Coach definition, not a live verdict. These pages show how the X-ray Coach defines this concept and where its thresholds sit, sourced from the coach's own code. Unlike the tactic pages, nothing here runs a live detector — example boards illustrate the rule, they don't execute it.
What it means
- Looks at *how* you arrive at moves in quiet, non-forced positions: snap decisions and a bias toward forward moves over the right retreat.
- Impulse rate is the one metric where higher is better — strong players recognize quiet positions quickly and bank their clock.
The exact rule the X-ray Coach applies
- Impulse rate (higher = better): share of moves played in ≤1 second when the position was balanced (eval within ±1 pawn). Excludes premoves, only-moves, recaptures, and moves with under 10 seconds on the clock.
- Missed-retreat blunder rate: share of moves that blundered when the engine's best move was to retreat a piece — a forward-bias signal.
- Critical moment: eval ∈ [−1.5, +1.5], one clearly-best move (alternatives drop ≥0.5), >10s remaining, not a forced recapture or only legal move.
Why it matters
Most games below master level are decided in quiet positions by rushed decisions, not by deep tactics.