l-thread

Long-Duration Thread: Autonomous Execution with Checkpoints

Before starting work, create a marker: mkdir -p ~/.claude/tmp && echo "l-thread" > ~/.claude/tmp/heavy-skill-active && date -u +"%Y-%m-%dT%H:%M:%SZ" >> ~/.claude/tmp/heavy-skill-active

For tasks too large for a single context window. Implements checkpoint/restore, automatic verification, and graceful recovery.

When to Use

• Large refactors spanning 10+ files
• Full feature implementation with tests
• Migration tasks (dependency upgrades, API changes)
• Any task estimated at >50% context window

Checkpoint Strategy

Automatic Checkpoints

Checkpoints are saved automatically at context usage thresholds. See hooks/checkpoint.md for actions at 70% / 80% / 90%.

Manual Checkpoints

Save checkpoints at these milestones:

• After completing a logical phase
• Before risky operations (schema changes, large refactors)
• After passing verification

Checkpoint Contents

See hooks/checkpoint.md for the full checkpoint JSON schema, storage location, and auto-checkpoint threshold actions.

Save/Restore Commands

# Save checkpoint
/checkpoint save "Completed phase 3"

# List checkpoints
/checkpoint list

# Restore from latest
/checkpoint restore

Verification Stack

Every checkpoint must pass Levels 1-3 before saving. Full verification (Levels 1-5) at task completion. See hooks/verification-check.md for the complete 5-level stack, per-agent requirements, and failure handling.

Workflow

Phase 1: Planning

Agent(planner, "Break down [task] into phases with dependencies and estimates")

Produce a phased plan with:

• Ordered phases with dependencies
• Token estimates per phase
• Checkpoint points identified
• Verification criteria per phase

Phase 2: Execution Loop

For each phase:

1. Start: Log phase start
2. Implement: Execute the phase work
3. Verify: Run verification stack
4. Checkpoint: Save state if milestone reached
5. Monitor: Check context usage, checkpoint if threshold hit

Phase 3: Completion

## Verification Summary
- [x] TypeScript compiles
- [x] Biome lint passes
- [x] Tests pass (N/N)
- [x] All phases completed

<promise>COMPLETE</promise>

Recovery from Interruption

When resuming after interruption:

1. Run checkpoint.ts restore to load latest state
2. Check git status for uncommitted work
3. Review remaining todos
4. Run verification to confirm baseline
5. Continue from next incomplete phase

Completion Promise

The task is NOT complete until:

1. All phases done
2. Verification passes (compile + lint + test)
3. Git is clean (all changes committed)
4. Summary provided with what was done

Only then output:

<promise>COMPLETE</promise>

Never claim completion with failing verification.

Example

User: "Migrate all class components to hooks across the app"

→ Agent(planner, "Break migration into phases by module")
Plan: 6 phases, ~4 context windows estimated

Phase 1: Core hooks (auth, routing)
  → Implement → Verify → Checkpoint at 30%
Phase 2: Feature hooks (dashboard, settings)
  → Implement → Verify → Checkpoint at 55%
  → Context at 70% → auto-checkpoint, continue
Phase 3: Shared components
  → Context at 90% → auto-checkpoint, hand off
  [New session resumes from checkpoint]
Phase 4-6: Continue...
  → Final verification → <promise>COMPLETE</promise>