The worker sorts tiles.
red goes in the left bin, orange in the right. It sorts, then it checks its own work. Watch.
Red bin
Orange bin
Something look off? Its check says no. Hold the button to see why.
Your eyes work differently. So you be the check: tap every tile sitting in the wrong bin.
Errors the worker’s own check found: 0. Errors you found: . Same tiles, same bins — the only difference is that your eyes aren’t its eyes.
Why its own check was worthless
The worker never lied. Through its eyes the work really was perfect — and that’s the trap. A check built from the doer’s own eyes inherits every blind spot that made the mistakes in the first place: it doesn’t verify the work, it re-counts the mistake. This is why a programmer’s own tests pass the programmer’s own bug, and why an AI agent asked to grade its own answer finds it excellent. Honesty doesn’t fix it — the worker was honest. The fix is structural: the check comes from outside, from eyes that don’t share the doer’s blind spots and sit outside the doer’s reach.