--- name: post-merge-cleanup description: Finish an already-merged branch. Proves the branch is an ancestor of the fetched default, classifies leftover artifacts as unique / redundant / superseded, returns to a clean --ff-only default checkout, and deletes the merged local branch — every discard confirmed per item. Routed to by $ca-cleanup. --- # post-merge-cleanup The walk back from a merged PR. Routed to by `$ca-cleanup`. The work has landed on the default branch. What is left is local: the branch you are standing on, and whatever the run left in the tree. This skill returns you to a clean, fast-forwarded default checkout without losing anything you have not explicitly agreed to lose. **It is ordinary lifecycle work and never needs `$ca-override`.** When it cannot proceed, it names the gate that stopped it. Issue #308 recorded the alternative: with no owner for this transition, the routing loop reached for `$ca-chore`, then for `$ca-override` — a bypass manufactured to cover a coverage hole. ## Pre-flight Read this, or STOP and surface the gap — never guess the default-branch name: - `/.codearbiter/CONTEXT.md` — the default-branch name. If HEAD is already the default branch, there is no transition to make. Report the dirty state read-only and exit; branch pruning across *other* branches belongs to `$ca-standup`. ## Phase 1 — Prove the merge · gate: BLOCK A branch that looks merged is not merged. Establish it against the network, not against a stale local ref: 1. `git fetch` the remote holding the default branch. A fetch that fails STOPs — an unfetched comparison proves nothing. 2. Confirm the current branch is an **ancestor** of the fetched default (`git merge-base --is-ancestor HEAD origin/`). This is the test that matters, and it is deliberately not `: gone]` upstream state: a squash-merged branch whose remote still exists is fully contained in the default branch and is safe to delete, while a `: gone]` branch whose commits never landed is not. 3. Report the proof as a fact — the default branch, the fetched SHA, and that HEAD is contained in it. If HEAD is **not** an ancestor, STOP. Name the un-landed commits and route to `$ca-pr`; nothing is deleted here. Gate: the remote is fetched and HEAD is proven an ancestor of the fetched default branch — or the skill has stopped. ## Phase 2 — Classify the residue · gate: BLOCK List every dirty tracked change, every untracked file, and every stash reachable from this branch. Classify each into exactly one of three, and say *why* for each: - **Redundant** — byte-identical to content already on the default branch, or a regenerated build artifact whose generator is committed and rerunnable. Safe to remove because removing it loses no information. - **Superseded** — an earlier form of something the merged PR already landed in a better shape. Name what supersedes it. - **Unique** — anything else. This is the default: an artifact that cannot be proven redundant or superseded IS unique. Uncertainty classifies as unique, not as redundant. Present the classification before touching anything. A file whose class you cannot establish is reported as unique with the reason you could not classify it. Gate: every dirty, untracked, and stashed artifact carries a class and a stated reason, with unclassifiable items counted as unique. ## Phase 3 — Resolve the residue · gate: STOP Per item, in the order Phase 2 listed them. Never batch: - **Unique** — offer to keep it: `$ca-commit` it on this branch before the transition, move it aside, or leave it in place and stop the cleanup. It is discarded only if the user explicitly confirms *that item by name*, with the Phase 2 reasoning in view. - **Redundant / superseded** — offer removal, one confirmation each, stating what it is and why it is safe. Declining leaves it exactly where it is. A stash is never dropped here. Stashes are reported with `git stash show` as the suggested next step, the same report-and-route contract `$ca-standup` holds. If anything the user chose to keep would block the checkout, STOP and say so rather than removing it anyway. A blocked checkout is a fine outcome; a silent discard is not. Gate: every item is resolved by an explicit per-item decision, and the working tree is clean enough to check out the default branch — or the skill has stopped with the blocker named. ## Phase 4 — Transition · gate: BLOCK Only after Phase 3 leaves the tree safe: 1. Check out the default branch, then **verify the checkout actually happened** (`git branch --show-current`). A checkout silently fails when another worktree holds the branch, and every step after this one would otherwise run against the wrong branch. 2. Fast-forward with `--ff-only`. A divergence means the default branch moved in a way this skill will not reconcile: report it and stop. Never a merge commit, never a rebase, never a reset. Gate: HEAD is confirmed on the default branch by re-read, and the fast-forward either succeeded or was reported as a refused divergence. ## Phase 5 — Delete the merged local branch · gate: STOP Offer deletion of the now-merged local branch, with the Phase 1 ancestry proof restated. One confirmation, naming the branch. - `git branch -d` only. Never `-D`: the safety check is the point, and if `-d` refuses, the ancestry proof and the refusal disagree — report both and stop. - The **remote** branch is never touched. If the user wants it gone, that is theirs to do or the platform's auto-delete-on-merge to do. Declining leaves the branch in place. That is a normal outcome, not a failure. Gate: the branch is deleted only after an explicit confirmation naming it, via `-d`, with the remote untouched. ## Phase 6 — Receipt One short summary: what landed, what was removed, what was kept, and where HEAD is now. State declines as declines — a cleanup the user stopped halfway is a correct outcome reported plainly, not an error. ## Hard rules - MUST fetch and prove `HEAD` is an ancestor of the fetched default branch before any deletion. MUST NOT infer merge state from a `: gone]` upstream alone. - MUST classify every artifact, and MUST treat anything not provably redundant or superseded as unique. - MUST NOT discard a unique or unclassifiable artifact without an explicit confirmation naming that item. - MUST confirm every removal and the branch deletion individually — no batched or implied yes. - MUST re-read the current branch after checkout before acting on it. - MUST use `--ff-only`, and MUST NOT merge, rebase, or reset to reach the default branch. - MUST use `git branch -d`, never `-D`; MUST NOT delete a remote branch, force-push, or write to the default branch. - MUST NOT drop a stash — report and route, as `$ca-standup` does. - MUST NOT route to `$ca-override` when blocked. Name the gate instead.