test(e2e): add Cypress scaffold + CI job

.github/workflows/ci.yml

@@ -83,3 +83,32 @@ jobs:
           path: |
             backend/coverage.xml
             frontend/coverage/**
+
+  e2e:
+    runs-on: ubuntu-latest
+    needs: [check]
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: "20"
+          cache: npm
+          cache-dependency-path: frontend/package-lock.json
+
+      - name: Cypress run
+        uses: cypress-io/github-action@v6
+        with:
+          working-directory: frontend
+          install-command: npm ci
+          build: npm run build
+          start: npm start
+          wait-on: http://localhost:3000
+          command: npm run e2e
+        env:
+          NEXT_TELEMETRY_DISABLED: "1"
+          # Force Clerk disabled in E2E to keep tests secretless/deterministic.
+          NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY: ""

frontend/cypress.config.ts

@@ -0,0 +1,11 @@
+import { defineConfig } from "cypress";
+
+export default defineConfig({
+  e2e: {
+    baseUrl: "http://localhost:3000",
+    video: false,
+    screenshotOnRunFailure: true,
+    specPattern: "cypress/e2e/**/*.cy.{ts,tsx,js,jsx}",
+    supportFile: "cypress/support/e2e.ts",
+  },
+});

frontend/cypress/e2e/activity_smoke.cy.ts

@@ -0,0 +1,7 @@
+describe("/activity page", () => {
+  it("loads without crashing", () => {
+    cy.visit("/activity");
+    // In secretless/unsigned state, UI should render the signed-out prompt.
+    cy.contains(/sign in to view the feed/i).should("be.visible");
+  });
+});

frontend/cypress/support/e2e.ts

@@ -0,0 +1,2 @@
+// Cypress support file.
+// Place global hooks/commands here.

frontend/package.json

@@ -10,7 +10,9 @@
     "test": "vitest run --passWithNoTests --coverage",
     "test:watch": "vitest",
     "dev:lan": "next dev --hostname 0.0.0.0 --port 3000",
-    "api:gen": "orval --config ./orval.config.ts"
+    "api:gen": "orval --config ./orval.config.ts",
+    "e2e": "cypress run",
+    "e2e:open": "cypress open"
   },
   "dependencies": {
     "@clerk/nextjs": "^6.37.1",
@@ -52,6 +54,7 @@
     "tailwindcss": "^3.4.17",
     "tailwindcss-animate": "^1.0.7",
     "typescript": "^5",
-    "vitest": "^2.1.8"
+    "vitest": "^2.1.8",
+    "cypress": "^14.0.0"
   }
 }