feat(vela): support end-to-end mocked turn cancelation

apps/vela-gateway/test/websocket-session.test.js

@@ -405,3 +405,67 @@ test('websocket rejects a second mocked turn while one is in flight', async () =
 		await server.close();
 	}
 });
+
+test('websocket cancel stops an active mocked turn and allows a new one without reconnecting', async () => {
+	const server = await startServer();
+
+	try {
+		const client = await connectWebSocket(server.port);
+		await client.nextMessage();
+		await client.nextMessage();
+
+		client.sendJson({ type: 'mocked.turn.trigger', payload: {} });
+		assert.deepEqual(await client.nextMessage(), {
+			type: 'session.state',
+			payload: { value: 'listening' }
+		});
+		assert.deepEqual(await client.nextMessage(), {
+			type: 'transcript.final',
+			payload: { text: '[mocked user] What is the current mocked vertical slice?' }
+		});
+		assert.deepEqual(await client.nextMessage(), {
+			type: 'session.state',
+			payload: { value: 'thinking' }
+		});
+
+		client.sendJson({ type: 'response.cancel', payload: {} });
+		assert.deepEqual(await client.nextMessage(), {
+			type: 'session.state',
+			payload: { value: 'idle' }
+		});
+		await assert.rejects(() => client.nextMessage(150), /timed out waiting for websocket message/);
+
+		client.sendJson({ type: 'mocked.turn.trigger', payload: {} });
+		assert.deepEqual(await client.nextMessage(), {
+			type: 'session.state',
+			payload: { value: 'listening' }
+		});
+
+		await client.close();
+	} finally {
+		await server.close();
+	}
+});
+
+test('websocket safely accepts cancel when no turn is active', async () => {
+	const server = await startServer();
+
+	try {
+		const client = await connectWebSocket(server.port);
+		await client.nextMessage();
+		await client.nextMessage();
+
+		client.sendJson({ type: 'response.cancel', payload: {} });
+		await assert.rejects(() => client.nextMessage(150), /timed out waiting for websocket message/);
+
+		client.sendJson({ type: 'mocked.turn.trigger', payload: {} });
+		assert.deepEqual(await client.nextMessage(), {
+			type: 'session.state',
+			payload: { value: 'listening' }
+		});
+
+		await client.close();
+	} finally {
+		await server.close();
+	}
+});