Parallel Task Processor with Async Subagents

Prerequisites

Required:

• Claude Code v2.0.60+ (for async subagent support)
• Git repository with remote configured
• GitHub CLI (gh) installed and authenticated: gh auth login
• GitHub repository (PR automation features require GitHub)

Optional:

• CI/CD configured for automated checks
• Sufficient API quota for parallel subagents

Non-GitHub Hosting: If using GitLab, Bitbucket, or other platforms, the PR automation features won't work. You can still use parallel task processing, but create PRs manually.

Overview

Leverages Claude Code's async subagents (v2.0.60+) to process multiple tasks in parallel, dramatically reducing implementation time.

Key Features

• Parallel Execution: Spawn multiple subagents to work on independent tasks simultaneously
• Background Mode: Subagents run in background, don't block orchestrator
• Auto-Notification: Subagents notify orchestrator when complete
• PR Automation: Automated gap analysis and PR comments after each phase

Parallelization Strategy

Level 1: Phase-Level Parallelization

Launch multiple phases in parallel when no dependencies exist. Use Claude Code's Task tool with multiple parallel calls:

// Batch 1: Independent phases (run in parallel)
// Send a single message with multiple Task tool calls:

Task(subagent_type: "tdd-developer", description: "Phase 1: Comparison", prompt: "...")
Task(subagent_type: "tdd-developer", description: "Phase 5: Performance", prompt: "...")
Task(subagent_type: "tdd-developer", description: "Phase 8: Notifications", prompt: "...")

// Wait for all to complete, then launch dependent phases

Level 2: Sub-Task Parallelization

Within a single phase, parallelize independent sub-tasks:

// Phase 1 split into 3 parallel streams (single message, multiple Task calls):

Task(subagent_type: "tdd-developer", description: "Discovery + Normalization", prompt: "Tasks 1.1, 1.2...")
Task(subagent_type: "tdd-developer", description: "Ranking + Reasoning", prompt: "Tasks 1.3, 1.4...")
Task(subagent_type: "tdd-developer", description: "Types + Tests", prompt: "Tasks 1.5, 1.6...")

// When all complete → Final task
Task(subagent_type: "tdd-developer", description: "Create PR", prompt: "Task 1.7...")

Execution Protocol

1. Analyze Dependencies

Phase Dependencies:
- Phase 1: None → Start immediately
- Phase 2: Depends on Phase 1
- Phase 3: Depends on Phase 2
- Phase 4: Depends on Phase 3
- Phase 5: None → Start immediately (parallel to 1-3)
- Phase 6: Depends on Phase 5
- Phase 7: Depends on Phase 3 + Phase 5
- Phase 8: None → Start immediately (parallel to all)
- Phase 9: Depends on all phases

2. Create Execution Batches

Batch 1 (Parallel):
- Phase 1 (large effort)
- Phase 5 (medium effort)
- Phase 8 (small effort)
→ Total: Large effort (instead of 3x sequential!)

Batch 2 (Parallel - after Phase 1):
- Phase 2 (large effort)
- Phase 6 (small effort, after Phase 5)
→ Total: Large effort

Batch 3 (Parallel - after Phase 2):
- Phase 3 (large effort)
→ Total: Large effort

Batch 4 (Parallel - after Phase 3):
- Phase 4 (medium effort)
- Phase 7 (large effort, also needs Phase 5)
→ Total: Large effort

Batch 5 (Sequential - after all):
- Phase 9 (medium effort)
→ Total: Medium effort

**Parallel execution reduces total effort by ~25% compared to sequential**

3. Spawn Async Subagents

Using Task Tool (parallel calls in single message):

To launch multiple phases in parallel, send a single message with multiple Task tool calls:

Task tool call 1:
  subagent_type: "tdd-developer"
  description: "Implement Phase 1: Comparison"
  prompt: "Work through tasks 1.1 through 1.7 from tasks/[task-file].md

    Tasks:
    - 1.1: Extend discovery engine
    - 1.2: Create score normalization
    - 1.3: Build ranking algorithm
    - 1.4: Add comparison reasoning
    - 1.5: Create TypeScript types
    - 1.6: Integration tests
    - 1.7: Create PR

    Follow test-driven development.
    Commit after each task.
    When complete, create PR and run gap analysis."

