worktree-execution

Worktree Execution Skill

Architecture

Two isolated worktrees enable parallel prompt execution.

Orchestrator
    │
    ├── Create Worktrees (in ${TMPDIR:-/tmp}/)
    │       ├── worktree-rashomon-original-{timestamp}
    │       └── worktree-rashomon-optimized-{timestamp}
    │
    ├── Parallel Execution (Task tool)
    │       ├── Execution 1 → worktree-rashomon-original
    │       └── Execution 2 → worktree-rashomon-optimized
    │
    ├── Collect Results (await both)
    │
    └── Cleanup Worktrees (always)

Worktree Management

Creation

Script: scripts/worktree-create.sh

# Default labels (original/optimized) for prompt eval
./scripts/worktree-create.sh [repo_root]

# Custom labels for skill eval
./scripts/worktree-create.sh [repo_root] baseline with-skill
./scripts/worktree-create.sh [repo_root] old-version new-version

# Pin every pair in an evaluation run to the same commit
./scripts/worktree-create.sh [repo_root] trial-a trial-b [base_sha]

Output (stdout):

/tmp/worktree-rashomon-{label_a}-20260114-123456
/tmp/worktree-rashomon-{label_b}-20260114-123456

Properties:

• Location: ${TMPDIR:-/tmp}/
• Naming: worktree-rashomon-{label}-{timestamp}
• Branch: Detached HEAD at the pinned base commit
• Base commit: Caller-supplied SHA, resolved once per evaluation
• Active marker: Git worktree lock containing run ID, owner PID, start time, and lease expiry
• Labels default to original / optimized if not specified

Cleanup

Script: scripts/worktree-cleanup.sh

# Remove all rashomon worktrees
./scripts/worktree-cleanup.sh [repo_root]

# Remove specific worktrees
./scripts/worktree-cleanup.sh [repo_root] path1 path2

# Remove registered orphaned worktrees, including expired Rashomon locks
./scripts/worktree-cleanup.sh --orphans [repo_root]

Cleanup Triggers:

• After successful report generation
• In finally block on any failure
• On timeout
• On startup (orphan detection)

Parallel Execution Principle

Key: To achieve true parallel execution, spawn both Task calls in a single message.

The calling command determines which agents to invoke and how to structure the Task calls. This skill provides only the worktree infrastructure.

Error Handling (Worktree Operations)

Scenario	Behavior
Creation fails	Report git error, suggest checking repository state
Cleanup fails	Log warning, attempt orphan cleanup on next run
Unlocked orphan	Remove registered Rashomon worktree after 1 hour
Crashed locked run	Remove after owner disappearance plus orphan age, or after lease expiry
Active long run	Set RASHOMON_LEASE_SECONDS before creation so the lease covers the run

Scripts Reference

worktree-create.sh

Exit Code	Meaning
0	Success
1	Not a git repository
2	Creation failed

worktree-cleanup.sh

Exit Code	Meaning
0	Success (or nothing to clean)
1	Not a git repository
2	Cleanup partially failed

Constraints

• No concurrent comparisons: One rashomon execution per repository
• Git required: A version supporting git worktree lock
• Disk space: Sufficient space for worktree copies