/undo

name: undo
description: >
  Safely undo the most recent git commit(s) on a feature branch.
  TRIGGER when the user says "undo my last commit", "undo last N
  commits", "oops revert that commit", "undo the commit but keep my
  changes", "uncommit", "revert my last change", "take back that
  commit", "/nyann:undo". Trigger on "revert" only when the user
  clearly means undoing a local commit (not `git revert` on a
  published one — see DISAMBIGUATION).
  DISAMBIGUATION: if the user says "revert a commit that's already
  on main" / "revert a pushed commit" / mentions a specific remote
  SHA, this is the `git revert` workflow — undo-skill refuses pushed
  commits by default. Explain the difference and either use
  --allow-pushed (risky) or direct them to `git revert <sha>`.
  Do NOT trigger on "undo the last edit" (that's editor-level) or
  "rollback the deploy" (that's infrastructure, out of scope).
  Do NOT trigger on main/master/develop — long-lived branches should
  never be history-rewritten; use `git revert` instead.

undo

Wraps `bin/undo.sh`. History-mutating operation — treat as destructive.

1. Always preview first

Before any mutation, run `bin/undo.sh --dry-run` and show the user which commits will be undone. The preview JSON lists them newest- first with SHA and subject. Read it back and ask the user to confirm — even for a single-commit undo.

Exception: the user's request explicitly included "don't ask" / "just do it" AND `--count` is 1 AND `--strategy` is `soft` (the safest default). For anything multi-commit or non-soft, always confirm.

2. Decide strategy

Default is `soft` (safest — all changes stay staged). When the user's intent is unclear, **you MUST call the `AskUserQuestion` tool** (not plain text):

{
  "questions": [
    {
      "question": "How should the commit be undone?",
      "header": "Strategy",
      "multiSelect": false,
      "options": [
        { "label": "Soft (Recommended)", "description": "Undo commit, keep changes staged" },
        { "label": "Mixed", "description": "Undo commit, keep changes in working tree (unstaged)" },
        { "label": "Hard", "description": "Undo commit AND discard all changes permanently" }
      ]
    }
  ]
}

For `hard`, warn the user twice: the work is gone after hard reset. Confirm before executing even after the picker selection.

3. Decide scope

• **`last-commit`** (default) — one commit.
• **`last-N-commits` with `--count <N>`** — multiple commits. Use

when the user says "undo the last 3 commits" or similar.

`last-N-commits` is more dangerous because commits partway down the stack are harder to recover. For N > 3, suggest using `git reflog`

• targeted revert instead of a bulk reset.

4. Pre-flight safety (script enforces; relay messages)

| Refusal reason | What to tell the user | |---|---| | `long-lived branch` | "Can't undo on main/master/develop. Use `git revert <sha>` to create a reverting commit." | | `merge commit` | "HEAD is a merge commit — undo with `git revert -m 1 <merge-sha>` manually." | | `already on upstream` | "The commit is already pushed to `<upstream>`. Either `git revert` it (safe) or pass `--allow-pushed` to force-push after the reset (only if nobody else pulled)." | | `detached HEAD` | "Detached HEAD — checkout a branch first." | | `fewer than N commits` | "Branch only has M commits; can't undo N." |

5. Invoke

bin/undo.sh --target <cwd> \
  [--scope last-commit|last-N-commits] [--count N] \
  [--strategy soft|mixed|hard] [--allow-pushed] [--dry-run]

6. Post-undo report

On success, echo back:

• What was undone (subjects from `undone_commits`).
• The new HEAD SHA.
• Where the changes are now: staged (soft), in working tree (mixed),

or gone (hard).

• For `soft`/`mixed`: suggest `git status` to see what's pending.
• For multi-commit undo: remind the user that `git reflog` can

recover the discarded history if they change their mind soon.

7. Hand-off

• "Re-commit with a new message" → `commit` skill after undo.
• "Now push the rewrite" → if undo required force-push (pushed

commit with `--allow-pushed`), they'll need `git push --force-with-lease`. Don't run this automatically; explain and let them decide.

• "Undo the undo" → `git reflog` + `git reset --hard <prior-sha>`.

Handle this as a separate one-off; don't add reflog logic to the undo skill itself.