commit-message-generator

Commit Message Generator

Turn the current git state into one or more well-formed Conventional Commit messages, each confirmed by the user before the commit lands. Never guess what changed — scripts/analyze-diff.py is the single source of truth.

Hard rules

Always run scripts/analyze-diff.py first. Never read the diff manually, never call git diff / git status / git ls-files yourself. The script's output is the only input you use to plan groups and write messages.
Staged wins. If the script reports State: staged, work with the staged files only. Ignore unstaged / untracked files — the user staged what they meant to stage.
If the script exits non-zero (nothing to commit), stop and tell the user.
Never commit without explicit user confirmation. Print the message, wait for a yes/edit/no response, then act. Never pass --no-verify, never amend, never git push.
Never add co-author trailers unless the user explicitly asks.
Never git add -A / git add .. Stage exactly the paths for the current group and nothing else.

Process

Step 1 — Inspect state

Run the analyzer:

python3 <skill-dir>/scripts/analyze-diff.py

Two possible states:

State: staged → skip to Step 3 (message generation for the staged diff).
State: unstaged → continue with Step 2 (propose groups).

Step 2 — Propose commit groups (unstaged state only)

Read Files and propose 1–4 logical commit groups. Apply the heuristics below. Then:

1 group → stage all files with git add -- <paths> and go to Step 3. Show the user the single-group plan first only if there is visible ambiguity; otherwise stage silently and move on.
2+ groups → print a numbered proposal like:
```
Proposed 2 commits:
  [1] feat(api): <files...>
  [2] docs: README.md, CHANGELOG.md
Confirm? (yes / edit / merge / cancel)
```
Responses:
- yes / lgtm → iterate groups in order (see Sequential loop).
- edit (or free-form feedback like "move X to group 2", "split group 1") → revise the proposal, re-print, re-prompt.
- merge → treat everything as one group; stage all, go to Step 3.
- cancel / no → stop. Do not stage anything.
More than 4 groups → do not propose. Print the file list grouped by top-level folder and ask the user to narrow scope before rerunning.

Step 3 — Generate the message

Re-run the analyzer if you just staged files, so scope/type signals reflect what is actually staged now. Then:

Pick the type from Suggested type, overriding only when the diff clearly says otherwise:
- feat — new user-visible capability
- fix — bug fix
- refactor — behavior-preserving code change
- test — tests only
- docs — documentation only
- chore — tooling, deps, meta files
Anything beyond this list (perf, build, ci, style, revert) or a breaking change → consult references/conventional-commits.md.
Pick the scope from Likely scopes:
- 1 scope → use it as-is (lowercase, short noun).
- 2 scopes touching one logical change → comma-separated (fix(api,ui):).
- >3 scopes → do not force a scope. See Gotchas below.
- Root-only files → omit scope.
- Generic top-level folder (src, lib, app) → look one level deeper in the file list for a meaningful scope (e.g. src/api/... → api).
Write the subject. Imperative mood, ≤72 chars, no trailing period. "add", not "added" or "adds".
Body — only if it earns its keep. Trivial diff → omit. Otherwise 2–5 bullets, one line each, facts only. Do not restate the subject.
Footers. Branch name matches [A-Z]{2,}-\d+ → add Refs: KEY-123. Breaking / revert / closes → see the reference file.

Step 4 — Confirmation loop

Print the message inside one fenced code block and ask Commit this? (yes / edit / no).

yes / lgtm / ship it / commit → run git commit -F - with the message on stdin. Report the resulting hash + subject on one line.
Feedback (any edit, reword, scope change, "shorter", etc.) → revise and loop back to the start of this step. Do not commit until confirmed.
no / cancel / abort → cancel semantics (below).

Step 5 — Sequential loop (multi-group runs only)

After each commit, print [N/M] committed <hash> <subject> and start the next group at Step 2 → staging for that group. Re-run the analyzer between groups. Stop when all groups are committed or the user cancels.

Grouping heuristics

One logical change spanning multiple folders (a shared type used in api/ + ui/, a rename that spans both) → one group.
Distinct top-level folders with clearly unrelated changes → separate groups.
Test changes for a same-run feature → keep with the feature. Tests for pre-existing code → separate test group.
Lockfile-only files (package-lock.json, yarn.lock, pnpm-lock.yaml, Cargo.lock, poetry.lock, go.sum) → their own chore(deps): update lockfile group.
Docs-only files (README, docs/, *.md) → their own docs group, unless the docs ship with a feature in the same diff.
Config / meta files (.github/, .gitignore, tooling configs) → their own chore group unless intertwined with a feature change.
Cap: max 4 groups per run.

Cancel semantics

If the user cancels a message confirmation mid-run:

Commits already made in this run stay committed — they were confirmed.
The current group's staged files are unstaged with git reset HEAD -- <paths>. File contents on disk are never modified.
Remaining groups are not started.
Print a one-line summary: Committed N of M groups; group K unstaged and skipped.

Message format

<type>[(scope)]: <short imperative subject>

[optional body — 2–5 bullets, one line each]

[optional footer(s)]

Allowed types: feat, fix, refactor, test, docs, chore. Extend only via the reference file.

Gotchas

More than 3 distinct scopes in one group. Do not force chore(misc): or silently drop the scope. Print the scope list and suggest re-grouping.
Mixed change types in one group (a feat + unrelated fix + docs). Same treatment: name the mix, suggest re-grouping.
Rename-only diff → refactor with the new name in the subject.
Breaking change, revert, merge, unfamiliar footer → read references/conventional-commits.md and follow its rules. Do not improvise.

Output

Single-group / already-staged run: one fenced code block with the message, one confirmation line. On confirmation, one line with hash + subject.

Multi-group run: the numbered group proposal, then per-group message-confirmation-commit cycles, with a [N/M] committed ... line after each. On cancel, the one-line summary described in Cancel semantics.

Nothing else. No essays, no explanations of what changed — the log and the diff already say it.