Exercise 03: Implement Feature

Objective

Delegate to the worker subagent to implement the auth feature according to the plan from Exercise 02.

Delegation Required

This exercise must use the Task tool with the specified subagent_type. Do not write pipeline artifacts manually. The grader cross-references produced_by fields and verifies files exist on disk.

Required Reading

• Finding and Fixing Bugs | Cursor Learn -- Preview for the debug exercise; understanding bug discovery informs implementation quality
• Developing Features | Cursor Learn -- End-to-end feature implementation with agents
• Artifact Schemas -- worker-result.json schema

CursorClaude Code

The worker agent reads plan.json and produces code + worker-result.json via the Task tool.

The worker is a model prompt that reads the plan artifact and writes both code and the result artifact. The schema validation (schema.py) runs identically in either system.

Context

The plan exists at sandbox/.pipeline/ISSUE-42/plan.json. The worker reads it and implements accordingly.

Tasks

1. Delegate to jg-worker with this prompt:

   Read sandbox/.pipeline/ISSUE-42/plan.json. Implement the auth feature in sandbox/: - Create sandbox/src/auth/login.ts -- POST /auth/login endpoint using jsonwebtoken - Create sandbox/src/auth/middleware.ts -- JWT validation middleware - Create sandbox/src/auth/login.test.ts -- tests for valid login, invalid credentials - Create sandbox/src/auth/middleware.test.ts -- tests for valid token, expired token, missing token - Register the auth routes in sandbox/src/app.ts - Write sandbox/.pipeline/ISSUE-42/worker-result.json with status, files_changed, blockers, summary, and "produced_by": "jg-worker"

2. Run tests:

   cd sandbox && npm test
   

   All tests must pass.

3. Verify the worker-result artifact:

   python3 sandbox/.cursor/pipeline/schema.py --validate sandbox/.pipeline/ISSUE-42/worker-result.json
   

Validation

python3 docs/practitioner/tutorials/verify.py --exercise 03

Checks: worker-result.json exists, passes schema, npm test passes, auth source files exist.

Reflection

• Did the worker follow the plan exactly, or did it deviate?
• Are the tests comprehensive? Do they cover edge cases?
• What would happen if the worker couldn't complete a step?

Answer

A valid worker-result.json should include:

{
  "status": "completed",
  "files_changed": ["src/auth/login.ts", "src/auth/middleware.ts", "src/auth/login.test.ts", "src/auth/middleware.test.ts", "src/app.ts"],
  "blockers": [],
  "summary": "Implemented JWT auth login endpoint and middleware with full test coverage",
  "produced_by": "jg-worker"
}

The worker must read plan.json and implement all steps. files_changed should match or be a subset of affected_files from the plan. npm test should pass after implementation.