[AI] Fix getResourceContent

* In trace_app, scripts don't show up in ResourceTreeModel, so check
  the Scripts handler data too
* Make sure never to use ResourceTreeModel if attached to a target
  unrelated to the trace
* Provide more guidance to the agent about when to call this function

Bug: 452333154
Change-Id: I04e617a4e351570c583b8c062a58d8ccc4616015
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/7129331
Commit-Queue: Connor Clark <[email protected]>
Auto-Submit: Connor Clark <[email protected]>
Reviewed-by: Paul Irish <[email protected]>

Author: Connor Clark

front_end/models/ai_assistance/agents/PerformanceAgent.ts

@@ -885,50 +885,60 @@ export class PerformanceAgent extends AiAgent<AgentFocus> {
     });
 
     const isFresh = Tracing.FreshRecording.Tracker.instance().recordingIsFresh(parsedTrace);
-    const hasScriptContents =
-        parsedTrace.metadata.enhancedTraceVersion && parsedTrace.data.Scripts.scripts.some(s => s.content);
+    const isTraceApp = Root.Runtime.Runtime.isTraceApp();
 
-    if (isFresh || hasScriptContents) {
-      this.declareFunction<{url: string}, {content: string}>('getResourceContent', {
-        description: 'Returns the content of the resource with the given url. Only use this for text resource types.',
-        parameters: {
-          type: Host.AidaClient.ParametersTypes.OBJECT,
-          description: '',
-          nullable: false,
-          properties: {
-            url: {
-              type: Host.AidaClient.ParametersTypes.STRING,
-              description: 'The url for the resource.',
-              nullable: false,
-            },
+    this.declareFunction<{url: string}, {content: string}>('getResourceContent', {
+      description:
+          'Returns the content of the resource with the given url. Only use this for text resource types. This function is helpful for getting script contents in order to further analyze main thread activity and suggest code improvements. When analyzing the main thread activity, always call this function to get more detail. Always call this function when asked to provide specifics about what is happening in the code. Never ask permission to call this function, just do it.',
+      parameters: {
+        type: Host.AidaClient.ParametersTypes.OBJECT,
+        description: '',
+        nullable: false,
+        properties: {
+          url: {
+            type: Host.AidaClient.ParametersTypes.STRING,
+            description: 'The url for the resource.',
+            nullable: false,
           },
         },
-        displayInfoFromArgs: args => {
-          return {title: lockedString('Looking at resource content…'), action: `getResourceContent('${args.url}')`};
-        },
-        handler: async args => {
-          debugLog('Function call: getResourceContent');
-
-          const url = args.url as Platform.DevToolsPath.UrlString;
+      },
+      displayInfoFromArgs: args => {
+        return {title: lockedString('Looking at resource content…'), action: `getResourceContent('${args.url}')`};
+      },
+      handler: async args => {
+        debugLog('Function call: getResourceContent');
+
+        const url = args.url as Platform.DevToolsPath.UrlString;
+        let content: string|undefined;
+
+        // First check parsedTrace.data.Scripts.
+        // Then, check ResourceTreeModel, but only when it is valid. Don't want to
+        // use if viewing a loaded trace from DevTools attached to an unrelated
+        // page.
+        const script = parsedTrace.data.Scripts.scripts.find(script => script.url === url);
+        if (script?.content !== undefined) {
+          content = script.content;
+        } else if (isFresh || isTraceApp) {
           const resource = SDK.ResourceTreeModel.ResourceTreeModel.resourceForURL(url);
           if (!resource) {
-            if (!resource) {
-              return {error: 'Resource not found'};
-            }
+            return {error: 'Resource not found'};
           }
 
-          const content = await resource.requestContentData();
-          if ('error' in content) {
-            return {error: `Could not get resource content: ${content.error}`};
+          const data = await resource.requestContentData();
+          if ('error' in data) {
+            return {error: `Could not get resource content: ${data.error}`};
           }
 
-          const key = `getResourceContent(${args.url})`;
-          this.#cacheFunctionResult(focus, key, content.text);
-          return {result: {content: content.text}};
-        },
+          content = data.text;
+        } else {
+          return {error: 'Resource not found'};
+        }
 
-      });
-    }
+        const key = `getResourceContent(${args.url})`;
+        this.#cacheFunctionResult(focus, key, content);
+        return {result: {content}};
+      },
+    });
 
     if (!context.external) {
       this.declareFunction<{eventKey: string}, {success: boolean}>('selectEventByKey', {