The trait's default implementation of transcribe_sync_with_abort fell
through to plain transcribe_sync, silently dropping the abort flag for
any backend that did not explicitly override it. That re-introduced the
5725836 wedge for SpeechModelAdapter (Parakeet today, any future
cloud STT or transformer adapter tomorrow): the live session's
drain_inference timeout would set the flag, the backend would ignore
it, the orphan inference thread would keep the engine Mutex held, and
the next start/stop would deadlock on it.
Removing the default impl makes the method required, so any backend
that does not implement it fails to compile. Compile-time enforcement
of cancellation completeness.
SpeechModelAdapter now implements the method explicitly with a
pre-decode short-circuit: if the abort flag is already set before we
dispatch into transcribe-rs (which owns the Parakeet decoder behind an
opaque call that has no cancellation hook), return an error
immediately. The in-flight decode itself is still uncancellable, but
that is documented with a SAFETY comment and bounded by the live
session's drain timeout dropping the receiver — the orphan exits the
instant it tries to send.
Regression tests:
- transcriber::tests::transcribe_sync_with_abort_is_required_and_flag_is_observed —
fake backend records the abort flag at dispatch time; proves the
trait method is required (file would not compile without it) and the
flag is actually piped through.
- local_engine::tests::speech_model_adapter_short_circuits_when_abort_set_pre_dispatch —
SpeechModelAdapter must NOT call the underlying decoder when the
abort flag was set before dispatch.
- local_engine::tests::speech_model_adapter_dispatches_decoder_when_abort_clear —
companion: clear flag must still dispatch (we did not kill
transcription entirely).
cargo test -p lumotia-transcription --lib: 64 passed, 0 failed.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Jake
e0e9a6e17a