# Plan: Document Favorites Feature Session

## Context
This session added the Favorites data-access and service layer to the Spring Boot app.
The goal is to capture everything done — files created, design decisions, and API surface —
in a new `docs/favorites-feature.md`, consistent with the style of existing docs files
(`docs/setup-summary.md`, `docs/integration-testing.md`).

---

## File to Create

### `docs/favorites-feature.md`

Content to include:

1. **What was built** — one-sentence summary
2. **Files created** — table of the two new files with their package paths
3. **FavoriteRepository** — method table (name, return type, reason)
   - Note on `@Transactional` on `deleteByUserIdAndItemId`
4. **FavoriteService** — method table (name, behaviour / error thrown)
   - Note on class-level `@Transactional` + `readOnly = true` overrides on reads
5. **Design decisions** — duplicate guard in `addFavorite`, existence check in `removeFavorite`
6. **Verification** — `mvn clean compile`

---

## Critical files (read-only reference)

| File | Role |
|---|---|
| `src/main/java/com/example/app/repository/FavoriteRepository.java` | Created this session |
| `src/main/java/com/example/app/service/FavoriteService.java` | Created this session |
| `docs/setup-summary.md` | Style reference |

---

## Verification

After creation:
```bash
# No compilation impact, but confirm the project still compiles clean
mvn clean compile
```