Recording an agent run at its non-deterministic boundaries turns an incident into a CI test.

Chronicle records an agent run as immutable envelopes at each non-deterministic boundary, then replays it, with cut-point replay serving a chosen subset of boundaries from the record while executing the rest live against new code. On six recorded failures, recording added 23 microseconds per crossing (0.008% of an assumed 300ms model call), full replay issued zero model calls and was bit-stable across 20 repetitions, and cut-point tests failed on faulty code while passing on guarded and benign changes for all six. This is the closest thing yet to a regression suite for agent behavior.