What is deterministic replay?
Deterministic replay executes a previously compiled skill as an explicit, ordered program of browser actions keyed to indexed DOM elements, without invoking a language model. Because the plan is fixed and re-resolved against the live page rather than regenerated, the same goal yields the same action path — fast, cheap, and auditable.
Why it matters
Replay is what makes a cache hit nearly free: once a skill is compiled, re-running it costs browser time, not model tokens. It also makes runs reproducible and reviewable, which matters for RPA and authorized testing where you need the same flow to behave identically across thousands of executions.