feat(mobile): Figma-like hide-UI toggle — Cmd/Ctrl+\ hotkey + floating button, snapshot-exact chrome restore

Chrome visibility is now a runtime toggle on any device instead of being
device-wired: mobile defaults to canvas-only, desktop to full UI, and the
floating top-right button (or Figma's Cmd/Ctrl+\ chord — free in KiCad,
only bare \ is bound) flips between them live.

- chrome-visibility.ts: module-global store (default isMobileMode(),
  session-only) + pure hotkey matcher (rejects AltGr backslash + repeats)
- WasmTool: capture-phase hotkey (stopped before the wx layer), floating
  toggle pill (matches the comment FAB design), useLayoutEffect apply with
  sync first call + retry; overlays follow the toggle, capability-gated on
  the kicad_editor bundle's kicadSetChrome export
- boot.ts mobile opt now installs touch gestures only
- kicadSetChrome: frame-keyed hide-time snapshot so restore re-shows ONLY
  what hide took away (blanket Show(true) surfaced KiCad's default-hidden
  Search/Properties/Net-Inspector panes); toolbars-only fallback otherwise
- tests: chrome-toggle.spec.ts (desktop hide/restore + geometric
  restore-exactness ±3px), mobile toggle round-trip, 12 new unit tests,
  test:web:mobile npm script

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/package.json

@@ -13,6 +13,7 @@
     "setup:kicad": "./scripts/setup-kicad-wasm.sh",
     "test:web": "npm run setup:kicad && playwright test --config=playwright-web.config.ts --project=firefox",
     "test:web:headed": "npm run setup:kicad && playwright test --config=playwright-web.config.ts --project=chromium --headed",
+    "test:web:mobile": "npm run setup:kicad && playwright test --config=playwright-web.config.ts --project=mobile-chromium --headed",
     "test:kicad:firefox": "npm run setup:kicad && playwright test --config=playwright-kicad.config.ts --project=firefox",
     "test:kicad:chrome": "npm run setup:kicad && playwright test --config=playwright-kicad.config.ts --project=chromium --headed",
     "test:kicad": "npm run test:kicad:firefox",

