Create New Worktree

Creates a new git worktree with:

• Shared assets (symlinked or copied)
• Independent environment per project type
• Proper .envrc configuration for direnv

Arguments

• worktree_name (required): Name for the worktree and branch
• assets_path (optional): Path to external assets directory to symlink from

Cookbook

Setup guide: cookbook/setup.md -- guided walkthrough for creating .worktree.yml (read when no config exists or user requests setup help)

Parallelization

CRITICAL: Use Task tool with model: haiku for parallel execution when:

• Setting up assets in multiple directories
• Installing dependencies in multiple environments
• Any operation that can run independently

Spawn separate haiku agents for each independent task to maximize parallelization.

Example - parallel environment setup:

Task(model: haiku, prompt: "Setup Python venv in /path/to/backend")
Task(model: haiku, prompt: "Run npm install in /path/to/frontend")
Task(model: haiku, prompt: "Create symlinks for assets in /path/to/data")

Send all independent Task calls in a SINGLE message to run them concurrently.

Pre-Flight Checks

1. Verify git repo root:

   git rev-parse --show-toplevel
   

2. Validate worktree name:

   • Must be provided
   • No spaces or special chars (except - and _)

3. Check for existing worktree/branch:

   • If worktree exists: STOP and report
   • If branch exists: Ask user to confirm reuse

4. Check for .worktree.yml:

   REPO_ROOT=$(git rev-parse --show-toplevel)
   find "$REPO_ROOT" -maxdepth 1 -name ".worktree.yml" -type f | head -1
   

   • If .worktree.yml exists: continue to Asset Discovery (Step 4) normally
   • If .worktree.yml does NOT exist: prompt the user via AskUserQuestion:

     No .worktree.yml found in your project. This file configures how worktrees set up assets (symlinks, copies) and environments. Without it, the skill infers configuration from directory structure and .gitignore.

     Would you like to create a .worktree.yml now? I can guide you through the setup. (You can skip this and the skill will use inference instead.)

   • If user says yes: read cookbook/setup.md and follow the guided creation flow. After creating the config, continue to Step 4 (Asset Discovery) using the new config.
   • If user says no or skips: continue to Step 4 (Asset Discovery) with inference mode.

Asset Discovery

When assets_path is provided

Use the provided path directly. Mirror its structure into the worktree via symlinks.

When assets_path is NOT provided (inference mode)

Step 1: Check for sibling assets directory

Look for directories matching <repo-name>-assets pattern:

REPO_NAME=$(basename "$(git rev-parse --show-toplevel)")
REPO_PARENT=$(dirname "$(git rev-parse --show-toplevel)")
ASSETS_CANDIDATES=(
  "$REPO_PARENT/${REPO_NAME}-assets"
  "$REPO_PARENT/assets"
  "$REPO_PARENT/.${REPO_NAME}-assets"
)

If found, use it as assets_path.

Step 2: Analyze .gitignore for local assets

If no sibling assets directory found, parse .gitignore to identify:

# Find gitignored directories/files that exist locally
git ls-files --others --ignored --exclude-standard --directory

Filter for:

• Directories containing data files (inputs/, data/, fixtures/)
• Environment files (.env, .env.local, *.env)
• Config files that vary per environment (config.local.*)
• Large binary directories (models/, weights/, cache/)

Step 3: Classify assets

For each discovered asset, classify:

Asset Type	Action	Reason
.env files	Copy	Secrets, may need per-worktree customization
inputs/, data/ dirs	Symlink	Large, read-only shared data
config.*.local	Copy	May need per-worktree customization
Binary/model dirs	Symlink	Large, read-only

Execution Flow

CRITICAL: AUTONOMOUS EXECUTION REQUIRED

This command MUST execute ALL steps (1-8) in sequence WITHOUT stopping for user input. After the branch skill invocation completes in Step 2, IMMEDIATELY continue to Step 3. Do NOT wait for user confirmation between steps.

Execution pattern:

1. Generate unique name
2. Invoke Skill(skill="branch", args="...") -> when it completes, CONTINUE IMMEDIATELY
3. Create worktree -> CONTINUE
4. Setup assets -> CONTINUE
5. Setup environment -> CONTINUE
6. Enable direnv -> CONTINUE
7. Commit changes -> CONTINUE
8. Display summary -> DONE

---

Execution Steps

Step 1: Generate unique name

UUID_PREFIX=$(uuidgen | cut -c1-6 | tr 'A-Z' 'a-z')
FULL_NAME="$UUID_PREFIX-<worktree_name>"

This ensures branch name and worktree directory match exactly.

