NNUE accumulator incremental maintenance: MakeMove/UnmakeMove hookup

2026-10-15T22:21:26Z

Wires the live NNUE accumulator (SEARCHER_THREAD_CONTEXT.sNnueAccum[2], added in the previous commit) into real incremental maintenance, hooked directly into the piece-movement primitives rather than re-deriving move type from MOVE in a separate pass: - chess.h: shared HalfKAv2_hm feature-index formula/constants (NnueFeatureIndex and friends), moved here from nnuefeatures.c so the reference dump and the real hot-path code can never drift apart. Prototypes for NnueAccumAddFeature/RemoveFeature/Recompute and the (still placeholder, zero-initialized) embedding table. LiftPiece/PlacePiece/SlidePiece/SlidePawn/SlidePieceWithoutSigs signatures gain an NNUE_ACCUMULATOR sNnueAccum[2] parameter. - nnueaccum.c (new): the embedding table storage and the three accumulator operations. Written as straight-line 256-float loops, structured for -O3 -ffast-math auto-vectorization on this box's AVX2+FMA target; explicit SIMD intrinsics and real weight loading are separate, deliberately deferred follow-ups. - move.c: all 8 Lift/Place/Slide(WithoutSigs) primitives now keep sNnueAccum incrementally correct for both perspectives on every call -- except when the piece is a king, where each primitive skips its own-color perspective entirely (that perspective needs a full recompute, not a delta, since every HalfKAv2_hm feature in it is own-king-relative; computing an incremental update for it only to discard it unread would be wasted work). MakeMove backs up that perspective into the current ply's PLY_INFO.sNnueAccumBackup before a king moves (castling or a plain step) and overwrites it via NnueAccumRecompute once the board reflects the final position; UnmakeMove restores it from the same backup slot. DEBUG builds tag the backup with the color it belongs to and poison it after consumption, release builds carry no overhead for either. - nnuefeatures.c: now a thin board-walking wrapper around the shared chess.h formula instead of its own duplicated copy. - testmove.c: TestLiftPlaceSlidePiece passes a local (unread) dummy accumulator pair -- the only caller of these primitives outside move.c, and it never needed NNUE awareness, just a real argument. Verified via the full precommit_check.sh (all 4 gates, including the new combined DEBUG=1 TEST=1 self-test, which exercises MakeMove/ UnmakeMove heavily via TestMoveGenerator's perft counts and TestLegalMoveGenerator) -- confirms nothing crashes and no existing invariant breaks. Does NOT yet confirm the actual property that matters (incrementally-maintained accumulator == recompute-from- scratch) -- no test exercises that yet; next step. Co-Authored-By: Claude Sonnet 5

Phase A NNUE: feature-indexing spec, annotation/training pipeline, dump nnuefeatures

2026-10-15T20:11:22Z

Builds out the NNUE Phase A prototype per docs/NNUE.md: - src/nnuefeatures.c: standalone HalfKAv2_hm feature-index reference implementation (new `dump nnuefeatures` command), sourced from Stockfish's half_ka_v2_hm.{h,cpp} (sf_16 tag), including the 0x88->64 square conversion typhoon's own board representation needs. - annotate_pgns/: sharded TWIC/self-play annotation harness (annotate.py), position extraction, quiet-position filtering (flat and game-shaped, plus an upstream --prefilter-quiet option), train/holdout game-level stratified split, WDL-sigmoid K fitting, the Python HalfKAv2_hm reference encoder (nnue_feature_spec.py) and its bit-for-bit cross-checker against the C side (cross_check_features.py), and a first PyTorch training pipeline (nnue_model.py, nnue_train.py, build_training_tensors.py) -- a 256x2-32-32-1-ish net trained locally on CPU against ~1.85M quiet TWIC positions as a pipeline/framework validation pass. - Finish an in-progress InitMagic/InitLMRTable/InitEval -> InitializeBitboardMagic/InitializeLMRTable/InitializeEval rename: chess.h's prototypes hadn't been updated to match the already-renamed definitions/call sites, leaving 4 implicit-function-declaration warnings. - tests/arasan.epd: new curated EPD suite. - docs/: add the project's design docs (previously untracked). Co-Authored-By: Claude Sonnet 5

typhoon.git/src/nnuefeatures.c, branch master

NNUE accumulator incremental maintenance: MakeMove/UnmakeMove hookup

Phase A NNUE: feature-indexing spec, annotation/training pipeline, dump nnuefeatures