Rewrite _EvalKing as a linear ring-scan and promote its terms to DNA-tunable constants; retune via mate-mining regression, ElasticNet/Ridge, and logistic-vs-material refits.

Splits _EvalKing's own king-location table from CountKingSafetyDefects' search-gate copy so future eval retunes can't silently perturb extension/reduction gate frequency. Bumps KING_BACK_FLIGHT_BONUS (+1 -> +3) and reorders/nudges the ring-scan sub-terms (minor/pawn/xray/undefended) to match relative rankings that replicated across three independent calibration methods, while leaving KING_QUEEN_PROXIMITY_DANGER and KING_MISSING_ONE_CASTLE_OPTION untouched pending further discussion.

Self-play (640 games) is roughly even (score 0.509, llr=+0.17, far from either SPRT bound) but consistently faster (nps candidate=1362140 vs head=1333682) at equal average depth -- landing as a wash/speed-neutral checkpoint, not a confirmed tactical improvement, for further tuning to build on.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

1 files changed, 29 insertions, 1 deletions

diff --git a/src/chess.h b/src/chess.h
index df59626..4d7015e 100755
--- a/src/chess.h
+++ b/src/chess.h
@@ -1363,7 +1363,12 @@ PAWN_HASH_ENTRY;
 typedef struct _KING_SAFETY_HASH_ENTRY
 {
     UINT64 u64Key;
-    ULONG uFileStormDefects[2];
+    // 2026-09-15: SCORE (direct centipawns), not a counter -- see
+    // eval.c's _ComputeFileStormDefects. KING_DEFECT_DUMP's debug
+    // sibling _ComputeFileStormDefectsSplit is untouched and still
+    // reports old counter units into KING_DEFECT_DUMP_INFO, unrelated
+    // to this cache.
+    SCORE iFileStormDefects[2];
 }
 KING_SAFETY_HASH_ENTRY;
 
@@ -1427,6 +1432,15 @@ typedef struct _KING_DEFECT_DUMP_INFO
     ULONG uMinorsAtHome;
     FLAG fMissingCastleShort;
     FLAG fMissingCastleLong;
+    // 2026-09-15: the REAL, current _EvalKing output (post-rewrite linear
+    // ring-scan sum, AFTER the REDUCED_MATERIAL_DOWN_SCALER multiply --
+    // i.e. exactly what gets added into this side's total eval) -- unlike
+    // every other field in this struct, which all come from the
+    // deliberately-frozen OLD counter mechanism (see uSafetyTableValue's
+    // comment). Added for a magnitude sanity check against other engines'
+    // king-safety terms (Crafty/Glaurung), not for regression mining --
+    // it postdates the CSVs the mining pipeline already produced.
+    SCORE iRealSafety;
 }
 KING_DEFECT_DUMP_INFO;
 #endif
@@ -2714,6 +2728,20 @@ extern const int g_BishopRayDeltas[4];
 extern const FLAG g_BishopRayPositiveDir[4];
 extern BITBOARD g_KnightAttacksBB[128];
 extern BITBOARD g_KingAttacksBB[128];
+
+// 2026-09-15: king-ring bitboard split for _EvalKing's linear-SCORE
+// rewrite -- front/back mirror EmptyAttackedSquare's old color-dependent
+// asymmetry and eval_tune/train_king_safety_model.py's BUCKET_SLOTS
+// (WHITE's front = the -17/-16/-15 delta triplet, BLACK's = +15/+16/+17);
+// side is the two same-rank neighbors (-1/+1), color-independent.
+// g_KingRingFrontBB[uColor][c] | g_KingRingBackBB[uColor][c] |
+// g_KingRingSideBB[c] == g_KingAttacksBB[c] always. Precomputed once at
+// startup (InitializeKingAttackTables, data.c) so the hot ring-scan can
+// intersect these with attack bitboards and CountBits() instead of
+// branching per square.
+extern BITBOARD g_KingRingFrontBB[2][128];
+extern BITBOARD g_KingRingBackBB[2][128];
+extern BITBOARD g_KingRingSideBB[128];
 extern BITBOARD g_PawnAttackOriginBB[2][128];
 extern BITBOARD g_RookOccupancyMask[128];
 extern BITBOARD g_BishopOccupancyMask[128];