fix(simulation): keep runtime stable on settings save

apps/control-station/src/components/simulation/SimulationViewport.tsx

@@ -62,6 +62,7 @@ export function SimulationViewport({
     project.viewerSettings.camera.invertVertical,
   );
   const [settingsError, setSettingsError] = useState<string | null>(null);
+  const worldManifestRevision = JSON.stringify(project.worldManifest);
 
   useEffect(() => {
     const settings = project.viewerSettings;
@@ -142,7 +143,10 @@ export function SimulationViewport({
       runtime.dispose();
       runtimeRef.current = null;
     };
-  }, [project.projectId, project.worldManifest]);
+  // Saving viewer preferences returns a fresh project object. Restart the GPU
+  // runtime only when the manifest content changes, not when its object identity
+  // changes after an otherwise unrelated settings PUT.
+  }, [project.projectId, worldManifestRevision]);
 
   const collisionAvailable = project.worldManifest?.collision.available ?? false;
   const commitViewerSettings = (settings: SimulationViewerSettings) => {

apps/control-station/test/simulationWorkspace.test.mjs

@@ -19,7 +19,7 @@ test("simulation is a dedicated Polygon workspace with a bounded feature slice",
   assert.match(productModel, /id: "simulations"[\s\S]*root: "polygon"[\s\S]*kind: "simulations"/);
   assert.match(workspaceHub, /case "simulations":[\s\S]*<SimulationWorkspace \/>/);
   assert.match(workspace, /simulation-catalog__table/);
-  assert.match(workspace, /<SimulationViewport project=\{selected\}/);
+  assert.match(workspace, /<SimulationViewport[\s\S]*project=\{selected\}/);
   assert.match(workspace, /<ConfirmationModal/);
   assert.match(styles, /styles\/simulation\.css/);
 });
@@ -103,4 +103,7 @@ test("PlayCanvas owns the realtime scene graph without an iframe or React entity
   assert.match(viewport, /Ось инверсии collision-слоя/);
   assert.match(viewport, /saveSimulationViewerSettings/);
   assert.match(viewport, /onProjectChange\?\.\(saved\)/);
+  assert.match(viewport, /const worldManifestRevision = JSON\.stringify\(project\.worldManifest\)/);
+  assert.match(viewport, /\[project\.projectId, worldManifestRevision\]/);
+  assert.doesNotMatch(viewport, /\[project\.projectId, project\.worldManifest\]/);
 });