NNUE accumulator struct scaffolding; fix 3 bugs found by DEBUG+TEST; add that gate

Partial checkpoint on the nnue-accumulator-plumbing branch, before the
MakeMove/UnmakeMove hookup itself:

- chess.h: NNUE_ACCUMULATOR struct (256 floats, pre-activation, float32
  for now -- quantization to int16 deliberately deferred until a real
  quantization-aware export pass exists, per docs/NNUE.md). Added the
  live, always-current SEARCHER_THREAD_CONTEXT.sNnueAccum[2] (one per
  color) and PLY_INFO.sNnueAccumBackup (the king-move full-recompute
  backup slot, DEBUG-only color tag declared for a later ASSERT).
  LIGHTWEIGHT_SEARCHER_CONTEXT also mirrors sNnueAccum[2] at the same
  relative position -- omitting that broke its byte-compatible-prefix
  contract with the full context the moment MakeMove/UnmakeMove will
  start touching it unconditionally (caught by this session's own
  TestSan self-test failure).

- Combining DEBUG=1 and TEST=1 for the first time (apparently ever)
  while chasing that failure immediately turned up three more real,
  pre-existing bugs, all in self-test-only code whose assert-guarded
  invariants had never been checked with asserts actually compiled in:
    - board.c: IsBoardLegal now rejects an en passant square whose rank
      doesn't match the side to move (and verifies the double-moved
      pawn/empty origin square), closing a gap VALID_EP_SQUARE alone
      can't catch.
    - testgenerate.c: TestCapturesAndPromotionsGenerator's fixture table
      had a self-contradictory FEN this new IsBoardLegal check would
      have caught; replaced with a genuine Black-to-move en passant
      position.
    - testgenerate.c: TestFindUnblockedSquaresSpeed called
      _GenerateAllMoves directly instead of the GenerateMoves wrapper,
      skipping the DEBUG-only pStack->board[uPly] snapshot
      WouldGiveCheck's own ASSERT checks against.

- precommit_check.sh / CLAUDE.md: added the DEBUG=1 TEST=1 combination
  as a permanent third pre-commit gate, given what its first-ever run
  turned up. Real cost (~235s of ~266s total, unoptimized build
  dominates), judged worth it.

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

1 files changed, 33 insertions, 4 deletions

diff --git a/src/precommit_check.sh b/src/precommit_check.sh
index c2d7d41..0525765 100755
--- a/src/precommit_check.sh
+++ b/src/precommit_check.sh
@@ -1,5 +1,6 @@
 #!/bin/sh
-# Pre-commit build/test gate: TEST=1 self-test suite + DEBUG=1 random-sample
+# Pre-commit build/test gate: TEST=1 self-test suite + a combined
+# DEBUG=1 TEST=1 self-test (asserts live) + DEBUG=1 random-sample
 # smoke test (debug_smoke_test.sh). Restores a normal release build
 # afterward so the working directory isn't left with a TEST/DEBUG-flavored
 # binary as a side effect of running this.
@@ -16,7 +17,7 @@ mkdir -p "$LOGDIR"
 FAIL=0
 TOTAL_START=$(date +%s)
 
-echo "=== [1/3] Self-test build (gmake TEST=1) ==="
+echo "=== [1/4] Self-test build (gmake TEST=1) ==="
 STEP_START=$(date +%s)
 gmake clean > "$LOGDIR/clean_test.log" 2>&1
 gmake -j5 TEST=1 GENETIC=1 SIXTYFOUR=1 > "$LOGDIR/build_test.log" 2>&1
@@ -36,7 +37,35 @@ fi
 STEP_END=$(date +%s)
 echo "    [$((STEP_END - STEP_START))s]"
 
-echo "=== [2/3] DEBUG smoke test (10 random ECM positions, sd 4) ==="
+# 2026-10-15: added after combining DEBUG=1 and TEST=1 for the first
+# time (ever, as far as anyone could tell) turned up three real,
+# previously-undiscovered bugs in a single run -- none in production
+# code, all in self-test-only harnesses whose assert-guarded invariants
+# had apparently never been checked with asserts actually compiled in
+# (plain TEST=1 has no DEBUG, so ASSERT is a no-op; DEBUG=1 alone never
+# links the self-test .o files at all). Unoptimized, so this step is
+# the slow one -- budget a couple of minutes, not seconds.
+echo "=== [2/4] Combined self-test build (gmake DEBUG=1 TEST=1) ==="
+STEP_START=$(date +%s)
+gmake clean > "$LOGDIR/clean_debugtest.log" 2>&1
+gmake -j5 DEBUG=1 TEST=1 GENETIC=1 > "$LOGDIR/build_debugtest.log" 2>&1
+if [ $? -ne 0 ]; then
+    echo "    BUILD FAILED -- see $LOGDIR/build_debugtest.log"
+    FAIL=1
+else
+    ./_typhoon --batch --command "" > "$LOGDIR/test_run_debugtest.log" 2>&1
+    STATUS=$?
+    if [ "$STATUS" -ne 0 ] || grep -qi "assertion failure\|PANIC" "$LOGDIR/test_run_debugtest.log"; then
+        echo "    SELF-TEST FAILED (exit=$STATUS) -- see $LOGDIR/test_run_debugtest.log"
+        FAIL=1
+    else
+        echo "    self-test passed"
+    fi
+fi
+STEP_END=$(date +%s)
+echo "    [$((STEP_END - STEP_START))s]"
+
+echo "=== [3/4] DEBUG smoke test (10 random ECM positions, sd 4) ==="
 STEP_START=$(date +%s)
 gmake clean > "$LOGDIR/clean_debug.log" 2>&1
 gmake -j5 GENETIC=1 DEBUG=1 MP=1 SIXTYFOUR=1 > "$LOGDIR/build_debug.log" 2>&1
@@ -50,7 +79,7 @@ fi
 STEP_END=$(date +%s)
 echo "    [$((STEP_END - STEP_START))s]"
 
-echo "=== [3/3] Restoring normal release build (GENETIC=1 PERF_COUNTERS=1 MP=1 SIXTYFOUR=1) ==="
+echo "=== [4/4] Restoring normal release build (GENETIC=1 PERF_COUNTERS=1 MP=1 SIXTYFOUR=1) ==="
 STEP_START=$(date +%s)
 gmake clean > "$LOGDIR/clean_release.log" 2>&1
 gmake -j5 GENETIC=1 PERF_COUNTERS=1 MP=1 SIXTYFOUR=1 > "$LOGDIR/build_release.log" 2>&1