Task tool call 2 (in same message for parallel execution):
  subagent_type: "tdd-developer"
  description: "Implement Phase 5: Performance"
  prompt: "Work through tasks 5.1 through 5.7..."

// Both subagents run in parallel
// Results returned when each completes

4. Monitor Progress

Check Subagent Status:

# List running background tasks
/tasks

# Background tasks complete and return results automatically
# Monitor the conversation for task completion notifications

5. Collect Results

When a subagent completes, it notifies the orchestrator:

// Subagent 1 completes Phase 1
Result: {
  phase: 1,
  pr_number: 16,
  files_changed: 6,
  tests_added: 50,
  gap_analysis: "docs/PR_16_GAP_ANALYSIS.md",
  status: "ready_for_review"
}

// Orchestrator receives notification
// Triggers next dependent phase (Phase 2)

6. Automated PR Workflow (Per Subagent)

Each subagent follows this protocol when its phase completes:

1. Run Tests: Full test suite for the phase
2. Create Branch: git checkout -b feat/phase-X-name
3. Push: git push -u origin feat/phase-X-name
4. Create PR: Using gh pr create
5. Wait for CI: 30-second delay
6. Check Status: gh pr view + gh pr checks
7. Generate Gap Analysis: Create docs/PR_X_GAP_ANALYSIS.md
8. Push Gap Analysis: Commit and push
9. Add PR Comment: Detailed changes summary
10. Notify Orchestrator: Return results

Example: Full Autonomous Run

# User starts the processor
skill: task-processor-parallel

# Orchestrator analyzes dependencies
→ Identifies 5 execution batches
→ Creates parallelization plan

# Batch 1: Launch 3 phases in parallel
→ Spawn Phase 1 subagent (tdd-developer)
→ Spawn Phase 5 subagent (tdd-developer)
→ Spawn Phase 8 subagent (tdd-developer)

# Orchestrator: "3 subagents launched, monitoring progress..."

# [After Phase 5 completes first - shortest effort]
# Phase 5 completes first (shortest)
→ Subagent 5 creates PR #20
→ Subagent 5 runs gap analysis
→ Subagent 5 notifies orchestrator: "Phase 5 done, PR #20 ready"

# Phase 1 completes
→ Subagent 1 creates PR #16
→ Subagent 1 runs gap analysis
→ Subagent 1 notifies orchestrator: "Phase 1 done, PR #16 ready"
→ Orchestrator triggers Phase 2 (depends on Phase 1)

# Phase 8 completes
→ Subagent 8 creates PR #23
→ Subagent 8 runs gap analysis
→ Subagent 8 notifies orchestrator: "Phase 8 done, PR #23 ready"

# Batch 2: Launch Phase 2 (depends on Phase 1 - just completed)
→ Spawn Phase 2 subagent (tdd-developer)

# ... Continue through all batches ...

# All phases complete
→ Orchestrator: "All 9 PRs created and reviewed!"
→ User reviews PRs and merges

Benefits

Time Savings

• Sequential: Sum of all phase efforts
• Parallel: Longest path through dependency graph
• Savings: ~25% reduction in total effort

Efficiency

• No idle time waiting for sequential tasks
• Better resource utilization
• Continuous progress across multiple fronts

Flexibility

• Can pause/resume individual subagents
• Can prioritize critical phases
• Can adjust parallelization on the fly

Limitations & Considerations

Max Concurrent Subagents

Recommended limits to avoid overwhelming resources:

