Worktree Fleet

A skill for running N independent agents in parallel, each isolated in its own git worktree on its own branch. Independence is validated before anything spawns — if two workers declare overlapping target_files, the skill refuses with a clear conflict message.

Decision tree — which fleet?

You want to run multiple agents in parallel. Which fleet?

1. Are the tasks independent (no shared files, no shared state)?
   YES → worktree-fleet  ← YOU ARE HERE
   NO  → continue

2. Does the work need iteration with a reviewer making accept/iterate decisions?
   YES → iterative-fleet
   NO  → continue

3. Is the work a one-shot DAG (each agent runs to completion, dependencies via depends_on)?
   YES → dag-fleet
   NO  → continue

4. None of the above?
   → You're the orchestrator. Open multiple Claude Code sessions.

When to use THIS skill

Tasks touch non-overlapping files (different modules, different docs, etc.)
You want merge-safe isolation — each worker on its own branch, no mid-flight conflicts possible
The merge decision is yours — after workers complete, you choose merge order / strategy
You want independent branches in git that you can inspect, cherry-pick, or discard

When NOT to use this skill

Workers need to coordinate or read each other's output → dag-fleet with depends_on
Tasks overlap files (even partially) → fix the task split first, then come back
You want headless workers + reviewer-in-loop → iterative-fleet
Work fits in the current conversation → use Claude Code's built-in Agent tool directly

fleet.json schema

{
  "fleet_name": "refactor-utils",
  "type": "worktree",
  "config": {
    "max_concurrent": 4,
    "model": "sonnet",
    "fallback_model": "haiku"
  },
  "workers": [
    {
      "id": "rename-foo",
      "task": "Rename foo() to baz() in src/utils/foo.ts and all callers",
      "target_files": ["src/utils/foo.ts", "src/**/*.test.ts"],
      "branch": "rename-foo-to-baz",
      "type": "code-run",
      "max_turns": 30,
      "max_budget_usd": 2.0
    }
  ]
}

New fields vs dag-fleet:

target_files (required per worker) — list of file globs this worker will touch. Overlap across workers = launch refuses with exit 2.
branch (required per worker) — git branch name for this worker's worktree. Must not already exist.

Worker type override (Claude only): Worktree workers always need Bash for git commit. If you set type to read-only, write, or reviewer, launch.sh will automatically override to code-run with a warning. The worktree itself provides isolation — Bash restrictions are unnecessary here. This override does not apply to codex workers (codex uses sandbox modes).

Provider support: Set "provider": "codex" at config or per-worker level to use OpenAI Codex CLI instead of Claude. Codex workers use --sandbox workspace-write (needed for git commit). See dag-fleet SKILL.md for full codex provider documentation (model aliases, reasoning_effort, limitations).

Default max_turns is 100 (not 50 like dag-fleet). Worktree workers typically edit, test, and commit — they need headroom.

Available scripts

Script	When to call	Args
`launch.sh`	Validate independence, create worktrees, spawn workers in tmux	`<fleet-root> [--dry-run]`
`status.sh`	Per-worktree progress, cost, completion state	`<fleet-name-or-root> [--json]`
`merge.sh`	Print merge plan (files changed, line counts) — no auto-merge	`<fleet-name-or-root>`
`cleanup.sh`	Remove git worktrees, requires --force	`<fleet-name-or-root> --force`

Launch procedure

Set FLEET_ROOT to an absolute path.
Create $FLEET_ROOT/fleet.json with the schema above.

For each worker, create $FLEET_ROOT/workers/{id}/prompt.md. Include:

Save ALL output to $FLEET_ROOT/workers/{id}/output/ — use absolute paths.

Run: bash ${CLAUDE_SKILL_DIR}/scripts/launch.sh $FLEET_ROOT
--dry-run validates independence without creating worktrees or spawning workers.
ALWAYS tell the user the exact status command so they can monitor manually:
```
bash ${CLAUDE_SKILL_DIR}/scripts/status.sh <fleet-name-or-root>
```
This is mandatory after every launch. The user must be able to check status without asking you.

IMPORTANT: Worker prompts MUST instruct the worker to commit its changes before exiting:

When you are done, commit your changes on the current branch with a descriptive message.

Without this, changes stay as unstaged modifications and cannot be merged via git merge.

After workers complete

Run merge.sh to see what each branch changed.
Decide your merge strategy (in-order, cherry-pick, etc.).
Merge manually — the skill does NOT auto-merge.
Run cleanup.sh --force to remove worktrees.

Rationalizations to reject

Agent says	Rebuttal
"The tasks overlap slightly but I can manage"	Overlapping target_files = reject. No exceptions. Fix the task split first. If you think you can manage it, you're wrong — merge conflicts in parallel worktrees are unrecoverable.
"I'll skip `--dry-run` since I wrote the fleet.json carefully"	Then dry-run will be fast. Run it. The independence validator catches things you didn't think of (glob overlap, bidirectional fnmatch).
"Two workers both need the config file, but in different sections"	Same file = overlap. The validator doesn't know about "sections." Split the config change into a separate sequential step, or have one worker own it.
"I'll auto-merge since the branches are clean"	Never auto-merge. Run `merge.sh`, read the output, decide strategy. The whole point of worktree-fleet is that the operator owns the merge decision.
"I can skip cleanup — the worktrees aren't hurting anything"	Worktrees hold branch locks. Stale worktrees block future branch creation and waste disk. Run `cleanup.sh --force` when done.

STRICT RULES

Never skip --dry-run validation for new fleet configurations.
Never merge without reviewing merge.sh output first.
cleanup.sh requires --force — no accidental removals.
Worktrees persist until you explicitly clean them up. They will not auto-remove.

$ARGUMENTS