PerfAI: pick no_navigation Insight set if it's the only choice

I noticed this bug when wondering why the AI had no idea about the
interaction I was asking it to debug. The code to select the first
insight assumed we'd find one with a navigation, but often for
interactions that is not the case. This CL updates the logic to:

1. If there is only 1 InsightSet, use that.
2. If there are >1, prefer the first with a navigation attached, but
   otherwise fallback to the first set otherwise.

This fixes the behaviour where for no-navigation traces the AI has no
idea about any insights.

(Long term we should still do the proper fixing where we tell the AI
about all of them).

[email protected]

Fixed: 449113697
Change-Id: I806ca7fa7770845c08b0d29afa3b8f484cb2793a
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7003546
Auto-Submit: Jack Franklin <[email protected]>
Reviewed-by: Connor Clark <[email protected]>
Commit-Queue: Connor Clark <[email protected]>

Author: jackfranklin

front_end/models/ai_assistance/data_formatters/PerformanceTraceFormatter.snapshot.txt

@@ -731,6 +731,29 @@ Available insights:
     example question: Which third parties are having the largest impact on my page performance?
 === end content
 
+Title: PerformanceTraceFormatter formatTraceSummary includes INP insight when there is no navigation
+Content:
+URL: https://b2607f8b04800100000289cb1c0a82ba72253000000000000000001.proxy.googlers.com/long-interaction/index.html?x=35
+Bounds: {min: 337943614456, max: 337947260898}
+CPU throttling: none
+Network throttling: none
+Metrics (lab / observed):
+  - INP: 139 ms, event: (eventKey: s-3347, ts: 337944870984)
+  - CLS: 0.00
+Metrics (field / real users): n/a – no data for this page in CrUX
+Available insights:
+  - insight name: INPBreakdown
+    description: Start investigating with the longest subpart. [Delays can be minimized](https://web.dev/articles/optimize-inp#optimize_interactions). To reduce processing duration, [optimize the main-thread costs](https://web.dev/articles/optimize-long-tasks), often JS.
+    relevant trace bounds: {min: 337944870984, max: 337945010222}
+    example question: Suggest fixes for my longest interaction
+    example question: Why is a large INP score problematic?
+    example question: What's the biggest contributor to my longest interaction?
+  - insight name: ThirdParties
+    description: 3rd party code can significantly impact load performance. [Reduce and defer loading of 3rd party code](https://web.dev/articles/optimizing-content-efficiency-loading-third-party-javascript/) to prioritize your page's content.
+    relevant trace bounds: {min: 337944792445, max: 337944809570}
+    example question: Which third parties are having the largest impact on my page performance?
+=== end content
+
 Title: PerformanceTraceFormatter formatNetworkRequests formats network requests that have redirects
 Content:
 ## Network request: http://localhost:3000/redirect3

front_end/models/ai_assistance/data_formatters/PerformanceTraceFormatter.test.ts

@@ -57,6 +57,14 @@ describeWithEnvironment('PerformanceTraceFormatter', () => {
       const output = formatter.formatTraceSummary();
       snapshotTester.assert(this, output);
     });
+
+    it('includes INP insight when there is no navigation', async function() {
+      const {formatter} = await createFormatter(this, 'slow-interaction-button-click.json.gz');
+      const output = formatter.formatTraceSummary();
+      assert.include(output, 'INP: 139 ms');
+      assert.include(output, 'insight name: INPBreakdown');
+      snapshotTester.assert(this, output);
+    });
   });
 
   it('formatCriticalRequests', async function() {

front_end/models/ai_assistance/performance/AIContext.ts

@@ -16,11 +16,26 @@ interface AgentFocusData {
   insight: Trace.Insights.Types.InsightModel|null;
 }
 
+/**
+ * Gets the first, most relevant InsightSet to use, following the logic of:
+ * 1. If there is only one InsightSet, use that.
+ * 2. If there are more, prefer the first we find that has a navigation associated with it.
+ * 3. If none with a navigation are found, fallback to the first one.
+ * 4. Otherwise, return null.
+ *
+ * TODO(cjamcl): we should just give the agent the entire insight set, and give
+ * summary detail about all of them + the ability to query each.
+ */
 function getFirstInsightSet(insights: Trace.Insights.Types.TraceInsightSets): Trace.Insights.Types.InsightSet|null {
-  // Currently only support a single insight set. Pick the first one with a navigation.
-  // TODO(cjamcl): we should just give the agent the entire insight set, and give
-  // summary detail about all of them + the ability to query each.
-  return [...insights.values()].filter(insightSet => insightSet.navigation).at(0) ?? null;
+  const insightSets = Array.from(insights.values());
+  if (insightSets.length === 0) {
+    return null;
+  }
+  if (insightSets.length === 1) {
+    return insightSets[0];
+  }
+
+  return insightSets.filter(set => set.navigation).at(0) ?? insightSets.at(0) ?? null;
 }
 
 export class AgentFocus {