The engines we ship.
Apr 22, 4 min
Skalpel is plural. three engines today, each doing one job. notes on what each one is for, and what's in flight.
Shipping today
**trajectory engine.** the primary engine. intervenes at decision boundaries when the drift detector reports a high-confidence drift event. narrows the choice set when it acts; does nothing the rest of the time.
**drift detector.** computes the on-task signal we steer on. produces one number per agent decision, conditioned on the run's history. the trajectory engine consumes it; future engines will too.
**compressor.** holds long agent context on-task as the run grows. trims structurally and semantically, not by raw token count. designed so the model sees the same shape of context at step fifty as it saw at step five.
In flight
we're working on two more. the first is a re-anchor primitive that brings a drifting run back to its original goal without restarting it. the second is a slow-burn check that runs in the background and surfaces inconsistencies in the run's working set. neither is shipping yet.
Philosophy
each engine does one job. they compose because they all read the same drift signal and they all leave your prompt, your model, and your code untouched. the install is one binary; the engines are toggles inside it.
ryan