alknet/tasks/call/protocol/abort-cascade-wiring.md

id, name, status, depends_on, scope, risk, impact, level

id	name	status	depends_on	scope	risk	impact	level
call/protocol/abort-cascade-wiring	Wire AbortCascade into CallAdapter inbound event path (ADR-016)	completed	call/protocol/abort-cascade	narrow	medium	component	implementation

Description

AbortCascade::cascade_abort is implemented and unit-tested in crates/alknet-call/src/protocol/abort.rs (20 tests cover depth-3 cascades, mixed Call/Subscribe entries, both AbortPolicy variants, and the "unknown root silently discarded" rule), but no caller invokes it. CallAdapter::handle_stream (adapter.rs:210–213) only dispatches EVENT_REQUESTED; an inbound call.aborted event is logged at debug! and dropped. As a result, ADR-016's cascade is a documented property that does not hold at runtime — when a wire client aborts a parent request, the parent's composed descendants keep running to completion, which is exactly the wasted-work / unwanted-side-effects case ADR-016 was written to prevent.

This task adds the missing bolt between the two halves.

Wire visibility (read before implementing)

ADR-016 Decision 2 (decisions/016-...:220–224) and the abort-cascade task (tasks/call/protocol/abort-cascade.md:68–74) are explicit: composed child request_ids are internal. The client only sees call.aborted for the root ID it sent; the server cascades internally. So the wiring should:

1. Receive the inbound call.aborted for root_request_id.
2. Call AbortCascade::cascade_abort(root_request_id, AbortPolicy::AbortDependents) — the wire caller does not choose the policy (ADR-016 Decision 6: the root gets the default AbortDependents; ContinueRunning is a handler-level opt-in for children, not a wire field).
3. Drop each descendant's pending entry (which cancels its future via Rust's async drop semantics — no call.aborted is sent on the wire for descendants).
4. Drop the root's pending entry (the trigger event already came from the wire; the server mirrors the abort locally).

Do not send call.aborted frames back to the client for descendant IDs — that would leak internal composition structure to the wire.

Implementation sketch

In CallAdapter::handle_stream (adapter.rs:200–228), replace the continue branch with a match on event type:

match envelope.r#type.as_str() {
    EVENT_REQUESTED => { /* existing dispatch path */ }
    EVENT_ABORTED => {
        let request_id = envelope.id.clone();
        let mut pending = connection.pending().lock();
        let mut cascade = AbortCascade::new(&mut pending);
        let aborted = cascade.cascade_abort(&request_id, AbortPolicy::AbortDependents);
        // also abort the root itself (cascade_abort does not touch the root)
        pending.handle_aborted(&request_id);
        if !aborted.is_empty() {
            tracing::debug!(count = aborted.len(), "abort cascade evicted descendants");
        }
    }
    other => {
        debug!(event_type = %other, id = %envelope.id, "ignoring non-requested/non-aborted event on inbound stream");
    }
}

AbortCascade already takes &mut PendingRequestMap; CallConnection::pending() returns &Arc<Mutex<PendingRequestMap>> (connection.rs:53–55). Import AbortCascade and AbortPolicy from super::abort and crate::registry::context respectively.

Integration test (the test that would have caught the gap)

Add an integration test in adapter.rs's tests module that exercises the full path:

1. Build a CallAdapter with a registry containing one parent op (parent/run) whose handler calls env.invoke("child", "run", ...).
2. Register child/run in the same registry.
3. Open a stub Connection, construct a CallConnection, manually register a pending entry for the parent's request_id, and simulate a composed child by registering a second pending entry with parent_request_id: Some(parent_id).
4. Send an EventEnvelope::aborted(parent_id) frame through handle_stream.
5. Assert both the parent and child entries are gone from PendingRequestMap.

The existing unit tests on AbortCascade cover the tree-walking logic; this test only needs to confirm the wiring — that an inbound abort frame actually reaches cascade_abort.

Acceptance Criteria

• CallAdapter::handle_stream handles EVENT_ABORTED (not just EVENT_REQUESTED)
• Inbound call.aborted triggers AbortCascade::cascade_abort with AbortPolicy::AbortDependents
• Root request's pending entry is also removed (cascade_abort skips the root)
• No call.aborted frames are sent on the wire for descendant IDs (internal-only cascade)
• Non-requested, non-aborted events still log at debug! and continue
• Integration test: parent abort removes parent + child from PendingRequestMap
• Integration test: abort for unknown request_id is a no-op (no panic, no removal)
• cargo test -p alknet-call succeeds
• cargo clippy -p alknet-call --all-targets succeeds with no warnings

References

• docs/reviews/004-post-implementation-sanity-check.md — W1 (full finding)
• docs/architecture/decisions/016-abort-cascade-for-nested-calls.md — ADR-016 (Decision 2: server-side cascade; Decision 6: policy is handler-set, not wire-set)
• docs/architecture/crates/call/call-protocol.md:497 — spec requiring the CallAdapter to walk the tree
• tasks/call/protocol/abort-cascade.md — completed task that built AbortCascade in isolation
• crates/alknet-call/src/protocol/abort.rs — existing AbortCascade impl
• crates/alknet-call/src/protocol/adapter.rs:200–228 — handle_stream (the site to modify)

Notes

The abort-cascade task (call/protocol/abort-cascade) built and tested AbortCascade but its acceptance criteria did not include wiring it into CallAdapter::handle_stream. The call-adapter task's acceptance criteria likewise omitted "inbound call.aborted triggers cascade." This task closes that integration gap — all the hard logic already exists and is tested; this task adds the ~30-line bolt and the one integration test that would have caught the gap.

Summary

handle_stream now matches EVENT_ABORTED → invokes AbortCascade::cascade_abort with AbortPolicy::AbortDependents, then aborts the root. Non-requested/non-aborted events still log at debug!. No descendant call.aborted frames sent on the wire. Two integration tests: cascade removes parent + child from PendingRequestMap; unknown request_id is a no-op. cargo test -p alknet-call (161 tests) and clippy clean.