tests/web/chrome-toggle.spec.ts

@@ -0,0 +1,131 @@
+import { test, expect, type Browser, type Page } from '@playwright/test';
+
+/**
+ * Figma-like "hide UI" toggle e2e (desktop): Cmd/Ctrl+\ and the floating
+ * button flip the editor between full UI and canvas-only, and a restore
+ * brings back EXACTLY the chrome that was visible before — panes KiCad keeps
+ * hidden by default (Search, Properties, …) must not appear. That last part
+ * is asserted geometrically: the GAL canvas box after hide→show must equal
+ * the pre-hide box (an over-shown panel would shrink the AUI center pane).
+ *
+ * Boots once (beforeAll) and runs the round trip over the shared page —
+ * the config is workers:1 / fullyParallel:false, so file order holds.
+ */
+
+const SCOPE = 'default';
+const FRONTEND_URL = process.env.WEB_APP_URL ?? 'http://localhost:3048';
+
+let page: Page;
+/** Full-UI GAL canvas box captured before the first hide — the restore-exactness baseline. */
+let fullUiBox: { x: number; y: number; width: number; height: number };
+
+/** Count of visible menubar titles (0 ⇒ menubar hidden). */
+async function visibleMenuTitles(pg: Page): Promise<number> {
+  return pg.evaluate(
+    () =>
+      Array.from(document.querySelectorAll('.wx-menu-title')).filter((el) => {
+        const r = el.getBoundingClientRect();
+        return r.width > 0 && r.height > 0 && getComputedStyle(el).display !== 'none';
+      }).length,
+  );
+}
+
+/** The visible GAL WebGL canvas box (same lookup as mobile-editor.spec.ts). */
+async function getGlBox(pg: Page): Promise<{ x: number; y: number; width: number; height: number }> {
+  const id = await pg.evaluate(() => {
+    const visible = Array.from(document.querySelectorAll('[id^="glcanvas-"]'))
+      .map((c) => c as HTMLCanvasElement)
+      .find((c) => {
+        const rect = c.getBoundingClientRect();
+        return window.getComputedStyle(c).display !== 'none' && rect.width > 0 && rect.height > 0;
+      });
+    return (visible ?? (document.querySelector('[id^="glcanvas-"]') as HTMLCanvasElement | null))?.id ?? null;
+  });
+  if (!id) throw new Error('No visible GL canvas found');
+  const box = await pg.locator(`#${id}`).boundingBox();
+  if (!box) throw new Error('GL canvas bounding box unavailable');
+  return box;
+}
+
+test.beforeAll(async ({ browser }: { browser: Browser }) => {
+  test.setTimeout(420_000); // cold load: 136 MB wasm download + compile
+  page = await browser.newPage({ baseURL: FRONTEND_URL });
+  await page.goto(`/${SCOPE}/projects/demo/demo.kicad_pcb`);
+  await expect(page.locator('#canvas')).toBeVisible({ timeout: 180000 });
+  await expect
+    .poll(() => page.title(), { timeout: 120000, intervals: [1000] })
+    .toMatch(/demo — PCB Editor/i);
+  // Loading overlays (boot + lib fat-load, both `inset-0 z-30`) must be gone
+  // before geometry is trusted.
+  await expect(page.locator('div.inset-0.z-30')).toHaveCount(0, { timeout: 180000 });
+});
+
+test.afterAll(async () => {
+  await page?.close();
+});
+
+test('Ctrl+\\ hides every non-canvas UI element; the canvas reclaims the viewport', async () => {
+  test.setTimeout(120_000);
+  const vp = page.viewportSize()!;
+
+  // full-UI baseline: menubar + console footer present, canvas NOT full-bleed
+  expect(await visibleMenuTitles(page), 'menubar visible before hide').toBeGreaterThan(0);
+  await expect(page.getByText(/console \(/)).toHaveCount(1);
+  fullUiBox = await getGlBox(page);
+  expect(fullUiBox.width, 'chrome occupies width before hide').toBeLessThan(vp.width * 0.95);
+
+  await page.keyboard.press('Control+\\');
+
+  await expect.poll(() => visibleMenuTitles(page), { timeout: 15000 }).toBe(0);
+  await expect
+    .poll(async () => (await getGlBox(page)).width, { timeout: 15000 })
+    .toBeGreaterThan(vp.width * 0.95);
+  expect((await getGlBox(page)).height, 'GL canvas height ≈ viewport').toBeGreaterThan(
+    vp.height * 0.9,
+  );
+  // shell overlays follow the toggle…
+  await expect(page.getByText(/console \(/)).toHaveCount(0);
+  // …but the toggle button itself stays reachable
+  await expect(page.locator('[data-testid="chrome-toggle"]')).toBeVisible();
+
+  await page.screenshot({ path: 'test-results/web-chrome-hidden.png', scale: 'css' });
+});
+
+test('the floating button restores EXACTLY the pre-hide chrome (no over-shown panes)', async () => {
+  test.setTimeout(120_000);
+
+  // still hidden from the previous test — restore via the button
+  await page.locator('[data-testid="chrome-toggle"]').click();
+
+  await expect.poll(() => visibleMenuTitles(page), { timeout: 15000 }).toBeGreaterThan(0);
+  await expect(page.getByText(/console \(/)).toHaveCount(1);
+
+  // The restored GAL canvas box must MATCH the pre-hide baseline: a blanket
+  // Show(true) would also reveal KiCad's default-hidden panels (Search,
+  // Properties, …), shrinking the AUI center pane and moving this box.
+  await expect
+    .poll(
+      async () => {
+        const b = await getGlBox(page);
+        return (
+          Math.abs(b.x - fullUiBox.x) <= 3 &&
+          Math.abs(b.y - fullUiBox.y) <= 3 &&
+          Math.abs(b.width - fullUiBox.width) <= 3 &&
+          Math.abs(b.height - fullUiBox.height) <= 3
+        );
+      },
+      {
+        message: 'restored GL canvas box must equal the pre-hide baseline (over-shown pane?)',
+        timeout: 15000,
+      },
+    )
+    .toBe(true);
+
+  // hotkey round trip still works after a button toggle
+  await page.keyboard.press('Control+\\'); // hide
+  await expect.poll(() => visibleMenuTitles(page), { timeout: 15000 }).toBe(0);
+  await page.keyboard.press('Control+\\'); // show
+  await expect.poll(() => visibleMenuTitles(page), { timeout: 15000 }).toBeGreaterThan(0);
+
+  await page.screenshot({ path: 'test-results/web-chrome-restored.png', scale: 'css' });
+});

tests/web/mobile-editor.spec.ts

@@ -280,20 +280,24 @@ test('pan: one-finger drag translates the view (not a rubber-band select)', asyn
   expect(dBack, 'panning back returns near baseline').toBeLessThan(dPan / 3);
 });
 
