Set scene time through the Cesium frame port, in the application too

frame.setTime moves from the conformance renderer into the shared Cesium
ports, so the application's renderer has it. It moves the clock and asks for
a frame, which on-demand drawing needs. It no longer stops the clock: the
conformance renderer stops its own at creation, and the application's clock
keeps whatever state its owner gave it.

src/render/cesium/appRenderer.js

@@ -7,11 +7,10 @@
  * The renderer it makes is transitional. Its ports are the shared Cesium
  * ports (`ports.js`), the ones the conformance renderer is checked with,
  * less the members that would not be true of the application yet: the
- * globe (it draws photoreal tiles the port does not know), `whenSettled`
- * (it would not wait for them), `frame.setTime` (it would stop the
- * application's clock). Those arrive with the layer families that need
- * them (phase 2 of the renderer plan); `checkRendererShape` lists what is
- * still missing.
+ * globe (it draws photoreal tiles the port does not know) and
+ * `whenSettled` (it would not wait for them). Those arrive with the layer
+ * families that need them (phase 2 of the renderer plan);
+ * `checkRendererShape` lists what is still missing.
  * Until a family is ported, its code reaches the Cesium viewer through
  * `cesiumViewerOf`, never through a renderer member, so no engine type
  * crosses the contract and each call marks code still to port. Ported code

src/render/cesium/appRenderer.test.mjs

@@ -318,7 +318,6 @@ test('the application refuses a renderer it cannot run on, and destroys it', asy
 });
 
 const EXPECTED_MISSING = [
-  'frame.setTime',
   'renderer.globe',
   'renderer.readPixels',
   'renderer.releaseUnused',

src/render/cesium/ports.js

@@ -347,6 +347,16 @@ export function createCesiumPorts(widget, { capabilities }) {
       targetFps = fps > 0 ? fps : 0;
       widget.targetFrameRate = targetFps || undefined;
     },
+    /**
+     * Moves the clock to `ms` and draws it. Whether the clock then runs on
+     * is its owner's: the application's clock keeps running if it was (a
+     * clock on Cesium's real-time step moves to its multiplier step, as
+     * setting its time does in Cesium).
+     */
+    setTime(ms) {
+      widget.clock.currentTime = Cesium.JulianDate.fromDate(new Date(ms));
+      frame.requestRender('time');
+    },
     time: () => Cesium.JulianDate.toDate(widget.clock.currentTime).getTime(),
   };
 

src/render/cesium/ports.test.mjs

@@ -697,3 +697,18 @@ test('an icon draws its atlas slot once the atlas has it, and again when it chan
   );
   ports.dispose();
 });
+
+test('setTime moves scene time and draws it, leaving the clock running or not', () => {
+  const { widget, scene } = tickingWidget();
+  let requested = 0;
+  scene.requestRender = () => (requested += 1);
+  widget.clock.shouldAnimate = true;
+  const ports = createCesiumPorts(widget, { capabilities: all });
+  const t = Date.UTC(2026, 5, 21, 12);
+  ports.frame.setTime(t);
+  assert.equal(ports.frame.time(), t);
+  assert.equal(widget.clock.shouldAnimate, true, 'still running');
+  assert.equal(requested, 1, 'one frame asked for');
+  assert.deepEqual(ports.frame.diagnostics().pendingReasons, ['time']);
+  ports.dispose();
+});

src/render/cesium/sceneRenderer.js

@@ -66,7 +66,8 @@ export async function createCesiumSceneRenderer({
     contextOptions: { webgl: { preserveDrawingBuffer: true } },
   });
   const scene = widget.scene;
-  // A fixed time, so lighting is the same in every capture.
+  // A fixed time, so lighting is the same in every capture; `setTime`
+  // moves it and it stays there.
   widget.clock.shouldAnimate = false;
   widget.clock.currentTime = Cesium.JulianDate.fromIso8601(
     '2026-06-21T18:00:00Z',
@@ -95,14 +96,6 @@ export async function createCesiumSceneRenderer({
     query: ports.query,
     report: ports.report,
   });
-  const frame = {
-    ...ports.frame,
-    setTime(ms) {
-      widget.clock.currentTime = Cesium.JulianDate.fromDate(new Date(ms));
-      widget.clock.shouldAnimate = false;
-      scene.requestRender();
-    },
-  };
 
   // --- Globe -----------------------------------------------------------------
 
@@ -269,7 +262,7 @@ export async function createCesiumSceneRenderer({
     contractVersion: '0',
     capabilities,
     canvas: scene.canvas,
-    frame,
+    frame: ports.frame,
     globe,
     // A member of a capability left out is absent, not stubbed.
     draw: capabilities.has('models')