feat(companion): add event surface snapshot helper

src/companion/runtimeClient.test.ts

@@ -703,6 +703,24 @@ describe('CompanionRuntimeClient', () => {
     });
   });
 
+  it('returns event surface snapshot', async () => {
+    const client = new CompanionRuntimeClient({
+      url: 'ws://127.0.0.1:1',
+    });
+    const pendingWait = client.waitForEvent('agent.stream', { timeoutMs: 10_000 }).catch(() => undefined);
+    const unsubscribe = client.subscribeEvents(() => undefined);
+
+    expect(client.getEventSurfaceSnapshot()).toEqual({
+      knownEventNames: ['agent.stream', 'agent.typing', 'context_warning'],
+      eventSubscriptionCount: 2,
+      pendingEventWaitCount: 1,
+    });
+
+    unsubscribe();
+    client.clearEventSubscriptions();
+    await pendingWait;
+  });
+
   it('waitForIdle resolves immediately when no work is pending', async () => {
     const client = new CompanionRuntimeClient({
       url: 'ws://127.0.0.1:1',