feat(test): add high-volume shell test and refine perf harness

packages/test-utils/src/perf-test-harness.ts

@@ -50,6 +50,7 @@ export interface PerfSnapshot {
   eventLoopDelayP95Ms: number;
   eventLoopDelayP99Ms: number;
   eventLoopDelayMaxMs: number;
+  heapUsed?: number;
 }
 
 /**
@@ -161,6 +162,7 @@ export class PerfTestHarness {
       eventLoopDelayP95Ms: 0,
       eventLoopDelayP99Ms: 0,
       eventLoopDelayMaxMs: 0,
+      heapUsed: process.memoryUsage().heapUsed,
     };
   }
 
@@ -374,6 +376,11 @@ export class PerfTestHarness {
       lines.push(
         `  CPU: ${cpuMs} (user: ${formatUs(result.median.cpuUserUs)}, system: ${formatUs(result.median.cpuSystemUs)})`,
       );
+      if (result.median.heapUsed !== undefined) {
+        lines.push(
+          `  Memory: ${(result.median.heapUsed / (1024 * 1024)).toFixed(1)} MB`,
+        );
+      }
 
       if (result.median.eventLoopDelayP99Ms > 0) {
         lines.push(

perf-tests/baselines.json

@@ -1,24 +1,30 @@
 {
   "version": 1,
-  "updatedAt": "2026-04-08T18:51:29.839Z",
+  "updatedAt": "2026-04-08T22:28:27.448Z",
   "scenarios": {
     "cold-startup-time": {
-      "wallClockMs": 1333.4230420000004,
-      "cpuTotalUs": 1711,
+      "wallClockMs": 927.553249999999,
+      "cpuTotalUs": 1470,
       "eventLoopDelayP99Ms": 0,
-      "timestamp": "2026-04-08T18:50:58.124Z"
+      "timestamp": "2026-04-08T22:27:54.871Z"
     },
     "idle-cpu-usage": {
-      "wallClockMs": 5001.926125,
-      "cpuTotalUs": 128518,
-      "eventLoopDelayP99Ms": 12.705791,
-      "timestamp": "2026-04-08T18:51:23.938Z"
+      "wallClockMs": 5000.460750000002,
+      "cpuTotalUs": 12157,
+      "eventLoopDelayP99Ms": 11.108351,
+      "timestamp": "2026-04-08T22:28:19.098Z"
     },
     "skill-loading-time": {
-      "wallClockMs": 1372.4463749999995,
-      "cpuTotalUs": 1550,
+      "wallClockMs": 930.0920409999962,
+      "cpuTotalUs": 1323,
       "eventLoopDelayP99Ms": 0,
-      "timestamp": "2026-04-08T18:51:29.839Z"
+      "timestamp": "2026-04-08T22:28:23.290Z"
+    },
+    "high-volume-shell-output": {
+      "wallClockMs": 936.6500410000008,
+      "cpuTotalUs": 1352,
+      "eventLoopDelayP99Ms": 0,
+      "timestamp": "2026-04-08T22:28:27.448Z"
     }
   }
 }

perf-tests/perf-usage.test.ts

@@ -150,4 +150,34 @@ describe('CPU Performance Tests', () => {
       harness.assertWithinBaseline(result);
     }
   });
+
+  it('high-volume-shell-output: handles large output efficiently', async () => {
+    const result = await harness.runScenario(
+      'high-volume-shell-output',
+      async () => {
+        const rig = new TestRig();
+        try {
+          rig.setup('perf-high-volume-output', {
+            fakeResponsesPath: join(__dirname, 'perf.high-volume.responses'),
+          });
+
+          return await harness.measure('high-volume-output', async () => {
+            await rig.run({
+              args: ['Generate 1M lines of output'],
+              timeout: 120000,
+              env: { GEMINI_API_KEY: 'fake-perf-test-key' },
+            });
+          });
+        } finally {
+          await rig.cleanup();
+        }
+      },
+    );
+
+    if (UPDATE_BASELINES) {
+      harness.updateScenarioBaseline(result);
+    } else {
+      harness.assertWithinBaseline(result);
+    }
+  });
 });

perf-tests/perf.high-volume.responses

@@ -0,0 +1,3 @@
+{"method":"generateContent","response":{"candidates":[{"content":{"parts":[{"text":"0"}],"role":"model"},"finishReason":"STOP","index":0}]}}
+{"method":"generateContentStream","response":[{"candidates":[{"content":{"parts":[{"text":"I will run a shell command to generate a lot of output."}],"role":"model"},"finishReason":"STOP","index":0}]}]}
+{"method":"generateContentStream","response":[{"candidates":[{"content":{"parts":[{"functionCall":{"name":"run_shell_command","args":{"command":"yes | head -n 1000000"}}}],"role":"model"},"finishReason":"STOP","index":0}]}]}