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.
61 lines
6.7 KiB
Markdown
61 lines
6.7 KiB
Markdown
---
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status: draft
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last_updated: 2026-06-22-22
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---
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# alknet-call
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Structured RPC over QUIC: operations, request/response, streaming subscriptions, and service discovery. Implements `ProtocolHandler` on ALPN `alknet/call`.
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## Documents
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| Document | Status | Description |
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|----------|--------|-------------|
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| [call-protocol.md](call-protocol.md) | draft | CallAdapter, EventEnvelope framing, stream model, PendingRequestMap, bidirectional calls |
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| [operation-registry.md](operation-registry.md) | draft | OperationSpec, Handler, OperationRegistry, AccessControl, service discovery, irpc integration |
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## Applicable ADRs
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| ADR | Title | Relevance |
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|-----|-------|-----------|
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| [001](../../decisions/001-alpn-protocol-dispatch.md) | ALPN-Based Protocol Dispatch | CallAdapter registers on ALPN `alknet/call` |
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| [002](../../decisions/002-protocol-handler-trait.md) | ProtocolHandler Trait | CallAdapter implements ProtocolHandler |
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| [003](../../decisions/003-crate-decomposition.md) | Crate Decomposition | alknet-call depends on alknet-core and irpc |
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| [013](../../decisions/013-rust-canonical-implementation.md) | Rust as Canonical Implementation Language | Adapter traits defined in Rust; TS is reference/browser adaptation |
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| [004](../../decisions/004-auth-as-shared-core.md) | Auth as Shared Core | AuthContext passed to call handlers |
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| [005](../../decisions/005-irpc-as-call-protocol-foundation.md) | irpc as Call Protocol Foundation | irpc provides framing and service dispatch |
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| [006](../../decisions/006-alpn-convention-and-connection-model.md) | ALPN String Convention | `alknet/call` ALPN, one ALPN per connection |
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| [007](../../decisions/007-bistream-type-definition.md) | BiStream Type Definition | CallAdapter receives Connection, not BiStream |
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| [008](../../decisions/008-secret-service-integration.md) | Vault Integration Point | Vault accessed at assembly layer, not on the wire |
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| [010](../../decisions/010-alpn-router-and-endpoint.md) | ALPN Router and Endpoint | Static handler registration |
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| [012](../../decisions/012-call-protocol-stream-model.md) | Call Protocol Stream Model | Bidirectional streams, EventEnvelope, ID-based correlation |
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| [014](../../decisions/014-secret-material-flow-and-capability-injection.md) | Secret Material Flow and Capability Injection | Call protocol carries no secret material; capabilities injected at assembly layer |
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| [015](../../decisions/015-privilege-model-and-authority-context.md) | Privilege Model and Authority Context | `internal` = authority switch not ACL skip; External/Internal visibility; handler identity + scoped env |
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| [016](../../decisions/016-abort-cascade-for-nested-calls.md) | Abort Cascade for Nested Calls | `call.aborted` cascades to descendants; default `abort-dependents`, `continue-running` opt-in |
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| [017](../../decisions/017-call-protocol-client-and-adapter-contract.md) | Call Protocol Client and Adapter Contract | `CallClient` opens connections; `from_call` imports remote ops; connection direction independent of call direction |
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| [022](../../decisions/022-handler-registration-provenance-and-composition-authority.md) | Handler Registration, Provenance, and Composition Authority | Registration bundle carries provenance, composition authority, scoped env, capabilities |
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| [023](../../decisions/023-operation-error-schemas.md) | Operation Error Schemas | Operations declare domain errors; `call.error` carries typed `details`; adapter fidelity |
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| [024](../../decisions/024-operation-registry-layering.md) | 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) |
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## Relevant Open Questions
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| OQ | Title | Status | Relevance |
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|----|-------|--------|-----------|
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| OQ-07 | Call protocol scope within a connection | resolved (ADR-012) | Stream model, multiplexing, scope |
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| OQ-13 | Operation path format and routing scope | resolved | `/{service}/{op}` is the correct design; remote dispatch is a separate layer |
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| OQ-14 | Batch operation semantics | resolved | Correlated `call.requested` events is the correct protocol design |
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| OQ-16 | Safe vault operations for call protocol exposure | resolved (ADR-014) | None exposed for now |
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| 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. |
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## Key Design Principles
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1. **One connection, full access**: An `alknet/call` connection gives access to the entire operation registry — calls, subscriptions, batch, schema.
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2. **Protocol is symmetric**: Both sides can initiate calls. The server calling a client uses the same EventEnvelope format and correlation.
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3. **Stream-agnostic correlation**: PendingRequestMap correlates by request ID, not by stream. The protocol works with any stream arrangement.
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4. **Operation registry is layered**: The curated layer (`Local` provenance) is static — registered at startup by the CLI binary, immutable for the process lifetime. Session (`Session`) and imported (`FromCall` etc.) ops are dynamic overlays at their respective scopes (per-session, per-connection). The registry supports JSON Schema discovery. See ADR-024.
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5. **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.
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6. **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.
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7. **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.
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8. **Abort cascades to descendants**: `call.aborted` for a parent request cascades to all non-terminal descendants. Default `abort-dependents`; `continue-running` opt-in. See ADR-016.
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9. **Internal calls switch authority context, not skip ACL**: The `internal` flag 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.
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10. **Provenance determines composition capability**: Only `Local` and `Session` ops 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. |