test_vs_head.sh: add NNUE_WEIGHTS to run an NNUE candidate vs HCE head

match_play.py's Engine passes identical engine_args to both sides, so
there was no way to get an NNUE candidate playing against the classic-
eval head_reference without patching match_play.py itself. Instead,
when NNUE_WEIGHTS is set this wraps the candidate binary in a thin
exec shim that always injects "--nnueweights $NNUE_WEIGHTS" -- works
unmodified because Engine spawns the given path directly via Popen
(no shell), so a shebang script in its place is indistinguishable
from a real binary to it. HEAD is untouched, so it keeps running HCE.

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

1 files changed, 23 insertions, 0 deletions

diff --git a/src/eval_tune/test_vs_head.sh b/src/eval_tune/test_vs_head.sh
index dbddf10..71b2282 100755
--- a/src/eval_tune/test_vs_head.sh
+++ b/src/eval_tune/test_vs_head.sh
@@ -62,6 +62,19 @@
 #   SPRT_ARGS="" TC_ARGS="--st 4 --odds 2" GAMES=1000 \
 #       test_vs_head.sh ../../head_reference/typhoon \
 #                        ../../head_reference/typhoon timeodds
+#
+# NNUE_WEIGHTS: path to a weights file (as produced by annotate_pgns/
+# export_nnue_weights.py). When set, the CANDIDATE binary is wrapped
+# in a thin exec shim that always injects "--nnueweights $NNUE_WEIGHTS"
+# ahead of whatever args match_play.py's Engine class passes it --
+# that's the only change needed, since Engine spawns the given path
+# directly via Popen (no shell), so a shebang script in its place works
+# unmodified. HEAD is untouched, so it keeps running the classic HCE --
+# this is how you get an NNUE-candidate-vs-HCE-reference match without
+# patching match_play.py's Engine (which currently passes identical
+# engine_args to both sides):
+#
+#   NNUE_WEIGHTS=/path/to/net.nnue test_vs_head.sh
 
 set -e
 
@@ -102,6 +115,16 @@ else
     cp -f ../typhoon ${CANDIDATE}
 fi
 
+if [ -n "${NNUE_WEIGHTS:-}" ]; then
+    NNUE_WRAPPER=/tmp/typhoon/typhoon_match_play_candidate_nnue
+    cat > "$NNUE_WRAPPER" <<WRAPPER
+#!/usr/bin/env bash
+exec "$CANDIDATE" --nnueweights "$NNUE_WEIGHTS" "\$@"
+WRAPPER
+    chmod +x "$NNUE_WRAPPER"
+    CANDIDATE="$NNUE_WRAPPER"
+fi
+
 python3 ./match_play.py \
         ${HEAD} \
         ${CANDIDATE} \