diff --git a/src/remote/api-client.test.ts b/src/remote/api-client.test.ts
new file mode 100644
index 0000000..b9c51a2
--- /dev/null
+++ b/src/remote/api-client.test.ts
@@ -0,0 +1,84 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+import { newWebSocketRpcSession, RpcTarget } from "capnweb";
+import { WebSocketServer, type WebSocket as ServerSocket } from "ws";
+import type { Remote } from "./remote.ts";
+import { ApiClient } from "./api-client.ts";
+
+// Relay stand-in: answers `authenticate` with a ServerApi-shaped stub so
+// ApiClient.connect runs its real handshake and dispose path over a genuine
+// WebSocket. That transport is the only place capnweb fires onRpcBroken with
+// "RPC session was shut down by disposing the main stub" — an in-memory session
+// doesn't reproduce it, so the bug would slip through a lighter fake.
+class FakeServerApi extends RpcTarget {
+  async ping() {
+    return true;
+  }
+}
+
+class FakeRelay extends RpcTarget {
+  async authenticate() {
+    return new FakeServerApi();
+  }
+}
+
+// In CI mode connect() never calls back into `remote` (that wiring is the
+// persistent-server path), so an empty stand-in is enough.
+const CI_MODE = { kind: "ci", branch: "main", sha: "" } as const;
+const NO_REMOTE = {} as unknown as Remote;
+
+async function startRelay() {
+  const wss = new WebSocketServer({ port: 0 });
+  await new Promise<void>((resolve) => wss.once("listening", () => resolve()));
+  const sockets: ServerSocket[] = [];
+  const closes: Promise<void>[] = [];
+  wss.on("connection", (socket) => {
+    sockets.push(socket);
+    closes.push(new Promise((resolve) => socket.once("close", () => resolve())));
+    newWebSocketRpcSession(socket as unknown as WebSocket, new FakeRelay());
+  });
+  const { port } = wss.address() as { port: number };
+  return {
+    endpoint: `http://127.0.0.1:${port}`,
+    dropConnection: () => sockets.forEach((s) => s.terminate()),
+    // The client's onRpcBroken can only fire once its transport is gone.
+    // Awaiting the server-observed close and then flushing the timer queue
+    // guarantees that window has fully passed, so "callback not called" means it
+    // genuinely never fired rather than that we asserted too early.
+    afterTransportClosed: async () => {
+      await Promise.all(closes);
+      await new Promise((resolve) => setTimeout(resolve, 50));
+    },
+    close: () => new Promise<void>((resolve) => wss.close(() => resolve())),
+  };
+}
+
+describe("ApiClient.connect (integration)", () => {
+  let relay: Awaited<ReturnType<typeof startRelay>> | undefined;
+
+  afterEach(async () => {
+    await relay?.close();
+    relay = undefined;
+  });
+
+  it("stays silent when the caller disposes the connection", async () => {
+    relay = await startRelay();
+    const onBroken = vi.fn();
+    const { dispose } = await ApiClient.connect(relay.endpoint, "token", CI_MODE, NO_REMOTE, onBroken);
+
+    dispose();
+    await relay.afterTransportClosed();
+
+    expect(onBroken).not.toHaveBeenCalled();
+  });
+
+  it("reports a broken connection when the transport drops mid-run", async () => {
+    relay = await startRelay();
+    const onBroken = vi.fn();
+    await ApiClient.connect(relay.endpoint, "token", CI_MODE, NO_REMOTE, onBroken);
+
+    relay.dropConnection();
+    await relay.afterTransportClosed();
+
+    expect(onBroken).toHaveBeenCalledWith(expect.any(Error));
+  });
+});
diff --git a/src/remote/api-client.ts b/src/remote/api-client.ts
index a580acb..31112e5 100644
--- a/src/remote/api-client.ts
+++ b/src/remote/api-client.ts
@@ -108,6 +108,11 @@ export class ApiClient extends RpcTarget implements ClientApi {
     const dispose = () => {
       if (disposed) return;
       disposed = true;
+      // Mark the connection broken before disposing the stub. Disposing makes
+      // capnweb fire onRpcBroken with "RPC session was shut down by disposing
+      // the main stub"; without this guard triggerBroken would report our own
+      // intentional teardown as a broken connection.
+      broken = true;
       stopPing();
       try { api[Symbol.dispose](); } catch { /* already gone */ }
       try { (unauthenticated as unknown as Disposable)[Symbol.dispose]?.(); } catch { /* already gone */ }