feat(ADM-018): completed feature

work/artifacts/F-007/implementer.md

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+# Implementer — F-007 Categories module
+
+done -> work/artifacts/F-007/implementer.md
+
+## Summary
+Implemented the categories module as a hexagonal backend slice with PostgreSQL persistence, Fastify routes, validation, tree handling, slug public URLs, and tests.
+
+## Changed files
+- `project/src/modules/categories/domain/category.ts`
+- `project/src/modules/categories/domain/errors.ts`
+- `project/src/modules/categories/domain/ports.ts`
+- `project/src/modules/categories/application/category-use-cases.ts`
+- `project/src/modules/categories/infrastructure/pg-category-repository.ts`
+- `project/src/modules/categories/api/categories.routes.ts`
+- `project/src/modules/categories/index.ts`
+- `project/migrations/005_categories.js`
+- `project/src/app/build-app.ts`
+- `project/src/modules/categories/tests/category-use-cases.test.ts`
+- `project/src/app/tests/categories.itest.ts`
+- `backlog/features.json`
+- `work/current.md`
+- `work/artifacts/F-007/architect.md`
+
+## Acceptance traceability
+1. Duplicate slug returns HTTP 409
+   - Implemented through `categories_categories.slug UNIQUE` and `CATEGORY_SLUG_EXISTS` mapping.
+   - Covered by `project/src/app/tests/categories.itest.ts` (`returns HTTP 409 for duplicate slug`).
+2. Category tree supports parent/child and blocks cycles
+   - Implemented with adjacency list `parent_id`, tree builder, self-parent guard, recursive descendant check.
+   - Covered by unit and integration tests.
+3. Public URL is `/categoria/<slug>`, never internal id
+   - Implemented `GET /categoria/:slug` and serialized `url: /categoria/<slug>`.
+   - Covered by integration test.
+4. `verify.sh` green
+   - Verified after implementation.
+
+## Commands run
+- `cd project && npm run typecheck` — PASS
+- `cd project && npm test` — PASS: 55 passed, 25 skipped (DB integration skipped without `TEST_DATABASE_URL`)
+- `cd project && npm run lint` — PASS after Prettier normalization
+- `cd project && npm run build` — PASS
+- `cd project && npm run lint:boundaries` — PASS: 61 files checked
+- `./scripts/verify.sh` — PASS
+
+## Notes
+- No new npm dependencies.
+- Category mutation routes are admin-only using the existing shared auth contract injected from the composition root.
+- Public reads (`GET /categories/tree`, `GET /categoria/:slug`) are unauthenticated.
+- Corrected delete behavior during review preparation: missing category now maps to `404 NOT_FOUND`; category with children maps to `409 CATEGORY_HAS_CHILDREN`.
+- Documentation stage should update README/API notes because new user-facing endpoints were added.