feat: Print object count and total sizes in get_heapsnapshot_details (#2325)

This emits object count and total shallow sizes for
get_heapsnapshot_details.

src/HeapSnapshotManager.ts

@@ -17,6 +17,12 @@ import {
 export type AggregatedInfoWithId =
   WithSymbolId<DevTools.HeapSnapshotModel.HeapSnapshotModel.AggregatedInfo>;
 
+export interface HeapSnapshotAggregateData {
+  aggregates: Record<string, AggregatedInfoWithId>;
+  objectCount: number;
+  totalSelfSize: number;
+}
+
 export interface HeapSnapshotClassDiff {
   className: string;
   addedCount: number;
@@ -74,7 +80,7 @@ export class HeapSnapshotManager {
   async getAggregates(
     filePath: string,
     filterName?: string,
-  ): Promise<Record<string, AggregatedInfoWithId>> {
+  ): Promise<HeapSnapshotAggregateData> {
     const snapshot = await this.getSnapshot(filePath);
     const filter =
       new DevTools.HeapSnapshotModel.HeapSnapshotModel.NodeFilter();
@@ -83,16 +89,21 @@ export class HeapSnapshotManager {
     }
     const aggregates: Record<string, AggregatedInfoWithId> =
       await snapshot.aggregatesWithFilter(filter);
+    let objectCount = 0;
+    let totalSelfSize = 0;
 
-    for (const key of Object.keys(aggregates)) {
+    for (const [key, aggregate] of Object.entries(aggregates)) {
       const id = await this.getOrCreateIdForClassKey(filePath, key);
-      const aggregate = aggregates[key];
-      if (aggregate) {
-        aggregate[stableIdSymbol] = id;
-      }
+      aggregate[stableIdSymbol] = id;
+      objectCount += aggregate.count;
+      totalSelfSize += aggregate.self;
     }
 
-    return aggregates;
+    return {
+      aggregates,
+      objectCount,
+      totalSelfSize,
+    };
   }
 
   async getStats(

src/McpContext.ts

@@ -17,7 +17,7 @@ import {
 } from './devtools/DevtoolsUtils.js';
 import {HeapSnapshotManager} from './HeapSnapshotManager.js';
 import type {
-  AggregatedInfoWithId,
+  HeapSnapshotAggregateData,
   HeapSnapshotClassDiff,
   HeapSnapshotDetailedClassDiff,
   DuplicateStringGroup,
@@ -972,7 +972,7 @@ export class McpContext implements Context {
   async getHeapSnapshotAggregates(
     filePath: string,
     filterName?: string,
-  ): Promise<Record<string, AggregatedInfoWithId>> {
+  ): Promise<HeapSnapshotAggregateData> {
     return await this.#heapSnapshotManager.getAggregates(filePath, filterName);
   }
 

src/McpResponse.ts

@@ -17,6 +17,7 @@ import {IssueFormatter} from './formatters/IssueFormatter.js';
 import {NetworkFormatter} from './formatters/NetworkFormatter.js';
 import {SnapshotFormatter} from './formatters/SnapshotFormatter.js';
 import type {
+  HeapSnapshotAggregateData,
   HeapSnapshotClassDiff,
   HeapSnapshotDetailedClassDiff,
   DuplicateStringGroup,
@@ -230,10 +231,7 @@ export class McpResponse implements Response {
   #images: ImageContentData[] = [];
   #heapSnapshotOptions?: {
     include: boolean;
-    aggregates?: Record<
-      string,
-      DevTools.HeapSnapshotModel.HeapSnapshotModel.AggregatedInfo
-    >;
+    aggregateData?: HeapSnapshotAggregateData;
     pagination?: PaginationOptions;
     stats?: DevTools.HeapSnapshotModel.HeapSnapshotModel.Statistics;
     staticData?: DevTools.HeapSnapshotModel.HeapSnapshotModel.StaticData | null;
@@ -461,16 +459,13 @@ export class McpResponse implements Response {
   }
 
