Implementation (300 Series)

The 300 series is where design artifacts become running code. Two skills cover different implementation scenarios. If the immediate problem is a failing automated test and the correct fix path is still unclear, use 402-test-correction from the 400 series before choosing whether to edit tests or source.

The two paths

Skill	When to use it
301-spec-implementation	The main implementation workflow — for substantial changes driven by a spec
302-test-implementation	The test-only path — for adding or repairing automated tests for behavior that already exists

301 is the primary implementation skill

Most feature work goes through 301. Use 302 only when production behavior is already in place and the goal is purely to improve test coverage — not to add missing behavior.

What 301 does internally

301 is not just a longer coding prompt. It is a phased, orchestrated workflow:

1. Synthesizes missing 201, 202, and 203 artifacts in memory if they do not exist
2. Runs 204-feature-validation before any code is written
3. Writes failing tests first
4. Implements the minimum production code to pass those tests
5. Runs a test-cleanup pass
6. Runs a production-cleanup pass
7. Validates via test, lint, and build passes

The internal cleanup phases mean 401-cleanup is not always necessary afterward — though a separate explicit cleanup pass remains useful on complex changes.

Skills in this series

• 301 Spec Implementation — the main implementation workflow
• 302 Test Implementation — the test-only path