feat(companion): add disconnect metadata to connection snapshots

src/companion/runtimeClient.test.ts

@@ -762,6 +762,8 @@ describe('CompanionRuntimeClient', () => {
       pendingEventWaitCount: 1,
       hasPendingWork: true,
       idle: false,
+      lastDisconnectCode: undefined,
+      lastDisconnectReason: undefined,
     });
 
     client.clearEventSubscriptions();
@@ -773,6 +775,70 @@ describe('CompanionRuntimeClient', () => {
       pendingEventWaitCount: 0,
       hasPendingWork: false,
       idle: true,
+      lastDisconnectCode: undefined,
+      lastDisconnectReason: undefined,
+    });
+  });
+
+  it('connection snapshot tracks manual disconnect code and reason', () => {
+    const client = new CompanionRuntimeClient({
+      url: 'ws://127.0.0.1:1',
+    });
+
+    client.disconnect(4100, 'manual stop');
+
+    expect(client.getConnectionSnapshot()).toEqual({
+      connected: false,
+      eventSubscriptionCount: 0,
+      pendingRequestCount: 0,
+      pendingEventWaitCount: 0,
+      hasPendingWork: false,
+      idle: true,
+      lastDisconnectCode: 4100,
+      lastDisconnectReason: 'manual stop',
+    });
+  });
+
+  it('connection snapshot tracks transport close code and reason', async () => {
+    class FakeWebSocket extends EventEmitter {
+      readyState: number = WebSocket.CONNECTING;
+
+      constructor() {
+        super();
+        queueMicrotask(() => {
+          this.readyState = WebSocket.OPEN;
+          this.emit('open');
+        });
+      }
+
+      send(_payload: string, callback?: (error?: Error) => void): void {
+        callback?.();
+      }
+
+      close(_code?: number, _reason?: string): void {
+        this.readyState = WebSocket.CLOSED;
+        this.emit('close', 4001, Buffer.from('transport closed'));
+      }
+    }
+
+    const client = new CompanionRuntimeClient({
+      url: 'ws://127.0.0.1:1',
+      websocketFactory: () => new FakeWebSocket() as unknown as WebSocket,
+    });
+    await client.connect();
+
+    const ws = (client as unknown as { ws: WebSocket | null }).ws;
+    ws?.close();
+
+    expect(client.getConnectionSnapshot()).toEqual({
+      connected: false,
+      eventSubscriptionCount: 0,
+      pendingRequestCount: 0,
+      pendingEventWaitCount: 0,
+      hasPendingWork: false,
+      idle: true,
+      lastDisconnectCode: 4001,
+      lastDisconnectReason: 'transport closed',
     });
   });