---
id: 03-claude-hooks
epic: library-evaluation-policy
title: Claude PreToolUse / PostToolUse hooks for library-policy nudge
type: technical-story
status: done
feature: tooling
depends-on: []
blocks: []
created: 2026-05-14T06:52:02+02:00
updated: 2026-05-14T19:21:52.308Z
---

## Goal

Write `.claude/hooks/library-policy-nudge.sh` — a single hook script that dispatches on `tool_use_type` to handle both `PreToolUse` (Bash invocations matching `pnpm add` / `pnpm i <pkg>`) and `PostToolUse` (Edit/Write on any `**/package.json`). On match, emit a non-blocking system-reminder pointing the agent at the `evaluate-library` skill with the exact invocation pattern. Register the hook in `.claude/settings.json` following the same pattern as `generator-first-nudge.sh`.

## Why

Agents (and developers) running `pnpm add` by reflex bypass the policy before the pre-commit gate fires. The PreToolUse hook injects the skill reminder _before_ the install runs — the cheapest possible intervention point. The PostToolUse hook catches the rarer case where an agent edits `package.json` directly without running the install command.

## Done when

- `.claude/hooks/library-policy-nudge.sh` exists, is executable, dispatches on `CLAUDE_TOOL_USE_TYPE` (or equivalent hook env var), and emits the reminder to stdout when a `pnpm add`/`pnpm i <pkg>` bash command is detected or when an Edit/Write tool targets a path matching `**/package.json`.
- The hook is registered in `.claude/settings.json` (or `.claude/settings.local.json` if per-repo convention) under both `PreToolUse` and `PostToolUse` event types, matching the registration pattern of `generator-first-nudge.sh`.
- The reminder text includes the literal string `/evaluate-library` and the argument template `<name> --tier <feature|core|app> --target <package-path>` so the agent sees the exact invocation.
- Bash smoke tests (same style as any existing hook tests): pipe a mocked Claude hook payload `{ "tool_input": { "command": "pnpm add foo" } }` into the script and assert stdout contains the skill-reminder marker; pipe a payload for `pnpm add -D foo` (devdep) and assert no reminder emitted; pipe an Edit payload on `src/feature.manifest.ts` and assert no reminder emitted.
- `pnpm lint && pnpm fallow:audit` pass.

## In scope

- `.claude/hooks/library-policy-nudge.sh` — the hook script.
- `.claude/settings.json` (or equivalent) — hook registration lines.
- Bash smoke tests for the hook script.

## Out of scope

- Hook auto-deny or blocking behavior — the hook is advisory only (non-blocking system-reminder).
- Hooks for `npm install` / `yarn add` — the repo is pnpm-only.
- Integration with the skill implementation (Story 04) — the hook emits a text reminder; the skill is a separate file.

## Tasks

- [x] Investigate how `generator-first-nudge.sh` is registered (read `.claude/settings.json` and the existing hook script) to confirm the env-var names, payload shape, and registration keys; then write `.claude/hooks/library-policy-nudge.sh` + register it in the settings file + write bash smoke tests covering `pnpm add <pkg>` (reminder), `pnpm add -D <pkg>` (no reminder), Edit on non-package.json (no reminder), Edit on `package.json` (reminder); all gates pass on this single commit.