How much of an agent's work is secretly repeatable?
Most of what an agent does, it has done before. Watchman records every tool call with its result and replays the ones whose answer has never changed.
THE QUESTION
If you recorded every tool call an agent made and compared the results, what fraction would turn out to be deterministic enough to stop paying for?
WHAT WE FOUND
- A tool call is only replayed when the same input has returned the same output every time it has been observed. The term for that is witnessed-deterministic, and the caution in it is deliberate: a result that has been identical so far might still change, so the replay is a bet, not a proof.
- The interesting artifact is not the cache, it is the census. Reporting what share of a workflow is repeatable tells you something nobody currently measures about their own agents.
- A cached answer served after the world moved is a worse failure than a slow one. Freshness-sensitive calls have to be excluded by policy rather than discovered by incident.