   setHeapSnapshotAggregates(
-    aggregates: Record<
-      string,
-      DevTools.HeapSnapshotModel.HeapSnapshotModel.AggregatedInfo
-    >,
+    aggregateData: HeapSnapshotAggregateData,
     options?: PaginationOptions,
   ) {
     this.#heapSnapshotOptions = {
       ...this.#heapSnapshotOptions,
       include: true,
-      aggregates,
+      aggregateData,
       pagination: options,
     };
   }
@@ -877,6 +872,10 @@ export class McpResponse implements Response {
       heapSnapshot?: {
         stats?: object;
         staticData?: object;
+        aggregateStats?: {
+          objectCount: number;
+          totalSelfSize: number;
+        };
       };
       heapSnapshotData?: object[];
       heapSnapshotNodes?: readonly object[];
@@ -1169,15 +1168,28 @@ Call ${handleDialog.name} to handle it before continuing.`);
         structuredContent.heapSnapshot = structuredContent.heapSnapshot || {};
         structuredContent.heapSnapshot.staticData = staticData;
       }
-      const aggregates = this.#heapSnapshotOptions.aggregates;
-      if (aggregates) {
-        const sortedEntries = HeapSnapshotFormatter.sort(aggregates);
+      const aggregateData = this.#heapSnapshotOptions.aggregateData;
+      if (aggregateData) {
+        const sortedEntries = HeapSnapshotFormatter.sort(
+          aggregateData.aggregates,
+        );
 
         const paginationData = this.#dataWithPagination(
           sortedEntries,
           this.#heapSnapshotOptions.pagination,
         );
 
+        response.push(`Objects: ${aggregateData.objectCount}`);
+        response.push(
+          `Total shallow size: ${DevTools.I18n.ByteUtilities.formatBytesToKb(
+            aggregateData.totalSelfSize,
+          )}`,
+        );
+        structuredContent.heapSnapshot = structuredContent.heapSnapshot || {};
+        structuredContent.heapSnapshot.aggregateStats = {
+          objectCount: aggregateData.objectCount,
+          totalSelfSize: aggregateData.totalSelfSize,
+        };
         structuredContent.pagination = paginationData.pagination;
         response.push(...paginationData.info);
 

src/tools/ToolDefinition.ts

@@ -6,7 +6,7 @@
 
 import type {ParsedArguments} from '../bin/chrome-devtools-mcp-cli-options.js';
 import type {
-  AggregatedInfoWithId,
+  HeapSnapshotAggregateData,
   HeapSnapshotClassDiff,
   HeapSnapshotDetailedClassDiff,
   DuplicateStringGroup,
@@ -107,10 +107,7 @@ export interface DevToolsData {
 export interface Response {
   appendResponseLine(value: string): void;
   setHeapSnapshotAggregates(
-    aggregates: Record<
-      string,
-      DevTools.HeapSnapshotModel.HeapSnapshotModel.AggregatedInfo
-    >,
+    aggregateData: HeapSnapshotAggregateData,
     options?: PaginationOptions,
   ): void;
   setHeapSnapshotStats(
@@ -258,7 +255,7 @@ export type Context = Readonly<{
   getHeapSnapshotAggregates(
     filePath: string,
     filterName?: string,
-  ): Promise<Record<string, AggregatedInfoWithId>>;
+  ): Promise<HeapSnapshotAggregateData>;
   getHeapSnapshotDuplicateStrings(
     filePath: string,
   ): Promise<DuplicateStringGroup[]>;

tests/tools/memory.test.js.snapshot

@@ -63,6 +63,8 @@ Showing 1-6 of 6 (Page 1 of 1).
 
 exports[`memory > get_heapsnapshot_details > with default options 1`] = `
 ## Heap Snapshot Data
+Objects: 11940
+Total shallow size: 802 kB
 Showing 1-157 of 157 (Page 1 of 1).
 id,name,count,selfSize,maxRetainedSize
 2,(system),3205,199 kB,655 kB
@@ -226,6 +228,8 @@ id,name,count,selfSize,maxRetainedSize
 
 exports[`memory > get_heapsnapshot_details > with objectsRetainedByContexts filterName 1`] = `
 ## Heap Snapshot Data
+Objects: 148
+Total shallow size: 3.5 kB
 Showing 1-4 of 4 (Page 1 of 1).
 id,name,count,selfSize,maxRetainedSize
 1,system / Context,116,2.5 kB,3.5 kB

tests/tools/memory.test.ts

@@ -168,11 +168,11 @@ describe('memory', () => {
           'tests/fixtures/example.heapsnapshot',
         );
 
-        const aggregates = await context.getHeapSnapshotAggregates(
+        const aggregateData = await context.getHeapSnapshotAggregates(
           filePath,
           'objectsRetainedByContexts',
         );
-        const aggregate = Object.values(aggregates).find(
+        const aggregate = Object.values(aggregateData.aggregates).find(
           a => a.name === 'Function',
         );
         assert.ok(aggregate);