From 79b2f4b3b8c258c6fbf97397343fdce84a278ebd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=A8=8B=E5=BA=8F=E5=91=98=E9=98=BF=E6=B1=9F=28Relakkes?=
 =?UTF-8?q?=29?= <relakkes@gmail.com>
Date: Mon, 22 Jun 2026 22:24:39 +0800
Subject: [PATCH] fix(desktop): avoid prewarming viewed history sessions (#880)

Viewing an existing transcript should only load history, not start the CLI prewarm path. Empty placeholder sessions still prewarm so new chats stay fast.

Fixes #880

Tested: cd desktop && bunx vitest run src/stores/chatStore.test.ts
Tested: bun run check:desktop
Confidence: high
Scope-risk: narrow
---
 desktop/src/stores/chatStore.test.ts | 34 ++++++++++++++++++++++++++++
 desktop/src/stores/chatStore.ts      | 11 ++++++++-
 2 files changed, 44 insertions(+), 1 deletion(-)

diff --git a/desktop/src/stores/chatStore.test.ts b/desktop/src/stores/chatStore.test.ts
index 17f1ba71..ff780feb 100644
--- a/desktop/src/stores/chatStore.test.ts
+++ b/desktop/src/stores/chatStore.test.ts
@@ -215,6 +215,40 @@ describe('chatStore history mapping', () => {
     })
   })
 
+  it('does not prewarm an existing transcript when opening it for history review', () => {
+    sessionStoreSnapshot.sessions = [{
+      id: TEST_SESSION_ID,
+      title: 'Existing transcript',
+      createdAt: '2026-06-20T10:00:00.000Z',
+      modifiedAt: '2026-06-20T10:30:00.000Z',
+      messageCount: 4,
+      projectPath: '/workspace/project',
+      workDir: '/workspace/project',
+      workDirExists: true,
+    }]
+
+    useChatStore.getState().connectToSession(TEST_SESSION_ID)
+
+    expect(sendMock).not.toHaveBeenCalledWith(TEST_SESSION_ID, { type: 'prewarm_session' })
+  })
+
+  it('still prewarms empty placeholder sessions so new chats start quickly', () => {
+    sessionStoreSnapshot.sessions = [{
+      id: TEST_SESSION_ID,
+      title: 'New Session',
+      createdAt: '2026-06-20T10:00:00.000Z',
+      modifiedAt: '2026-06-20T10:00:00.000Z',
+      messageCount: 0,
+      projectPath: '/workspace/project',
+      workDir: '/workspace/project',
+      workDirExists: true,
+    }]
+
+    useChatStore.getState().connectToSession(TEST_SESSION_ID)
+
+    expect(sendMock).toHaveBeenCalledWith(TEST_SESSION_ID, { type: 'prewarm_session' })
+  })
+
   it('preserves thinking blocks when restoring transcript history', () => {
     const messages: MessageEntry[] = [
       {
diff --git a/desktop/src/stores/chatStore.ts b/desktop/src/stores/chatStore.ts
index 07c28a5c..a6247145 100644
--- a/desktop/src/stores/chatStore.ts
+++ b/desktop/src/stores/chatStore.ts
@@ -892,6 +892,11 @@ async function fetchAndMapSessionHistory(sessionId: string) {
 
 const historyLoadsInFlight = new Map<string, Promise<void>>()
 
+function shouldPrewarmSession(sessionId: string): boolean {
+  const knownSession = useSessionStore.getState().sessions.find((session) => session.id === sessionId)
+  return !knownSession || knownSession.messageCount === 0
+}
+
 export const useChatStore = create<ChatStore>((set, get) => ({
   sessions: {},
 
@@ -938,7 +943,11 @@ export const useChatStore = create<ChatStore>((set, get) => ({
     if (runtimeSelection) {
       wsManager.send(sessionId, { type: 'set_runtime_config', ...runtimeSelection })
     }
-    if (!sessionId.startsWith('__') && !useTeamStore.getState().getMemberBySessionId(sessionId)) {
+    if (
+      !sessionId.startsWith('__') &&
+      !useTeamStore.getState().getMemberBySessionId(sessionId) &&
+      shouldPrewarmSession(sessionId)
+    ) {
       wsManager.send(sessionId, { type: 'prewarm_session' })
     }