Add /prepare-release command

.claude/commands/prepare-release.md

@@ -0,0 +1,55 @@
+---
+description: Scaffold gem release prep — preflight, bump, verify, then push a release branch and open a PR
+argument-hint: [patch|minor|major|X.Y.Z]
+allowed-tools: Bash(git status:*), Bash(git fetch:*), Bash(git log:*), Bash(git diff:*), Bash(git tag:*), Bash(git rev-parse:*), Bash(git rev-list:*), Bash(git branch:*), Bash(git switch:*), Bash(git restore:*), Bash(git add:*), Bash(git commit:*), Bash(git push:*), Bash(gh pr create:*), Bash(gh pr view:*), Bash(bundle install:*), Bash(bundle exec:*), Bash(grep:*), Bash(rg:*), Bash(ls:*), Bash(date:*), Read, Edit, Write, Glob, Grep
+---
+
+Prepare a gem release. Bump kind: **$ARGUMENTS** (empty = infer from commits since last tag).
+
+End state: a `release-X.Y.Z` branch pushed to origin with an open PR titled `Release X.Y.Z` and body `🎉`. The PR diff is the review surface — the CHANGELOG is the release notes.
+
+The user runs the irreversible steps after the PR merges. **Never** run `bundle exec rake release`, `gem push pkg/minitest-attributes-X.Y.Z.gem`, or `git tag vX.Y.Z && git push origin vX.Y.Z`.
+
+## Preflight
+
+Bail loudly on any failure — don't try to fix state silently.
+
+- On `main`, working tree clean, not behind `origin/main` (`git fetch origin main` then `git rev-list --count HEAD..origin/main` → `0`).
+- `lib/minitest/attributes/version.rb` `VERSION`, `Gemfile.lock`'s `minitest-attributes (X.Y.Z)` line under `PATH → specs:`, and the latest `git tag --sort=-v:refname | head -1` (stripped of leading `v`) all agree. A mismatch usually means a prior release was half-finished — surface it and stop.
+
+## Bump
+
+If `$ARGUMENTS` is empty, infer from `git log <latest_tag>..HEAD`:
+
+- Any commit subject containing `Breaking`, or starting with `Add ` or `Change ` → **minor**
+- Otherwise → **patch**
+
+This gem is pre-1.0; breaking changes still bump the minor (no major path). Print the inferred bump and the resulting `X.Y.Z`, then proceed without confirming.
+
+If `$ARGUMENTS` is `patch`/`minor`/`major`, bump that segment. If it's `X.Y.Z`, use literally. Anything else → bail.
+
+## Apply
+
+1. Edit `lib/minitest/attributes/version.rb` — replace the `VERSION = "..."` literal.
+2. Edit `CHANGELOG.md` — insert `## [X.Y.Z] - YYYY-MM-DD` (today, absolute via `date +%Y-%m-%d`) directly below `## [Unreleased]` with blank lines around it. The Unreleased entries shift down to attribute the new release; the new Unreleased block stays empty.
+3. `bundle install` — should change only `Gemfile.lock`'s `minitest-attributes (X.Y.Z)` line. Surface anything else.
+
+## Verify
+
+`bundle exec rake` — tests + RuboCop. Bail on red.
+
+## Shape check
+
+`git diff --stat` should touch only `lib/minitest/attributes/version.rb`, `CHANGELOG.md`, `Gemfile.lock`. Anything else is a red flag — stop and ask before pushing.
+
+## Branch + PR
+
+```
+git switch -c release-X.Y.Z
+git add lib/minitest/attributes/version.rb CHANGELOG.md Gemfile.lock
+git commit -m "Release X.Y.Z"
+git push -u origin release-X.Y.Z
+gh pr create --title "Release X.Y.Z" --body "🎉"
+```
+
+Print the PR URL.

.claude/rules/testing.md

@@ -0,0 +1,8 @@
+---
+description: Rules for writing tests
+globs: test/**/*.rb
+---
+
+- Do not use `setup` methods. Create the necessary objects inline within each test method.
+- Use plain `Struct`s or small classes as records; the gem must not depend on ActiveRecord or ActiveSupport to be tested.
+- Every branch of `assert_attributes` (plain, nil, Time, rich text) needs both a passing case and a failing case that checks the failure message.

.gitignore

@@ -6,3 +6,6 @@
 /pkg/
 /spec/reports/
 /tmp/
+
+!.claude/
+.claude/settings.local.json