rewrite: pre-commit hook for 10-line net limit — drop JS check (#548)

.githooks/pre-commit

@@ -1,19 +1,15 @@
 #!/usr/bin/env bash
-# Pre-commit hook: enforce 777-line limit on JS files
+# Pre-commit hook: enforce 10-line net addition limit
 # Install: git config core.hooksPath .githooks
 
-FAIL=0
-for f in $(git diff --cached --name-only --diff-filter=ACM | grep '\.js$' | grep -v node_modules | grep -v tests/); do
-  LINES=$(wc -l < "$f" | tr -d ' ')
-  if [ "$LINES" -gt 777 ]; then
-    echo "BLOCKED: $f is $LINES lines (max: 777)"
-    echo "  Extract into a module. app.js is a thin wrapper."
-    FAIL=1
-  fi
-done
+ADDITIONS=$(git diff --cached --numstat | awk '{s+=$1} END {print s+0}')
+DELETIONS=$(git diff --cached --numstat | awk '{s+=$2} END {print s+0}')
+NET=$((ADDITIONS - DELETIONS))
 
-if [ $FAIL -eq 1 ]; then
-  echo ""
-  echo "No JS file may exceed 777 lines. Break it up."
+if [ "$NET" -gt 10 ]; then
+  echo "BLOCKED: Net addition is $NET lines (max: 10)."
+  echo "  Delete code elsewhere to compensate."
   exit 1
 fi
+
+echo "✓ Pre-commit: net $NET lines (limit: 10)"