Bentham's Panopticon is a ring of cells around a central tower. The inmate can never see whether the guard is in the tower, so must act as if always watched. Foucault's claim: this makes power cheap and automatic — surveillance is internalized and the inmate becomes the principle of their own subjection.
Here that claim is a measurement. With the shutter open, inmates read the beam and deviate the instant it swings away — so you must light everyone, always: maximum watch cost. Close the shutter and observation becomes unverifiable: each inmate knows only the base rate — that they might be watched — and can no longer time their deviance. A narrow, sweeping, unverifiable beam disciplines the whole ring at a fraction of the cost.
Every time the eye actually catches a deviant, that inmate's internal stock climbs and decays only slowly. Build it high enough and you can switch the lamp off entirely — the tower empty, the cost zero — and the ring keeps watching itself.
Something in the simulation stopped unexpectedly — the lesson continues without it. You can move on; nothing you did was wrong.