diff --git a/studio/frontend/src/app/provider.tsx b/studio/frontend/src/app/provider.tsx
index 8abb1df63e..1cc3d1ee57 100644
--- a/studio/frontend/src/app/provider.tsx
+++ b/studio/frontend/src/app/provider.tsx
@@ -255,7 +255,7 @@ const MAC_NATIVE_CHROME_STYLE = {
   "--studio-non-chat-content-top-inset": "34px",
   "--studio-hidden-route-top-inset": "34px",
   "--studio-chat-header-height": "44px",
-  "--studio-chat-header-padding-top": "8px",
+  "--studio-chat-header-padding-top": "7px",
   "--studio-chat-control-height": "33px",
   "--studio-chat-header-right-inset": "0px",
 } as CSSProperties;
diff --git a/studio/frontend/src/components/app-sidebar.tsx b/studio/frontend/src/components/app-sidebar.tsx
index 8aa4db99f4..d263a6a739 100644
--- a/studio/frontend/src/components/app-sidebar.tsx
+++ b/studio/frontend/src/components/app-sidebar.tsx
@@ -1183,7 +1183,11 @@ export function AppSidebar() {
     <Sidebar
       collapsible="icon"
       variant="sidebar"
-      className="font-heading group-data-[collapsible=icon]:[&_[data-sidebar=sidebar]]:bg-white dark:group-data-[collapsible=icon]:[&_[data-sidebar=sidebar]]:bg-background"
+      className={cn(
+        "font-heading group-data-[collapsible=icon]:[&_[data-sidebar=sidebar]]:bg-white dark:group-data-[collapsible=icon]:[&_[data-sidebar=sidebar]]:bg-background",
+        usesNativeMacTitlebar &&
+          "group-data-[collapsible=icon]:[&_[data-sidebar=sidebar]]:border-r-0",
+      )}
     >
       <SidebarHeader
         className={cn(
@@ -1205,6 +1209,7 @@ export function AppSidebar() {
               />
             )}
             <div
+              data-tauri-drag-region={usesNativeMacTitlebar || undefined}
               className={cn(
                 "relative z-10 flex items-center gap-[8.5px] group-data-[collapsible=icon]:hidden",
                 showCompactMacBrand &&
diff --git a/studio/frontend/src/features/chat/chat-page.tsx b/studio/frontend/src/features/chat/chat-page.tsx
index 8ae6c6fb15..eb046031bc 100644
--- a/studio/frontend/src/features/chat/chat-page.tsx
+++ b/studio/frontend/src/features/chat/chat-page.tsx
@@ -781,6 +781,7 @@ function GeneralCompareHeader({
   // Controlled so the body-portaled popover can't linger over another tab off-route.
   const active = useChatActive();
   const [selectorOpen, setSelectorOpen] = useState(false);
+
   const { pinned } = useSidebar();
   return (
     <div
@@ -3192,7 +3193,7 @@ export function ChatPage({
     // Provides `active` to ChatRuntimeProvider (drops the message views/composers
     // while off-route, keeping the runtime alive) and to the compare chrome.
     <ChatActiveContext.Provider value={active}>
-    <div className="flex min-h-0 min-w-0 flex-1 basis-0 bg-background overflow-hidden">
+    <div className="flex min-h-0 min-w-0 flex-1 basis-0 overflow-hidden bg-background">
       {/* Portaled surfaces render to document.body, escaping the parent's hidden
           wrapper, so gate them on `active` to keep them off other tabs. */}
       {active && <GuidedTour {...tour.tourProps} />}
diff --git a/tests/studio/test_desktop_reliability_frontend_contract.py b/tests/studio/test_desktop_reliability_frontend_contract.py
index a576e3fe42..4848a82535 100644
--- a/tests/studio/test_desktop_reliability_frontend_contract.py
+++ b/tests/studio/test_desktop_reliability_frontend_contract.py
@@ -28,6 +28,7 @@ APP_PROVIDER = FRONTEND / "app/provider.tsx"
 
 CLIPBOARD_FILES = FRONTEND / "features/chat/utils/clipboard-files.ts"
 TAURI_CAPABILITIES = REPO / "studio/src-tauri/capabilities/default.json"
+CHAT_PAGE = FRONTEND / "features/chat/chat-page.tsx"
 
 
 def test_file_actions_route_through_native_commands_only_in_tauri():
@@ -216,6 +217,34 @@ def test_expanded_titlebar_button_and_corner_match_sidebar_edge():
     )
 
 
+def test_visible_mac_sidebar_header_is_a_drag_region():
+    source = APP_SIDEBAR.read_text(encoding = "utf-8")
+    header = source.split("<SidebarHeader", 1)[1].split("</SidebarHeader>", 1)[0]
+    drag_region = "data-tauri-drag-region={usesNativeMacTitlebar || undefined}"
+
+    assert drag_region in header
+    assert header.index(drag_region) < header.index('"relative z-10 flex items-center')
+
+
+def test_mac_chat_header_controls_share_the_titlebar_row():
+    source = CHAT_PAGE.read_text(encoding = "utf-8")
+    provider = APP_PROVIDER.read_text(encoding = "utf-8")
+
+    assert "shouldUseNativeMacWindowTitlebar" not in source
+    assert "[--studio-content-top-inset:var(--studio-mac-titlebar-height" not in source
+    assert source.count("var(--studio-mac-traffic-light-inset") == 2
+    assert '"--studio-chat-header-padding-top": "7px"' in provider
+    assert "pt-[var(--studio-content-top-inset,0px)] md:flex-row" in source
+    assert "absolute top-[var(--studio-content-top-inset,0px)]" in source
+
+
+def test_collapsed_mac_sidebar_hides_divider():
+    source = APP_SIDEBAR.read_text(encoding = "utf-8")
+
+    assert "group-data-[collapsible=icon]:[&_[data-sidebar=sidebar]]:border-r-0" in source
+    assert "top-[var(--studio-mac-titlebar-height,34px)]" not in source
+
+
 def test_chat_sidebar_row_actions_visible_on_coarse_pointers():
     """unslothai/unsloth#7276: Recents chat kebab must be tappable on iPad."""
     sidebar_source = APP_SIDEBAR.read_text(encoding = "utf-8")