-test('editor is canvas-only: no menubar, GL canvas fills the viewport', async () => {
-  await shot('chrome');
-
-  // The menubar is real DOM (.wx-menu-title per menu); AUI toolbars/panels are
-  // canvas islands, so the GL-canvas-fills-viewport check below is what proves
-  // THEY are gone (hidden AUI panes release their space to the center pane).
-  const menus = await page.evaluate(
+/** Count of visible menubar titles (0 ⇒ menubar hidden). */
+async function visibleMenuTitles(pg: Page): Promise<number> {
+  return pg.evaluate(
     () =>
       Array.from(document.querySelectorAll('.wx-menu-title')).filter((el) => {
         const r = el.getBoundingClientRect();
         return r.width > 0 && r.height > 0 && getComputedStyle(el).display !== 'none';
       }).length,
   );
-  expect(menus, 'no visible menubar titles').toBe(0);
+}
+
+test('editor is canvas-only: no menubar, GL canvas fills the viewport', async () => {
+  await shot('chrome');
+
+  // The menubar is real DOM (.wx-menu-title per menu); AUI toolbars/panels are
+  // canvas islands, so the GL-canvas-fills-viewport check below is what proves
+  // THEY are gone (hidden AUI panes release their space to the center pane).
+  expect(await visibleMenuTitles(page), 'no visible menubar titles').toBe(0);
 
   // the drawing canvas reclaims the whole viewport
   const box = await getGlBox(page);
@@ -304,3 +308,30 @@ test('editor is canvas-only: no menubar, GL canvas fills the viewport', async ()
   // the shell's own persistent overlays are gone too
   expect(await page.getByText(/console \(/).count(), 'console toggle hidden').toBe(0);
 });
+
+test('the floating toggle brings the full UI up and back off (Figma-like hide-UI)', async () => {
+  // Canvas-only is the mobile DEFAULT, but the toggle must stay reachable.
+  const toggle = page.locator('[data-testid="chrome-toggle"]');
+  await expect(toggle, 'toggle button present in canvas-only mode').toBeVisible();
+
+  await toggle.tap();
+  await expect
+    .poll(() => visibleMenuTitles(page), { timeout: 15000 })
+    .toBeGreaterThan(0);
+  // console footer follows the toggle (full shell UI back)
+  await expect(page.getByText(/console \(/)).toHaveCount(1);
+  // chrome takes real estate again (side toolbars + layers panel eat width)
+  const shown = await getGlBox(page);
+  const vp = page.viewportSize()!;
+  expect(shown.width, 'chrome reclaims width').toBeLessThan(vp.width * 0.95);
+  await shot('toggle-shown');
+
+  // …and back to canvas-only, leaving the file in its baseline hidden state.
+  await toggle.tap();
+  await expect.poll(() => visibleMenuTitles(page), { timeout: 15000 }).toBe(0);
+  await expect
+    .poll(async () => (await getGlBox(page)).width, { timeout: 15000 })
+    .toBeGreaterThan(vp.width * 0.95);
+  expect(await page.getByText(/console \(/).count(), 'console toggle hidden again').toBe(0);
+  await shot('toggle-rehidden');
+});

wasm/bindings/kicad_editor_embind.cpp

@@ -24,6 +24,7 @@
 #ifdef __EMSCRIPTEN__
 #include <emscripten.h>
 #include <emscripten/bind.h>
+#include <algorithm>
 #include <string>
 #include <vector>
 #include <wx/app.h>
@@ -124,13 +125,34 @@ static bool kicadOpenFile( std::string path )
 }
 
 
-// Canvas-only mobile chrome toggle (features/mobile): hide/show every AUI pane
+// Canvas-only chrome toggle (features/mobile): hide/show every AUI pane
 // except the central draw canvas, plus the menubar and status bar, so the GAL
 // canvas fills the frame. Generic wxFrame/wxAui surface only (keeps this TU
 // header-light and serves both editor frames). Hidden bars release their space
 // because the wasm port's frame client-area math skips !IsShown() bars (native
 // parity, see wxwidgets/src/wasm/frame.cpp). Returns false until the editor
 // frame exists — main() builds it after runtime init — so JS polls this.
+
+// Hide-time visibility snapshot. KiCad keeps several panes hidden by default
+// (Search, Properties, Net Inspector, …), so a blanket Show(true) on restore
+// would surface panes the user never had open — restore only what the hide
+// actually took away. Keyed to the frame so a snapshot never leaks onto a
+// different frame's wxAuiManager.
+static struct
+{
+    wxFrame*              frame = nullptr;
+    bool                  valid = false;
+    bool                  menuShown = false;
+    bool                  statusShown = false;
+    std::vector<wxString> paneNames;
+} s_chromeSnap;
+
+static bool chromeSkipsPane( const wxAuiPaneInfo& aPane )
+{
+    // keep the central editor canvas (named "DrawFrame" in both editors)
+    return aPane.dock_direction == wxAUI_DOCK_CENTER || aPane.name == wxT( "DrawFrame" );
+}
+
 static bool kicadSetChrome( bool aShow )
 {
     wxFrame* frame =
@@ -139,15 +161,50 @@ static bool kicadSetChrome( bool aShow )
     if( !frame )
         return false;
 
