diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ca5ac99..6c4dc46 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -19,9 +19,14 @@ jobs:
         uses: actions/setup-node@v4
         with:
           node-version: '20'
+          cache: yarn
+          cache-dependency-path: server/yarn.lock
+
+      - name: Setup Yarn Classic
+        run: npm install --global yarn@1.22.22
 
       - name: Install dependencies
-        run: npm install
+        run: yarn install --frozen-lockfile
 
       - name: Run Gemini compatibility tests
-        run: npm run test:gemini-compat
+        run: yarn test:gemini-compat