Backporting a Pull Request

Automates the patch-release backport flow from RELEASING.md §Patch Releases. Invoke as:

/backport <PR-number> [target-branch]

Requires an authenticated gh CLI (gh auth status).

Rules (DO NOT VIOLATE)

• Never git push. Print the push command at the end and let the user run it.
• Never add Co-Authored-By: Claude ... to any commit.
• Always cherry-pick with git cherry-pick -x -s (records origin SHA, adds signoff, matches existing patch-branch history).
• Always work in .claude/worktrees/backport-pr-<N>, never in the primary checkout.
• Flyway migrations: cherry-pick as-is. DO NOT RENAME OR RE-TIMESTAMP (see RELEASING.md §Flyway migrations).
• If a conflict cannot be resolved unambiguously and does not apply conceptually, ask the user via AskUserQuestion. DO NOT IMPROVISE.

Resolving the canonical remote

origin may point at a fork. Resolve the canonical remote once and use $CANON everywhere below:

CANON=$(git remote -v | awk '/DependencyTrack\/dependency-track.*\(fetch\)/ {print $1; exit}')

If empty, ask the user which remote tracks the canonical repo.

Workflow

1. Validate state

• Confirm CWD is the primary repo (not already a worktree).

• Resolve $CANON per §Resolving the canonical remote, then git fetch $CANON.

• If target-branch was omitted, derive it from the PR's backport label:

  gh pr view <N> --json labels -q '.labels[].name | select(startswith("backport/"))'
  

  If backport/5.0.5, the target branch is 5.0.x. On zero or multiple matches, ask the user via AskUserQuestion, offering branches matching [0-9]+\.[0-9]+\.x.

2. Locate the PR's commits

gh pr view <N> --json state,baseRefName,mergeCommit

• state is not MERGED: abort. DO NOT GUESS.
• baseRefName is not main: tell the user which branch the PR targeted and ask before continuing.

Take MERGE from mergeCommit.oid, then check how it was merged:

git rev-parse --verify --quiet "${MERGE}^2"

• Merge commit (^2 resolves): the PR's commits are preserved in main.

  git log --reverse --format=%H "${MERGE}^1..${MERGE}^2"  # oldest first
  

• Squash or rebase merge (^2 missing): MERGE itself is the only commit to pick.

3. Set up the worktree

Path: .claude/worktrees/backport-pr-<N> (in-tree, git-ignored).

• Reuse (path exists, worktree registered): cd in, verify git status is clean (else ask the user), then git checkout -B backport-pr-<N> $CANON/<target-branch>.
• Fresh: git worktree add -b backport-pr-<N> .claude/worktrees/backport-pr-<N> $CANON/<target-branch>.
• Leftover branch (worktree gone, branch remains, git worktree add errors with a branch named '…' already exists): glance at git log backport-pr-<N> ^$CANON/<target-branch> to confirm nothing valuable, git branch -D backport-pr-<N>, retry.
• If git worktree add half-succeeded (partial directory plus a stale branch), delete both and git worktree prune before retrying.

4. Apply each commit

For each SHA from step 2, in order.

First, skip what is already there:

git log $CANON/<target-branch> --grep="cherry picked from commit <sha>" --format=%H

Non-empty means already backported. Skip it and note that in the summary.

Otherwise git cherry-pick -x -s <sha>.

• Clean: continue.
• Trivial conflict (import order, non-overlapping adjacent edits): resolve, git add, GIT_EDITOR=true git cherry-pick --continue (--continue opens $EDITOR and hangs otherwise).
• Non-trivial but conceptually applies: git cherry-pick --abort, recreate manually, commit per §Manual commit format.
• Does not apply conceptually (target refactored/removed): git cherry-pick --abort, then AskUserQuestion with options (skip / reduced port / port differently). DO NOT INVENT A RESOLUTION.

Inspecting a conflict before resolving

Conflict markers can include unrelated main-only lines that anchored the hunk's context. Naively accepting "incoming" smuggles those into the backport.

Before resolving, run git show <sha> -- <conflicted-file> to show the authoritative diff. If the >>>>>>> side has extra lines git show doesn't list, drop them.

5. Manual commit format

For manually-recreated commits (not cherry-picked):

• Mirror the original subject + body.
• Add Co-Authored-By: <Name> <email> for the original commit's author. Omit if that email equals git config user.email. Never add Co-Authored-By: Claude ....
• git commit -s (adds Signed-off-by). Author identity = default git config. Pass the message via HEREDOC.

6. Post-backport checks

Run from the worktree. Flyway lints must be pinned to the patch branch. The default BASE_REF is origin/main, which would compare against the wrong history here.

On failure, report and stop.

7. Summary

Print, in this order:

1. The worktree path.

2. One row per commit from step 2. Every commit gets a row, including skipped ones:

   Status	Commit	Subject
   picked / manual / skipped / already	<short-sha>	...

   <short-sha> is the source commit on main, not the new one. For skipped, give the reason.

3. The push command (DO NOT RUN IT):

   cd .claude/worktrees/backport-pr-<N> && git push -u origin backport-pr-<N>
   

If any row is not picked, state that on one line above the table.