The sequential tool path only noticed a user interrupt after the running
tool returned: with the deadline disabled it ran the tool inline (fully
blocking), and with a deadline it waited in 5s slices without ever
checking agent._interrupt_requested. Any tool without cooperative
is_interrupted() polling (image_generate, tts, transcription, skills
sync, ...) held the whole turn hostage — the reported symptom was a
redirect queued ~40s behind a FAL image generation + upscale pass.
Executor backstop (class fix, covers ALL tools):
- _run_sequential_tool_execution_middleware always dispatches on the
daemon worker (timeout None no longer means inline blocking) and polls
the interrupt flag every 1s.
- On interrupt: 3s cooperative grace (mirrors the concurrent path), then
synthesize a cancelled tool result (_ToolCancelledResult), emit the
terminal post_tool_call with status=cancelled, and abandon the worker.
- _ToolCancelledResult suppresses downstream post-hook double emission
exactly like _ToolTimeoutResult, so an abandoned worker finishing late
cannot report success for a cancelled call.
- clarify (interactive, _NEVER_PARALLEL_TOOLS) keeps the inline path —
it owns its own human wait.
Cooperative layer in the reported offender:
- image_generation_tool: blind handler.get() (generation + Clarity
upscale) replaced with _wait_fal_result(), which polls is_interrupted()
in 0.5s slices and raises ImageGenerationInterrupted immediately.
- _upscale_image propagates the interrupt instead of swallowing it into
the "upscale failed, use original" fallback.
Message alternation is preserved: the cancelled result is a normal tool
result for the call_id. Sabotage-verified: with the old wait loop
restored, the new tests fail (tool blocks full runtime); with the fix
they pass in ~4s.
