Dark theme (default): Fusion-like blue-grey viewport #2e3440, darker chrome, subtle grid, light text, blue accent; light theme kept as a second Tokens set; toggle on the application bar (sun/moon), ui.set {dark}, kept between runs (eframe storage; browser local storage on the web); viewport, sketch, glyph, view cube, timeline and overlay colours all come from the theme; preview spinner and state in ui.inspect

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01AS5Tn3xieewUSg3uxrMVdL

crates/ui-egui/src/control.rs

@@ -95,6 +95,7 @@ pub fn handle(app: &mut SolveApp, ctx: &egui::Context, req: &ControlRequest) ->
             "renderer": if app.viewport.gpu.is_some() { "gpu" } else { "cpu" },
             "frame_ms": app.frame_ms,
             "build_ms": app.viewport.build_ms,
+            "preview": {"active": app.preview.active, "busy": app.preview.busy, "error": app.preview.error, "ms": app.preview.ms, "replaced": app.preview.replaced},
         })),
         "ui.set" => {
             let mut cur = serde_json::to_value(&app.ui).unwrap_or(json!({}));