-    if( wxMenuBar* menuBar = frame->GetMenuBar() )
-        menuBar->Show( aShow );
+    wxMenuBar*    menuBar = frame->GetMenuBar();
+    wxStatusBar*  statusBar = frame->GetStatusBar();
+    wxAuiManager* mgr = wxAuiManager::GetManager( frame );
+
+    if( !aShow )
+    {
+        // A repeated hide keeps the original snapshot (idempotent).
+        if( !s_chromeSnap.valid || s_chromeSnap.frame != frame )
+        {
+            s_chromeSnap.frame = frame;
+            s_chromeSnap.menuShown = menuBar && menuBar->IsShown();
+            s_chromeSnap.statusShown = statusBar && statusBar->IsShown();
+            s_chromeSnap.paneNames.clear();
+
+            if( mgr )
+            {
+                wxAuiPaneInfoArray& panes = mgr->GetAllPanes();
+
+                for( size_t i = 0; i < panes.GetCount(); ++i )
+                {
+                    wxAuiPaneInfo& pane = panes.Item( i );
+
+                    if( !chromeSkipsPane( pane ) && pane.IsShown() )
+                        s_chromeSnap.paneNames.push_back( pane.name );
+                }
+            }
+
+            s_chromeSnap.valid = true;
+        }
+    }
+
+    // A show with no snapshot (or one taken on a different frame) falls back
+    // to revealing the standard chrome instead of obeying stale state.
+    const bool haveSnap = s_chromeSnap.valid && s_chromeSnap.frame == frame;
+
+    if( menuBar )
+        menuBar->Show( aShow && ( haveSnap ? s_chromeSnap.menuShown : true ) );
 
     // Kept alive rather than detached: KiCad SetStatusText()s on every cursor
     // move, and wxFrameBase wxCHECKs a null status bar.
-    if( wxStatusBar* statusBar = frame->GetStatusBar() )
-        statusBar->Show( aShow );
+    if( statusBar )
+        statusBar->Show( aShow && ( haveSnap ? s_chromeSnap.statusShown : true ) );
 
-    if( wxAuiManager* mgr = wxAuiManager::GetManager( frame ) )
+    if( mgr )
     {
         wxAuiPaneInfoArray& panes = mgr->GetAllPanes();
 
@@ -155,16 +212,37 @@ static bool kicadSetChrome( bool aShow )
         {
             wxAuiPaneInfo& pane = panes.Item( i );
 
-            // keep the central editor canvas (named "DrawFrame" in both editors)
-            if( pane.dock_direction == wxAUI_DOCK_CENTER || pane.name == wxT( "DrawFrame" ) )
+            if( chromeSkipsPane( pane ) )
                 continue;
 
-            pane.Show( aShow );
+            if( !aShow )
+            {
+                pane.Show( false );
+            }
+            else if( haveSnap )
+            {
+                if( std::find( s_chromeSnap.paneNames.begin(), s_chromeSnap.paneNames.end(),
+                               pane.name )
+                    != s_chromeSnap.paneNames.end() )
+                {
+                    pane.Show( true );
+                }
+            }
+            else if( pane.IsToolbar() )
+            {
+                // Show with no (or a stale, other-frame) snapshot: reveal the
+                // toolbars only — blanket-showing plain panels would surface
+                // the default-hidden ones.
+                pane.Show( true );
+            }
         }
 
         mgr->Update();
     }
 
+    if( aShow )
+        s_chromeSnap.valid = false;
+
     frame->SendSizeEvent();
     return true;
 }

web/standalone/src/App.tsx

@@ -1,12 +1,13 @@
 import { Route, Routes } from "react-router-dom";
 import { VersionBadge } from "@/components/VersionBadge";
-import { isMobileMode } from "@/lib/mobile-mode";
+import { useChromeHidden } from "@/lib/chrome-visibility";
 import { HomePage } from "@/pages/HomePage";
 import { LibToolPage } from "@/pages/LibToolPage";
 import { ProjectView } from "@/pages/ProjectView";
 import { ToolPage } from "@/pages/ToolPage";
 
 export default function App() {
+  const chromeHidden = useChromeHidden();
   return (
     <>
       <Routes>
@@ -19,8 +20,8 @@ export default function App() {
         <Route path="/:scope/libs/:name" element={<LibToolPage />} />
       </Routes>
       {/* Version + source link, bottom-right on every route (home + editor).
-          Mobile mode is canvas-only — no persistent overlays. */}
-      {!isMobileMode() && <VersionBadge />}
+          Keys off the Figma-like hide-UI toggle (hidden is the mobile default). */}
+      {!chromeHidden && <VersionBadge />}
     </>
   );
 }

