docs: auth section + env vars

README.md

@@ -111,6 +111,49 @@ npm run build
 npm test
 ```
 
+## Authentication
+
+Cyclone ships with username/password authentication and three predefined roles.
+
+**Roles:**
+
+| Role     | Can read | Can write (upload, parse, reconcile) | Can manage users |
+| -------- | -------- | ------------------------------------ | ---------------- |
+| `viewer` | ✅       | ❌                                   | ❌               |
+| `user`   | ✅       | ✅                                   | ❌               |
+| `admin`  | ✅       | ✅                                   | ✅               |
+
+**Bootstrap.** On first start, set `CYCLONE_ADMIN_USERNAME` and
+`CYCLONE_ADMIN_PASSWORD` (min 12 chars) in your environment. Cyclone creates the
+first admin automatically. On subsequent starts these env vars are ignored, so
+rotating the bootstrap password doesn't affect an already-seeded admin — use the
+CLI below to reset it. When running via `docker compose`, both vars are
+required: compose refuses to start with a clear error if either is missing.
+
+**CLI.** Manage users from the command line:
+
+```
+python -m cyclone users create alice --role user --password 'hunter2hunter2'
+python -m cyclone users list
+python -m cyclone users disable alice
+python -m cyclone users reset-password alice
+python -m cyclone users set-role alice --role admin
+```
+
+**Login.** Browse to `http://localhost:5173` (dev) or `http://localhost:8081`
+(Docker), sign in on the `/login` page, and you'll be redirected to the
+dashboard. Sessions are stored server-side in SQLite with a 24-hour sliding
+expiry — every authenticated request refreshes the TTL, so an active user
+never gets logged out.
+
+**Dev escape hatch.** Set `CYCLONE_AUTH_DISABLED=1` to bypass auth entirely
+(the backend auto-grants admin on every request). **NEVER set this in
+production** — it's a single env-var trip from wide-open to the public
+internet. The Docker compose file does not honor this flag.
+
+See `docs/superpowers/specs/2026-06-22-cyclone-auth-design.md` for the full
+design.
+
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