Worktree Agent Skill for Claude

Worktree Agent Rules

Mandatory rules for any agent dispatched with isolation: "worktree".

Rule 1: Verify Your Working Directory

On start, run pwd. Your path MUST contain .claude/worktrees/.

If your CWD is the main repo path, STOP and report the error.

Rule 2: Create Feature Branch First

git checkout -b <branch-name>

Never commit on the default worktree-agent-* branch. Create your feature branch FIRST.

If git checkout -b <branch-name> fails with "a branch named X already exists":

# Option A: the branch has no commits beyond main — safe to reset and reuse
git branch -D <branch-name>
git checkout -b <branch-name>

# Option B: the branch is checked out in another active worktree — use a unique name
git checkout -b <branch-name>-2   # or append timestamp: $(date +%s)

If git checkout -b <branch-name> fails with "X is already used by worktree at Y":

# Branch is live in another worktree — use a unique suffix
git checkout -b <branch-name>-$(date +%s)

To update a branch held by another worktree (e.g. an existing PR branch): work detached from origin/<branch> and push with git push origin HEAD:<branch>. gh pr merge's post-merge local-checkout errors are harmless.

Rule 3: Use Worktree-Relative Paths

Never hardcode absolute paths from the main repo. Use $(git rev-parse --show-toplevel)/path.

Exception: Reading gitignored ADR files requires the main repo absolute path.

Rule 4: Ignore Auto-Plan Hooks

Keep planning inline instead of creating task_plan.md. If the auto-plan hook fires, continue with the current task and keep your attention on implementation.

Rule 5: Stage Specific Files Only

git add path/to/specific/file.py

Never git add ., git add -A, or git add --all. Verify with git diff --cached --stat.

Rule 6: Do Not Touch the Main Worktree

Never write to paths outside your worktree directory. Never run git checkout in the main repo.

Rule 7: Commit with Conventional Format

Use the commit message specified in your prompt. No attribution lines.

Rule 8: Run Both ruff Checks Before Declaring CI-Ready

For any Python code changes, run both checks before pushing or creating a PR:

ruff check . --config pyproject.toml
ruff format --check . --config pyproject.toml

Running only ruff check misses formatting violations. The Tests / lint CI job runs both — if you skip ruff format --check, the PR will fail CI and cannot merge due to branch protection.

Rule 9: Run Preflight Check on Start

Run the preflight script at the start of any worktree task to confirm clean state:

bash scripts/worktree-preflight.sh <intended-branch-name>

If it exits 1, fix the reported issue before proceeding.

Post-Merge Cleanup

After a PR is merged, the dispatcher runs:

bash scripts/worktree-cleanup.sh --force

This prunes stale .git/worktrees entries and deletes zombie branches (harness-created branches with no active worktree that are already merged into main). Run manually when git worktree list shows stale locked entries.

Failure Modes This Prevents

| Failure | Rule | Without It |

|---------|------|-----------|

| Agent edits main repo files | 1, 6 | Changes leak to main, get stashed/lost |

| Context wasted on task_plan.md | 4 | Implementation budget consumed by planning |

| Commit on wrong branch | 2 | Orchestrator merges wrong content |

| PR has changes from 2 ADRs | 5, 6 | Cross-contamination between agents |

| Branch locked by worktree | 2 | Fatal error on checkout |

| PR fails CI on format | 8 | Merge blocked; ruff format --check was skipped |

| New task fails to create worktree | 9 | Branch name collision from prior stale run |