ADR-023 adds error_schemas to OperationSpec so operations can declare their domain-level failure modes (FILE_NOT_FOUND, RATE_LIMITED, etc.) distinct from protocol-level codes (NOT_FOUND, FORBIDDEN, etc.). The call.error payload gains an optional 'details' field carrying the typed error payload conforming to the declared schema. from_openapi/to_openapi map OpenAPI response status codes to/from ErrorDefinitions, making the adapter contract from ADR-017 faithful on the error axis. Also fixes W2 (KeyVersionMismatch stale comment in encryption.md — ADR-021 implements rotation without this variant) and W4 (derive_encryption_key_for_version missing from service.md method list). Spec updates: operation-registry.md (OperationSpec, ErrorDefinition, Handler error mapping, services/schema), call-protocol.md (call.error payload, CallError, ResponseEnvelope), README.md, overview.md, open-questions.md (OQ-24), call/README.md, encryption.md, service.md.
status, last_updated
| status | last_updated |
|---|---|
| draft | 2026-06-22 |
alknet-call
Structured RPC over QUIC: operations, request/response, streaming subscriptions, and service discovery. Implements ProtocolHandler on ALPN alknet/call.
Documents
| Document | Status | Description |
|---|---|---|
| call-protocol.md | draft | CallAdapter, EventEnvelope framing, stream model, PendingRequestMap, bidirectional calls |
| operation-registry.md | draft | OperationSpec, Handler, OperationRegistry, AccessControl, service discovery, irpc integration |
Applicable ADRs
| ADR | Title | Relevance |
|---|---|---|
| 001 | ALPN-Based Protocol Dispatch | CallAdapter registers on ALPN alknet/call |
| 002 | ProtocolHandler Trait | CallAdapter implements ProtocolHandler |
| 003 | Crate Decomposition | alknet-call depends on alknet-core and irpc |
| 004 | Auth as Shared Core | AuthContext passed to call handlers |
| 005 | irpc as Call Protocol Foundation | irpc provides framing and service dispatch |
| 006 | ALPN String Convention | alknet/call ALPN, one ALPN per connection |
| 007 | BiStream Type Definition | CallAdapter receives Connection, not BiStream |
| 008 | Vault Integration Point | Vault accessed at assembly layer, not on the wire |
| 010 | ALPN Router and Endpoint | Static handler registration |
| 012 | Call Protocol Stream Model | Bidirectional streams, EventEnvelope, ID-based correlation |
| 014 | Secret Material Flow and Capability Injection | Call protocol carries no secret material; capabilities injected at assembly layer |
| 015 | Privilege Model and Authority Context | internal = authority switch not ACL skip; External/Internal visibility; handler identity + scoped env |
| 016 | Abort Cascade for Nested Calls | call.aborted cascades to descendants; default abort-dependents, continue-running opt-in |
| 017 | Call Protocol Client and Adapter Contract | CallClient opens connections; from_call imports remote ops; connection direction independent of call direction |
| 022 | Handler Registration, Provenance, and Composition Authority | Registration bundle carries provenance, composition authority, scoped env, capabilities |
| 023 | Operation Error Schemas | Operations declare domain errors; call.error carries typed details; adapter fidelity |
Relevant Open Questions
| OQ | Title | Status | Relevance |
|---|---|---|---|
| OQ-07 | Call protocol scope within a connection | resolved (ADR-012) | Stream model, multiplexing, scope |
| OQ-13 | Operation path format and routing scope | resolved | /{service}/{op} is the correct design; remote dispatch is a separate layer |
| OQ-14 | Batch operation semantics | resolved | Correlated call.requested events is the correct protocol design |
| OQ-16 | Safe vault operations for call protocol exposure | resolved (ADR-014) | None exposed for now |
| OQ-19 | Session-scoped operation registries | resolved | Agent-written operations overlaid on global registry via OperationEnv trait layering. Protocol doesn't need changes; OperationEnv must remain a trait |
Key Design Principles
- One connection, full access: An
alknet/callconnection gives access to the entire operation registry — calls, subscriptions, batch, schema. - Protocol is symmetric: Both sides can initiate calls. The server calling a client uses the same EventEnvelope format and correlation.
- Stream-agnostic correlation: PendingRequestMap correlates by request ID, not by stream. The protocol works with any stream arrangement.
- Operation registry is static: Operations are registered at startup by the CLI binary. The registry supports JSON Schema discovery.
- irpc is one dispatch backend: Local operations dispatch directly. irpc service calls (in-process, type-safe) are internal. The call protocol is the external interface.
- Local dispatch only: The operation registry dispatches to local handlers. Remote dispatch (federation, head/worker routing) would be a separate mechanism at a different layer, not a modification to alknet-call's path format.
- No secret material on the wire: The call protocol carries no private keys, API keys, mnemonics, or decrypted credentials. Handlers receive outbound credentials through
OperationContext.capabilities, injected at the assembly layer. See ADR-014. - Abort cascades to descendants:
call.abortedfor a parent request cascades to all non-terminal descendants. Defaultabort-dependents;continue-runningopt-in. See ADR-016. - Internal calls switch authority context, not skip ACL: The
internalflag marks composition-originated calls. ACL runs against the handler's composition authority, not the caller's and not as a blanket skip. Operations have External/Internal visibility. Scoped composition env bounds reachability. See ADR-015, ADR-022. - Provenance determines composition capability: Only
LocalandSessionops can compose. Leaves (FromOpenAPI,FromMCP,FromCall) are forwarding stubs — they don't get composition authority or a scoped env. The assembly layer is the sole grantor of composition authority. See ADR-022.