The previous code path for the keyboard preview's ASR controller
cancelled the consumer task at the exact moment it closed the
audio stream:
asrTask?.cancel() // ← kills the .final consumer
asrTask = nil
...
bufferContinuation?.finish() // tells ASR "no more audio"
The cancellation cascaded: the for-await on the events stream
exited → the AsyncStream's `continuation.onTermination` fired →
ASR.cancel() ran → producer task was marked cancelled → the
producer's `if !Task.isCancelled { yield(.final) }` guard
suppressed the .final event. Net result: nobody told the UI to
leave `.processing`, and the disc sat there forever.
Fix (4 changes):
1) `stop()` no longer cancels the consumer. The consumer task
exits naturally when the events stream finishes, sees the
`.final` event the producer still yields, and transitions
the phase out of `.processing`. This is the primary fix.
2) `start()` cancels any leftover `asrTask` at the entry point
as a safety net — covers the "user smashes the disc twice
quickly" race where a previous consumer is still draining.
3) `stop()` schedules a 3-second safety-net Task: if the ASR
pipeline never produces a `.final` (analyzer hang, system
glitch), force the phase back to `.idle` so the user isn't
stuck. Normal recordings complete well under 3 seconds, so
the timeout is only hit on the unhappy path.
4) `KeyboardPreviewSheet` adds `.onDisappear { asr.stop() }`
so closing the sheet mid-recording releases the
AVAudioSession and mic. `stop()` is idempotent (no-op on
non-recording phases), safe to call here.
State machine: `phase = .processing` now has TWO transition
paths out — the consumer receiving `.final` (fast path) and
the 3-second safety net (fallback). Both are required; the
fast path is the common case, the fallback is the
"guaranteed-progress" guarantee.
Testability: `asrTask` was `private`; relaxed to `internal` so
the regression test in
`OSGKeyboardTests/PreviewASRControllerStateTests.swift` can
install a known consumer task and assert `stop()` does not
cancel it. The class is `@MainActor` so Swift 6 isolation
rules still prevent production code outside the class from
racing on it.
Tests:
- `testStopDoesNotCancelConsumerTask` — primary fix regression.
- `testStopIsIdempotent` — `.onDisappear` after a manual stop
doesn't misbehave.
- 27/27 tests pass (25 existing + 2 new).
- BUILD SUCCEEDED.
🤖 Generated with Claude Code
Rocky