What does closing the testing loop actually look like when your agent ships the code

The phrase gets thrown around constantly but most setups are still just "agent writes code, human does QA" which is not a closed loop at all, that is the same old process with faster typing at the front end
Agent pushes a PR and then what, someone pulls it down and manually clicks through the feature, or a CI pipeline runs unit tests that catch maybe a quarter of the real issues. Neither of those closes anything Would love to hear from anyone running something where the agent gets real end to end feedback on whether its output works before a human even opens the PR