Root cause of the live-test bugs (2026-09-19): pi passes every run's
AbortSignal to tool execute, but toPiTool dropped it — agent.abort()
only landed at the next step boundary, so a long local grep held its
turn hostage until the dev server's memory restart killed the run
mid-tool, freezing the record at its write-ahead state (the 'went
back in time' rollback).
- lh-tool: execute ctx gains signal (parent + timeout combined); every
call races a 30s system-level timeout with a 250ms cooperative grace —
abort kills a stuck tool but lets a poll-the-signal tool deliver its
partial results. Pre-aborted signals never fire listeners: checked
upfront. toolTimeoutMs is the test seam (pdfModelOverride idiom).
- fs-shared: walkFiles returns {timedOut, aborted} instead of throwing —
abort yields partial results.
- grep: the scan phase was unbounded (the walk's 10s deadline only
bounded collection) — same budget now checked per file; find/grep
check the signal and return partials with a notice.
- pending/chat: streamingToolActivity names the ACTUAL running tool —
a part sits input-streaming through its whole execution, so the old
shimmer called minutes-long greps 'Writing a question…'.
Tests: toPiTool guard (forward, abort, timeout, grace, question
bypass, ToolInputError passthrough), walk mid-abort, find/grep
pre-abort + mid-run abort, activity labels. Gates: 617/617.
