap();
+    let mut actor = Vault::new(db, GlobalActors::spawn_message_bus())
+        .await
+        .unwrap();
 
     let err = actor.decrypt(1).await.unwrap_err();
-    assert!(matches!(err, KeyHolderError::NotBootstrapped));
+    assert!(matches!(err, Error::NotBootstrapped));
 }
 
 #[tokio::test]
 #[test_log::test]
-async fn new_restores_sealed_state() {
+async fn test_new_restores_sealed_state() {
     let db = db::create_test_pool().await;
-    let actor = common::bootstrapped_keyholder(&db).await;
+    let actor = common::bootstrapped_vault(&db).await;
     drop(actor);
 
-    let mut actor2 = KeyHolder::new(db).await.unwrap();
+    let mut actor2 = Vault::new(db, GlobalActors::spawn_message_bus())
+        .await
+        .unwrap();
     let err = actor2.decrypt(1).await.unwrap_err();
-    assert!(matches!(err, KeyHolderError::NotBootstrapped));
+    assert!(matches!(err, Error::Sealed));
 }
 
 #[tokio::test]
 #[test_log::test]
-async fn unseal_correct_password() {
+async fn test_unseal_correct_password() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
 
     let plaintext = b"survive a restart";
     let aead_id = actor
@@ -92,7 +102,9 @@ async fn unseal_correct_password() {
         .unwrap();
     drop(actor);
 
-    let mut actor = KeyHolder::new(db.clone()).await.unwrap();
+    let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
+        .await
+        .unwrap();
     let seal_key = SafeCell::new(b"test-seal-key".to_vec());
     actor.try_unseal(seal_key).await.unwrap();
 
@@ -102,9 +114,9 @@ async fn unseal_correct_password() {
 
 #[tokio::test]
 #[test_log::test]
-async fn unseal_wrong_then_correct_password() {
+async fn test_unseal_wrong_then_correct_password() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
 
     let plaintext = b"important data";
     let aead_id = actor
@@ -113,11 +125,13 @@ async fn unseal_wrong_then_correct_password() {
         .unwrap();
     drop(actor);
 
-    let mut actor = KeyHolder::new(db.clone()).await.unwrap();
+    let mut actor = Vault::new(db.clone(), GlobalActors::spawn_message_bus())
+        .await
+        .unwrap();
 
     let bad_key = SafeCell::new(b"wrong-password".to_vec());
     let err = actor.try_unseal(bad_key).await.unwrap_err();
-    assert!(matches!(err, KeyHolderError::InvalidKey));
+    assert!(matches!(err, Error::InvalidKey));
 
     let good_key = SafeCell::new(b"test-seal-key".to_vec());
     actor.try_unseal(good_key).await.unwrap();

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

@@ -1,22 +1,20 @@
-use std::collections::HashSet;
-
+use crate::common;
 use arbiter_crypto::safecell::{SafeCell, SafeCellHandle as _};
 use arbiter_server::{
-    actors::keyholder::KeyHolderError,
+    actors::vault::Error,
     crypto::encryption::v1::Nonce,
     db::{self, models, schema},
 };
 
 use diesel::{ExpressionMethods as _, QueryDsl, SelectableHelper, dsl::update};
 use diesel_async::RunQueryDsl;
-
-use crate::common;
+use std::collections::HashSet;
 
 #[tokio::test]
 #[test_log::test]
-async fn create_decrypt_roundtrip() {
+async fn test_create_decrypt_roundtrip() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
 
     let plaintext = b"hello arbiter";
     let aead_id = actor
@@ -30,19 +28,19 @@ async fn create_decrypt_roundtrip() {
 
 #[tokio::test]
 #[test_log::test]
-async fn decrypt_nonexistent_returns_not_found() {
+async fn test_decrypt_nonexistent_returns_not_found() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
 
     let err = actor.decrypt(9999).await.unwrap_err();
-    assert!(matches!(err, KeyHolderError::NotFound));
+    assert!(matches!(err, Error::NotFound));
 }
 
 #[tokio::test]
 #[test_log::test]
-async fn ciphertext_differs_across_entries() {
+async fn test_ciphertext_differs_across_entries() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
 
     let plaintext = b"same content";
     let id1 = actor
@@ -78,9 +76,9 @@ async fn ciphertext_differs_across_entries() {
 
