test(studio): mock composition thumbnails in smoke

scripts/studio-runtime-smoke.mjs

@@ -10,6 +10,8 @@ export const SMOKE_COMPOSITION_HTML =
   '<!doctype html><html><body><div data-composition-id="root" data-width="1920" ' +
   'data-height="1080" data-duration="1" data-start="0"><div class="clip" ' +
   'data-hf-id="title" data-start="0" data-duration="1">Test</div></div></body></html>';
+const SMOKE_THUMBNAIL_SVG =
+  '<svg xmlns="http://www.w3.org/2000/svg" width="16" height="9"><rect width="16" height="9"/></svg>';
 
 function json(body, status = 200) {
   return { status, contentType: "application/json", body: JSON.stringify(body) };
@@ -75,6 +77,11 @@ function projectPreviewResponse(pathname) {
     : text(SMOKE_COMPOSITION_HTML, "text/html");
 }
 
+function projectThumbnailResponse(pathname) {
+  if (!pathname.startsWith(`${PROJECT_PATH}/thumbnail/`)) return undefined;
+  return text(SMOKE_THUMBNAIL_SVG, "image/svg+xml");
+}
+
 function gsapAnimationsResponse(pathname) {
   if (!pathname.startsWith(`${PROJECT_PATH}/gsap-animations/`)) return undefined;
   return json({ animations: [], timelineVar: "tl", preamble: "", postamble: "" });
@@ -85,6 +92,7 @@ function getStudioSmokeResponse(pathname) {
     GET_RESPONSES.get(pathname) ??
     projectFileResponse(pathname) ??
     projectPreviewResponse(pathname) ??
+    projectThumbnailResponse(pathname) ??
     gsapAnimationsResponse(pathname)
   );
 }

scripts/studio-runtime-smoke.test.mjs

@@ -44,6 +44,15 @@ describe("Studio runtime smoke fixtures", () => {
     assert.deepEqual(bodyOf("GET", "/api/projects/smoke-test/lint"), { findings: [] });
   });
 
+  it("returns an image for composition thumbnail requests", () => {
+    const response = studioSmokeApiResponse(
+      "GET",
+      "http://localhost:5199/api/projects/smoke-test/thumbnail/index.html?t=3",
+    );
+    assert.ok(response && response !== null);
+    assert.equal(response.contentType, "image/svg+xml");
+  });
+
   it("marks unknown API requests as fixture failures", () => {
     assert.equal(studioSmokeApiResponse("GET", "http://localhost:5199/api/new-endpoint"), null);
     assert.equal(studioSmokeApiResponse("GET", "http://localhost:5199/src/main.tsx"), undefined);