web/standalone/src/components/WasmTool.tsx

@@ -14,7 +14,7 @@ import {
   type KicadDoc,
   type Tool,
 } from "@pcbjam/shared";
-import { ChevronDown, ChevronUp, Loader2 } from "lucide-react";
+import { ChevronDown, ChevronUp, EyeOff, Loader2, PanelsTopLeft } from "lucide-react";
 import {
   currentScope,
   libsSourceConfig,
@@ -84,10 +84,30 @@ import { MemoryExhaustedDialog } from "@/recovery/MemoryExhaustedDialog";
 import type { SourceDescriptor } from "@/lib/project-source-shared";
 import { SourceChip } from "@/components/SourceChip";
 import { isMobileMode } from "@/lib/mobile-mode";
+import {
+  isChromeToggleHotkey,
+  toggleChromeHidden,
+  useChromeHidden,
+} from "@/lib/chrome-visibility";
 
 // Tools with the v2 items bridge (kicadCollabSnapshotItems/ApplyItems embind exports).
 const COLLAB_TOOLS = new Set<Tool>(["pl_editor", "eeschema", "pcbnew"]);
 
+// Chrome (editor UI) toggle: only the merged kicad_editor bundle exports
+// kicadSetChrome (gerbview/calculator/pl_editor don't) — everything about the
+// toggle is feature-gated on the export being there.
+function chromeSetter(win: Window): ((show: boolean) => boolean) | null {
+  const fn = (win as { Module?: { kicadSetChrome?: unknown } }).Module
+    ?.kicadSetChrome;
+  return typeof fn === "function" ? (fn as (show: boolean) => boolean) : null;
+}
+
+// Tooltip only — the matcher accepts both chords on any platform.
+const CHROME_HOTKEY_LABEL =
+  typeof navigator !== "undefined" && /Mac/i.test(navigator.platform)
+    ? "⌘\\"
+    : "Ctrl+\\";
+
 // Which library item kind each tool browses — drives the load-screen pre-sync
 // (warm the right bundles into IDB while the wasm downloads). Tools that don't
 // browse a library are omitted (no pre-sync).
@@ -690,9 +710,13 @@ export function WasmTool({
 }) {
   const containerRef = React.useRef<HTMLDivElement>(null);
   const startedRef = React.useRef(false);
-  // Canvas-only mobile mode (features/mobile): the shell hides its persistent
-  // overlays, boot installs the touch-gesture shim + hides the editor chrome.
+  // Mobile device (features/mobile): boot installs the touch-gesture shim.
+  // Chrome/overlay visibility is the separate runtime toggle below.
   const mobileUi = React.useMemo(() => isMobileMode(), []);
+  // Figma-like "hide UI" toggle: mobile defaults to hidden, the floating
+  // button / Cmd+\ flips it live; shell overlays key off this, and the layout
+  // effect below applies it to the wasm frame.
+  const chromeHidden = useChromeHidden();
   const driftRef = React.useRef<{ stop(): void } | null>(null);
   const presenceRef = React.useRef<PresenceHandle | null>(null);
   const presenceBridgeRef = React.useRef<{ destroy(): void } | null>(null);
@@ -979,6 +1003,18 @@ export function WasmTool({
     };
     win.addEventListener("keydown", swallowBrowserSave, true);
 
+    // Cmd/Ctrl+\ (Figma's hide-UI chord) is ours alone: unlike Cmd+S it must
+    // NOT reach the wx layer, so also stop propagation — capture on window
+    // fires before wx's bubble-phase window listeners (wasm/app.cpp).
+    const chromeHotkey = (e: KeyboardEvent) => {
+      if (!isChromeToggleHotkey(e)) return;
+      if (!chromeSetter(win)) return; // bundle without the export
+      e.preventDefault();
+      e.stopImmediatePropagation();
+      toggleChromeHidden();
+    };
+    win.addEventListener("keydown", chromeHotkey, true);
+
     void (async () => {
       try {
         // Resolve the per-tool asset base at runtime (CDN manifest → versioned
@@ -1173,6 +1209,7 @@ export function WasmTool({
 
     return () => {
       win.removeEventListener("keydown", swallowBrowserSave, true);
+      win.removeEventListener("keydown", chromeHotkey, true);
       commentsRef.current?.destroy();
       commentsRef.current = null;
       presenceBridgeRef.current?.destroy();
@@ -1196,6 +1233,49 @@ export function WasmTool({
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [tool, slug, assetBaseUrl, append]);
 
