PreAct
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Computer-using agents drive real software through the screen, but they solve every task from scratch. Ask one to repeat a task and it re-reads the screen and re-reasons every tap, paying the full cost again. PreAct fixes this by compiling the first successful run into a small state-machine program, where states check the screen and transitions act, then replaying that program on later runs instead of invoking the agent.
Compile runs into a state machine: A completed task is captured as an explicit program rather than a free-form trace, turning a one-off solution into a reusable artifact that can be executed deterministically.
Replay with no per-step model calls: Replaying the compiled program runs 8.5 to 13 times faster than the agent because it needs no per-step language-model calls on repeated tasks.
Safe by construction: At each step PreAct checks that the screen matches what the program expects before acting, and hands control back to the agent the moment something is off, and it only stores programs an independent evaluator confirms solve the task from a clean state.
Why it matters: This turns computer-using agents from interactive tools that re-reason everything into repeatable operational systems, which is exactly what is needed to deploy them on recurring real work.
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