Close the last fire-and-forget gap from the previous fixes: the task:moved
(away from in-progress) and task:deleted listeners no longer call the
synchronous fire-and-forget `abortInFlightTaskWork`. Instead they track an
awaited disposal promise per task in `pendingTaskDisposals`. The task:moved
(to in-progress) dispatch path awaits any in-flight disposal for the same
task before calling `execute()`, so a fast bounce (in-progress → todo →
in-progress) no longer races the conflict-cleanup path against a still-live
shell.
`awaitAbortInFlightTaskWork` now claims each session surface (activeSessions,
activeStepExecutors, activeWorkflowStepSessions, activeSubagentSessions)
synchronously before awaiting any async abort. This lets concurrent disposal
calls for the same task dedupe naturally — the second call finds the maps
empty and no-ops, preserving the existing single-abort/single-dispose
contract that the soft-delete and user-cancel tests assert.
Adds a regression test in executor-user-cancel covering the re-dispatch
ordering: an immediate task:moved-to-in-progress that follows a still-running
task:moved-away must wait for abort to complete before execute() runs.
The legacy `abortInFlightTaskWork` is removed (no callers).
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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