fix(chat): add saved AI defaults and harden suggestions

.memory/knowledge/tech-stack.md

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+# Tech Stack & Development
+
+## Stack
+- **Frontend**: SvelteKit 2, TypeScript, Bun (package manager), DaisyUI + Tailwind CSS, svelte-i18n, svelte-maplibre
+- **Backend**: Django REST Framework, Python, django-allauth, djmoney, django-geojson, LiteLLM, duckduckgo-search
+- **Database**: PostgreSQL + PostGIS
+- **Cache**: Memcached
+- **Infrastructure**: Docker, Docker Compose
+- **Repo**: github.com/Alex-Wiesner/voyage
+- **License**: GNU GPL v3.0
+
+## Development Commands
+
+### Frontend (prefer Bun)
+- `cd frontend && bun run format` — fix formatting (6s)
+- `cd frontend && bun run lint` — check formatting (6s)
+- `cd frontend && bun run check` — Svelte type checking (12s; 0 errors, 6 warnings expected)
+- `cd frontend && bun run build` — build (32s)
+- `cd frontend && bun install` — install deps (45s)
+
+### Backend (Docker required; uv for local Python tooling)
+- `docker compose exec server python3 manage.py test` — run tests (7s; 6/30 pre-existing failures expected)
+- `docker compose exec server python3 manage.py migrate` — run migrations
+
+### Pre-Commit Checklist
+1. `cd frontend && bun run format`
+2. `cd frontend && bun run lint`
+3. `cd frontend && bun run check`
+4. `cd frontend && bun run build`
+
+## Environment & Configuration
+
+### .env Loading
+- **Library**: `python-dotenv==1.2.2` (in `backend/server/requirements.txt`)
+- **Entry point**: `backend/server/main/settings.py` calls `load_dotenv()` at module top
+- **Docker**: `docker-compose.yml` sets `env_file: .env` on all services — single root `.env` file shared
+- **Root `.env`**: `/home/alex/projects/voyage/.env` — canonical for Docker Compose setups
+
+### Settings File
+- **Single file**: `backend/server/main/settings.py` (no split/environment-specific settings files)
+
+### Server-side Env Vars (from `settings.py`)
+| Var | Default | Purpose |
+|---|---|---|
+| `SECRET_KEY` | (required) | Django secret key |
+| `GOOGLE_MAPS_API_KEY` | `""` | Google Maps integration |
+| `STRAVA_CLIENT_ID` / `STRAVA_CLIENT_SECRET` | `""` | Strava OAuth |
+| `FIELD_ENCRYPTION_KEY` | `""` | Fernet key for `UserAPIKey` encryption |
+| `OSRM_BASE_URL` | `"https://router.project-osrm.org"` | Routing service |
+| `VOYAGE_AI_PROVIDER` | `"openai"` | Instance-level default AI provider |
+| `VOYAGE_AI_MODEL` | `"gpt-4o-mini"` | Instance-level default AI model |
+| `VOYAGE_AI_API_KEY` | `""` | Instance-level AI API key |
+
+### Per-User LLM API Key Pattern
+LLM provider keys stored per-user in DB (`UserAPIKey` model, `integrations/models.py`):
+- `UserAPIKey` table: `(user, provider)` unique pair → `encrypted_api_key` (Fernet-encrypted text field)
+- `FIELD_ENCRYPTION_KEY` env var required for encrypt/decrypt
+- `llm_client.get_llm_api_key(user, provider)` → user key → instance key fallback (matching provider only) → `None`
+- No global server-side LLM API keys — every user must configure their own per-provider key via Settings UI (or instance admin configures fallback)
+
+## Known Issues
+- Docker dev setup has frontend-backend communication issues (500 errors beyond homepage)
+- Frontend check: 0 errors, 6 warnings expected (pre-existing in `CollectionRecommendationView.svelte` + `RegionCard.svelte`)
+- Backend tests: 6/30 pre-existing failures (2 user email key errors + 4 geocoding API mocks)
+- Local Python pip install fails (network timeouts) — use Docker