fix(tests): use word boundaries in _check_blocked_words, fix test assertion

- _check_blocked_words now uses word boundaries for word keywords
  (same logic as _check_conditional_patterns)
- This prevents false positives like 'alternative' matching 'alter'
- Punctuation keywords still use substring matching
- Fixed incorrect test assertion: 'drop' IS all word chars (expect True)

litellm/proxy/guardrails/guardrail_hooks/litellm_content_filter/content_filter.py

@@ -1260,10 +1260,21 @@ class ContentFilterGuardrail(CustomGuardrail):
             return None
 
         text_lower: Final = text.lower()
+        import re
         for keyword, (action, description) in self.blocked_words.items():
-            if keyword in text_lower:
-                verbose_proxy_logger.debug("Blocked word '%s' found with action %s", keyword, action)
-                return (keyword, action, description)
+            # Use word boundaries for word-character keywords to prevent false positives
+            # (e.g., "alternative" matching "alter")
+            # Punctuation-only keywords (e.g., "=", ">") use substring matching
+            if _is_word_char_pattern(keyword):
+                pattern = r"\b" + re.escape(keyword) + r"\b"
+                if re.search(pattern, text_lower):
+                    verbose_proxy_logger.debug("Blocked word '%s' found with action %s", keyword, action)
+                    return (keyword, action, description)
+            else:
+                # Punctuation-only: use substring matching
+                if keyword in text_lower:
+                    verbose_proxy_logger.debug("Blocked word '%s' found with action %s", keyword, action)
+                    return (keyword, action, description)
         return None
 
     def _handle_conditional_match(

tests/test_litellm/proxy/guardrails/guardrail_hooks/content_filter/test_content_filter_regression.py

@@ -35,9 +35,9 @@ class TestWordCharPatternHelper:
 
     def test_mixed_words(self):
         """Words with punctuation mixed in have word characters."""
-        # These should still be treated as word patterns for boundary purposes
-        # since they contain word characters
-        assert _is_word_char_pattern("drop") is False  # Backslash is not word char
+        # 'drop' is all word characters (letters), so it should be True
+        assert _is_word_char_pattern("drop") is True
+        # '--' is punctuation-only, so it should be False
         assert _is_word_char_pattern("--") is False  # Dashes
 
     def test_empty_string(self):