diff --git a/.forgejo/workflows/ci.yml b/.forgejo/workflows/ci.yml
index a3387bf..2b78dd7 100644
--- a/.forgejo/workflows/ci.yml
+++ b/.forgejo/workflows/ci.yml
@@ -160,8 +160,10 @@ jobs:
         run: npm ci
         working-directory: frontend
 
+      # tsconfig.test.json, not the default: the default leaves the unit tests out
+      # so the Docker build (which has only frontend/) can type-check the app.
       - name: Type check
-        run: npx vue-tsc --noEmit
+        run: npx vue-tsc --noEmit -p tsconfig.test.json
         working-directory: frontend
 
       - name: Unit tests
diff --git a/frontend/tsconfig.json b/frontend/tsconfig.json
index e323b46..1400e6e 100644
--- a/frontend/tsconfig.json
+++ b/frontend/tsconfig.json
@@ -15,5 +15,6 @@
     "noImplicitReturns": true,
     "types": []
   },
-  "include": ["src"]
+  "include": ["src"],
+  "exclude": ["src/**/*.test.ts"]
 }
diff --git a/frontend/tsconfig.test.json b/frontend/tsconfig.test.json
new file mode 100644
index 0000000..9cb4d28
--- /dev/null
+++ b/frontend/tsconfig.test.json
@@ -0,0 +1,9 @@
+{
+  // The app's config plus its unit tests. tsconfig.json leaves the tests out because
+  // the production build type-checks in a Docker stage that copies only frontend/,
+  // and grammar.test.ts reads ../core/testdata, which is not there (run 8478).
+  // CI's typecheck lane runs THIS file, so the tests are still type-checked.
+  "extends": "./tsconfig.json",
+  "include": ["src"],
+  "exclude": []
+}