feat(webui): show forked history boundary

webui/src/hooks/useSessions.ts

@@ -20,7 +20,7 @@ export function useSessions(): {
   error: string | null;
   refresh: () => Promise<void>;
   createChat: (workspaceScope?: WorkspaceScopePayload | null) => Promise<string>;
-  forkChat: (sourceChatId: string, beforeUserIndex: number) => Promise<string>;
+  forkChat: (sourceChatId: string, beforeUserIndex: number, title?: string) => Promise<string>;
   deleteChat: (key: string) => Promise<void>;
 } {
   const { client, token } = useClient();
@@ -92,8 +92,9 @@ export function useSessions(): {
   const forkChat = useCallback(async (
     sourceChatId: string,
     beforeUserIndex: number,
+    title?: string,
   ): Promise<string> => {
-    const chatId = await client.forkChat(sourceChatId, beforeUserIndex);
+    const chatId = await client.forkChat(sourceChatId, beforeUserIndex, title);
     const key = `websocket:${chatId}`;
     optimisticKeysRef.current.add(key);
     setSessions((prev) => [
@@ -103,7 +104,7 @@ export function useSessions(): {
         chatId,
         createdAt: new Date().toISOString(),
         updatedAt: new Date().toISOString(),
-        title: "",
+        title: title ?? "",
         preview: "",
         workspaceScope: null,
       },
@@ -131,6 +132,7 @@ export function useSessionHistory(key: string | null): {
   error: string | null;
   refresh: () => void;
   version: number;
+  forkBoundaryMessageCount: number | null;
   /** ``true`` when the replayed transcript ends with a trace row (turn still in flight). */
   hasPendingToolCalls: boolean;
 } {
@@ -145,6 +147,7 @@ export function useSessionHistory(key: string | null): {
     loading: boolean;
     error: string | null;
     hasPendingToolCalls: boolean;
+    forkBoundaryMessageCount: number | null;
     version: number;
   }>({
     key: null,
@@ -152,6 +155,7 @@ export function useSessionHistory(key: string | null): {
     loading: false,
     error: null,
     hasPendingToolCalls: false,
+    forkBoundaryMessageCount: null,
     version: 0,
   });
 
@@ -163,6 +167,7 @@ export function useSessionHistory(key: string | null): {
         loading: false,
         error: null,
         hasPendingToolCalls: false,
+        forkBoundaryMessageCount: null,
         version: 0,
       });
       return;
@@ -178,6 +183,7 @@ export function useSessionHistory(key: string | null): {
           loading: true,
           error: null,
           hasPendingToolCalls: false,
+          forkBoundaryMessageCount: null,
           version: 0,
         });
     (async () => {
@@ -191,6 +197,7 @@ export function useSessionHistory(key: string | null): {
             loading: false,
             error: null,
             hasPendingToolCalls: false,
+            forkBoundaryMessageCount: null,
             version: prev.key === key ? prev.version + 1 : 1,
           }));
           return;
@@ -202,12 +209,16 @@ export function useSessionHistory(key: string | null): {
         }));
         const last = ui[ui.length - 1];
         const hasPending = last?.kind === "trace";
+        const forkBoundary = typeof body.fork_boundary_message_count === "number"
+          ? Math.max(0, Math.min(body.fork_boundary_message_count, ui.length))
+          : null;
         setState((prev) => ({
           key,
           messages: ui,
           loading: false,
           error: null,
           hasPendingToolCalls: hasPending,
+          forkBoundaryMessageCount: forkBoundary,
           version: prev.key === key ? prev.version + 1 : 1,
         }));
       } catch (e) {
@@ -219,6 +230,7 @@ export function useSessionHistory(key: string | null): {
             loading: false,
             error: null,
             hasPendingToolCalls: false,
+            forkBoundaryMessageCount: null,
             version: prev.key === key ? prev.version + 1 : 1,
           }));
         } else {
@@ -228,6 +240,7 @@ export function useSessionHistory(key: string | null): {
             loading: false,
             error: (e as Error).message,
             hasPendingToolCalls: false,
+            forkBoundaryMessageCount: null,
             version: prev.key === key ? prev.version : 0,
           }));
         }
@@ -245,6 +258,7 @@ export function useSessionHistory(key: string | null): {
       error: null,
       refresh,
       version: 0,
+      forkBoundaryMessageCount: null,
       hasPendingToolCalls: false,
     };
   }
@@ -258,6 +272,7 @@ export function useSessionHistory(key: string | null): {
       error: null,
       refresh,
       version: 0,
+      forkBoundaryMessageCount: null,
       hasPendingToolCalls: false,
     };
   }
@@ -268,6 +283,7 @@ export function useSessionHistory(key: string | null): {
     error: state.error,
     refresh,
     version: state.version,
+    forkBoundaryMessageCount: state.forkBoundaryMessageCount,
     hasPendingToolCalls: state.hasPendingToolCalls,
   };
 }