feat(tests): Storybook visual regression harness (Playwright)

apps/storybook/tests/visual.spec.ts

@@ -0,0 +1,51 @@
+import { test, expect } from "@playwright/test";
+
+/**
+ * Iterates every story registered in Storybook and takes a screenshot.
+ *
+ * Storybook exposes its story manifest at /index.json (Storybook 7+). For
+ * each entry where `type === "story"`, we navigate to the iframe URL and
+ * snapshot.
+ *
+ * Today the index is empty (no components in the repo). The harness still
+ * runs — it just finds zero stories. The moment a story lands, the
+ * baseline is captured on first run and subsequent runs diff against it.
+ */
+type StoryEntry = {
+  id: string;
+  title: string;
+  name: string;
+  type: "story" | "docs";
+};
+
+async function fetchStoryIndex(baseURL: string): Promise<StoryEntry[]> {
+  const res = await fetch(`${baseURL}/index.json`);
+  if (!res.ok) return [];
+  const json = (await res.json()) as {
+    entries?: Record<string, StoryEntry>;
+  };
+  return Object.values(json.entries ?? {}).filter((e) => e.type === "story");
+}
+
+test.describe("Storybook visual regression", () => {
+  test("captures a screenshot for every registered story", async ({
+    page,
+    baseURL,
+  }) => {
+    const stories = await fetchStoryIndex(baseURL!);
+    if (stories.length === 0) {
+      test.skip(
+        true,
+        "No stories registered yet — visual regression harness is inactive until the first story lands.",
+      );
+      return;
+    }
+    for (const story of stories) {
+      await test.step(`${story.title} — ${story.name}`, async () => {
+        await page.goto(`/iframe.html?id=${story.id}&viewMode=story`);
+        await page.waitForLoadState("networkidle");
+        await expect(page).toHaveScreenshot(`${story.id}.png`);
+      });
+    }
+  });
+});

package.json

@@ -12,6 +12,7 @@
     "test": "turbo run test",
     "test:e2e": "turbo run test:e2e",
     "test:stories": "turbo run test:stories",
+    "test:visual": "pnpm --filter @repo/storybook exec concurrently -k -s first -n 'SB,VRT' -c 'magenta,blue' 'pnpm --filter @repo/storybook exec http-server storybook-static --port 6006 --silent' 'pnpm --filter @repo/storybook exec wait-on tcp:6006 && pnpm exec playwright test'",
     "typecheck": "turbo run typecheck",
     "conformance": "node scripts/conformance.mjs",
     "work": "node scripts/work/cli.mjs",