Diagnoses a conflation in the pre-ADR-024 spec: the OperationRegistry inherited immutability by analogy from ADR-010's HandlerRegistry (ALPN-level), but the TLS-config argument that justifies HandlerRegistry immutability does not apply to the operation registry, which lives behind a single ALPN (alknet/call). This made from_call (which discovers ops over a live connection at runtime) structurally incompatible with the blanket immutability claim. ADR-024 layers the operation registry by trust boundary: curated (Local) ops are static and immutable — the startup trust boundary is where their composition authority is granted; session (Session) and imported (FromCall etc.) ops are dynamic at their respective scopes (per-session, per-connection) — their trust boundaries are per-scope, not per-startup. The principle: immutability follows the trust boundary. Immutability is the security control for composing ops (can escalate privilege); provenance + composition authority are the controls for non-composing ops (can't escalate). The OperationEnv trait becomes the integration point (Arc<dyn OperationEnv>), following the IdentityProvider precedent (ADR-004): the CallAdapter composes the root OperationContext.env per incoming call from the active layers (curated base + connection overlay + session overlay). Children inherit the parent's composite env by Arc::clone — overlay composition happens once at the root and propagates through the composition tree. Resolves review #002 C6 (OperationContext.env type identity crisis): the field is split into scoped_env: ScopedOperationEnv (reachability data, from the registration bundle) and env: Arc<dyn OperationEnv + Send + Sync> (dispatch trait object). One field was being used as two different types (reachability set with .allows() and dispatch trait with .invoke()); Localizes W4 (hot-swap ↔ registry mutability coupling) to the connection scope: no global mutable registry to hot-swap; overlays replace naturally with connect/disconnect and session start/end. Schema-drift on reconnect is a per-connection overlay-rebuild concern, not a global hot-swap protocol. Partially addresses W3 (CallClient registry security): the registry-shape sub-question is resolved by the overlay model; the capability-exposure sub-question (what capabilities a remote peer can trigger) remains for ADR-017 — ADR-024 does not overclaim resolution there. Amends OQ-04 to scope its immutability claim to the HandlerRegistry and cross-reference ADR-024 for the operation registry. Generalizes OQ-19's session-overlay mechanism to also cover connection-scoped remote imports — both are per-scope dynamic overlays on the static curated base, using the same trait-layering mechanism.
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6.7 KiB
status, last_updated
| status | last_updated |
|---|---|
| draft | 2026-06-22-22 |
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 |
| 013 | Rust as Canonical Implementation Language | Adapter traits defined in Rust; TS is reference/browser adaptation |
| 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 |
| 024 | Operation Registry Layering | Curated (static) + session/connection overlays (dynamic); OperationEnv as trait-object integration point; OperationContext.env split into scoped_env (data) and env (dispatch trait) |
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 curated registry via OperationEnv trait layering. Protocol doesn't need changes; OperationEnv must remain a trait. Generalized by ADR-024 to cover connection-scoped overlays. |
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 layered: The curated layer (
Localprovenance) is static — registered at startup by the CLI binary, immutable for the process lifetime. Session (Session) and imported (FromCalletc.) ops are dynamic overlays at their respective scopes (per-session, per-connection). The registry supports JSON Schema discovery. See ADR-024. - 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.