+  // kicadSetChrome, once the editor is up (null on bundles without it).
+  const setChromeFn = React.useMemo(
+    () => (ready ? chromeSetter(window) : null),
+    [ready],
+  );
+
+  // Apply the chrome-visibility state to the wasm frame. A LAYOUT effect with
+  // a synchronous first attempt: `ready` unmounts the opaque boot overlay in
+  // this same commit, and a passive effect would let one frame of full chrome
+  // paint on mobile. appliedRef skips the initial "shown" apply — never
+  // relayout a frame this component never hid.
+  const appliedRef = React.useRef<boolean | null>(null);
+  React.useLayoutEffect(() => {
+    if (!setChromeFn) return;
+    if (appliedRef.current === chromeHidden) return;
+    if (appliedRef.current === null && !chromeHidden) return;
+
+    const apply = () => {
+      try {
+        return setChromeFn(!chromeHidden) === true;
+      } catch (err) {
+        append(`[chrome] kicadSetChrome failed: ${String(err)}`);
+        return true; // don't retry a throwing binding
+      }
+    };
+    if (apply()) {
+      appliedRef.current = chromeHidden;
+      return;
+    }
+    // The editor frame can lag `ready` (waitForWxUi falls through after 25 s)
+    // — retry briefly rather than dropping the toggle.
+    const t0 = Date.now();
+    const tick = window.setInterval(() => {
+      if (apply()) {
+        appliedRef.current = chromeHidden;
+        window.clearInterval(tick);
+      } else if (Date.now() - t0 > 30_000) {
+        window.clearInterval(tick);
+      }
+    }, 300);
+    return () => window.clearInterval(tick);
+  }, [setChromeFn, chromeHidden, append]);
+
   return (
     <div className="relative h-screen w-screen overflow-hidden bg-[#1a1a2e]">
       {/*
@@ -1312,19 +1392,35 @@ export function WasmTool({
         </div>
       )}
 
-      {/* Top-right overlay chips: who else is in this file (awareness roster) +
-          where this project lives / whether Save persists (chip hidden in
-          canvas-only mobile mode). */}
-      {ready && (peers.length > 0 || (sourceDescriptor && !mobileUi)) && (
-        <div className="absolute right-3 top-3 z-20 flex items-center gap-2">
-          {peers.length > 0 && (
-            <PresenceRoster peers={peers} activeSheetPath={activeSheetPath} />
-          )}
-          {sourceDescriptor && !mobileUi && (
-            <SourceChip descriptor={sourceDescriptor} />
-          )}
-        </div>
-      )}
+      {/* Top-right overlay row: who else is in this file (awareness roster),
+          where this project lives / whether Save persists (chip hidden while
+          the UI is hidden), and the Figma-like hide/show-UI toggle — the one
+          control that stays up in canvas-only mode. */}
+      {ready &&
+        (setChromeFn !== null ||
+          peers.length > 0 ||
+          (sourceDescriptor && !chromeHidden)) && (
+          <div className="absolute right-3 top-3 z-20 flex items-center gap-2">
+            {peers.length > 0 && (
+              <PresenceRoster peers={peers} activeSheetPath={activeSheetPath} />
+            )}
+            {sourceDescriptor && !chromeHidden && (
+              <SourceChip descriptor={sourceDescriptor} />
+            )}
+            {setChromeFn !== null && (
+              <button
+                data-testid="chrome-toggle"
+                aria-pressed={chromeHidden}
+                // same pill design as the comment-bar toggle below it
+                className="flex h-8 min-w-8 items-center justify-center rounded-full bg-black/70 text-white shadow-sm ring-1 ring-inset ring-white/20 hover:bg-black/85"
+                title={`${chromeHidden ? "Show" : "Hide"} UI (${CHROME_HOTKEY_LABEL})`}
+                onClick={() => toggleChromeHidden()}
+              >
+                {chromeHidden ? <PanelsTopLeft size={15} /> : <EyeOff size={15} />}
+              </button>
+            )}
+          </div>
+        )}
 
       {/* Figma-like comments (0005): GAL pin dots + this DOM layer (hit targets,
           thread popovers, comment mode, panel). */}
@@ -1373,7 +1469,7 @@ export function WasmTool({
         </button>
       )}
 
