[aw-failures] [P0] Avenger: Claude Code CLI abnormal exit (code 159) — 2nd crash today, distinct from tracked exit-139

[github-actions]

Fix the Claude Code CLI crash in Avenger — exit code 159, now 2 occurrences in one day.

Affected workflow: Avenger (.github/workflows/avenger.lock.yml)
Runs analyzed:

• §31797105737 — failed 2026-08-14T11:39:34Z at "Execute Claude Code CLI"; agentic-workflows audit reports ##[error]Process completed with exit code 159.
• §31777889016 — failed 2026-08-14T07:04Z, same step, self-filed as [aw] Avenger failed #52665 ("claude engine terminated unexpectedly", no exit code captured in that issue).

Root cause (partial — needs a full stack trace from the next occurrence)

Exit 159 (128+31, SIGSYS/bad-syscall under the standard shell signal-exit convention) is a different signature from the tracked exit-139 (SIGSEGV) pattern in #51789 — that issue is scoped to the copilot engine; this is the claude engine. audit on §31797105737 shows the network/firewall layer healthy up to the crash (102 allowed requests, 0 blocked, all expected domains), so this looks like a sandbox/runtime-level fault rather than network or auth. The run log tail only captures the last agent JSON message, not the actual crash frame, so root cause isn't fully confirmed yet.

Proposed remediation

1. Add core-dump / signal capture (ulimit -c unlimited or equivalent) to the Claude harness wrapper so the next crash preserves a stack trace instead of just the last streamed message.
2. Check whether a seccomp/sandbox policy change coincides with the first occurrence at 07:04 UTC today.
3. Track separately from [aw-failures] [P0] Fix Copilot CLI harness segfault (exit 139) killing Agent Performance Analyzer #51789 — different engine (claude vs copilot) and different exit code, even though both are "engine terminated unexpectedly" crashes.

Success criteria

3 consecutive scheduled Avenger runs complete without an "engine terminated unexpectedly" / non-zero-exit crash in the "Execute Claude Code CLI" step.

Related to #52665, #51789

References:

• §31797105737
• §31777889016
  Related to [aw-failures] [aw] Failure Investigator Report — 2026-08-13 19:10 UTC (6h) #52570

Generated by 🔍 [aw] Failure Investigator (6h) · agent · 151.5 AIC · ⌖ 46.8 AIC · ⊞ 5.3K · ◷

• expires on Aug 21, 2026, 5:23 AM UTC-08:00

[github-actions]

🍪 Issue Monster selected this for Copilot

I've identified this issue as a good candidate for automated resolution and requested assignment to the Copilot coding agent.

If assignment succeeds, the Copilot coding agent will analyze the issue and create a pull request with the fix.

Om nom nom! 🍪

🍪 Om nom nom by Issue Monster · gpt54 · 1.96 AIC · ⌖ 7.94 AIC · ⊞ 13.3K · ◷