Implement Plan

• Max 4 concurrent subagents (tool limitation)
• Tasks touching the same file(s) go in the same subagent or sequential batches — never parallel
• Small related tasks can be grouped into one subagent to reduce overhead
• Large independent tasks get their own subagent

3. Execute Batches

For each batch, spawn plan-implementer subagents using the Task tool with subagent_type: "plan-implementer".

Each subagent prompt must include:

• Exact tasks to implement (copy from the plan, don't paraphrase loosely)
• File paths and context needed to work independently
• Constraints or edge cases from the plan

Use model: "fast" for straightforward tasks. Omit model for complex ones.

Wait for all subagents in a batch to complete before starting the next batch.

4. Handle Failures

When a subagent reports PARTIAL or FAILED:

• Read its report to understand what failed and why
• Decide: retry with more context, reassign to a different batch, or implement the fix yourself if trivial
• Don't retry blindly — adjust the prompt or approach

5. Verify

After all batches complete:

1. Run yarn build to confirm everything compiles
2. Run yarn lint and yarn type-check
3. If the plan touched React components/hooks, run the repo-standard verification commands and add yarn test when runtime behavior or tests changed
4. For UI changes, verify in the browser with playwright-cli across chrome, firefox, and webkit, plus a mobile viewport flow in each engine when relevant

6. Report

Summarize to the user:

## Plan Execution Summary

### Completed
- Task 1 — files modified
- Task 2 — files modified

### Failed (if any)
- Task N — reason, what was tried

### Verification
- Build: PASS/FAIL
- Lint: PASS/FAIL
- Type-check: PASS/FAIL

Key Principles

• You orchestrate, subagents implement. Don't code changes yourself unless it's a trivial one-liner fix for a subagent failure.
• Context is precious. Every build log and file read you do in the main thread is context you can't get back. Delegate liberally.
• Parallelize aggressively. The faster batches finish, the faster the plan is done. Only serialize when dependencies demand it.
• Verify at the end, not in between. Subagents run their own build checks. You do a final holistic verification.