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
- The Tactics tab (?view=tactics) lists positions where your move was a blunder and the engine's best move carried a tactic you missed. Koga classifies each such best move together with its full engine line; the coach then decides whether the label is a real missed tactic.
- A Koga label alone is not enough — the missed line must actually win something. Since 2026-08-14 the Position Hypermarket's tactic filter applies this same payoff rule, so the two products agree on what a tactic is.
The exact rule the X-ray Coach applies
- Missed-tactic gate: the best move carries at least one non-soft Koga motif AND its line nets ≥ 2 pawns for you within one or two moves — material is read after the opponent's reply, so a piece they recapture (even on another square) never counts — or the line forces mate in one or two moves.
- Endgame relaxation: in the endgame the payoff bar drops to ≥ 1 pawn — a clean extra pawn there is often decisive.
- Soft motifs never qualify on their own: counterThreat, counterTactics, preparatoryMove, missedOpportunity, unforcedError — they describe counter-play, preparation, or hindsight, not a winning shot.
- Headline tiles group by MOTIF-role labels only; 'enabling' and 'follow-up' roles are internal classifier signals and never become tiles.
- Discriminators demote dubious labels before display: hanging piece, attacking a pinned piece, pin-subsumed-by-fork, symmetric exchanges, and punishment-line forks.
- Hidden tactics are suppressed app-wide until their detectors are trusted: counterThreat, windmill, bombardinio, promotion, preparatoryMove, insufficientlyDefended. Removing a key re-enables that tactic everywhere.
- 'Hide pawn-dependent' toggle: the GM view that a pawn is never a valid tactical target — when on, tactics whose target is a pawn are dropped.
- Depth filter: Koga's deeper_tactics (executing at PV depth ≥ 2) are display-only — shown when the depth filter is raised, never feeding the Tactics Score.
- If Koga is unreachable, a position reads 'unknown', never 'quiet' — an outage removes tactics from the view instead of mislabelling positions as tactic-free.
Why it matters
This is the coach's single definition of 'a tactic you missed': motif plus payoff, not motif alone. A knight move that touches two pieces is only a fork if taking one of them actually survives the opponent's best reply — the payoff walk is what keeps geometric noise off the tab.
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