The typhoon chess playing engine. https://git.acknak.org/cgit/typhoon.git/atom?h=master 2026-08-29T07:30:53Z 2026-08-29T07:30:53Z Scott Gasch scott@gasch.org 2026-08-29T07:30:53Z urn:sha1:917bf1260ae217bdcbdbc11c2c37cdb5d3a8eae9 Killer tiers now try both of this ply's own killers before either ply-2-back one, matching Crafty's ordering. Two earlier attempts at this same swap were reverted for regressing; this pass lands on top of NumLeftoverMovesToSelect (more SelectBestWithHistory budget to reach these lower-tier slots) and a real bug fix below, and beats interleaved order head-to-head on solves, node count, and first-move beta cutoff across the three curated suites. The bug: mvNullmoveRefutations's empty-killer-slot backfill could only ever contain a capturing move (TryNullmovePruning only wrote it inside the capture-refutation branch), but IS_SAME_MOVE's mask includes the pCaptured bits, so that backfilled value could never match a real quiet candidate -- the backfill was silently dead code. Fixed by recording genuinely quiet null-move refutations into a new, separate mvNullmoveQuietRefutations array (kept separate so it can't clobber the capture history mvNullmoveRefutations still needs for the Botvinnik-Markoff same-piece-two-squares extension check) and backfilling the regular killer table from that instead. The check-evasion killer table intentionally does *not* get this backfill: a null-move refutation can never legitimately be an escaping-check move (null moves can't deliver check), so backfilling there risks IS_SAME_MOVE cross-context false positives instead of the old guaranteed-inert no-op. Measured at sd10 across ecm_ringers/ecm_confident_quick/ecm_hard_quick against head_reference (commit d11e973): 115/191 solves (vs. 116 baseline), 924.36M total nodes (vs. 933.23M), first-move beta cutoff within 0.1-0.9 points of baseline on all three suites -- and clearly better than the same fix under interleaved order (113/191 solves, 963.10M nodes), which loses to head_reference on every metric. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01EortUUkDVpsfrbqshBJYJg 2016-06-02T01:58:58Z Scott Gasch scott.gasch@gmail.com 2016-06-02T01:58:58Z urn:sha1:3fd43cd5fcb22bb65bf2a92a25d95d801b11c9e0