TDD (Go) — Vertical-Slice Red/Green/Refactor

This skill exists to stop: accepted behavior from being implemented in broad horizontal batches, guessed contracts, or tests coupled to private implementation.

🤖 0. HOW TO USE

• Build (default): implement one accepted behavior at a time through vertical RED -> GREEN -> REFACTOR slices.
• Bug fix: start from one observable failing example after the desired behavior is accepted.
• Handoff: transfer unsettled decisions, broader architecture evidence, or remaining pure cleanup through the canonical routing artifact.

Output: green behavior tests through public interfaces plus a bounded implementation; never an imagined batch of cases written ahead of learning.

🧩 Companion Go pack: the backend-go-* skills referenced below (testing, testify, design-patterns, performance, observability…) are a separate pack, not bundled in this kit. Everything in this skill runs without them; where they are named, apply your project's own Go conventions instead.

This skill is the process layer on top of backend-go-testing. Use it whenever you build a new feature or fix a non-trivial bug in this repo.

• This skill answers: when do I write the test, and in what order?
• backend-go-testing answers: what does a good Go test look like? (table-driven, testify, goleak, build tags, etc.)