diff --git a/src/components/conversations/conversation-detail-panel.tsx b/src/components/conversations/conversation-detail-panel.tsx
index cea7a4f..1d2286d 100644
--- a/src/components/conversations/conversation-detail-panel.tsx
+++ b/src/components/conversations/conversation-detail-panel.tsx
@@ -137,7 +137,7 @@ const ConversationTabView = memo(function ConversationTabView({
   const tWelcome = useTranslations("Folder.chat.welcomeInputPanel")
   const sharedT = useTranslations("Folder.chat.shared")
   const { folder, folderId, refreshConversations } = useFolderContext()
-  const { bindConversationTab } = useTabContext()
+  const { bindConversationTab, setTabRuntimeConversationId } = useTabContext()
   const { setSessionStats } = useSessionStats()
   const {
     appendOptimisticTurn,
@@ -177,6 +177,19 @@ const ConversationTabView = memo(function ConversationTabView({
   const canAutoConnect =
     hasPersistedConversation || (agentsLoaded && usableAgentCount > 0)
 
+  // Expose the runtime session key to the tab so the aux panel (Diff sidebar)
+  // can look up live turns even before the DB conversation is created.
+  useEffect(() => {
+    if (effectiveConversationId !== conversationId) {
+      setTabRuntimeConversationId(tabId, effectiveConversationId)
+    }
+  }, [
+    tabId,
+    effectiveConversationId,
+    conversationId,
+    setTabRuntimeConversationId,
+  ])
+
   // Clear pendingCleanup when tab is (re)opened
   useEffect(() => {
     setPendingCleanup(effectiveConversationId, false)
@@ -544,7 +557,13 @@ const ConversationTabView = memo(function ConversationTabView({
           }
 
           setCreatedConversationId(newConversationId)
-          bindConversationTab(tabId, newConversationId, selectedAgent, title)
+          bindConversationTab(
+            tabId,
+            newConversationId,
+            selectedAgent,
+            title,
+            effectiveConversationId
+          )
           moveMessageInputDraft(
             buildNewConversationDraftStorageKey({ folderId }),
             buildConversationDraftStorageKey(selectedAgent, newConversationId)
diff --git a/src/components/layout/aux-panel-session-files-tab.tsx b/src/components/layout/aux-panel-session-files-tab.tsx
index 1515faf..938160b 100644
--- a/src/components/layout/aux-panel-session-files-tab.tsx
+++ b/src/components/layout/aux-panel-session-files-tab.tsx
@@ -265,7 +265,8 @@ export function SessionFilesTab() {
   const { tabs, activeTabId } = useTabContext()
 
   const activeTab = tabs.find((t) => t.id === activeTabId)
-  const conversationId = activeTab?.conversationId
+  const conversationId =
+    activeTab?.runtimeConversationId ?? activeTab?.conversationId
 
   if (!activeTab) {
     return (
diff --git a/src/contexts/tab-context.tsx b/src/contexts/tab-context.tsx
index d9e2265..c68bef3 100644
--- a/src/contexts/tab-context.tsx
+++ b/src/contexts/tab-context.tsx
@@ -24,6 +24,10 @@ interface TabItemInternal {
   id: string
   kind: "conversation"
   conversationId: number | null
+  /** The runtime session key used by ConversationRuntimeContext.
+   *  For new conversations this is a virtual (negative) ID that differs
+   *  from the persisted `conversationId`. */
+  runtimeConversationId?: number
   agentType: AgentType
   title: string
   isPinned: boolean
@@ -55,7 +59,12 @@ interface TabContextValue {
     tabId: string,
     conversationId: number,
     agentType: AgentType,
-    title: string
+    title: string,
+    runtimeConversationId?: number
+  ) => void
+  setTabRuntimeConversationId: (
+    tabId: string,
+    runtimeConversationId: number
   ) => void
   reorderTabs: (reorderedTabs: TabItem[]) => void
 }
@@ -558,13 +567,20 @@ export function TabProvider({ children }: TabProviderProps) {
       tabId: string,
       conversationId: number,
       agentType: AgentType,
-      title: string
+      title: string,
+      runtimeConversationId?: number
     ) => {
       let nextActiveTabId: string | null = null
       setTabs((prev) =>
         prev.flatMap((tab) => {
           if (tab.id === tabId) {
-            const nextTab = { ...tab, conversationId, agentType, title }
+            const nextTab = {
+              ...tab,
+              conversationId,
+              agentType,
+              title,
+              runtimeConversationId,
+            }
             return [nextTab]
           }
 
@@ -594,6 +610,17 @@ export function TabProvider({ children }: TabProviderProps) {
     [syncFolderContext]
   )
 
+  const setTabRuntimeConversationId = useCallback(
+    (tabId: string, runtimeConversationId: number) => {
+      setTabs((prev) =>
+        prev.map((tab) =>
+          tab.id === tabId ? { ...tab, runtimeConversationId } : tab
+        )
+      )
+    },
+    []
+  )
+
   const value = useMemo(
     () => ({
       tabs,
@@ -609,6 +636,7 @@ export function TabProvider({ children }: TabProviderProps) {
       toggleTileMode,
       openNewConversationTab,
       bindConversationTab,
+      setTabRuntimeConversationId,
       reorderTabs,
     }),
     [
@@ -625,6 +653,7 @@ export function TabProvider({ children }: TabProviderProps) {
       toggleTileMode,
       openNewConversationTab,
       bindConversationTab,
+      setTabRuntimeConversationId,
       reorderTabs,
     ]
   )