client-methods

Client Methods

Rule

Browser/client code imports named methods, hooks, or client modules instead of hand-writing REST calls to framework or app routes.

Why

Route shapes are transport details. If components and docs call fetch("/_agent-native/...") or template /api/* routes directly, every caller has to rediscover auth, base paths, request-source headers, JSON parsing, error handling, optimistic updates, sync invalidation, and route quirks. A named client method gives the UI, docs, and future agents one stable contract.

How

1. Look for an existing client API first.

   Need	Use
   App action reads/writes	useActionQuery / useActionMutation from @agent-native/core/client
   Imperative action calls	callAction from @agent-native/core/client
   Browser application state	readClientAppState, writeClientAppState, setClientAppState, deleteClientAppState
   Navigation/app-state sync	useAgentRouteState / useSemanticNavigationState from @agent-native/core/client
   Agent chat context	Agent chat client helpers from @agent-native/core/client
   Ask the user a multiple-choice question from app code	askUserQuestion from @agent-native/core/client (renders inline in the agent panel; answer goes to the agent — do not build a custom modal)
   Live sync	useDbSync, useChangeVersion, useChangeVersions
   Listen to the shared SSE/poll change stream	subscribeSyncEvents from @agent-native/core/client — never open a second EventSource to /_agent-native/events
   Extension iframe calls	appAction, appFetch, extensionFetch from the extension runtime

   Action fetch behavior: every useActionQuery / useActionMutation / callAction request is bounded by a 60s timeout, and timeouts surface as errors instead of retrying silently. useActionQuery cancels superseded requests automatically via React Query's abort signal. For imperative calls, callAction(name, params, { method, signal, timeoutMs }) accepts an AbortSignal and a timeoutMs override for legitimately long operations.

2. If no client API exists, add the narrowest helper at the boundary.

   • Put shared framework helpers in packages/core/src/client/*.
   • Put template-local helpers in templates/<app>/app/hooks/*, templates/<app>/app/lib/*, or an existing local client module.
   • Export reusable core helpers from @agent-native/core/client; add a leaf export when callers may need to avoid the broad barrel.
   • Keep raw fetch, agentNativePath, and route paths inside that helper, not scattered through components or docs.
   • Add focused tests for URL construction, headers, response parsing, error shape, and any sync invalidation.

3. Teach the helper, not the route.

   Docs, skills, examples, and generated code should show:

   await setClientAppState("selection", selection, { keepalive: true });
   

   not:

   await fetch("/_agent-native/application-state/selection", {
     method: "PUT",
     body: JSON.stringify(selection),
   });
   

Exceptions

Raw route calls are acceptable only inside low-level client helpers or for route-shaped protocols that cannot be hidden cleanly:

• multipart uploads
• streaming/SSE/WebSocket transports
• OAuth redirects and callback URL construction
• webhooks and external provider callbacks
• extension sandbox appFetch / extensionFetch, which are themselves exposed client methods
• tests that assert route construction

Even for exceptions, prefer a named helper as soon as more than one caller needs the behavior.

Don't

• Don't put fetch("/_agent-native/..."), fetch(agentNativePath(...)), or template /api/* calls directly in React components for normal app data, actions, settings, or application state.
• Don't document route calls as the way client code should do work.
• Don't add pass-through /api/* routes just to make client fetches look simpler; expose an action and call it with action hooks.
• Don't duplicate auth/session/base-path/request-source/error parsing logic in every component.

Related Skills

• actions — app operations shared by UI and agent.
• context-awareness — application-state navigation and selection helpers.
• real-time-sync — keeping helper-backed UI reads fresh.
• server-plugins — when a new route is actually warranted.

References

• references/legacy-client-fetch-audit-2026-06-03.md — known legacy cleanup targets found when this rule was added.