feat(agents): add git-worktree skill and update pr-flow to use it (#79)

Co-authored-by: Claude <noreply@anthropic.com>

Author: nkoji21

.agents/skills/git-worktree/SKILL.md

@@ -0,0 +1,36 @@
+---
+name: git-worktree
+description: 変更内容をもとにブランチ名を決定し、/tmp 配下に git worktree を作成して変更ファイルをコピーする
+user-invocable: true
+allowed-tools: Bash
+---
+
+Create a git worktree for the current changes so they can be worked on in isolation without affecting the current branch.
+
+1. Run `git status` and `git diff` to understand what has changed
+2. Decide the most appropriate branch name based on the changes
+
+   Naming convention:
+   - Prefix: feat/fix/refactor/docs/chore/test
+   - Format: `{prefix}/{specific-content-in-kebab-case}`
+   - Examples: feat/user-auth, fix/login-error, refactor/api-client
+
+3. Create a worktree at `/tmp/{branch-name}` on a new branch from `main`:
+   ```
+   git worktree add /tmp/{branch-name} -b {branch-name} main
+   ```
+
+4. Copy all modified/untracked files from the current working directory into the worktree, preserving directory structure:
+   ```
+   # For each changed file shown in git status (macOS-compatible):
+   rsync -R {file} /tmp/{branch-name}/
+   ```
+
+5. Report the worktree path and branch name to the caller.
+
+## Cleanup
+
+The worktree must be removed by the caller after work is complete:
+```
+git worktree remove /tmp/{branch-name}
+```

.agents/skills/pr-flow/SKILL.md

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+---
+name: pr-flow
+description: Full PR workflow - branch, commit, open draft PR, AI review loop, then squash-merge. Use when you want end-to-end automation from staged changes to merged PR.
+user-invocable: true
+allowed-tools: Bash, Skill, Agent
+---
+
+Orchestrate the full pull request workflow from staged changes to squash-merged PR.
+
+## Phase 1: Worktree + Branch
+
+Use the Skill tool to invoke the `git-worktree` skill.
+
+After the skill completes, note the worktree path (`/tmp/{branch-name}`) and branch name it reports.
+Perform all subsequent work inside that worktree directory.
+
+After Phase 5 completes (or if the workflow stops early), remove the worktree:
+```
+git worktree remove /tmp/{branch-name}
+```
+
+## Phase 2: Commit
+
+Capture the current HEAD sha before committing:
+```
+BEFORE_SHA=$(git rev-parse HEAD)
+```
+
+Use the Skill tool to invoke the `git-commit` skill.
+
+After the skill completes, check whether a commit was made:
+```
+AFTER_SHA=$(git rev-parse HEAD)
+```
+
+If `BEFORE_SHA == AFTER_SHA`, stop and inform the user that there was nothing to commit.
+
+## Phase 3: Open PR
+
+Use the Skill tool to invoke the `git-pr` skill.
+
+After the skill completes, capture the PR URL:
+```
+gh pr view --json url --jq '.url'
+```
+
+If `gh pr create` failed because a PR already exists, retrieve the existing PR URL with the same command.
+
+Store this URL — you will use it in every subsequent `gh pr comment` and `gh pr merge` call.
+
+## Phase 4: Review Loop
+
+You may run this loop at most **3 times**. Track the iteration count starting at 0.
+
+### 4a. Launch reviewer subagent
+
+Use the Agent tool to launch the `pr-reviewer` subagent with this prompt (substitute the actual PR URL):
+
+```
+Review the PR at <PR_URL>. Run `gh pr diff <PR_URL>` to get the diff. Analyze it for bugs, logic errors, security issues, and style/convention violations. Return structured findings exactly as your instructions specify — the REVIEW_RESULT block only, no prose outside it.
+```
+
+### 4b. Validate and post the review comment
+
+Before posting, verify that the subagent's response contains a `REVIEW_RESULT` ... `END_REVIEW_RESULT` block. If the block is absent or malformed, post this warning instead and proceed to Phase 5:
+```
+gh pr comment <PR_URL> --body "[AI-generated review by Claude Code] Warning: reviewer returned malformed output. Skipping auto-fix. Please review manually."
+```
+
+Otherwise, post the findings:
+```
+gh pr comment <PR_URL> --body "[AI-generated review by Claude Code]
+
+<formatted review findings here>"
+```
+
+Format findings as a markdown list. Each item: severity label (`must-fix` / `suggestion` / `nitpick`), file/location, description.
+
+### 4c. Evaluate findings
+
+- **No issues** or **only `suggestion`/`nitpick`**: proceed to Phase 5.
+- **`must-fix` issues exist AND iteration < 3**:
+  - Read each flagged file before editing. Fix each `must-fix` issue.
+  - Capture HEAD sha before invoking git-commit:
+    ```
+    FIX_BEFORE=$(git rev-parse HEAD)
+    ```
+  - Use the Skill tool to invoke `git-commit` to commit the fixes.
+  - Check if the commit actually happened:
+    ```
+    FIX_AFTER=$(git rev-parse HEAD)
+    ```
+  - If `FIX_BEFORE == FIX_AFTER` (nothing was committed): post a comment explaining the fix could not be committed, then stop. Do NOT loop.
+  - Increment iteration count and return to step 4a.
+- **`must-fix` issues exist AND iteration == 3**:
+  - Post comment:
+    ```
+    gh pr comment <PR_URL> --body "[AI-generated review by Claude Code] Reached maximum auto-fix iterations (3). Remaining must-fix issues require manual attention."
+    ```
+  - Stop. Do NOT proceed to merge.
+
+## Phase 5: LGTM + Merge
+
+Post the LGTM comment:
+```
+gh pr comment <PR_URL> --body "[AI-generated LGTM by Claude Code]
+
+No must-fix issues found. Proceeding to auto-merge."
+```
+
+Trigger squash merge:
+```
+gh pr merge <PR_URL> --squash --auto
+```
+
+If the merge command fails, report the exact error to the user and stop. Do not retry automatically.
+
+Report the final PR URL and merge status to the user.