-      {!mobileUi && (
+      {!chromeHidden && (
         <div className="absolute bottom-0 left-0 right-0 z-20">
           <button
             className="flex items-center gap-1 bg-black/70 px-3 py-1 font-mono text-xs text-white"

web/standalone/src/lib/chrome-visibility.test.ts

@@ -0,0 +1,104 @@
+import { afterEach, describe, expect, it } from "vitest";
+import {
+  getChromeHidden,
+  isChromeToggleHotkey,
+  resetChromeHiddenForTests,
+  setChromeHidden,
+  subscribeChromeHidden,
+  toggleChromeHidden,
+} from "./chrome-visibility";
+
+/**
+ * Chrome-visibility store (features/mobile, Figma-like "hide UI" toggle):
+ * module-global hidden/shown state every shell consumer shares, defaulting to
+ * the device signal (isMobileMode) and toggled at runtime by the floating
+ * button / Cmd+\ hotkey. Plus the pure hotkey matcher.
+ */
+
+afterEach(() => resetChromeHiddenForTests());
+
+describe("chrome-visibility store", () => {
+  it("defaults via device detection (desktop-like test env → shown)", () => {
+    // node env has no window: the lazy default must resolve to "not hidden"
+    // rather than crash on the missing global.
+    expect(getChromeHidden()).toBe(false);
+  });
+
+  it("set + toggle flip the state", () => {
+    setChromeHidden(true);
+    expect(getChromeHidden()).toBe(true);
+    toggleChromeHidden();
+    expect(getChromeHidden()).toBe(false);
+    toggleChromeHidden();
+    expect(getChromeHidden()).toBe(true);
+  });
+
+  it("notifies subscribers on every change, in subscription order", () => {
+    const seen: string[] = [];
+    subscribeChromeHidden(() => seen.push(`a:${getChromeHidden()}`));
+    subscribeChromeHidden(() => seen.push(`b:${getChromeHidden()}`));
+
+    setChromeHidden(true);
+    toggleChromeHidden();
+    expect(seen).toEqual(["a:true", "b:true", "a:false", "b:false"]);
+  });
+
+  it("does not notify on a no-op set", () => {
+    setChromeHidden(false); // resolves the lazy default to false
+    let calls = 0;
+    subscribeChromeHidden(() => calls++);
+    setChromeHidden(false);
+    expect(calls).toBe(0);
+  });
+
+  it("unsubscribe stops notifications", () => {
+    let calls = 0;
+    const off = subscribeChromeHidden(() => calls++);
+    setChromeHidden(true);
+    off();
+    setChromeHidden(false);
+    expect(calls).toBe(1);
+  });
+});
+
+describe("isChromeToggleHotkey", () => {
+  const key = (over: Partial<Parameters<typeof isChromeToggleHotkey>[0]>) => ({
+    key: "\\",
+    code: "Backslash",
+    metaKey: false,
+    ctrlKey: false,
+    altKey: false,
+    repeat: false,
+    ...over,
+  });
+
+  it("accepts Ctrl+\\ and Cmd+\\", () => {
+    expect(isChromeToggleHotkey(key({ ctrlKey: true }))).toBe(true);
+    expect(isChromeToggleHotkey(key({ metaKey: true }))).toBe(true);
+  });
+
+  it("accepts the physical Backslash key even when the layout maps it elsewhere", () => {
+    // e.g. HU layout: physical US-backslash key produces "ű"
+    expect(isChromeToggleHotkey(key({ ctrlKey: true, key: "ű" }))).toBe(true);
+  });
+
+  it("accepts a layout-produced backslash on a different physical key", () => {
+    expect(isChromeToggleHotkey(key({ ctrlKey: true, code: "IntlBackslash" }))).toBe(true);
+  });
+
+  it("rejects bare \\ (that's KiCad's Decrease Via Size)", () => {
+    expect(isChromeToggleHotkey(key({}))).toBe(false);
+  });
+
+  it("rejects AltGr-produced backslash (ctrl+alt while typing \\ in a field)", () => {
+    expect(isChromeToggleHotkey(key({ ctrlKey: true, altKey: true }))).toBe(false);
+  });
+
+  it("rejects key auto-repeat (held hotkey must not strobe the layout)", () => {
+    expect(isChromeToggleHotkey(key({ ctrlKey: true, repeat: true }))).toBe(false);
+  });
+
+  it("rejects other ctrl shortcuts", () => {
+    expect(isChromeToggleHotkey(key({ ctrlKey: true, key: "s", code: "KeyS" }))).toBe(false);
+  });
+});

