feat(editor): toolbar rides inside the header — one row, not two

With the marketing nav gone from the editor header, its middle was ~700px
of dead space at 1280 while the toolbar occupied a whole second 38px bar.
The unified toolbar strip now fills that middle through a new AppHeader
editorToolbar slot: one 44px row where there used to be 44+38 — a full
row returned to the code and the canvas.

The strip keeps its own class names, so everything that keyed on them
keeps working untouched: the container queries, the docked-chat
padding-right, and the internal flex-wrap. When it truly cannot fit, the
strip wraps and the header grows (height: auto on the modifier class)
instead of clipping or overlapping; brand and the right-side controls
stay pinned to the first line. Inside the header the strip drops its own
background and border so it reads as one bar, not a box within a bar.

Mobile keeps the previous layout (no strip; the mobile tab bar remains).

frontend/src/App.css

@@ -477,3 +477,56 @@ body {
 @media (prefers-reduced-motion: reduce) {
   .velxio-ants { animation: none; }
 }
+
+/* ── Editor: toolbar riding inside the header ─────────────────────────────
+   With the marketing nav gone from the editor header, its middle was dead
+   space while the toolbar occupied a whole second bar. The strip now fills
+   that middle: one 44px row instead of 44+38 — a full row returned to the
+   code/canvas. The strip keeps its own class names (container queries, the
+   docked-chat padding-right) and wraps internally when it truly cannot
+   fit; the header then grows instead of clipping or overlapping. */
+.app-header--with-toolbar {
+  height: auto;
+  min-height: 44px;
+}
+
+.header-editor-toolbar {
+  flex: 1 1 auto;
+  min-width: 0;
+  display: flex;
+  align-self: stretch;
+  margin: 0 10px;
+}
+
+.header-editor-toolbar .unified-toolbar {
+  flex: 1 1 auto;
+  min-width: 0;
+  /* Skin: it is part of the header now, not a bar of its own. */
+  background: transparent;
+  border-bottom: none;
+  min-height: 44px;
+  align-items: center;
+}
+
+/* Keep the brand block and the right-side controls pinned to the first
+   line when the strip wraps the header taller. */
+.app-header--with-toolbar .header-left,
+.app-header--with-toolbar .header-right {
+  align-self: flex-start;
+  min-height: 44px;
+  display: flex;
+  align-items: center;
+}
+
+.app-header--with-toolbar .header-content {
+  align-items: stretch;
+}
+
+/* The editor zone / toolbar inside the strip: no own chrome, blend into
+   the header instead of painting a nested dark box with its own border. */
+.header-editor-toolbar .editor-toolbar,
+.header-editor-toolbar .unified-toolbar-editor .editor-toolbar {
+  background: transparent;
+  border-bottom: none;
+  height: 44px;
+}

frontend/src/components/layout/AppHeader.tsx

@@ -22,6 +22,11 @@ interface AppHeaderProps {
    *  toolbar is starved of on small screens; the logo still links home.
    *  Same mechanism the Tauri desktop build uses (VITE_DESKTOP). */
   editorMenu?: React.ReactNode;
+  /** Editor variant: the unified toolbar strip rendered in the header's
+   *  middle — the space the marketing nav used to occupy. One row instead
+   *  of header + toolbar stacked; the strip wraps internally when narrow
+   *  and the header grows to fit (height: auto on the modifier class). */
+  editorToolbar?: React.ReactNode;
 }
 
 const SAVE_STATUS_COPY: Record<AutoSaveState['status'], { label: string; color: string }> = {
@@ -68,7 +73,7 @@ const AutoSaveIndicator: React.FC<{ state: AutoSaveState }> = ({ state }) => {
   );
 };
 
-export const AppHeader: React.FC<AppHeaderProps> = ({ autoSave, editorMenu }) => {
+export const AppHeader: React.FC<AppHeaderProps> = ({ autoSave, editorMenu, editorToolbar }) => {
   const location = useLocation();
   const currentProject = useProjectStore((s) => s.currentProject);
   const [menuOpen, setMenuOpen] = useState(false);
@@ -98,7 +103,7 @@ export const AppHeader: React.FC<AppHeaderProps> = ({ autoSave, editorMenu }) =>
     location.pathname === localize(path) ? ' header-nav-link-active' : '';
 
   return (
-    <header className="app-header">
+    <header className={"app-header" + (editorToolbar ? ' app-header--with-toolbar' : '')}>
       <div className="header-content">
         <div className="header-left">
           {/* Brand */}
@@ -216,6 +221,9 @@ export const AppHeader: React.FC<AppHeaderProps> = ({ autoSave, editorMenu }) =>
           )}
         </div>
 
+        {/* Editor toolbar strip — fills the middle the nav vacated. */}
+        {editorToolbar && <div className="header-editor-toolbar">{editorToolbar}</div>}
+
         {/* Right: language + share + auth + mobile hamburger */}
         <div className="header-right">
           <LanguageSwitcher />

frontend/src/pages/EditorPage.tsx

@@ -376,62 +376,16 @@ export const EditorPage: React.FC = () => {
     [explorerWidth],
   );
 
