diff --git a/.github/workflows/f2-3-ci.yml b/.github/workflows/f2-3-ci.yml
index d88560f..d6f5b83 100644
--- a/.github/workflows/f2-3-ci.yml
+++ b/.github/workflows/f2-3-ci.yml
@@ -31,7 +31,15 @@ jobs:
       - name: Install
         run: npm ci
       - name: Typecheck
-        run: npm run typecheck
+        run: npm run typecheck 2>&1 | tee typecheck.log
+      - name: Upload TypeScript diagnostic
+        if: always()
+        uses: actions/upload-artifact@v4
+        with:
+          name: f2-3-typecheck-diagnostic
+          path: api-v3/typecheck.log
+          if-no-files-found: warn
+          retention-days: 3
       - name: Tests
         run: npm test
       - name: Build