[bug-hunter] ready-to-make-pr skips committed diff when upstream tracking is unset

Start in .github/workflows/gh-aw-fragments/safe-output-create-pr.md, especially lines 17-21 and 33-37, 43-47. Trace how upstream_sha is resolved and compare that with the diff and stat commands using @{upstream}; reproduce the no-tracking-branch case from the issue. Done means committed changes against origin/main produce a nonzero diff/stat and include the self-review checklist item.

Impact

ready-to-make-pr can return status: ok with diff_line_count: 0 even when there are committed local changes that should be reviewed.

This happens when a repo has an origin/main remote available but no local upstream tracking branch (@{upstream} is unset). In that case, the script successfully computes upstream_sha from origin/main, but still builds diff/stat only from @{upstream} and HEAD. The self-review checklist item is skipped, so users can create a PR without the intended pre-PR diff review context.

Reproduction Steps

1. Save and run this script:

import json
import subprocess
import tempfile
from pathlib import Path

repo_root = Path('/home/runner/work/ai-github-actions/ai-github-actions')
fragment = repo_root / '.github/workflows/gh-aw-fragments/safe-output-create-pr.md'
text = fragment.read_text()
start = text.index('    py: |')
end = text.index('safe-outputs:')
block = text[start:end].splitlines()[1:]
py_lines = []
for line in block:
    if line.startswith('      '):
        py_lines.append(line[6:])
    elif line.strip() == '':
        py_lines.append('')
py_code = '\n'.join(py_lines).rstrip() + '\n'

with tempfile.TemporaryDirectory() as td:
    base = Path(td)
    repo = base / 'repo'
    remote = base / 'remote.git'
    repo.mkdir()

    def run(cmd, cwd=repo):
        p = subprocess.run(cmd, cwd=cwd, capture_output=True, text=True)
        if p.returncode != 0:
            raise RuntimeError(f"cmd failed: {' '.join(cmd)}\nstdout={p.stdout}\nstderr={p.stderr}")
        return p

    run(['git', 'init', '-b', 'main'])
    run(['git', 'config', 'user.email', 'test@example.com'])
    run(['git', 'config', 'user.name', 'Test'])
    (repo / 'file.txt').write_text('hello\n')
    run(['git', 'add', 'file.txt'])
    run(['git', 'commit', '-m', 'init'])

    subprocess.run(['git', 'clone', '--bare', str(repo), str(remote)], capture_output=True, text=True, check=True)
    run(['git', 'remote', 'add', 'origin', str(remote)])
    run(['git', 'fetch', 'origin'])

    # Local committed change; no upstream tracking configured.
    (repo / 'extra.txt').write_text('extra line\n')
    run(['git', 'add', 'extra.txt'])
    run(['git', 'commit', '-m', 'add extra'])

    p = subprocess.run(['python3', '-c', py_code], cwd=repo, capture_output=True, text=True, check=True)
    output = json.loads(p.stdout.strip())
    expected = run(['git', 'diff', '--merge-base', 'origin/main']).stdout

    print('status=', output.get('status'))
    print('diff_line_count_reported=', output.get('diff_line_count'))
    print('expected_diff_lines_against_origin_main=', len(expected.splitlines()))
    print('script_stdout_json=', json.dumps(output, indent=2))

2. Run: python3 repro_ready_to_make_pr_diff_bug.py

Expected vs Actual

Expected: when upstream_sha resolves from origin/main, the script should produce a non-empty diff/stat for committed local changes and include the self-review checklist item.

Actual: script reports diff_line_count: 0 and omits self-review checklist despite committed changes.

Observed output:

status= ok
diff_line_count_reported= 0
expected_diff_lines_against_origin_main= 8
script_stdout_json= {
  "status": "ok",
  "checklist": [
    "Confirm the requested task is fully completed and validated before creating or pushing PR changes."
  ],
  "contributing_guide": null,
  "pr_template": null,
  "diff_line_count": 0
}

Failing Test

A minimal failing assertion equivalent to the script above:

assert output['status'] == 'ok'
assert output['diff_line_count'] > 0  # Fails: reports 0 despite committed changes

Evidence

• .github/workflows/gh-aw-fragments/safe-output-create-pr.md:17-21 computes upstream_sha from fallback refs (@{upstream}, origin/HEAD, origin/main).
• .github/workflows/gh-aw-fragments/safe-output-create-pr.md:33-37 and 43-47 still run diff/stat only against @{upstream} and HEAD, never using upstream_sha.
• The reproduction above shows a deterministic mismatch: expected_diff_lines_against_origin_main=8 while diff_line_count_reported=0.

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• expires on Sep 24, 2026, 11:26 AM UTC