diff --git a/.github/workflows/astro.yml b/.github/workflows/astro.yml
index a022833..f3b19f6 100644
--- a/.github/workflows/astro.yml
+++ b/.github/workflows/astro.yml
@@ -62,6 +62,29 @@ jobs:
         with:
           path: ${{ env.BUILD_PATH }}/dist
 
+  lighthouse:
+    name: Lighthouse CI
+    runs-on: ubuntu-latest
+    needs: build
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Setup Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: "22"
+          cache: npm
+          cache-dependency-path: package-lock.json
+      - name: Install dependencies
+        run: npm ci
+        working-directory: ${{ env.BUILD_PATH }}
+      - name: Build with Astro
+        run: npx astro build
+        working-directory: ${{ env.BUILD_PATH }}
+      - name: Run Lighthouse CI
+        run: npx @lhci/cli@0.14.x autorun
+        working-directory: ${{ env.BUILD_PATH }}
+
   deploy:
     environment:
       name: github-pages
diff --git a/.lighthouserc.json b/.lighthouserc.json
new file mode 100644
index 0000000..94c5d2d
--- /dev/null
+++ b/.lighthouserc.json
@@ -0,0 +1,19 @@
+{
+  "ci": {
+    "collect": {
+      "staticDistDir": "./dist",
+      "numberOfRuns": 1
+    },
+    "assert": {
+      "assertions": {
+        "categories:performance": ["warn", { "minScore": 0.8 }],
+        "categories:accessibility": ["error", { "minScore": 0.9 }],
+        "categories:best-practices": ["warn", { "minScore": 0.9 }],
+        "categories:seo": ["warn", { "minScore": 0.9 }]
+      }
+    },
+    "upload": {
+      "target": "temporary-public-storage"
+    }
+  }
+}
diff --git a/docs/backlog.md b/docs/backlog.md
index ca3887c..ad64947 100644
--- a/docs/backlog.md
+++ b/docs/backlog.md
@@ -11,21 +11,6 @@ construction" placeholders. The old AI-generated versions have been archived at
 `src/pages/ai-generated/old-entry-point.astro` and
 `src/pages/ai-generated/old-hello.astro`.
 
-## Low Priority
-
-### Type external CDN scripts
-
-`_score.ts` uses `@ts-expect-error` for a CDN ESM import of the WaveSurfer
-regions plugin. Consider bundling these dependencies or adding typed wrappers.
-
-- File: `src/pages/ai-generated/do-olls-that-will-talk/_score.ts`
-
-### Add Lighthouse CI to GitHub Actions
-
-No performance budget exists. Lighthouse CI in the workflow would catch regressions.
-
-- File: `.github/workflows/astro.yml`
-
 ## Improvements
 
 ### Consider bundling WaveSurfer and YouTube API
@@ -46,3 +31,9 @@ Loading these from CDN introduces external dependencies. Bundling via npm would
 - **Inline trivial npm script wrappers** — justfile recipes already call tools
   directly (`eslint`, `tsc`, `astro`, `prettier`, `vitest`); only `precommit`
   and `prepush` delegate to npm because they run multi-step pipelines.
+- **Type external CDN scripts** — added ambient module declaration
+  `_regions.d.ts` for the WaveSurfer RegionsPlugin CDN URL; removed
+  `@ts-expect-error` and inline casts from `_score.ts`.
+- **Add Lighthouse CI to GitHub Actions** — added `lighthouse` job to
+  `astro.yml` (runs after build, uses `@lhci/cli`); added `.lighthouserc.json`
+  with accessibility error threshold and performance/SEO/best-practices warnings.
diff --git a/src/pages/ai-generated/do-olls-that-will-talk/_regions.d.ts b/src/pages/ai-generated/do-olls-that-will-talk/_regions.d.ts
new file mode 100644
index 0000000..14a4c92
--- /dev/null
+++ b/src/pages/ai-generated/do-olls-that-will-talk/_regions.d.ts
@@ -0,0 +1,32 @@
+// Typed ambient declaration for the WaveSurfer RegionsPlugin CDN ESM build.
+// This removes the @ts-expect-error on the CDN import in _score.ts.
+
+declare module "https://cdn.jsdelivr.net/npm/wavesurfer.js@7/dist/plugins/regions.esm.js" {
+  export interface RegionParams {
+    start: number;
+    end: number;
+    color?: string;
+    content?: string;
+    resize?: boolean;
+    drag?: boolean;
+    id?: string;
+  }
+
+  export interface Region {
+    start: number;
+  }
+
+  export interface RegionsPluginInstance {
+    addRegion(params: RegionParams): Region;
+    on(
+      event: "region-clicked",
+      fn: (region: Region, event: { stopPropagation(): void }) => void
+    ): void;
+  }
+
+  const RegionsPlugin: {
+    create(): RegionsPluginInstance;
+  };
+
+  export default RegionsPlugin;
+}
diff --git a/src/pages/ai-generated/do-olls-that-will-talk/_score.ts b/src/pages/ai-generated/do-olls-that-will-talk/_score.ts
index 326faf0..cab4eef 100644
--- a/src/pages/ai-generated/do-olls-that-will-talk/_score.ts
+++ b/src/pages/ai-generated/do-olls-that-will-talk/_score.ts
@@ -1,7 +1,7 @@
 // File: _score.ts
 
-// @ts-expect-error - CDN ESM import without type declarations
 import RegionsPlugin from "https://cdn.jsdelivr.net/npm/wavesurfer.js@7/dist/plugins/regions.esm.js";
+import type { RegionsPluginInstance } from "https://cdn.jsdelivr.net/npm/wavesurfer.js@7/dist/plugins/regions.esm.js";
 
 declare global {
   interface Window {
@@ -167,14 +167,13 @@ if (!isBrowser()) {
       url: "/audio/do-olls-clip.mp4",
     });
 
-    const regions = ws.registerPlugin(RegionsPlugin.create());
+    const regions = ws.registerPlugin(
+      RegionsPlugin.create()
+    ) as RegionsPluginInstance;
 
     ws.on("ready", () => {
       markers.forEach((m, i) => {
-        // regions is untyped (CDN plugin), so we go through unknown.
-        (
-          regions as { addRegion: (cfg: Record<string, unknown>) => void }
-        ).addRegion({
+        regions.addRegion({
           start: m.time,
           end: m.time + 0.05,
           color: categoryColor[m.category],
@@ -202,14 +201,7 @@ if (!isBrowser()) {
       if (playPause) playPause.textContent = "Play";
     });
 
-    (
-      regions as {
-        on: (
-          evt: string,
-          fn: (r: { start: number }, e: { stopPropagation: () => void }) => void
-        ) => void;
-      }
-    ).on("region-clicked", (r, e) => {
+    regions.on("region-clicked", (r, e) => {
       e.stopPropagation();
       ws.setTime(r.start);
     });