xqt2023-ux/Subagent-Driven Development

Subagent-Driven Development

Execute plan by dispatching fresh subagent per task, with code review after each.

Core principle: Fresh subagent per task + review between tasks = high quality, fast iteration

Overview

vs. Executing Plans (parallel session):

• Same session (no context switch)
• Fresh subagent per task (no context pollution)
• Code review after each task (catch issues early)
• Faster iteration (no human-in-loop between tasks)

When to use:

• Staying in this session
• Tasks are mostly independent
• Want continuous progress with quality gates

When NOT to use:

• Need to review plan first (use executing-plans)
• Tasks are tightly coupled (manual execution better)
• Plan needs revision (brainstorm first)

The Process

1. Load Plan

Read plan file, create TodoWrite with all tasks.

2. Execute Task with Subagent

For each task:

Dispatch fresh subagent:

Task tool (general-purpose):
  description: "Implement Task N: [task name]"
  prompt: |
    You are implementing Task N from [plan-file].

    Read that task carefully. Your job is to:
    1. Implement exactly what the task specifies
    2. Write tests (following TDD if task says to)
    3. Verify implementation works
    4. Commit your work
    5. Report back

    Work from: [directory]

    Report: What you implemented, what you tested, test results, files changed, any issues

Subagent reports back with summary of work.

3. Review Subagent's Work

Dispatch code-reviewer subagent:

Task tool (code-reviewer):
  Use template at skills/collaboration/requesting-code-review/code-reviewer.md

  WHAT_WAS_IMPLEMENTED: [from subagent's report]
  PLAN_OR_REQUIREMENTS: Task N from [plan-file]
  BASE_SHA: [commit before task]
  HEAD_SHA: [current commit]
  DESCRIPTION: [task summary]

Code reviewer returns: Strengths, Issues (Critical/Important/Minor), Assessment

4. Apply Review Feedback

If issues found:

• Fix Critical issues immediately
• Fix Important issues before next task
• Note Minor issues

Dispatch follow-up subagent if needed:

"Fix issues from code review: [list issues]"

5. Mark Complete, Next Task

• Mark task as completed in TodoWrite
• Move to next task
• Repeat steps 2-5

6. Final Review

After all tasks complete, dispatch final code-reviewer:

• Reviews entire implementation
• Checks all plan requirements met
• Validates overall architecture

7. Complete Development

After final review passes:

• Announce: "I'm using the Finishing a Development Branch skill to complete this work."
• Switch to skills/collaboration/finishing-a-development-branch
• Follow that skill to verify tests, present options, execute choice

Example Workflow

You: I'm using Subagent-Driven Development to execute this plan.

[Load plan, create TodoWrite]

Task 1: Hook installation script

[Dispatch implementation subagent]
Subagent: Implemented install-hook with tests, 5/5 passing

[Get git SHAs, dispatch code-reviewer]
Reviewer: Strengths: Good test coverage. Issues: None. Ready.

[Mark Task 1 complete]

Task 2: Recovery modes

[Dispatch implementation subagent]
Subagent: Added verify/repair, 8/8 tests passing

[Dispatch code-reviewer]
Reviewer: Strengths: Solid. Issues (Important): Missing progress reporting

[Dispatch fix subagent]
Fix subagent: Added progress every 100 conversations

[Verify fix, mark Task 2 complete]

...

[After all tasks]
[Dispatch final code-reviewer]
Final reviewer: All requirements met, ready to merge

Done!

Advantages

vs. Manual execution:

• Subagents follow TDD naturally
• Fresh context per task (no confusion)
• Parallel-safe (subagents don't interfere)

vs. Executing Plans:

• Same session (no handoff)
• Continuous progress (no waiting)
• Review checkpoints automatic

Cost:

• More subagent invocations
• But catches issues early (cheaper than debugging later)

Red Flags

Never:

• Skip code review between tasks
• Proceed with unfixed Critical issues
• Dispatch multiple implementation subagents in parallel (conflicts)
• Implement without reading plan task

If subagent fails task:

• Dispatch fix subagent with specific instructions
• Don't try to fix manually (context pollution)

Integration

Pairs with:

• skills/collaboration/writing-plans (creates the plan)
• skills/collaboration/requesting-code-review (review template)
• skills/testing/test-driven-development (subagents follow this)

Alternative to:

• skills/collaboration/executing-plans (parallel session)

See code-reviewer template: skills/collaboration/requesting-code-review/code-reviewer.md