Mirrors vs record and replay
Replay returns the recorded answer to the recorded call; a mirror answers new calls from a world model.
Where they differ
Replay breaks on any argument it has not seen; a world model computes the answer.
A mirror still uses recordings as evidence and as the ground truth for scoring.
When to pick which
record and replay remains the right tool when its own strengths are what you need; a mirror is for testing an agent against a backend that behaves like production without being production.
Related: /glossary/mirror/pricing