fix(desktop): swap session in-place when switching workDir on empty session

Instead of close tab → delete session → create session → open tab (which
causes visual flicker and tab jumping), create the new session first then
replace the tab's sessionId in-place via a new replaceTabSession method.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

desktop/src/components/chat/ChatInput.tsx

@@ -531,16 +531,17 @@ export function ChatInput() {
               value={gitInfo?.workDir || activeSession?.workDir || ''}
               onChange={async (newWorkDir) => {
                 if (!activeTabId) return
-                // Recreate session with new workDir
+                const oldId = activeTabId
                 const { deleteSession, createSession } = useSessionStore.getState()
-                const { closeTab, openTab } = useTabStore.getState()
+                const { replaceTabSession } = useTabStore.getState()
                 const { disconnectSession, connectToSession } = useChatStore.getState()
-                disconnectSession(activeTabId)
-                closeTab(activeTabId)
-                await deleteSession(activeTabId)
+                // Create new session first, then swap tab in-place
                 const newId = await createSession(newWorkDir)
-                openTab(newId, t('sidebar.newSession'))
+                disconnectSession(oldId)
+                replaceTabSession(oldId, newId)
                 connectToSession(newId)
+                // Clean up old session in background
+                deleteSession(oldId).catch(() => {})
               }}
             />
           )}

desktop/src/stores/tabStore.ts

@@ -29,6 +29,7 @@ type TabStore = {
   setActiveTab: (sessionId: string) => void
   updateTabTitle: (sessionId: string, title: string) => void
   updateTabStatus: (sessionId: string, status: Tab['status']) => void
+  replaceTabSession: (oldSessionId: string, newSessionId: string) => void
   moveTab: (fromIndex: number, toIndex: number) => void
 
   saveTabs: () => void
@@ -93,6 +94,17 @@ export const useTabStore = create<TabStore>((set, get) => ({
     }))
   },
 
+  replaceTabSession: (oldSessionId, newSessionId) => {
+    const { activeTabId } = get()
+    set((s) => ({
+      tabs: s.tabs.map((t) =>
+        t.sessionId === oldSessionId ? { ...t, sessionId: newSessionId } : t,
+      ),
+      activeTabId: activeTabId === oldSessionId ? newSessionId : activeTabId,
+    }))
+    get().saveTabs()
+  },
+
   moveTab: (fromIndex, toIndex) => {
     if (fromIndex === toIndex) return
     const { tabs } = get()