-  return (
-    <div className="app">
-      <AppHeader autoSave={autoSave} editorMenu={!isMobile ? <EditorMenuBar /> : undefined} />
-
-      {/* ── Mobile tab bar (top, above panels) ── */}
-      {isMobile && (
-        <nav className="mobile-tab-bar">
-          <button
-            className={`mobile-tab-btn${mobileView === 'code' ? ' mobile-tab-btn--active' : ''}`}
-            onClick={() => setMobileView('code')}
-          >
-            <svg
-              width="16"
-              height="16"
-              viewBox="0 0 24 24"
-              fill="none"
-              stroke="currentColor"
-              strokeWidth="2"
-              strokeLinecap="round"
-              strokeLinejoin="round"
-            >
-              <polyline points="16 18 22 12 16 6" />
-              <polyline points="8 6 2 12 8 18" />
-            </svg>
-            <span>&lt;/&gt; {t('editor.shell.code')}</span>
-          </button>
-          <button
-            className={`mobile-tab-btn${mobileView === 'circuit' ? ' mobile-tab-btn--active' : ''}`}
-            onClick={() => setMobileView('circuit')}
-          >
-            <svg
-              width="16"
-              height="16"
-              viewBox="0 0 24 24"
-              fill="none"
-              stroke="currentColor"
-              strokeWidth="2"
-              strokeLinecap="round"
-              strokeLinejoin="round"
-            >
-              <rect x="2" y="7" width="20" height="14" rx="2" />
-              <path d="M16 7V5a2 2 0 0 0-2-2h-4a2 2 0 0 0-2 2v2" />
-              <line x1="12" y1="12" x2="12" y2="16" />
-              <line x1="10" y1="14" x2="14" y2="14" />
-            </svg>
-            <span>{t('editor.shell.circuit')}</span>
-          </button>
-        </nav>
-      )}
-
-      {/* ── Unified top toolbar (desktop only) ──
-          Editor controls + canvas controls share a single full-width row so
-          the bar doesn't reflow when the editor/canvas splitter is dragged.
-          The canvas controls (board selector, Serial, Scope, zoom, Add) are
-          portaled into `canvasHeaderSlot` from inside SimulatorCanvas. */}
-      {!isMobile && (
+  /* ── Unified toolbar (desktop) ──
+     Editor controls + canvas controls in one strip; the canvas side is
+     portaled into `canvasHeaderSlot` from SimulatorCanvas. Since the
+     marketing nav left the editor header, the header's middle is empty
+     space — so this strip now rides INSIDE the AppHeader row (via the
+     editorToolbar prop) instead of being a second bar: one 44px row where
+     there used to be 44+38. On narrow widths the strip wraps internally
+     and the header grows; the docked AI chat is avoided by the same
+     padding-right the strip always had. */
+  const unifiedToolbar = !isMobile ? (
         <div className="unified-toolbar">
           <button
             className="explorer-toggle-btn unified-toolbar-explorer-toggle"
@@ -524,8 +478,63 @@ export const EditorPage: React.FC = () => {
           </div>
           <div className="unified-toolbar-canvas" ref={setCanvasHeaderSlot} />
         </div>
+  ) : undefined;
+
+  return (
+    <div className="app">
+      <AppHeader
+        autoSave={autoSave}
+        editorMenu={!isMobile ? <EditorMenuBar /> : undefined}
+        editorToolbar={unifiedToolbar}
+      />
+
+      {/* ── Mobile tab bar (top, above panels) ── */}
+      {isMobile && (
+        <nav className="mobile-tab-bar">
+          <button
+            className={`mobile-tab-btn${mobileView === 'code' ? ' mobile-tab-btn--active' : ''}`}
+            onClick={() => setMobileView('code')}
+          >
+            <svg
+              width="16"
+              height="16"
+              viewBox="0 0 24 24"
+              fill="none"
+              stroke="currentColor"
+              strokeWidth="2"
+              strokeLinecap="round"
+              strokeLinejoin="round"
+            >
+              <polyline points="16 18 22 12 16 6" />
+              <polyline points="8 6 2 12 8 18" />
+            </svg>
+            <span>&lt;/&gt; {t('editor.shell.code')}</span>
+          </button>
+          <button
+            className={`mobile-tab-btn${mobileView === 'circuit' ? ' mobile-tab-btn--active' : ''}`}
+            onClick={() => setMobileView('circuit')}
+          >
+            <svg
+              width="16"
+              height="16"
+              viewBox="0 0 24 24"
+              fill="none"
+              stroke="currentColor"
+              strokeWidth="2"
+              strokeLinecap="round"
+              strokeLinejoin="round"
+            >
+              <rect x="2" y="7" width="20" height="14" rx="2" />
+              <path d="M16 7V5a2 2 0 0 0-2-2h-4a2 2 0 0 0-2 2v2" />
+              <line x1="12" y1="12" x2="12" y2="16" />
+              <line x1="10" y1="14" x2="14" y2="14" />
+            </svg>
+            <span>{t('editor.shell.circuit')}</span>
+          </button>
+        </nav>
       )}
 
+
       <div className="app-container" ref={containerRef}>
         {/* ── Editor side ── */}
         <div