Authentication

You have a chat surface or a hook driving an agent and you want every agent run to know who the request came from. By the end of this guide, your frontend will forward a token, the runtime will pass it through, and your agent code will read the resulting user info on every turn.

When to use this#

• Multi-tenant apps where the agent reads or writes per-user data.
• Tool gating where some tools should only run for authorised users.
• Audit and billing where every run needs an identity to attribute it to.
• Session-aware UX where the agent's behaviour depends on the user's role or permissions.

If you don't need any of those, skip auth entirely. The agent runs anonymously and the frontend never has to care about tokens.

Tool gating#

The most common reason to wire auth is so individual tools can decline to run. Read the resolved user inside the tool's handler and bail if the role doesn't match:

def delete_record(record_id: str, *, user: User):
    if "admin" not in user.permissions:
        raise PermissionError("admin role required")
    # do the delete

This composes with Human in the loop: gate on auth first, surface a confirmation card next, execute last.

Thread authorization#

Verifying who the caller is doesn't yet stop them reaching someone else's conversation. How much of that you have to build depends on which runtime you're running.

The Intelligence Platform scopes most thread routes#

The Intelligence runtime requires an identifyUser callback — construction throws without one (or without at least one Channel). It runs on the server, once per request, and the id it returns is the scope the runtime hands to the platform. (intelligence below is a CopilotKitIntelligence instance; Connect your runtime to Intelligence covers building it.)

const runtime = new CopilotRuntime({
  agents: { default: agent },
  intelligence,
  identifyUser: async (request) => {
    const session = await verifyAppSession(request); // Your server-side auth.
    if (!session?.user) throw new Error("Unauthorized"); // Backstop; see below.

    return { id: session.user.id, name: session.user.name };
  },
});

Where a route does resolve the caller, what matters next is whether that id is actually carried to the platform as a scope:

onBeforeHandler: async ({ request, route }) => {
  // Switch rather than an array `includes`, so `route` narrows and
  // `route.threadId` type-checks — all three variants carry one.
  switch (route.method) {
    case "threads/events":
    case "threads/state":
    case "agent/stop":
      break;
    default:
      return;
  }

  // None of these is scoped platform-side; check your own ownership record.
  const user = await verifyRequest(request);
  if (!(await userOwnsThread(user.id, route.threadId))) {
    throw new Response("Not found", { status: 404 });
  }
},

For everything in the Yes rows there is no ownership table to build. What you own is identifyUser itself:

• Derive the id from a server-verified credential. The callback receives the raw Request; whatever it returns is trusted from there on. Reading a user id straight out of a header or request body hands every caller the ability to name themselves.
• Return a stable id. It is the key threads hang off. Change it — swapping an email for a subject claim, say — and that user's existing threads stop resolving.
• Send the 401 from onRequest. Beyond the status codes being wrong — an identifyUser that throws surfaces as a 500, a malformed id as a 400 — routes like agent/stop never call it, so a check placed only here isn't reached on every request. Authenticate in onRequest, which runs on every route and can throw a Response directly, and keep the throw inside identifyUser as a backstop.

See Scope Rich Threads to the signed-in user for the full runtime contract.

Scope threads yourself#

Without the Intelligence Platform there is no server-side binding between a threadId and a user. A threadId is just an opaque id travelling in a request: if user A learns user B's, every thread route accepts it. The rest of this section is the pattern for a custom store, a plain SSE runtime, or the local in-memory runner — and it's also what you narrow to threads/events, threads/state, and agent/stop if you are on the platform.

Own the mapping

Whatever stores your threads, keep a record of who each one belongs to. The minimum is a table your runtime can query:

create table thread_owners (
  thread_id text primary key,
  user_id   text not null
);
create index on thread_owners (user_id);

Write a row when a conversation is first created — see minting a thread with your own API for where that hooks into the chat lifecycle.

Enforce it in onBeforeHandler

onRequest runs before routing, so it can't see which thread is being addressed. onBeforeHandler runs after, and receives a route that names the operation and — for thread-scoped routes — the threadId:

const handler = createCopilotRuntimeHandler({
  runtime,
  basePath: "/api/copilotkit",
  hooks: {
    onRequest: async ({ request }) => {
      // Authenticate first: reject anonymous callers outright.
      const user = await verifyRequest(request);
      if (!user) throw new Response("Unauthorized", { status: 401 });
    },

    onBeforeHandler: async ({ request, route }) => {
      const user = await verifyRequest(request);

      // Routes that name a thread directly.
      if ("threadId" in route) {
        if (!(await userOwnsThread(user.id, route.threadId))) {
          throw new Response("Forbidden", { status: 403 });
        }
        return;
      }

      // agent/run and agent/connect carry the thread in the body instead.
      if (route.method === "agent/run" || route.method === "agent/connect") {
        // Clone: the handler still needs to read the original body.
        const { threadId } = await request.clone().json();
        if (threadId && !(await userOwnsThread(user.id, threadId))) {
          throw new Response("Forbidden", { status: 403 });
        }
      }
    },
  },
});

The routes that carry a threadId on route are agent/stop, threads/update, threads/archive, threads/messages, threads/events, and threads/state.

Filter the thread list

threads/list has no threadId to check, so onBeforeHandler has nothing to authorize against. Off the platform the route returns whatever the configured store holds — the local in-memory runner filters by agentId only, and a custom store returns exactly what you wrote. Build the list from your own ownership table instead, and drive the chat with the selected id.

Filter server-side. Hiding rows in the UI leaves the underlying route open.

Security checklist#

• Always validate the token on the backend. Never trust the frontend's claim.
• Scope every read and write to the resolved user. Auth context only matters if you actually use it to filter data.
• Authenticate in onRequest. It is the only hook that runs on every route. identifyUser names a caller; it does not gate one, and some routes never invoke it.
• Bind threads to a user. On the Intelligence Platform that means a correct identifyUser, plus your own guard on threads/events, threads/state, and agent/stop; off it, an ownership check on every thread route rather than only at login. See Thread authorization.
• Don't log raw tokens. Log the resolved user id (or anonymous) instead.
• Use HTTPS in production. The Bearer token is sensitive.
• Refresh strategy. Your frontend is responsible for rotating expired tokens before they reach the agent. CopilotKit doesn't refresh on your behalf.