fix(dev-lead): force-with-lease retry when a rebase rewrites branch history (#647)

[don-petry]

Closes #647

Problem

push_with_merge_guard (scripts/lib/auto-merge.sh) ran a plain git push. When an engine resolved a rebase under a non-rebase intent (on-mention, review-changes), the rewritten branch history could never be published — the push was rejected non-fast-forward and the whole run failed red, even though the rebase and conflict resolution succeeded.

Observed in run #27471503333 (@dev-lead - resolve the rebase main conflict on PR #624), which left PR #624 stuck dirty for a day. Only the dedicated rebase intent worked, because prompts/dev-lead/rebase.md has the engine force-push itself.

Fix

When the plain push is rejected non-fast-forward and HEAD has diverged from its upstream (i.e. history was rewritten), retry once with --force-with-lease:

• The lease (our remote-tracking ref) makes the retry abort if the remote advanced under us, so a concurrent push by someone else is never clobbered.
• A normal non-fast-forward where the branch is not diverged (remote legitimately advanced) still fails exactly as before — no force.
• All callers invoke push_with_merge_guard with no args, so the behavior change is scoped to the rejected-push path only.

This mirrors the established force-push in the dedicated rebase intent.

Tests

tests/dev-lead/unit/test_auto_merge.bats — added 2 cases (force-with-lease retry succeeds on rewritten history; no force-push when branch isn't diverged). Full suite: 25/25 pass, shellcheck --severity=warning -x clean.

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Note: the original symptom (PR #624 stuck) was already resolved manually by rebasing + force-pushing it; #624 has since merged and closed #573. This PR fixes the underlying push path so it can't recur.

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Generated by Claude Code

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: ASSERTIVE

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Run ID: 20fadeee-cfaa-4046-af30-73e1260f289c

📥 Commits

Reviewing files that changed from the base of the PR and between 6042fcd and 3d374b3.

📒 Files selected for processing (2)

• scripts/lib/auto-merge.sh
• tests/dev-lead/unit/test_auto_merge.bats

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/github-actions-failure-vtnmt0

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[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[don-petry]

Dev-Lead — review-changes (no-changes)

No changes were needed for this PR.

[gemini-code-assist]

Code Review

This pull request introduces a retry mechanism using --force-with-lease in scripts/lib/auto-merge.sh when a push is rejected due to a non-fast-forward error and the local branch has diverged from its upstream (indicating a history rewrite). It also adds corresponding unit tests in tests/dev-lead/unit/test_auto_merge.bats. The review feedback suggests improving readability in the test stub helper by extracting the outer function's positional parameter into a named local variable to avoid confusion with the inner script's escaped positional parameters inside the heredoc.

[gemini-code-assist]

Mixing escaped and unescaped positional parameters (like \$1 and ${1:-}) inside a double-quoted heredoc (<<EOF) can be confusing and hard to maintain. It is not immediately obvious that ${1:-} refers to the argument of the outer function _install_git_stub_force rather than the generated script's own $1 (which is matched as \$1 on line 197).

Using a clearly named local variable (e.g., local mode="${1:-}") and referencing it as "$mode" makes the distinction between generation-time expansion and runtime evaluation much clearer.

_install_git_stub_force() {
  local mode="${1:-}"
  cat > "$STUB_BIN_DIR/git" <<EOF
#!/usr/bin/env bash
case "\$1" in
  push)
    shift
    for a in "\$@"; do
      [ "\$a" = "--force-with-lease" ] && exit 0
    done
    echo "  ! [rejected]        feature -> feature (non-fast-forward)" >&2
    exit 1
    ;;
  rev-parse)
    case "\$*" in
      *"@{u}"*) echo "origin/feature" ;;
      *)        echo "deadbeefcafe" ;;
    esac
    exit 0
    ;;
  merge-base)
    # --is-ancestor <upstream> HEAD: 0 = upstream reachable (not diverged),
    # 1 = diverged (history rewritten by a rebase).
    [ "$mode" = "diverged" ] && exit 1 || exit 0
    ;;

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