 #[tokio::test]
 #[test_log::test]
-async fn nonce_never_reused() {
+async fn test_nonce_never_reused() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
 
     let n = 5;
     for i in 0..n {
@@ -124,7 +122,7 @@ async fn nonce_never_reused() {
 #[test_log::test]
 async fn broken_db_nonce_format_fails_closed() {
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
     let root_key_history_id = common::root_key_history_id(&db).await;
 
     let mut conn = db.get().await.unwrap();
@@ -142,10 +140,10 @@ async fn broken_db_nonce_format_fails_closed() {
         .create_new(SafeCell::new(b"must fail".to_vec()))
         .await
         .unwrap_err();
-    assert!(matches!(err, KeyHolderError::BrokenDatabase));
+    assert!(matches!(err, Error::BrokenDatabase));
 
     let db = db::create_test_pool().await;
-    let mut actor = common::bootstrapped_keyholder(&db).await;
+    let mut actor = common::bootstrapped_vault(&db).await;
     let id = actor
         .create_new(SafeCell::new(b"decrypt target".to_vec()))
         .await
@@ -159,5 +157,5 @@ async fn broken_db_nonce_format_fails_closed() {
     drop(conn);
 
     let err = actor.decrypt(id).await.unwrap_err();
-    assert!(matches!(err, KeyHolderError::BrokenDatabase));
+    assert!(matches!(err, Error::BrokenDatabase));
 }

useragent/flutter_rust_bridge.yaml

@@ -0,0 +1,3 @@
+rust_input: crate::api
+rust_root: rust/
+dart_output: lib/src/rust

useragent/lib/features/callouts/callout_event.dart

@@ -18,7 +18,6 @@ sealed class CalloutEvent with _$CalloutEvent {
     required CalloutData data,
   }) = CalloutEventAdded;
 
-  const factory CalloutEvent.cancelled({
-    required String id,
-  }) = CalloutEventCancelled;
+  const factory CalloutEvent.cancelled({required String id}) =
+      CalloutEventCancelled;
 }

useragent/lib/features/callouts/show_callout.dart

@@ -14,11 +14,8 @@ Future<void> showCallout(BuildContext context, WidgetRef ref, String id) async {
     barrierLabel: MaterialLocalizations.of(context).modalBarrierDismissLabel,
     barrierColor: Colors.transparent,
     transitionDuration: const Duration(milliseconds: 320),
-    pageBuilder: (_, animation, _) => _CalloutOverlay(
-      id: id,
-      data: data,
-      animation: animation,
-    ),
+    pageBuilder: (_, animation, _) =>
+        _CalloutOverlay(id: id, data: data, animation: animation),
   );
 }
 
@@ -35,21 +32,24 @@ class _CalloutOverlay extends ConsumerWidget {
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
-    ref.listen(
-      calloutManagerProvider.select((map) => map.containsKey(id)),
-      (wasPresent, isPresent) {
+    ref.listen(calloutManagerProvider.select((map) => map.containsKey(id)), (
+      wasPresent,
+      isPresent,
+    ) {
       if (wasPresent == true && !isPresent && context.mounted) {
         Navigator.of(context).pop();
       }
-      },
-    );
+    });
 
     final content = switch (data) {
-      ConnectApprovalData(:final pubkey, :final clientInfo) => SdkConnectCallout(
+      ConnectApprovalData(:final pubkey, :final clientInfo) =>
+        SdkConnectCallout(
           pubkey: pubkey,
           clientInfo: clientInfo,
-        onAccept: () => ref.read(calloutManagerProvider.notifier).sendDecision(id, true),
-        onDecline: () => ref.read(calloutManagerProvider.notifier).sendDecision(id, false),
+          onAccept: () =>
+              ref.read(calloutManagerProvider.notifier).sendDecision(id, true),
+          onDecline: () =>
+              ref.read(calloutManagerProvider.notifier).sendDecision(id, false),
         ),
     };
 

useragent/lib/features/callouts/show_callout_list.dart

@@ -14,7 +14,8 @@ Future<void> showCalloutList(BuildContext context, WidgetRef ref) async {
     barrierLabel: MaterialLocalizations.of(context).modalBarrierDismissLabel,
     barrierColor: Colors.transparent,
     transitionDuration: const Duration(milliseconds: 280),
-    pageBuilder: (_, animation, __) => _CalloutListOverlay(animation: animation),
+    pageBuilder: (_, animation, __) =>
+        _CalloutListOverlay(animation: animation),
   );
 
   if (selectedId != null && context.mounted) {
@@ -51,7 +52,9 @@ class _CalloutListOverlay extends ConsumerWidget {
               child: AnimatedBuilder(
                 animation: barrierAnim,
                 builder: (_, __) => ColoredBox(
-                  color: Colors.black.withValues(alpha: 0.35 * barrierAnim.value),
+                  color: Colors.black.withValues(
+                    alpha: 0.35 * barrierAnim.value,
+                  ),
                 ),
               ),
             ),

useragent/lib/features/connection/arbiter_url.dart

@@ -50,7 +50,9 @@ class ArbiterUrl {
     try {
       return base64Url.decode(base64Url.normalize(cert));
     } on FormatException catch (error) {
-      throw FormatException("Invalid base64 in 'cert' query parameter: ${error.message}");
+      throw FormatException(
+        "Invalid base64 in 'cert' query parameter: ${error.message}",
+      );
     }
   }
 }