Investigate pr merge failure

[strawgate]

Investigate https://github.com/elastic/ai-github-actions-playground/actions/runs/22513303976 for why it failed, what did the agent do that it shouldn't have knowing the limitations of gh aw patch methods

[github-actions]

3 related issues

• Assistant updates to PRs are not working #206 — it investigates a PR-update failure path in push_to_pull_request_branch and documents upstream gh-aw patch-generation limitations plus mitigations, which can help explain this issue’s merge failure investigation.
• [agentics] Mention in PR failed #407 — it captures a concrete Failed to apply patch code-push failure in a PR workflow, which provides a closely related failure mode and debugging context for this issue.
• Copilot seems to do weird stuff #292 — it investigates agent behavior where work stopped short of the expected persisted PR outcome, which is useful context when analyzing what the agent did versus what it should have done.

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[github-actions]

TL;DR: the run did not fail overall, but the code-push operation failed because the agent used a rebase/cherry-pick conflict-resolution path and then emitted a multi-commit push_to_pull_request_branch patch that git am --3way could not apply cleanly.

Recommendation

Treat this as a prompt/guardrail enforcement gap: block rebase/merge-style history rewriting before allowing push_to_pull_request_branch, and require direct file conflict resolution with single-parent commits only.

Findings

• The run is marked success at workflow level, but code push failed inside safe outputs.
  • /tmp/gh-aw/agent/logs463/logs/0_run _ conclusion.txt:716-717,727
  • GH_AW_CODE_PUSH_FAILURE_ERRORS: push_to_pull_request_branch:Failed to apply patch
• The active prompt explicitly says for conflict resolution: no git merge, no git rebase because push_to_pull_request_branch uses git format-patch.
  • /tmp/gh-aw/agent/logs463/logs/run _ activation/12_Print prompt.txt:257-261
• The agent still executed rebase/cherry-pick flow:
  • git --no-pager rebase origin/main at /tmp/gh-aw/agent/logs463/logs/run _ agent/34_Execute GitHub Copilot CLI.txt:84-86
  • git --no-pager cherry-pick dd49fb0 2792c43 at .../34_Execute GitHub Copilot CLI.txt:95-97
• Agent emitted push_to_pull_request_branch with patch path /tmp/gh-aw/aw-copilot-expand-ingest-pipeline-test-bench.patch:
  • /tmp/gh-aw/agent/logs463/logs/run _ agent/40_Ingest agent output.txt:40-49
• Safe outputs tried git am --3way, hit conflict in peek/src/components/IngestPipelinesPage.tsx, and failed at patch 10/18:
  • /tmp/gh-aw/agent/logs463/logs/run _ safe_outputs/8_Process Safe Outputs.txt:188-211
  • Includes Patch failed at 0010 ... and Failed to apply patch
• Safe outputs then cancelled remaining outputs:
  • /tmp/gh-aw/agent/logs463/logs/run _ safe_outputs/8_Process Safe Outputs.txt:3986-3994

Verification

I verified this by inspecting the run metadata and extracted run logs:

Workflow run 22513303976: conclusion=success
Code push failure recorded: push_to_pull_request_branch:Failed to apply patch
Prompt rule present: no git rebase for conflict resolution
Agent actions: rebase + cherry-pick
Safe output application: git am --3way -> conflict -> failed at patch 0010

Concrete log evidence referenced above is from:

• /tmp/gh-aw/agent/logs463/logs/run _ activation/12_Print prompt.txt
• /tmp/gh-aw/agent/logs463/logs/run _ agent/34_Execute GitHub Copilot CLI.txt
• /tmp/gh-aw/agent/logs463/logs/run _ agent/40_Ingest agent output.txt
• /tmp/gh-aw/agent/logs463/logs/run _ safe_outputs/8_Process Safe Outputs.txt
• /tmp/gh-aw/agent/logs463/logs/0_run _ conclusion.txt

Detailed Action Plan

1. In the mention-in-pr workflow prompt path (.github/workflows/gh-aw-mention-in-pr-no-sandbox.md + compiled lock), add a stricter instruction that if merge conflicts exist, the agent must not run rebase/cherry-pick and must resolve by file edits only.
2. Add runtime enforcement in safe-input/safe-output processing to reject push_to_pull_request_branch when the agent session contains forbidden history-rewrite commands (git rebase, git merge, merge-commit creation).
3. Add a clearer failure surface in conclusion handling so runs with code-push failure don’t read as “success” without an explicit warning comment.
4. Add a regression test scenario (same class as [agentics] Mention in PR failed #407) where a branch is behind main and patch replay conflicts at mid-series commit, ensuring the workflow reports actionable failure and does not silently appear green.

Related Items

Type	Link / Path	Relevance
Issue	#463	Current investigation request
Issue	#407	Same failure class (push_to_pull_request_branch: Failed to apply patch)
Run	https://github.com/elastic/ai-github-actions-playground/actions/runs/22513303976	Investigated run
Log file	/tmp/gh-aw/agent/logs463/logs/run _ safe_outputs/8_Process Safe Outputs.txt:188-211	Exact patch conflict/failure
Log file	/tmp/gh-aw/agent/logs463/logs/run _ activation/12_Print prompt.txt:257-261	Explicit no-rebase instruction
Workflow source	.github/workflows/gh-aw-mention-in-pr-no-sandbox.md	Prompt/rule source in this repo
Fragment	.github/workflows/gh-aw-fragments/safe-output-push-to-pr.md	Shared push-to-PR limitations

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[strawgate]

/ai isn't that exactly what we already require? Make a PR with what we need to change