A tooling review predicted a PID-1 signal problem from two symptoms we could not
explain: `OOMKilled: true` with **ExitCode 0**, and `--continue` failing to find
a conversation that plainly existed. Traced it, and the prediction was right --
though the culprit is not PID 1, it is one level below.
The path is tini (PID 1) -> entrypoint.sh (exec'd) -> expect -> spawn -> claude
`spawn` CANNOT be an exec: expect has to stay alive to drive the pty. So expect
is the process Docker signals, and everything depends on it passing things on.
It did neither, in two lines:
1. NO SIGNAL FORWARDING, no trap of any kind. `docker stop` sent SIGTERM to
expect, which died and took the pty with it. Claude Code never got a SIGTERM,
so it never ran SessionEnd hooks and never wrote lastSessionId/history --
which are written ONLY at a graceful shutdown. That is the entire reason
`claude --continue` answered "No conversation found to continue" with 33 MB of
transcripts in the volume beside it, and why we resume by scraping a session
id off a transcript filename.
2. `eof { exit }` RETURNED 0 FOR EVERY DEATH. A bare `exit` in expect is exit
ZERO. When the OOM-killer took the child, expect saw EOF and reported a clean
exit. `OOMKilled: true` with `ExitCode 0` was never Docker being odd -- it was
this line. It also meant `--restart on-failure` would read a memory kill as
success, which is why the policy had to be `unless-stopped`.
Fixed and MEASURED, old against new, in a container:
child exits 7 old -> 0 (the bug) new -> 7
SIGTERM to wrapper old -> 143, child's trap NEVER RAN
new -> 42, child trapped and cleaned up
Same file in both images; they were byte-identical, so the port copy takes the
same change.
Consequences worth stating: a kill now reports 137 rather than 0, so exit codes
mean what they say; `docker stop` gives Claude Code a real SIGTERM, so it runs
SessionEnd and writes the session index -- which may make the transcript-filename
resume unnecessary. That is not assumed here: the resume path stays as it is
until it is verified redundant.
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