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+# SpiceBook
+
+Notebook interface for SPICE circuit simulation.
+
+- **Frontend**: Astro 5 SSR + React 19 islands (`frontend/`)
+- **Backend**: FastAPI + ngspice (`backend/`)
+- **Production**: https://spicebook.warehack.ing
+- **Repo**: git.supported.systems:warehack.ing/spicebook.git
+
+## Development
+
+```bash
+# Local dev (Docker)
+make dev
+# Frontend: http://localhost:4321
+# Backend:  http://localhost:8099
+
+# Local dev (no Docker)
+cd backend && uv run uvicorn spicebook.main:app --host 0.0.0.0 --port 8099 --reload
+cd frontend && npm run dev -- --host 0.0.0.0 --port 4322
+```
+
+## Deployment to Production
+
+Production runs on `warehack.ing` (149.28.126.25) behind caddy-docker-proxy.
+
+```bash
+# 1. Push changes
+git push origin main
+
+# 2. SSH to production server
+ssh -A warehack-ing@warehack.ing
+
+# 3. Pull and rebuild
+cd ~/spicebook
+git pull origin main
+make prod
+
+# 4. Verify
+docker compose -f docker-compose.yml -f docker-compose.prod.yml logs --tail=20
+```
+
+### Production environment notes
+
+- `.env` on the production server is NOT tracked in git — edit it directly on the server when adding new env vars
+- `BACKEND_INTERNAL_URL=http://backend:8000` must be set for SSR server-side fetches (frontend talks to backend over Docker network)
+- `notebooks/user/` must be world-writable (chmod 777) because the backend runs as non-root user `spicebook` but the bind mount is owned by `warehack-ing`
+- The `@resvg/resvg-js` native binary requires `node:20-slim` (Debian glibc) — Alpine won't work
+- OG image font comes from `@fontsource/inter` in `node_modules`, not a separate font file
+
+### Caddy routing
+
+Caddy routes `/api/*`, `/health`, `/docs`, `/openapi.json` to the backend (port 8000). Everything else goes to the frontend (port 4321). No Caddy config changes needed for new frontend routes — they're caught by the frontend's SSR handler.
+
+## Architecture
+
+### SSR Data Flow
+
+Notebook pages fetch metadata server-side via `server-api.ts`:
+- `fetchNotebookMeta(id)` calls `BACKEND_INTERNAL_URL/api/notebooks/{id}` with a 5s timeout
+- Title, engine, and tags populate SEO meta tags at render time
+- If the backend is unreachable, pages degrade to generic metadata
+
+### OG Image Pipeline
+
+`/og/[id].png` and `/og/default.png` are SSR API routes that:
+1. Fetch notebook metadata from the backend (same internal URL)
+2. Render JSX layout with Satori (SVG)
+3. Rasterize to PNG with @resvg/resvg-js (native Rust NAPI binding)
+4. Return with cache headers (1h client / 24h CDN for notebooks, 24h/7d for default)
+
+### Key Environment Variables
+
+| Variable | Where | Purpose |
+|----------|-------|---------|
+| `PUBLIC_API_URL` | Build-time (Vite) | Client-side API base URL. Empty string = same origin (prod) |
+| `BACKEND_INTERNAL_URL` | Runtime (process.env) | SSR server-to-server API URL over Docker network |
+| `SPICEBOOK_DOMAIN` | Docker labels | Caddy reverse proxy domain |
+| `CORS_EXTRA_ORIGINS` | Backend | Additional CORS origins for embed framing |
+
+## Build & Test
+
+```bash
+cd frontend
+npx astro check    # TypeScript type checking
+npm run build      # Full SSR build
+```
+
+## Style Guide
+
+- Date-based versioning (YYYY.MM.DD)
+- Dark theme: slate-950 background, slate-200 text
+- Icons: astro-icon with lucide set (server-rendered SVGs, zero JS)
+- React components use `client:load` for interactive islands