Handoff modes

Handoff describes how a request is routed between local and cloud execution.

const session = await navigator.napcar.ai.requestSession({
  task: "summarization",
  handoff: "required",
  localOnly: true,
});

Modes

• off — no local handoff; the website behaves normally.
• optional — prefer local when available, allow a cloud fallback only if the user/site policy permits it.
• required — local execution only. If local is unavailable, the request fails with local_required_but_unavailable. No cloud fallback.
• user-forced-local — the user configured this site to use local execution even where it would normally call a cloud provider.
• user-block-cloud — the user configured Napcar to block known cloud LLM endpoints; calls are blocked and a local substitution may be offered.

The last two are user policies configured in chrome://llm, not something a site requests. Napcar-native APIs never fall back to the cloud by default.

Failure behavior

If local is unavailable and the mode is required or user-block-cloud, the request fails closed. If the mode is optional, the original request proceeds only when cloud fallback is allowed for that origin.