Step 2: Create branch with spec directory

Invoke the branch skill with the full name:

Skill(skill="branch", args="$FULL_NAME")

Creates AND COMMITS (CRITICAL):

• Branch: $FULL_NAME (e.g., a1b2c3-feature-name)
• Spec dir: specs/<YYYY>/<MM>/$FULL_NAME/
• Backlog: 000-backlog.md

Why commit is critical: If spec dir is not committed before git worktree add, the files won't exist in the new worktree (worktree is created from the branch's committed state).

AFTER branch COMPLETES: Do NOT stop. Do NOT show todos. IMMEDIATELY proceed to Step 3.

Step 3: Create worktree

git worktree add "trees/$FULL_NAME" "$FULL_NAME"

Branch and worktree directory now have the same name.

Step 4: Setup assets based on .worktree.yml

4a. Discover all .worktree.yml files:

find "$WORKTREE_PATH" -name ".worktree.yml" -type f

4b. For each config file, process assets with correct path resolution:

for CONFIG_FILE in $(find "$WORKTREE_PATH" -name ".worktree.yml"); do
  CONFIG_DIR=$(dirname "$CONFIG_FILE")
  CONFIG_RELATIVE=$(realpath --relative-to="$WORKTREE_PATH" "$CONFIG_DIR")

  # Read source from config (use yq or grep+sed)
  SOURCE_VALUE=$(yq '.assets.source' "$CONFIG_FILE")

  # CRITICAL: Resolve source relative to CONFIG_DIR, not CWD
  if [[ -n "$SOURCE_VALUE" && "$SOURCE_VALUE" != "null" ]]; then
    ASSETS_SOURCE=$(cd "$CONFIG_DIR" && realpath "$SOURCE_VALUE")
  else
    # Fallback to inference
    ASSETS_SOURCE="$INFERRED_ASSETS_PATH/$CONFIG_RELATIVE"
  fi

  # Process symlinks
  for ASSET in $(yq '.assets.symlink[]' "$CONFIG_FILE"); do
    SOURCE="$ASSETS_SOURCE/$ASSET"
    TARGET="$CONFIG_DIR/$ASSET"
    rm -rf "$TARGET"
    ln -sf "$SOURCE" "$TARGET"
  done

  # Process copies
  for ASSET in $(yq '.assets.copy[]' "$CONFIG_FILE"); do
    SOURCE="$ASSETS_SOURCE/$ASSET"
    TARGET="$CONFIG_DIR/$ASSET"
    [[ -f "$SOURCE" ]] && cp "$SOURCE" "$TARGET"
  done

  # Process root_symlinks (gitignored dirs symlinked from repo root)
  if ! REPO_ROOT=$(git -C "$WORKTREE_PATH" rev-parse --show-toplevel); then
    REPO_ROOT="$WORKTREE_PATH"
  fi
  # For worktrees, resolve to the main repo root
  MAIN_WORKTREE=$(git -C "$WORKTREE_PATH" worktree list --porcelain | head -1 | sed 's/^worktree //')
  [[ -n "$MAIN_WORKTREE" ]] && REPO_ROOT="$MAIN_WORKTREE"

  ROOT_SYMLINKS=$(yq '.root_symlinks[]' "$CONFIG_FILE" || true)
  for ASSET in $ROOT_SYMLINKS; do
    [[ -z "$ASSET" || "$ASSET" == "null" ]] && continue
    SOURCE="$REPO_ROOT/$ASSET"
    TARGET="$WORKTREE_PATH/$ASSET"
    if [[ -e "$SOURCE" ]]; then
      rm -rf "$TARGET"
      ln -sf "$SOURCE" "$TARGET"
    else
      echo "WARN: root_symlink source not found: $SOURCE"
    fi
  done
done

If action = COPY:

cp -r "$SOURCE_PATH" "$WORKTREE_PATH/$RELATIVE_PATH"

If action = SYMLINK:

# Remove placeholder if exists (may show as deleted in git status - expected)
rm -rf "$WORKTREE_PATH/$RELATIVE_PATH"

# Create symlink with absolute path to source
ln -sf "$ABSOLUTE_SOURCE_PATH" "$WORKTREE_PATH/$RELATIVE_PATH"

Important: Symlinked paths that replace tracked placeholder files will show as deleted in git status. This is expected and should NOT be committed.

COMMON BUG: Do NOT resolve assets.source from repo root or CWD. Always cd to the config file's directory first.

Step 5: Detect and setup environment

PARALLELIZE: When multiple environments are configured, spawn separate haiku agents for each.

