From 1a4b3077f94bb65c5f8675af7fc2a23613372419 Mon Sep 17 00:00:00 2001
From: Alex Rudenko <alexrudenko@chromium.org>
Date: Mon, 15 Sep 2025 14:20:30 +0200
Subject: [PATCH] fix: define tracing categories

---
 package.json             |  6 +++---
 src/tools/performance.ts | 38 +++++++++++++++++++++++++++++++++-----
 2 files changed, 36 insertions(+), 8 deletions(-)

diff --git a/package.json b/package.json
index ea0a5ad2..cf674d7f 100644
--- a/package.json
+++ b/package.json
@@ -14,9 +14,9 @@
     "generate-docs": "npm run build && node --experimental-strip-types scripts/generate-docs.ts",
     "start": "npm run build && node build/src/index.js",
     "start-debug": "DEBUG=mcp:* DEBUG_COLORS=false npm run build && node build/src/index.js",
-    "test": "npm run build && npx puppeteer browsers install chrome@latest && node --test-reporter spec --test-force-exit --test 'build/tests/**/*.test.js'",
-    "test:only": "npm run build && npx puppeteer browsers install chrome@latest && node --test-reporter spec --test-force-exit --test --test-only 'build/tests/**/*.test.js'",
-    "test:only:no-build": "npx puppeteer browsers install chrome@latest && node --test-reporter spec --test-force-exit --test --test-only 'build/tests/**/*.test.js'",
+    "test": "npm run build && node --test-reporter spec --test-force-exit --test 'build/tests/**/*.test.js'",
+    "test:only": "npm run build && node --test-reporter spec --test-force-exit --test --test-only 'build/tests/**/*.test.js'",
+    "test:only:no-build": "node --test-reporter spec --test-force-exit --test --test-only 'build/tests/**/*.test.js'",
     "prepare": "node --experimental-strip-types scripts/prepare.ts"
   },
   "files": [
diff --git a/src/tools/performance.ts b/src/tools/performance.ts
index b56a74b9..560b278f 100644
--- a/src/tools/performance.ts
+++ b/src/tools/performance.ts
@@ -49,9 +49,31 @@ export const startTrace = defineTool({
       });
     }
 
-    // TODO(jacktfranklin): determine the exact list of categories and
-    // align with DevTools
-    await page.tracing.start();
+    // This panel may be opened with trace data recorded in other tools.
+    // Keep in sync with the categories arrays in:
+    // https://source.chromium.org/chromium/chromium/src/+/main:third_party/devtools-frontend/src/front_end/panels/timeline/TimelineController.ts
+    // https://github.com/GoogleChrome/lighthouse/blob/master/lighthouse-core/gather/gatherers/trace.js
+    const categories = [
+      '-*',
+      'blink.console',
+      'blink.user_timing',
+      'devtools.timeline',
+      'disabled-by-default-devtools.screenshot',
+      'disabled-by-default-devtools.timeline',
+      'disabled-by-default-devtools.timeline.invalidationTracking',
+      'disabled-by-default-devtools.timeline.frame',
+      'disabled-by-default-devtools.timeline.stack',
+      'disabled-by-default-v8.cpu_profiler',
+      'disabled-by-default-v8.cpu_profiler.hires',
+      'latencyInfo',
+      'loading',
+      'disabled-by-default-lighthouse',
+      'v8.execute',
+      'v8',
+    ];
+    await page.tracing.start({
+      categories,
+    });
 
     if (request.params.reload) {
       await page.goto(pageUrlForTracing, {
@@ -98,8 +120,14 @@ async function stopTracingAndAppendOutput(
     response.appendResponseLine('The performance trace has been stopped.');
     if (result) {
       const insightText = insightOutput(result);
-      response.appendResponseLine('Insights with performance opportunities:');
-      response.appendResponseLine(insightText);
+      if (insightText) {
+        response.appendResponseLine('Insights with performance opportunities:');
+        response.appendResponseLine(insightText);
+      } else {
+        response.appendResponseLine(
+          'No insights has been found. The performance looks good!',
+        );
+      }
     }
   } catch (e) {
     logger(