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 for blunders driven by *state* rather than position: coming back rusty, playing too long in one sitting, or tilting after a loss.
The exact rule the X-ray Coach applies
- Rust: the first 2 games of a session that follows ≥ 72 hours without a game. (A session is a run of games with gaps under 6 hours.)
- Late-in-session blunders: blunder rate in games played deep into a single sitting (fatigue).
- Tilt: blunder rate during losing streaks (after consecutive losses).
Why it matters
These leaks are fixed by habits (warm up, stop after N games, take a break after a loss), not by studying chess — so naming them is half the cure.