🤖 fix: persist chat processors across navigation to preserve streaming state

Change-Id: Id26c2f8f576aa25052337c08bd99979d3b6327ee
Signed-off-by: Test <test@example.com>

Author: Test

mobile/app/_layout.tsx

@@ -6,6 +6,7 @@ import { SafeAreaProvider } from "react-native-safe-area-context";
 import { StatusBar } from "expo-status-bar";
 import { View } from "react-native";
 import { ThemeProvider, useTheme } from "../src/theme";
+import { WorkspaceChatProvider } from "../src/contexts/WorkspaceChatContext";
 
 function AppFrame(): JSX.Element {
   const theme = useTheme();
@@ -71,7 +72,9 @@ export default function RootLayout(): JSX.Element {
     <QueryClientProvider client={client}>
       <SafeAreaProvider>
         <ThemeProvider>
-          <AppFrame />
+          <WorkspaceChatProvider>
+            <AppFrame />
+          </WorkspaceChatProvider>
         </ThemeProvider>
       </SafeAreaProvider>
     </QueryClientProvider>

mobile/src/contexts/WorkspaceChatContext.tsx

@@ -0,0 +1,64 @@
+import type { JSX, ReactNode } from "react";
+import { createContext, useCallback, useContext, useRef } from "react";
+import { createChatEventExpander } from "../messages/normalizeChatEvent";
+import type { ChatEventExpander } from "../messages/normalizeChatEvent";
+
+interface WorkspaceChatContextValue {
+  /**
+   * Get or create a ChatEventExpander for the given workspace.
+   * Processors are cached per workspaceId to preserve streaming state across navigation.
+   */
+  getExpander(workspaceId: string): ChatEventExpander;
+
+  /**
+   * Clear the processor for a specific workspace (e.g., when workspace is deleted).
+   */
+  clearExpander(workspaceId: string): void;
+
+  /**
+   * Clear all processors (e.g., on logout).
+   */
+  clearAll(): void;
+}
+
+const WorkspaceChatContext = createContext<WorkspaceChatContextValue | null>(null);
+
+export function WorkspaceChatProvider({ children }: { children: ReactNode }): JSX.Element {
+  // Store processors keyed by workspaceId
+  // Using ref to avoid re-renders when processors are created/destroyed
+  const expandersRef = useRef<Map<string, ChatEventExpander>>(new Map());
+
+  const getExpander = useCallback((workspaceId: string): ChatEventExpander => {
+    const existing = expandersRef.current.get(workspaceId);
+    if (existing) {
+      return existing;
+    }
+
+    // Lazy-create processor on first access
+    const newExpander = createChatEventExpander();
+    expandersRef.current.set(workspaceId, newExpander);
+    return newExpander;
+  }, []);
+
+  const clearExpander = useCallback((workspaceId: string): void => {
+    expandersRef.current.delete(workspaceId);
+  }, []);
+
+  const clearAll = useCallback((): void => {
+    expandersRef.current.clear();
+  }, []);
+
+  return (
+    <WorkspaceChatContext.Provider value={{ getExpander, clearExpander, clearAll }}>
+      {children}
+    </WorkspaceChatContext.Provider>
+  );
+}
+
+export function useWorkspaceChat(): WorkspaceChatContextValue {
+  const context = useContext(WorkspaceChatContext);
+  if (!context) {
+    throw new Error("useWorkspaceChat must be used within WorkspaceChatProvider");
+  }
+  return context;
+}

mobile/src/messages/normalizeChatEvent.ts

@@ -12,7 +12,7 @@ import { createChatEventProcessor } from "@/browser/utils/messages/ChatEventProc
 
 type IncomingEvent = WorkspaceChatEvent | DisplayedMessage | string | number | null | undefined;
 
-interface ChatEventExpander {
+export interface ChatEventExpander {
   expand(event: IncomingEvent | IncomingEvent[]): WorkspaceChatEvent[];
 }
 
@@ -420,5 +420,3 @@ export function createChatEventExpander(): ChatEventExpander {
 
   return { expand };
 }
-
-export type { ChatEventExpander };

mobile/src/screens/WorkspaceScreen.tsx

@@ -30,8 +30,8 @@ import { useWorkspaceSettings } from "../hooks/useWorkspaceSettings";
 import type { ThinkingLevel, WorkspaceMode } from "../types/settings";
 import { FloatingTodoCard } from "../components/FloatingTodoCard";
 import type { TodoItem } from "../components/TodoItemView";
-import { createChatEventExpander } from "../messages/normalizeChatEvent";
 import type { DisplayedMessage, FrontendWorkspaceMetadata, WorkspaceChatEvent } from "../types";
+import { useWorkspaceChat } from "../contexts/WorkspaceChatContext";
 import { applyChatEvent, TimelineEntry } from "./chatTimelineReducer";
 import type { SlashSuggestion } from "@/browser/utils/slashCommands/types";
 import { parseCommand } from "@/browser/utils/slashCommands/parser";
@@ -185,7 +185,7 @@ function WorkspaceScreenInner({
   const theme = useTheme();
   const spacing = theme.spacing;
   const insets = useSafeAreaInsets();
-  const expanderRef = useRef(createChatEventExpander());
+  const { getExpander } = useWorkspaceChat();
   const api = useApiClient();
   const {
     mode,
@@ -411,10 +411,6 @@ function WorkspaceScreenInner({
   const pendingTodosRef = useRef<TodoItem[] | null>(null);
   const [tokenDisplay, setTokenDisplay] = useState({ total: 0, tps: 0 });
 
-  useEffect(() => {
-    expanderRef.current = createChatEventExpander();
-  }, [workspaceId]);
-
   // Load branches in creation mode
   useEffect(() => {
     if (!isCreationMode || !creationContext) return;
@@ -477,7 +473,8 @@ function WorkspaceScreenInner({
     hasCaughtUpRef.current = false;
     pendingTodosRef.current = null;
 
-    const expander = expanderRef.current;
+    // Get persistent expander for this workspace (survives navigation)
+    const expander = getExpander(workspaceId!);
     const subscription = api.workspace.subscribeChat(workspaceId!, (payload) => {
       // Track streaming state and tokens (60s trailing window like desktop)
       if (payload && typeof payload === "object" && "type" in payload) {
@@ -609,7 +606,7 @@ function WorkspaceScreenInner({
       subscription.close();
       wsRef.current = null;
     };
-  }, [api, workspaceId, isCreationMode, recordStreamUsage]);
+  }, [api, workspaceId, isCreationMode, recordStreamUsage, getExpander]);
 
   // Reset timeline, todos, and editing state when workspace changes
   useEffect(() => {