Detect project type by presence of:

File	Project Type
pyproject.toml, requirements.txt	Python
package.json	Node.js
Cargo.toml	Rust
go.mod	Go
Gemfile	Ruby

For each project root (may be multiple in monorepo) - RUN IN PARALLEL:

# Send ALL environment setup tasks in a SINGLE message:
Task(model: haiku, prompt: "Setup Python venv at <path1>: create .venv, install deps")
Task(model: haiku, prompt: "Setup Node at <path2>: npm install")
Task(model: haiku, prompt: "Setup Python venv at <path3>: create .venv, install deps")

Python projects

1. Create .envrc:

   dotenv_if_exists .env
   source .venv/bin/activate
   

2. Symlink .env to worktree root:

   ln -sf <relative_path_to_root>/.env .env
   

3. Create venv and install:

   python3 -m venv .venv
   source .venv/bin/activate
   pip install -r requirements.txt
   [ -f requirements.dev.txt ] && pip install -r requirements.dev.txt
   [ -f pyproject.toml ] && pip install -e .
   

Node.js projects

1. Create .envrc:

   dotenv_if_exists .env
   PATH_add node_modules/.bin
   

2. Install dependencies:

   npm install  # or yarn/pnpm based on lockfile
   

Other project types

Detect and configure accordingly. Prioritize:

• Linking environment files
• Installing dependencies
• Setting up direnv

Step 6: Enable direnv

For each configured directory:

direnv allow

If direnv not installed, warn but continue.

Step 7: Commit setup changes

CRITICAL: Commit all worktree setup changes to leave a clean state.

cd "$WORKTREE_PATH"
git add -A
git status --short

# Only commit if there are changes
if ! git diff --cached --quiet; then
  git commit -m "chore(worktree): setup $WORKTREE_NAME

- Configure asset symlinks
- Setup development environment
- Create .envrc for direnv"
fi

What gets committed:

• New files: .envrc, copied assets
• Deleted placeholders: files replaced by symlinks show as deleted (expected)

What stays untracked (gitignored):

• .venv/, node_modules/, .env (secrets)

Step 8: Summary

Display:

Worktree created:
  Path: trees/<UUID>-<worktree_name>
  Branch: <worktree_name>
  Spec: specs/<YYYY>/<MM>/<worktree_name>/

Assets configured:
  [COPY] .env
  [SYMLINK] data/inputs -> /abs/path/to/assets/data/inputs
  [SYMLINK] models/ -> /abs/path/to/assets/models/

Environments setup:
  - ./app (Python, venv created)
  - ./frontend (Node.js, npm installed)

Error Handling

Condition	Action
Worktree exists	STOP, report path
Branch exists	Ask to reuse or abort
Assets path not found	STOP if explicit, warn if inferred
venv creation fails	Warn, continue with other dirs
Dependency install fails	Warn, continue
direnv not installed	Warn, continue
Symlink target missing	Warn, skip that asset

Project Configuration (Optional)

Projects can define .worktree.yml at repo root or in subdirectories:

# .worktree.yml
assets:
  source: ../my-project-assets  # Override default discovery

  symlink:
    - data/inputs
    - models/

  copy:
    - .env
    - config.local.yml

environments:
  - path: backend
    type: python

  - path: frontend
    type: node

skip_branch_command: false  # Set true to skip /branch integration

# Symlink gitignored directories from repo root into worktrees
# NOT resolved from assets.source — uses main worktree root as base
root_symlinks:
  - .specs               # External specs git repo (shared across worktrees)

When .worktree.yml exists, use its configuration instead of inference.

Path Resolution Rules (CRITICAL)

All paths in .worktree.yml are resolved relative to the config file's directory, NOT the current working directory or repo root.

When processing .worktree.yml:

1. Determine config directory:

   CONFIG_DIR=$(dirname "$CONFIG_FILE")
   

2. Resolve assets.source:

   # If source is relative path
   ASSETS_SOURCE=$(cd "$CONFIG_DIR" && realpath "$SOURCE_VALUE")
   

3. Resolve symlink/copy paths:

   • Source: $ASSETS_SOURCE/<path>
   • Target: $WORKTREE_PATH/$CONFIG_RELATIVE_PATH/<path>

Example - Monorepo with subproject config

repo/
|-- .worktree.yml              # Root config (if any)
`-- services/
    `-- api/
        `-- .worktree.yml      # Subproject config

If services/api/.worktree.yml has:

assets:
  source: ../../../repo-assets/services/api
  copy:
    - .env

Resolution:

CONFIG_DIR="services/api"
# source resolved from CONFIG_DIR:
ASSETS_SOURCE=$(cd "services/api" && realpath "../../../repo-assets/services/api")
# -> /abs/path/repo-assets/services/api

# .env source: $ASSETS_SOURCE/.env
# .env target: $WORKTREE_PATH/services/api/.env

Common Bug: Using CWD instead of CONFIG_DIR

WRONG:

# Resolves source relative to repo root - INCORRECT
ASSETS_SOURCE=$(realpath "$SOURCE_VALUE")

CORRECT:

# Resolves source relative to where .worktree.yml is located
ASSETS_SOURCE=$(cd "$CONFIG_DIR" && realpath "$SOURCE_VALUE")