buildlisted
Install: claude install-skill kish21/product-playbook
# `/build` — Phase 2 · Development ⑤ · run as an **engineer**
> Part of **product-playbook**. Reads + updates the project spine (`PRODUCT.md`, or the project's existing docs — resolve per MECHANISMS.md §Spine resolution).
> Apply `PRINCIPLES.md` (bundled `PRINCIPLES.md`; see README for its path per install mode) — load-bearing: **per-feature contract (security in the DoD)**,
> **secure-by-construction**, **prompts→`prompts/` YAML**, **doc↔code reconciled**, **measure before
> fixing**, **no swallowed errors**, **reuse-before-write**, **trace callers (live-path)**,
> **generic-not-domain-specific**.
> War stories behind every rule live in the repo at `references/case-files-build.md` — open it there when a rule needs its evidence.
> **Companions — opened on demand, never up front:** `references/feature-archetypes.md` (the rules that apply only to gates · async jobs · latency fixes · trust boundaries) · `references/live-path-checks.md` (proving a change is really wired in).
## Contract
- **Purpose:** implement one feature to a verified, secure, documented definition-of-done.
- **Reads:** `PRODUCT.md#Scope`, `#Plan`, `#Contracts`, `#Structure` — **plus `DESIGN.md` + `#Design` for any feature with a user-facing screen** (UI products).
- **Writes:** a row in `PRODUCT.md#Build log` + `docs/features/<feature>.md`.
- **Gate type:** `derivation` — computable from the ticket + `#Contracts`. Batchable - a `derivation` run may chain with its neighbours and end in ONE review. (`docs/stat