diff --git a/AGENTS.md b/AGENTS.md
index 089e5c1..32e7eae 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -34,3 +34,12 @@
 - [docs/DEPLOYMENT.md](docs/DEPLOYMENT.md) — CI/CD pipeline, Cloud Run, GCP setup
 - [docs/RELIABILITY.md](docs/RELIABILITY.md) — Error handling, fallbacks, reconnection
 - [docs/SECURITY.md](docs/SECURITY.md) — API key management, eval safety
+
+## Cursor Cloud specific instructions
+
+- **Frontend**: `cd frontend && npm run dev` starts Vite on port 5199. No API keys needed for the 3D viewer itself.
+- **Backend**: `cd backend && uvicorn main:app --port 8000` starts FastAPI. The server starts fine without keys, but WebSocket chat requires `OPENROUTER_API_KEY`.
+- **Tests**: `cd backend && pytest tests/ -v` — 30 tests pass without any API key. 4 tests (`test_graph.py`, `test_main.py` WebSocket tests) fail without `OPENROUTER_API_KEY` because `build_graph()` validates the key at graph construction time.
+- **Frontend build**: `cd frontend && npx vite build` — no lint tool configured for frontend.
+- **Vite proxies**: The frontend dev server proxies `/api/horizons` → JPL, `/ws` → backend:8000, `/api/dsn` → NASA, `/api/tdrs` → CelesTrak. These are public APIs, no keys needed.
+- **No database**: Both repos are stateless. ai-attr uses git notes; aii uses in-memory `MemorySaver`.