---
id: 05-human-guide
epic: 2026-05-14-library-evaluation-policy
title: Human reading-room guide — docs/guides/adding-a-library.md
type: technical-story
status: done
feature: docs
depends-on: [04-evaluate-library-skill]
blocks: [09-claude-md-update]
---

## Goal

Write `docs/guides/adding-a-library.md` — the human-readable guide explaining the library evaluation policy with worked examples (one approved, one rejected), the tier trigger, the four enforcement layers, and how to invoke the skill. The guide targets a maintainer reading the repo for the first time.

## Why

ADR-022 is the source of truth but is written for decision-record density, not onboarding. The guide translates the policy into a narrative that answers "why does this exist?" and "what do I actually do?" before a developer encounters the pre-commit gate for the first time. Worked examples anchor the abstract filter list to concrete outcomes.

## Done when

- `docs/guides/adding-a-library.md` exists with: (1) a "Why this exists" section explaining the uncodified-surface problem and the three signals from the PRD; (2) the tier trigger (feature/core packages require traces; app-tier does not; devdeps exempt); (3) the four enforcement layers (Claude hook → skill → pre-commit → sandcastle) in latency order; (4) step-by-step "how to add a library" walkthrough pointing at the `/evaluate-library` skill; (5) a worked approved example (brief — the full trace lives in `EXAMPLES/` from Story 04); (6) a worked rejected example (`trpc-to-openapi`, `named-consumer: fail`); (7) a link to ADR-022 and `docs/library-decisions/_template.md`.
- `pnpm lint && pnpm fallow:audit` pass.

## In scope

- `docs/guides/adding-a-library.md` — the guide document.

## Out of scope

- The skill itself (Story 04) — already landed.
- CLAUDE.md update (Story 09) — that bullet points here and to ADR-022 but lands separately.
- Changing any existing guide or ADR.

## Tasks

- [x] Write `docs/guides/adding-a-library.md` with all seven sections from Done when (why, tier trigger, four layers, how-to walkthrough, worked approved + rejected examples, cross-links); all gates pass on this single commit.
