perf(tools): optimize validate-refs cache lookup and add unit tests

Makefile

@@ -40,6 +40,7 @@ test:
 	@python3 tools/check-code-test.py
 	@python3 tools/check-claims-test.py
 	@python3 tools/next-batch-test.py
+	@python3 tools/validate-refs-test.py
 
 duplicates:
 	@python3 tools/check-duplicates.py --strict

tools/validate-refs-test.py

@@ -0,0 +1,41 @@
+#!/usr/bin/env python3
+"""Unit tests for tools/validate-refs.py"""
+
+import importlib.util
+import unittest
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+TOOLS_DIR = Path(__file__).resolve().parent
+spec = importlib.util.spec_from_file_location("validate_refs", TOOLS_DIR / "validate-refs.py")
+validate_refs = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(validate_refs)
+
+
+class TestValidateRefs(unittest.TestCase):
+    def test_clean(self):
+        self.assertEqual(validate_refs.clean("https://example.com/foo."), "https://example.com/foo")
+        self.assertEqual(validate_refs.clean("https://example.com/foo,;:!?"), "https://example.com/foo")
+        self.assertEqual(validate_refs.clean("https://example.com/foo)"), "https://example.com/foo")
+        self.assertEqual(validate_refs.clean("https://example.com/foo(bar)"), "https://example.com/foo(bar)")
+
+    def test_strip_fences(self):
+        text = "line1\n```py\nhttps://example.com\n```\nline2"
+        stripped = validate_refs.strip_fences(text)
+        self.assertIn("line1", stripped)
+        self.assertIn("line2", stripped)
+        self.assertNotIn("https://example.com", stripped)
+
+    def test_probe_success(self):
+        mock_response = MagicMock()
+        mock_response.status = 200
+        mock_response.__enter__.return_value = mock_response
+
+        with patch("urllib.request.urlopen", return_value=mock_response):
+            url, status = validate_refs.probe("https://example.com", timeout=5)
+            self.assertEqual(url, "https://example.com")
+            self.assertEqual(status, 200)
+
+
+if __name__ == "__main__":
+    unittest.main()