docs: add CONTRIBUTING.md with setup, architecture, PR guidelines

CONTRIBUTING.md

@@ -0,0 +1,84 @@
+# Contributing
+
+Thanks for your interest in Movies Diary! This is a personal project but contributions are welcome — bug fixes, new features, docs improvements, or picking up the deprecated TUI.
+
+## Getting started
+
+1. Fork and clone the repo
+2. Copy `.env.example` to `.env` and fill in at least `JWT_SECRET` and `OMDB_API_KEY`
+3. Install Rust (stable, 2024 edition) and Node.js (for the SPA)
+4. Run the backend and worker:
+
+```bash
+cargo run -p presentation   # HTTP server on :3000
+cargo run -p worker          # event worker (separate terminal)
+```
+
+5. Run the SPA dev server:
+
+```bash
+cd spa && npm install && npm run dev
+```
+
+## Before submitting a PR
+
+```bash
+make           # runs fmt-check + clippy + test
+```
+
+Or individually:
+
+```bash
+cargo fmt --check
+cargo clippy -- -D warnings
+cargo test
+cd spa && npx tsc --noEmit
+```
+
+All four must pass. PRs with clippy warnings or failing tests won't be merged.
+
+## Architecture
+
+The project follows hexagonal (ports & adapters) architecture. See `architecture.mmd` for the full diagram.
+
+**Key rule:** presentation handlers never touch repositories directly — all domain logic goes through use cases in the `application` crate.
+
+```
+domain         → pure types, traits (ports), zero deps
+application    → use cases, orchestration
+presentation   → Axum handlers, routes, OpenAPI
+worker         → event consumer, background jobs
+adapters/*     → implements domain ports (sqlite, postgres, AP, etc.)
+spa/           → React SPA (TanStack Router + shadcn/ui)
+```
+
+### Adding a new feature
+
+1. **Domain first** — models in `domain/src/models/`, ports in `ports.rs`, events in `events.rs`
+2. **Adapters** — implement ports in both `sqlite` and `postgres` adapters, add migration
+3. **Application** — use cases in `application/src/<domain>/`, wire into `context.rs`
+4. **API types** — DTOs in `api-types/src/`
+5. **Presentation** — handler file in `handlers/<domain>.rs`, routes in `routes.rs`
+6. **SPA** — API client in `spa/src/lib/api/`, hook in `spa/src/hooks/`, components
+7. **Classic HTML** — Askama template + CSS in `static/style.css`
+
+### Database adapters
+
+Both SQLite and PostgreSQL are supported. If you add a migration or repository, implement it for both. The postgres adapter uses `$1, $2` params and `TIMESTAMPTZ`; SQLite uses `?` and text datetimes.
+
+### Federation (ActivityPub)
+
+Federation is feature-gated (`#[cfg(feature = "federation")]`). If your feature should federate, add domain events, handle them in `activitypub/src/event_handler.rs`, and create an AP object + inbound handler.
+
+## Code style
+
+- No comments unless the *why* is non-obvious
+- Concise commit messages
+- One feature per PR — don't bundle unrelated changes
+- Follow existing patterns (check a similar feature for reference)
+
+## Areas seeking help
+
+- **TUI** (`crates/tui`) — deprecated, needs a maintainer to bring it up to feature parity
+- **Tests** — integration tests for newer features (goals, watchlist, federation)
+- **Docs** — API usage examples, deployment guides

README.md

@@ -271,6 +271,10 @@ Omit `user_id` for a global instance wrap-up. The worker computes stats in the b
 
 **Video:** Requires `ffmpeg` installed. Set `WRAPUP_FONT_PATH` and `WRAPUP_LOGO_PATH` for branded slides. Set `WRAPUP_BG_DIR` to a directory of background images for frutiger aero-style glass-panel slides. Cast profile photos and movie posters are embedded automatically. Download via `GET /api/v1/wrapups/{id}/video`.
 
+## Contributing
+
+See [CONTRIBUTING.md](CONTRIBUTING.md) for setup instructions, architecture overview, and PR guidelines.
+
 ## License
 
 MIT License. See [LICENSE](LICENSE).