feat: unify on single repo-root compose file for dev and prod

AGENTS.md

@@ -13,6 +13,26 @@ Backend (run from `backend/`):
 
 Frontend (run from `frontend/`): `npm install`, `npm run dev`, `npm run build` (typecheck + build).
 
+## Multi-container ops
+
+One `docker-compose.yml` at the repo root for dev and prod. Dev specifics
+live in `.devcontainer/devcontainer.json` only — never add dev-only services,
+profiles, or override files. Containers: `api` (FastAPI :8000, attached),
+`frontend` (Vite :3000), `langflow` (:7860), `lfx` (:6004), `watchtower`
+(prod only, not in `runServices`).
+
+- Backend suite (attached container, from `backend/`): `uv run pytest`.
+- Frontend build (node lives in `frontend`, reach it via exec from the repo
+  root): `docker compose exec frontend npm run build`. Fallback without a
+  docker socket: VS Code "Attach to Running Container" → frontend.
+- Logs/restart: `docker compose logs -f <service>`, `docker compose restart api`.
+- If `exec` misses the project, find it via `docker compose ls`.
+- CI runs on Forgejo (`.forgejo/workflows/`): backend pytest, frontend
+  build, compose validation. Needs a Runner with the `docker` label online.
+- Prod: own `.env` with secrets + `FRONTEND_MODE=preview`; code updates via
+  `git pull` + restart, image rebuilds only for dependency changes
+  (`docker compose up -d --build`).
+
 ## Definition of done
 
 - New behavior has tests; `uv run pytest` is green before reporting completion.