Safe-outputs PR creation fails with "Failed to pin branch" on cross-repo checkouts (git dubious ownership)

[dsyme]

Summary

When a workflow uses a cross-repository checkout into a subdirectory (e.g. ${GITHUB_WORKSPACE}/github), the safe-outputs create_pull_request handler fails with:

{"result":"error","error":"Failed to pin branch 'dsyme/ci-perf/seeds-runner-track4-workload...'"}

The branch genuinely exists locally (the agent's own git branch --list confirms it), so the failure is not a missing branch.

Root cause

The safe-outputs MCP server runs git inside the cross-repo checkout subdirectory (repoCwd, resolved from the checkout manifest). That subdirectory is a separate git repository whose top-level is not GITHUB_WORKSPACE.

actions/setup/sh/configure_git_credentials.sh only adds GITHUB_WORKSPACE as a git safe.directory. The cross-repo checkout subdirectories are never trusted, so when the pinning step runs git rev-parse --verify refs/heads/<branch>^{commit} in that directory, git aborts with "dubious ownership". This surfaces as Failed to pin branch.

Evidence from the run: the agent's recovery step ran git config --global --add safe.directory /home/runner/work/github-automation/github-automation/github and then the git branch --list succeeded — confirming the dubious-ownership diagnosis.

Fix

configure_git_credentials.sh should consult the checkout manifest ($RUNNER_TEMP/gh-aw/safeoutputs/checkout-manifest.json) and add each cross-repo checkout path (${GITHUB_WORKSPACE}/<path>) as a git safe.directory, in addition to GITHUB_WORKSPACE.

Repro context

• Failing run: github/github-automation actions run 27759556197 (job 82130420621)
• Workflow: .github/workflows/ci-perf.lock.yml