PR #2558 enqueued a Task at the start of new requests so the v1 SDK
would accept TaskUpdater.start_work() — fix#1 of the v0→v1 migration
gap (PR #2170). But after Task is enqueued, the executor enters
"task mode" and the SDK rejects raw Message enqueues at the terminal
step:
{"code":-32603,"message":"Received Message object in task mode.
Use TaskStatusUpdateEvent or TaskArtifactUpdateEvent instead."}
Synth-E2E 2026-05-03T11:00:34Z surfaced this on the very first run
after the prior fix cascaded. Validation site is the same
a2a/server/agent_execution/active_task.py — the framework's job is
to enforce the v1 invariant; we're catching up to it.
The fix routes both terminal events through TaskUpdater helpers:
- success: updater.complete(message=msg) wraps in
TaskStatusUpdateEvent(state=COMPLETED, final=True)
- error: updater.failed(message=...) wraps in
TaskStatusUpdateEvent(state=FAILED, final=True)
Both helpers exist in a2a-sdk ≥ 1.0; verified via
TaskUpdater.complete signature.
Tests:
- conftest TaskUpdater stub now records complete/failed calls AND
routes the message back through event_queue.enqueue_event so the
~20 legacy tests asserting on enqueue_event keep working
- 2 new regression tests pin the contract:
* test_terminal_success_routes_via_updater_complete
* test_terminal_error_routes_via_updater_failed
- Both NEW tests verified to FAIL on staging-baseline (without this
fix) and PASS with it — they'd catch the regression before staging
if the wheel-smoke gate covered task-mode terminal events too
(separate yak-shave for #131 follow-up)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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