feat(jsonl): enhance message counting logic for AIGroup interactions

- Added logic to await the first main-thread assistant message after a UserGroup to accurately count AIGroup messages.
- Updated tests to reflect the new message counting behavior, ensuring correct results in session file analysis.

src/main/utils/jsonl.ts

@@ -328,6 +328,8 @@ export async function analyzeSessionFileMetadata(
   let firstUserMessage: { text: string; timestamp: string } | null = null;
   let firstCommandMessage: { text: string; timestamp: string } | null = null;
   let messageCount = 0;
+  // After a UserGroup, await the first main-thread assistant message to count the AIGroup
+  let awaitingAIGroup = false;
   let gitBranch: string | null = null;
 
   let activityIndex = 0;
@@ -357,6 +359,15 @@ export async function analyzeSessionFileMetadata(
 
     if (isParsedUserChunkMessage(parsed)) {
       messageCount++;
+      awaitingAIGroup = true;
+    } else if (
+      awaitingAIGroup &&
+      parsed.type === 'assistant' &&
+      parsed.model !== '<synthetic>' &&
+      !parsed.isSidechain
+    ) {
+      messageCount++;
+      awaitingAIGroup = false;
     }
 
     if (!gitBranch && 'gitBranch' in entry && entry.gitBranch) {

test/main/utils/jsonl.test.ts

@@ -166,7 +166,7 @@ describe('jsonl', () => {
 
         expect(result.firstUserMessage?.text).toBe('hello world');
         expect(result.firstUserMessage?.timestamp).toBe('2026-01-01T00:00:00.000Z');
-        expect(result.messageCount).toBe(1);
+        expect(result.messageCount).toBe(2);
         expect(result.isOngoing).toBe(true);
         expect(result.gitBranch).toBe('feature/test');
       } finally {