[willtong-aq]

Fixes #107.

Summary

DockerCodeExecToolProvider runs commands under timeout --kill-after=5s <N>s and mapped every exit 124 or 137 to error_kind="timeout". Both can occur before the limit: a 137 usually means an outside SIGKILL, for example the kernel out-of-memory killer, and a 124 can come from a nested timeout. The model was told "Command timed out after N seconds" without the real exit code. format_result also dropped stdout from error results.

Changes

• Docker backend: exit 124 or 137 is a timeout only when the elapsed time is at least the limit. An earlier 124 or 137 keeps the real exit code, stdout and stderr, adds a note to stderr and sets no error_kind. The elapsed time is measured in the worker thread around exec_run.
• base.py format_result: the error branch also writes <stdout> when stdout is not empty. An error result with empty stdout formats exactly as before.
• Tests cover the limit boundary, early 124 and 137, and format_result.
• CHANGELOG.md: an Unreleased / Fixed entry.

Before and after

echo allocating; python3 -c "x = b'a' * (1024 ** 3)", timeout=60, container limited to 256 MiB.

Before:

<shell_results>
<error_kind>timeout</error_kind>
<details>Command timed out after 60 seconds</details>
</shell_results>

After:

<shell_results>
<exit_code>137</exit_code>
<stdout>allocating
</stdout>
<stderr>Exit code 137 after 0.33 seconds, before the 60 second limit. This usually means the process was killed with SIGKILL, possibly by the out-of-memory killer.</stderr>
</shell_results>

Validation

Against a real python:3.12-slim container limited to 256 MiB and 1 CPU:

• out-of-memory command: exit 137 after about 0.3 s, the note above, no "timed out"
• timeout 3 sleep 60 with timeout=60: exit 124 after 3.1 s, note "The limit did not stop this command."
• sleep 60 with timeout=5, and a command that ignores TERM with timeout=3: still reported as timeouts
• exit 0 and exit 1: output unchanged

ruff format --check, ruff check and ty check pass. uv run --extra docker pytest tests/test_docker_execution.py passes locally (17 passed).

Limits

• The note is hedged: an exit code does not show who sent SIGKILL, and Docker's State.OOMKilled is container-wide.
• Docker API overhead counts towards the elapsed time, so an early exit very close to the limit can still read as a timeout.
• Local and E2B backends do not map 124 or 137 to a timeout and are unchanged.