diff --git a/core/http/react-ui/src/components/Sidebar.jsx b/core/http/react-ui/src/components/Sidebar.jsx
index 1607c060c..58438fd51 100644
--- a/core/http/react-ui/src/components/Sidebar.jsx
+++ b/core/http/react-ui/src/components/Sidebar.jsx
@@ -130,12 +130,14 @@ export default function Sidebar({ isOpen, onClose }) {
   }, [location.pathname])
 
   const toggleCollapse = () => {
-    setCollapsed(prev => {
-      const next = !prev
-      try { localStorage.setItem(COLLAPSED_KEY, String(next)) } catch (_) { /* ignore */ }
-      window.dispatchEvent(new CustomEvent('sidebar-collapse', { detail: { collapsed: next } }))
-      return next
-    })
+    // Side effects (persist + broadcast) live in the handler body, never inside
+    // the setState updater: StrictMode double-invokes updaters in dev, and the
+    // synchronous sidebar-collapse dispatch re-entered setState from the
+    // listeners mid-update, so the toggle silently no-op'd in dev builds.
+    const next = !collapsed
+    try { localStorage.setItem(COLLAPSED_KEY, String(next)) } catch (_) { /* ignore */ }
+    setCollapsed(next)
+    window.dispatchEvent(new CustomEvent('sidebar-collapse', { detail: { collapsed: next } }))
   }
 
   const toggleSection = (id) => {
diff --git a/core/http/react-ui/src/pages/Talk.jsx b/core/http/react-ui/src/pages/Talk.jsx
index f8e49e102..d898bd67b 100644
--- a/core/http/react-ui/src/pages/Talk.jsx
+++ b/core/http/react-ui/src/pages/Talk.jsx
@@ -127,9 +127,12 @@ export default function Talk() {
       .finally(() => setModelsLoading(false))
   }, [])
 
-  // Auto-scroll transcript
+  // Auto-scroll the transcript's own overflow container. scrollIntoView bubbles
+  // to every scrollable ancestor (incl. the window), which yanked the whole
+  // page down to the transcript box on mount; scoping to the box avoids it.
   useEffect(() => {
-    transcriptEndRef.current?.scrollIntoView({ behavior: 'smooth' })
+    const box = transcriptEndRef.current?.parentElement
+    box?.scrollTo({ top: box.scrollHeight, behavior: 'smooth' })
   }, [transcript])
 
   // Mirror Chat.jsx: connect / disconnect client MCP servers as the user toggles them.