diff --git a/frontend/src/shared/state/dashboardLayoutSlice.ts b/frontend/src/shared/state/dashboardLayoutSlice.ts
index 29ccdc0f..e2b067fb 100644
--- a/frontend/src/shared/state/dashboardLayoutSlice.ts
+++ b/frontend/src/shared/state/dashboardLayoutSlice.ts
@@ -589,13 +589,9 @@ function addMissingCards<T extends { x: number; y: number; width: number; height
 function clearOtherDocks(state: { browserCards: Record<string, BrowserCardPosition>; viewCards: Record<string, ViewCardPosition> }, sessionId: string, keepBrowserId?: string): void {
   for (const bc of Object.values(state.browserCards)) {
     if (bc.docked_to !== sessionId) continue;
-    // The card being (re-)docked must survive its own clear: layout sync re-asserts docks, and deleting the assertee would vanish a live browser.
+    // The card being (re-)docked must survive its own clear: layout sync re-asserts docks.
     if (bc.browser_id === keepBrowserId) continue;
-    // An agent-owned browser displaced by its replacement is a corpse (the agent spins a fresh one when a tab dies); releasing it to the canvas painted dead stacked windows next to the chat.
-    if (bc.spawned_by === sessionId) {
-      delete state.browserCards[bc.browser_id];
-      continue;
-    }
+    // Corpse cleanup happens in WebSocketManager via removeBrowserCardCleanly, NOT here: a bare store delete gets resurrected by the backend layout sync as a free card.
     bc.docked_to = null;
   }
   for (const vc of Object.values(state.viewCards)) {
diff --git a/frontend/src/shared/ws/WebSocketManager.ts b/frontend/src/shared/ws/WebSocketManager.ts
index cd297690..7b36e50c 100644
--- a/frontend/src/shared/ws/WebSocketManager.ts
+++ b/frontend/src/shared/ws/WebSocketManager.ts
@@ -843,6 +843,12 @@ class WebSocketManager {
               let glowLabel = 'Use Browser';
               if (parentCard) {
                 pos = placeBrowserBesideChat(layoutState, parentCard, parentId, browserCard.width, browserCard.height, browserCard.browser_id);
+                // A replacement browser buries its predecessor: the agent spins a fresh card when a tab dies, and the displaced spawned sibling must be torn down through the FULL path (a bare store delete gets resurrected by the backend layout sync as a free stacked window).
+                for (const old of Object.values(layoutState.browserCards)) {
+                  if (old.browser_id !== browserCard.browser_id && old.spawned_by === parentId && !old.keep_open) {
+                    void import('@/shared/browserTeardown').then(({ removeBrowserCardCleanly }) => removeBrowserCardCleanly(old.browser_id, store.dispatch));
+                  }
+                }
                 // Default home is INSIDE the chat: the card overlays the chat's dock slot while the
                 // chat is expanded; the beside-chat spot stays the undock/collapse fallback.
                 store.dispatch(setBrowserDocked({ browserId: browserCard.browser_id, dockedTo: parentId }));