fix(frontend): reconnect stream on same-session resume

frontend/src/shell/AppShell.tsx

@@ -32,6 +32,7 @@ import { useEffect, useMemo, useRef, useState } from "react";
  */
 export function AppShell() {
   const [activeSessionId, setActiveSessionId] = useState<string | null>(null);
+  const [streamGeneration, setStreamGeneration] = useState(0);
   const [creatingSession, setCreatingSession] = useState(false);
   const [awaitingQuestion, setAwaitingQuestion] = useState(false);
   const { data: sessions = [] } = useQuery<SessionSummary[]>({
@@ -100,6 +101,7 @@ export function AppShell() {
   }
   async function doResume(id: string) {
     const s = sessions.find((x) => x.id === id) ?? null;
+    const reconnectSameSession = activeSessionId === id;
     // Optimistic switch: change to the session view IMMEDIATELY so the click feels
     // instant (the resume POST spawns a Pi process and can take seconds). The
     // working spinner shows straight away; the backend calls run after.
@@ -111,6 +113,7 @@ export function AppShell() {
     setActiveSessionId(id);
     try {
       await resumeSession(id);
+      if (reconnectSameSession) setStreamGeneration((value) => value + 1);
       // Optimistic phase paint: colour the re-entry phase before the first gate.
       // The manifest's `phase` is the 1-based current phase (1..8).
       try {
@@ -218,7 +221,7 @@ export function AppShell() {
   // session sits idle or a gate awaits the reviewer (pendingWidget).
   const running = working && !finalized;
 
-  useSessionStream(activeSessionId);
+  useSessionStream(activeSessionId, streamGeneration);
 
   // A backend "session_exit" system event (e.g. the replay server emitting it
   // when the reviewer picks "Esci") asks us to leave the live session view and