Scenario	Max Parallel	Reason
Small tasks (< 30 min each)	4-5	Token budget, context quality
Medium tasks (1-2 hours)	2-3	Avoid merge conflicts
Large tasks (half day+)	1-2	Resource contention

Guidelines:

• Start conservative (2-3 parallel) and increase if stable
• Monitor token usage with /stats command
• If subagents produce poor results, reduce parallelism
• Complex codebases benefit from less parallelism

Context Cost

• Each subagent has its own context window
• More parallel agents = higher token usage
• Monitor costs with /stats

Merge Conflicts

• Parallel work may touch same files
• Mitigate: Design tasks to minimize overlap
• Use clear file ownership per phase

CI Load

• Multiple PRs may overload CI
• Mitigate: Stagger PR creation
• Use draft PRs to delay CI

Troubleshooting Parallel Subagents

Subagent Fails or Produces Poor Results

Symptoms:

• Subagent returns incomplete work
• Code doesn't compile or tests fail
• Subagent seems "lost" or unfocused

Diagnosis:

1. Check task complexity - may be too large for single subagent
2. Check task dependencies - may need output from another phase
3. Check context - subagent may lack necessary codebase knowledge

Solutions:

• Break task into smaller sub-tasks
• Run the phase sequentially instead of parallel
• Provide more context in the subagent prompt
• Reduce number of parallel subagents

Subagent Hangs or Times Out

Symptoms:

• /tasks shows subagent running for unusually long time
• No progress updates

Solutions:

1. Check /tasks for status
2. If stuck, cancel and retry with smaller scope
3. Consider running that phase sequentially

Merge Conflicts Between Parallel Phases

Symptoms:

• git push fails with conflict errors
• PRs can't be merged

Solutions:

1. Identify which files conflict
2. Determine which phase's changes are correct
3. Manually resolve conflicts
4. Re-run validation on merged code
5. Prevention: Assign clear file ownership per phase

Inconsistent State Across Phases

Symptoms:

• Phase A created interface X
• Phase B expected different interface
• Integration fails

Solutions:

1. Define interfaces/contracts BEFORE parallel execution
2. Create shared types/interfaces in a prerequisite phase
3. Re-run dependent phase after fixing interface

Debugging Checklist

When parallel execution fails:

• Check each subagent's output for errors
• Verify no file conflicts between phases
• Ensure dependencies were correctly identified
• Check if task was too complex for parallelization
• Review if phases had hidden dependencies
• Consider falling back to sequential execution

Production Completion Criteria

Each subagent must ensure its phase is production-ready before reporting complete:

1. All sub-tasks implemented: Code written and committed
2. All tests pass: Full test suite for the phase passes
3. End-to-end works: The phase's functionality works in the full flow
4. No blocking issues: Fix all issues discovered, don't defer them

Critical Rule for Subagents

When a subagent encounters an issue during validation:

• DO NOT report the phase as complete with caveats
• DO NOT say "phase done, but there's an unrelated issue"
• DO fix all blocking issues before reporting complete
• DO re-validate end-to-end after each fix
• DO only report complete when production-ready

Orchestrator Validation

After all phases complete, the orchestrator must:

1. Run full integration test suite across all phases
2. Validate the complete end-to-end user flow
3. Ensure all PRs are mergeable without conflicts
4. If ANY issue found, assign to appropriate subagent to fix
5. Only declare "all phases complete" when production-ready

AI Instructions

1. Analyze dependencies before spawning subagents
2. Create execution batches based on dependency graph
3. Spawn subagents with run_in_background: true
4. Monitor progress via /tasks command
5. Collect results as subagents complete
6. Trigger dependent phases when prerequisites met
7. Track PR status for all parallel phases
8. Update task list with real-time progress
9. Validate end-to-end before declaring any phase complete
10. Fix all blocking issues in-place, never defer them

References

• See reference.md
• Claude Code documentation on Task tool and subagents
• See .claude/skills/task-processor-auto/SKILL.md for PR automation details

---

Skill created for autonomous agent implementation with async subagents