Start here
output disciplineSteady
Structured Extraction
Turn a messy customer message into strict JSON without inventing a value you weren't given.
Play6 hidden cases
Practice ground for prompt writers
Your prompt looks fine.
Six hidden cases disagree.
Write one instruction. Run it against cases you cannot see. Then find out what broke, and what your fix broke next.
- Real model runs
- Inputs stay hidden
- No sign-up
/6
The arena
Tap a case to see what it caught.
Amount kept: The reply picked the delivery fee instead of the refund amount.
Demo board. Real runs use hidden cases and a live model.
Choose a challenge
Each one trains a different reflex. Start with the flagship.
instruction boundariesTricky
Following Rules
Handle real customer requests while obeying policy, including the ones you must refuse or escalate.
Play6 hidden cases
constraint controlSteady
Rewrite Without Losing Meaning
Make text shorter or simpler without dropping a single fact that matters.
Play6 hidden cases
How a run works
Three moves. About a minute per attempt.
Write one prompt
A short instruction is enough to start.
Six cases push back
Hidden inputs, live model, no peeking.
Fix one thing
Watch what your edit fixes and breaks.
Stop guessing. Find the case that breaks it.
The first run takes about a minute. Your prompt stays in the tab, and every score comes from the model.