web/standalone/src/lib/chrome-visibility.ts

@@ -0,0 +1,75 @@
+/**
+ * Chrome (editor UI) visibility — the Figma-like "hide UI" toggle state
+ * (features/mobile).
+ *
+ * One module-global boolean every shell consumer shares: WasmTool applies it
+ * to the wasm frame (kicadSetChrome), the floating button and the Cmd+\ /
+ * Ctrl+\ hotkey flip it, and the shell overlays (version badge, source chip,
+ * console toggle) key their visibility off it.
+ *
+ * Session semantics, like Figma: nothing is persisted — a reload restores the
+ * device default (isMobileMode: mobile → hidden, desktop → shown; `?mobile=`
+ * still forces it). Being module-global the toggled state survives SPA
+ * navigation (e.g. editor → Home keeps the badge hidden); tool switches are
+ * full page loads, so in practice that only affects Home.
+ */
+
+import { useSyncExternalStore } from "react";
+import { isMobileMode } from "./mobile-mode";
+
+// Resolved lazily so merely importing the module never touches `window`
+// (unit tests run in the node environment).
+let hidden: boolean | null = null;
+const listeners = new Set<() => void>();
+
+export function getChromeHidden(): boolean {
+  hidden ??= typeof window === "undefined" ? false : isMobileMode();
+  return hidden;
+}
+
+export function setChromeHidden(value: boolean): void {
+  if (value === getChromeHidden()) return;
+  hidden = value;
+  for (const listener of [...listeners]) listener();
+}
+
+export function toggleChromeHidden(): void {
+  setChromeHidden(!getChromeHidden());
+}
+
+/** Returns the unsubscriber. */
+export function subscribeChromeHidden(listener: () => void): () => void {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+}
+
+export function useChromeHidden(): boolean {
+  return useSyncExternalStore(subscribeChromeHidden, getChromeHidden);
+}
+
+/** Test-only: back to the unresolved default, all subscribers dropped. */
+export function resetChromeHiddenForTests(value: boolean | null = null): void {
+  hidden = value;
+  listeners.clear();
+}
+
+/**
+ * The Figma "hide UI" shortcut: Cmd+\ (mac) / Ctrl+\. Free in KiCad — only
+ * BARE `\` is bound (Decrease Via Size, pcbnew), no modifier+backslash
+ * anywhere. Matches by key OR physical code so it works on layouts where `\`
+ * moved (or the Backslash key produces something else). Rejects altKey
+ * because AltGr-typed `\` (HU/DE layouts) reports ctrl+alt — typing a
+ * backslash into a text field must not toggle the UI — and rejects repeats so
+ * holding the chord doesn't strobe full AUI relayouts.
+ */
+export function isChromeToggleHotkey(e: {
+  key: string;
+  code: string;
+  metaKey: boolean;
+  ctrlKey: boolean;
+  altKey: boolean;
+  repeat: boolean;
+}): boolean {
+  if (!(e.metaKey || e.ctrlKey) || e.altKey || e.repeat) return false;
+  return e.key === "\\" || e.code === "Backslash" || e.code === "IntlBackslash";
+}

web/standalone/src/wasm/boot.ts

@@ -78,9 +78,10 @@ export interface BootOptions {
    *  `--frame=<token>` in `Module.arguments`; parsed in single_top.cpp. Omitted
    *  ⇒ the bundle's build-time default frame. See `TOOL_FRAME` in constants.ts. */
   frame?: string;
-  /** Canvas-only mobile mode (features/mobile): install the touch-gesture shim
-   *  (pinch-zoom / one-finger pan / tap-select) on the input canvas and hide the
-   *  editor chrome (toolbars/panels/menubar) once the frame is up. */
+  /** Mobile device (features/mobile): install the touch-gesture shim
+   *  (pinch-zoom / one-finger pan / tap-select) on the input canvas. Gestures
+   *  only — chrome visibility is owned by the shell's chrome-visibility store
+   *  (WasmTool applies it via kicadSetChrome). */
   mobile?: boolean;
 }
 
@@ -468,32 +469,6 @@ async function doBoot(opts: BootOptions): Promise<void> {
       log("[boot] runtime initialized");
       const canvas = (w.Module as { canvas?: HTMLCanvasElement }).canvas;
       if (canvas) canvas.style.display = "block";
-      if (opts.mobile) {
-        // Hide the editor chrome (toolbars/panels/menubar) so the canvas fills
-        // the frame. kicadSetChrome (embind) returns false until the editor
-        // frame exists — main() builds it after runtime init — so poll.
-        const mod = w.Module as unknown as {
-          kicadSetChrome?: (show: boolean) => boolean;
-        };
-        const t0 = Date.now();
-        const tick = setInterval(() => {
-          let hidden = false;
-          try {
-            hidden = mod.kicadSetChrome?.(false) === true;
-          } catch (err) {
-            log(`[boot] mobile: kicadSetChrome failed: ${String(err)}`);
-            clearInterval(tick);
-            return;
-          }
-          if (hidden) {
-            log("[boot] mobile: editor chrome hidden");
-            clearInterval(tick);
-          } else if (Date.now() - t0 > 120_000) {
-            log("[boot] mobile: gave up waiting for the editor frame");
-            clearInterval(tick);
-          }
-        }, 300);
-      }
       onStatus("");
     },
     // Resolve wasm + pthread worker against the asset base, not the SPA route.