diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 8b6ebdc565a..6c57445a71d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -957,6 +957,38 @@ jobs:
           if-no-files-found: ignore
           retention-days: 14
 
+  check-validator-sizes:
+    name: Check validator file sizes
+    runs-on: ubuntu-latest
+    # Non-blocking: report violations but don't fail the build until existing files are cleaned up
+    continue-on-error: true
+    permissions:
+      contents: read
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
+
+      - name: Check validator file sizes
+        id: check
+        run: |
+          set +e
+          OUTPUT=$(NO_COLOR=1 bash scripts/check-validator-sizes.sh 2>&1)
+          EXIT_CODE=$?
+          echo "$OUTPUT"
+          echo "exit_code=$EXIT_CODE" >> "$GITHUB_OUTPUT"
+          echo "## Validator File Size Check" >> "$GITHUB_STEP_SUMMARY"
+          echo "" >> "$GITHUB_STEP_SUMMARY"
+          echo "Checking \`*_validation.go\` files against the 768-line hard limit (AGENTS.md)." >> "$GITHUB_STEP_SUMMARY"
+          echo "" >> "$GITHUB_STEP_SUMMARY"
+          echo "\`\`\`" >> "$GITHUB_STEP_SUMMARY"
+          echo "$OUTPUT" >> "$GITHUB_STEP_SUMMARY"
+          echo "\`\`\`" >> "$GITHUB_STEP_SUMMARY"
+          if [ "$EXIT_CODE" -ne 0 ]; then
+            echo "" >> "$GITHUB_STEP_SUMMARY"
+            echo "⚠️ This check is currently non-blocking. Fix violations to keep the codebase healthy." >> "$GITHUB_STEP_SUMMARY"
+          fi
+          exit "$EXIT_CODE"
+
   lint-go:
     runs-on: ubuntu-latest
     permissions:
diff --git a/Makefile b/Makefile
index e43c3205f1c..ecba6ab3bde 100644
--- a/Makefile
+++ b/Makefile
@@ -611,6 +611,12 @@ lint-errors:
 check-file-sizes:
 	@bash scripts/check-file-sizes.sh
 
+# Check that *_validation.go files stay within the 768-line hard limit
+# Set WARN_ONLY=1 to report violations without failing (non-blocking mode)
+.PHONY: check-validator-sizes
+check-validator-sizes:
+	@bash scripts/check-validator-sizes.sh
+
 # Validate all project files
 .PHONY: lint
 lint: fmt-check fmt-check-json lint-cjs golint
@@ -802,6 +808,8 @@ help:
 	@echo "  lint-cjs         - Lint JavaScript (.cjs) and JSON files in actions/setup/js"
 	@echo "  lint-json        - Lint JSON files in pkg directory (excluding actions/setup/js)"
 	@echo "  lint-errors      - Lint error messages for quality compliance"
+	@echo "  check-file-sizes - Check Go file sizes and function counts (informational)"
+	@echo "  check-validator-sizes - Check *_validation.go files against the 768-line hard limit"
 	@echo "  security-scan    - Run all security scans (gosec, govulncheck, trivy)"
 	@echo "  security-gosec   - Run gosec Go security scanner"
 	@echo "  security-govulncheck - Run govulncheck for known vulnerabilities"
diff --git a/scripts/check-validator-sizes.sh b/scripts/check-validator-sizes.sh
new file mode 100755
index 00000000000..017ba94a8ed
--- /dev/null
+++ b/scripts/check-validator-sizes.sh
@@ -0,0 +1,76 @@
+#!/bin/bash
+# check-validator-sizes.sh - Enforce the 512-line hard limit on validator files
+#
+# This script finds any *_validation.go file that exceeds the limit and reports it.
+#
+# Exit codes:
+#   0 - All validator files are within the limit (or WARN_ONLY=1)
+#   1 - One or more validator files exceed the limit
+
+set -euo pipefail
+
+# Disable colors when not connected to a TTY, when NO_COLOR is set, or when
+# TERM=dumb — this keeps output readable when captured into CI step summaries.
+if [ -t 1 ] && [ -z "${NO_COLOR:-}" ] && [ "${TERM:-}" != "dumb" ]; then
+    RED='\033[0;31m'
+    YELLOW='\033[1;33m'
+    GREEN='\033[0;32m'
+    NC='\033[0m'
+else
+    RED=''
+    YELLOW=''
+    GREEN=''
+    NC=''
+fi
+
+# Hard limit (lines per validator file)
+HARD_LIMIT=768
+
+# Set WARN_ONLY=1 to make the check non-blocking (report but always exit 0)
+WARN_ONLY="${WARN_ONLY:-0}"
+
+over_limit=0
+
+echo "Checking validator file sizes in pkg/ directory (limit: ${HARD_LIMIT} lines)..."
+echo ""
+
+# Find all *_validation.go files, excluding test files
+while IFS= read -r file; do
+    # wc -l counts newline characters; a file without a trailing newline is
+    # undercounted by 1. Go source files always end with a newline (enforced by
+    # gofmt), so in practice the count is exact.
+    line_count=$(wc -l < "$file")
+
+    if [ "$line_count" -gt "$HARD_LIMIT" ]; then
+        echo -e "${RED}OVER LIMIT${NC}: $file"
+        echo -e "   Lines: ${RED}$line_count${NC} / ${HARD_LIMIT} (exceeded by $((line_count - HARD_LIMIT)))"
+        echo ""
+        over_limit=$((over_limit + 1))
+    fi
+done < <(find pkg -name "*_validation.go" ! -name "*_test.go" -type f | sort)
+
+echo "------------------------------------------------------------"
+
+if [ "$over_limit" -eq 0 ]; then
+    echo -e "${GREEN}All validator files are within the ${HARD_LIMIT}-line limit${NC}"
+    exit 0
+fi
+
+echo -e "${YELLOW}$over_limit validator file(s) exceed the ${HARD_LIMIT}-line hard limit${NC}"
+echo ""
+echo "See AGENTS.md 'Validation Complexity Guidelines' for guidance:"
+echo "  - Target size: 100-200 lines per validator"
+echo "  - Hard limit:  ${HARD_LIMIT} lines (refactor if exceeded)"
+echo ""
+echo "When to split a validator:"
+echo "  - File exceeds ${HARD_LIMIT} lines"
+echo "  - File contains 2+ unrelated validation domains"
+echo "  - Complex cross-dependencies require separate testing"
+
+if [ "$WARN_ONLY" = "1" ]; then
+    echo ""
+    echo "Note: Running in warn-only mode (WARN_ONLY=1). Fix these files to pass a future blocking check."
+    exit 0
+fi
+
+exit 1