fix(theme): stop the boot theme re-send from resurrecting hidden chrome

Since comments-ux 0002, WasmTool re-sends the shell theme through
kicadSetColorTheme on every boot; setColorTheme ran CommonSettingsChanged
unconditionally, which recreates the menubar/toolbars — and they come back
SHOWN, undoing the kicadSetChrome(false) the read-only viewer and mobile
canvas-only mode applied moments earlier (CI: read-only-editor +
mobile-editor "9 visible menu titles").

Two-part fix in pcbjam_theme:
- early-out when the requested theme AND the wx dark-chrome flag are
  already applied — the every-boot re-send (still needed for warm
  relaunches with stale MEMFS settings) becomes a true no-op;
- after a REAL apply, re-assert the hidden chrome via a hook the merged
  image installs (kicadSetChrome(false) when the snapshot says hidden),
  queued with CallAfter from inside the fiber body so FIFO lands it
  behind the CallAfter-deferred ReCreateMenuBar. Covers viewers/mobile
  users toggling dark mode mid-session.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Y32etYBCKV6t1qDoLoGmgF

wasm/bindings/kicad_editor_embind.cpp

@@ -83,6 +83,14 @@ bool        pcbCollabTestClearSelection();
 void        pcbSetColorTheme( std::string aTheme );
 void        pcbSetDarkChrome( bool aDark );
 
+// Post-theme-apply hook shared with pcbjam_theme.h — identical inline-variable
+// definition instead of including that header (this TU stays header-light);
+// keep the two declarations in sync.
+namespace pcbjam_theme
+{
+inline void ( *g_afterThemeApplied )() = nullptr;
+}
+
 bool        schEditorActive();
 int         schLibsSymbolUsage( std::string aLibNickname, std::string aSymbolName );
 void        schCollabApply( std::string aJson );
@@ -398,6 +406,15 @@ static void collabSetStyle( std::string aJson )
 // Each side no-ops on a null frame.
 static void setColorTheme( std::string aTheme )
 {
+    // A real theme apply rebuilds the menubar/toolbars, which come back
+    // SHOWN — re-hide them when the chrome is supposed to be hidden
+    // (read-only viewer / mobile canvas-only). Installed here, not in
+    // pcbjam_theme.h, because the chrome snapshot is merged-image state.
+    pcbjam_theme::g_afterThemeApplied = []() {
+        if( s_chromeSnap.valid )
+            kicadSetChrome( false );
+    };
+
     pcbSetColorTheme( aTheme );
     schSetColorTheme( aTheme );
 }

wasm/bindings/pcbjam_theme.h

@@ -31,6 +31,17 @@ extern "C" bool wxWasmGetDarkAppearance();
 
 namespace pcbjam_theme {
 
+/** Merged-image hook (installed by kicad_editor_embind.cpp): re-assert the
+ *  canvas-only chrome state after a theme apply. CommonSettingsChanged
+ *  recreates the menubar (CallAfter-deferred, eda_base_frame.cpp) and the
+ *  toolbars, and they come back SHOWN — without this, a theme apply
+ *  resurrects the chrome kicadSetChrome(false) hid (read-only viewer /
+ *  mobile canvas-only). Inline variable: the dispatcher TU re-declares the
+ *  identical definition instead of including this (deliberately
+ *  header-light) — keep the two in sync. Null in the standalone bundles,
+ *  which have no chrome API. */
+inline void ( *g_afterThemeApplied )() = nullptr;
+
 /** Set the chrome appearance FLAG only — no widget traffic, no fiber. Safe
  *  from the browser main thread at any point (it writes one bool in shared
  *  wasm memory); the embedder calls it at onRuntimeInitialized, BEFORE main()
@@ -77,22 +88,40 @@ inline void setColorTheme( EDA_DRAW_FRAME* aFrame, const std::string& aTheme )
         return;
 
     pcbjam_collab::runOnFiber( aFrame, [aFrame, aTheme]() {
-        if( APP_SETTINGS_BASE* cfg = aFrame->config() )
+        // The shell only ever sends our dark theme name or the builtin
+        // default, so the chrome appearance rides on that distinction.
+        const bool         dark = aTheme != "_builtin_default";
+        const wxString     theme = wxString::FromUTF8( aTheme.c_str() );
+        APP_SETTINGS_BASE* cfg = aFrame->config();
+
+        // The shell re-sends its theme on EVERY boot (a warm relaunch can
+        // have stale MEMFS settings from a HomePage theme switch) — skip the
+        // apply when nothing changes: CommonSettingsChanged below is not
+        // free, it rebuilds the menubar and toolbars.
+        if( cfg && cfg->m_ColorTheme == theme && dark == wxWasmGetDarkAppearance() )
+            return;
+
+        if( cfg )
         {
-            cfg->m_ColorTheme = wxString::FromUTF8( aTheme.c_str() );
+            cfg->m_ColorTheme = theme;
             // Persist now — wasm sessions never exit cleanly, so the normal
             // save-on-close path would lose the choice.
             Pgm().GetSettingsManager().Save( cfg );
         }
 
-        // wx chrome first (panels/toolbars), then the GAL canvas colors. The
+        // wx chrome first (panels/toolbars), then the GAL canvas colors.
-        // shell only ever sends our dark theme name or the builtin default,
+        syncChromeAppearance( dark );
-        // so the chrome appearance rides on that distinction.
-        syncChromeAppearance( aTheme != "_builtin_default" );
 
         // 0 flags: no env/text vars changed; the frame's override chain still
         // unconditionally reloads colors and recaches the view.
         aFrame->CommonSettingsChanged( 0 );
+
+        // Queued from INSIDE the fiber body, AFTER CommonSettingsChanged: the
+        // menubar rebuild it triggers is itself a CallAfter on this same
+        // handler, so FIFO puts the re-assert behind the rebuilt (shown)
+        // menubar.
+        if( void ( *hook )() = g_afterThemeApplied )
+            aFrame->CallAfter( hook );
     } );
 }