Fix task cancellation: abort handlers and kill shell processes#61
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Fix task cancellation: abort handlers and kill shell processes#61
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- Add KillOnDrop wrapper around tokio::process::Child in execute_shell() to ensure spawned processes are killed when their task is dropped - Store JoinHandle alongside oneshot receiver in WaitingFor::Handler so cancel() can abort running handler tasks - Cancel only aborts foreground tasks; background tasks keep running - Kill chain: cancel() → handle.abort() → future dropped → KillOnDrop dropped → start_kill() → SIGKILL sent to child process - Add 5 cancellation tests covering pending queue, foreground abort, background preservation, and mixed scenarios - No changes to EffectHandler trait or handler signatures
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- Add cancel_foreground() to ToolExecutor: aborts only the active
foreground task and returns error events for it
- Add has_running_foreground() query method
- App::cancel() now has two layers:
1. If foreground tool running → cancel just that tool, error sent
to LLM which continues its turn
2. Otherwise → cancel entire turn (agent stream + all tools)
- Esc behavior stacks: deny approval → cancel tool → end turn
SIGKILL to bash alone orphans its children (sleep, find, etc.) because SIGKILL can't be caught or forwarded. Fix by spawning bash in its own process group (setpgid) and killing the negative PID on drop, which kills the entire group including all children.
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Problem
Cancelling tool execution (Ctrl-C) had two bugs:
JoinHandlewas discarded aftertokio::spawn, socancel()couldn't stop running handlerstokio::process::Childdoes NOT kill on drop, it detaches the processSolution
KillOnDropwrapper (io.rs): Wrapstokio::process::Childand callsstart_kill()(sync SIGKILL) in itsDropimpl. Spawned bash processes can never outlive their task.JoinHandlestored inWaitingFor::Handler(exec.rs): The handle lives alongside the oneshot receiver in the enum variant — no new fields onActivePipeline, no way for them to get out of sync.Background tasks survive cancel: Cancel means "stop the current LLM turn", not "kill everything". Running background tasks keep going.
Kill chain on Ctrl-C
No trait changes
EffectHandlertraitTests
5 new cancellation tests:
test_cancel_clears_pending_queuetest_cancel_aborts_running_foregroundtest_cancel_preserves_completed_background_taskstest_cancel_preserves_running_background_taskstest_cancel_with_mixed_running_and_completed_background