A frontend test that runs only when someone remembers it protects nothing. The gate is the same place as every other release check: it boots the app, runs the suite, and exits non-zero on a failure. The boot is part of the gate, not an assumption.
About 1 min of reading
Write the gate with clean-up
Boot and wait
Before you run it, say out loud what it will print. Then open the answer.
Run the suite
Before you run it, say out loud what it will print. Then open the answer.
Clean up always
Before you run it, say out loud what it will print. Then open the answer.
Run the gate
Before you run it, say out loud what it will print. Then open the answer.
Boot, wait for readiness, warm, assert, clean up. Five steps, and each one is visible in the output.
Split by speed, not by importance. Fast document tests run on every release; browser tests run on the ones that touch the frontend.
The gate starts the server, waits for the first good response, runs the suite, then stops the server. A gate that assumes a running server fails on a machine that has none.
Request the page once before the assertions so a cold start does not look like a slow page. The warm-up is not an assertion.
Clean up in both branches. A gate that leaves a server running holds a port and blocks the next run.
Each one is defined here on this site. Open the entry for the full definition and the other words it points at.