docs(llms): setup agents documentation

docs/agent-guides/routing-and-cloud.md

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+# Routing and Ontime Cloud
+
+Use for navigation, URLs, endpoints, websockets, auth, cookies, assets, redirects, presets, or local-storage scope.
+
+## Deployment invariant
+
+Support root and runtime-prefixed deployments:
+
+```text
+local:  http://localhost:4001/timer
+cloud:  https://cloud.example/client-hash/timer
+```
+
+Prefix is deployment data. Never assume `/`.
+
+## Client
+
+- `apps/client/src/externals.ts`: derives `baseURI`, `serverURL`, `websocketUrl` from document base/current origin.
+- `BrowserRouter`: uses `baseURI` basename.
+- APIs/assets: use `common/api/constants.ts` or base-aware helpers.
+- App navigation: use React Router. Never strip/guess/re-add prefix from `window.location.pathname`.
+- Persisted browser state: use existing base-aware scoping where prefixes need isolation.
+
+## Server
+
+- `updateRouterPrefix()` in `apps/server/src/externals.ts`: normalises `ROUTER_PREFIX`.
+- `apps/server/src/app.ts`: mounts routes below that prefix.
+- Domain routers: paths relative to mount; never derive prefix.
+- Websockets, auth redirects, cookie paths, share URLs: preserve prefix.
+
+## URL rules
+
+Use `URL`, React Router, or existing helpers instead of string manipulation. Preserve:
+
+- leading/trailing slashes and runtime prefix;
+- query params, auth tokens, navigation locks;
+- preset aliases and canonical view paths;
+- `https`/`wss` behind proxies;
+- static/user asset paths.
+
+Never infer Ontime Cloud from hostname alone. Generated base markup marks cloud; runtime prefixes also serve non-cloud reverse proxies.
+
+## Cloud capabilities
+
+Gate unavailable local-network integrations in cloud, including OSC output. Keep server behaviour and UI availability aligned.
+
+## Verification
+
+Test both root and a prefix such as `/client-hash`. Include relevant queries, redirects, cookies, websocket paths, presets, assets. Root-only routing coverage is incomplete.