Create Development Worktree

Create an isolated git worktree for feature work, ensuring workspace isolation and clean baseline.

The Process

Step 1: Ensure .worktrees/ is Gitignored

CRITICAL: Verify worktree directory is gitignored to prevent accidental commits.

Run:

if ! git check-ignore -q .worktrees 2>/dev/null; then
  echo "Adding .worktrees/ to .gitignore"
  echo ".worktrees/" >> .gitignore
  git add .gitignore
  git commit -m "chore: add .worktrees/ to gitignore

Co-Authored-By: Claude <noreply@anthropic.com>"
fi

Description: dev-worktree: check if .worktrees is gitignored and add if missing

Step 2: Determine Branch Name

Extract from .claude/PLAN.md first line or infer from feature name:

Run:

# Extract from PLAN.md if exists
feature_name=$(grep -m1 '^# ' .claude/PLAN.md 2>/dev/null | sed 's/^# //' | tr '[:upper:] ' '[:lower:]-' | sed 's/[^a-z0-9-]//g')

# Or ask user if needed

Description: dev-worktree: extract or prompt for feature name

Branch name format: feature/${feature_name}

Step 3: Create Worktree

Run:

# Create worktree with new branch
git worktree add .worktrees/${feature_name} -b feature/${feature_name}

# Change to worktree directory
cd .worktrees/${feature_name}

Description: dev-worktree: create isolated git worktree with feature branch

Step 4: Run Project Setup

Auto-detect and run setup based on project files:

Run:

# Node.js
if [ -f package.json ]; then
  npm install
fi

# Python
if [ -f requirements.txt ]; then
  pip install -r requirements.txt
fi
if [ -f pyproject.toml ]; then
  poetry install || pip install -e .
fi
if [ -f pixi.toml ]; then
  pixi install
fi

# Rust
if [ -f Cargo.toml ]; then
  cargo build
fi

# Go
if [ -f go.mod ]; then
  go mod download
fi

Description: dev-worktree: auto-detect project type and install dependencies

Step 5: Verify Clean Baseline (MANDATORY)

A worktree without a verified baseline is a trap. You will not know if failures are yours or pre-existing.

Run:

# Examples - auto-detect test command
if [ -f package.json ] && grep -q '"test"' package.json; then
  npm test
elif [ -f Cargo.toml ]; then
  cargo test
elif [ -f pytest.ini ] || [ -f pyproject.toml ]; then
  pytest
elif [ -f go.mod ]; then
  go test ./...
fi

Description: dev-worktree: auto-detect and run project test suite

If tests fail: Report failures and note that baseline has issues. Do NOT proceed silently. If tests pass: Report clean baseline.

Rationalization Prevention (Baseline Verification)

Thought	Reality
"Tests will pass, they passed on main"	Worktree setup can break things. Verify.
"Baseline check takes too long"	Debugging pre-existing failures takes longer. Run now.
"I'll notice if something is broken later"	You won't know if the failure is yours or inherited. Run now.
"Dependencies installed fine, should be good"	Install success != test success. Run tests.
"Main branch is green, worktree will be too"	Worktree has different env, paths, symlinks. Verify independently.

Drive-Aligned Framing

Claiming clean baseline without running tests is NOT HELPFUL — every failure becomes ambiguous and you can't tell if bugs are yours or inherited. Your assumption is not verification.

Why Skipping Hurts the Thing You Care About Most

Your Drive	Why You Skip	What Actually Happens	The Drive You Failed
Helpfulness	"Skip baseline to start faster"	Broken baseline infects all work, every failure is ambiguous	Anti-helpful
Competence	"I know the codebase well enough"	Your mental model is stale. The worktree reveals conflicts you didn't anticipate.	Incompetent
Efficiency	"Skip worktree setup to save time"	Merge conflicts later cost 10x the setup time	Anti-efficient

Step 6: Report Ready

Report completion status:

✓ Worktree created: .worktrees/${feature_name}
✓ Branch: feature/${feature_name}
✓ Dependencies installed
✓ Tests passing (or note if failed)

Ready for implementation.

Safety Checks

Execute before creating worktree:

• Verify .worktrees/ is gitignored
• Add to .gitignore if missing
• Commit gitignore change

Execute after creating worktree:

• Run project setup (npm install, etc.)
• Verify clean baseline with tests
• Report status

Red Flags

Critical - Never deviate from these rules:

• Do not create worktree without verifying gitignore
• Do not skip project setup commands
• Do not proceed without reporting test status

Critical - Always follow these rules:

• Verify .worktrees/ is ignored before creating
• Auto-detect project type and run appropriate setup
• Report test baseline status

Common Patterns

Node.js Project

# .worktrees/ gitignored → create worktree → npm install → npm test

Python Project

# .worktrees/ gitignored → create worktree → pixi install → pytest

Rust Project

# .worktrees/ gitignored → create worktree → cargo build → cargo test

Workflow Transition

After worktree creation, the workspace is ready. Proceed to dev-implement to start implementing tasks.

Current working directory: .worktrees/${feature_name}

All implementation work happens here, keeping main workspace clean.