fix: implement semantic version sorting

- Add sort_versions_semantically function using packaging library
- Fix issue where pre-release versions appeared before stable (5.2rc1 vs 5.2.5)
- Handle edge cases: dev, post, invalid versions with graceful fallback
- Add comprehensive test suite covering all scenarios
- Maintain backward compatibility with existing functionality

test_specific_case.py

@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+"""Test the specific case mentioned in the task: 5.2rc1 vs 5.2.5"""
+
+from pypi_query_mcp.core.version_utils import sort_versions_semantically
+
+def test_specific_case():
+    """Test the exact case mentioned in the task requirements."""
+    print("=" * 60)
+    print("Testing Specific Task Requirement")
+    print("=" * 60)
+    
+    # The exact problem mentioned in the task
+    versions = ["5.2rc1", "5.2.5"]
+    
+    # Old way (string sorting)
+    old_sorted = sorted(versions, reverse=True)
+    
+    # New way (semantic sorting)
+    new_sorted = sort_versions_semantically(versions, reverse=True)
+    
+    print(f"Original versions: {versions}")
+    print(f"Old string sorting: {old_sorted}")
+    print(f"New semantic sorting: {new_sorted}")
+    print()
+    
+    print("Analysis:")
+    print(f"  Problem: '5.2rc1' was appearing before '5.2.5' in string sorting")
+    print(f"  String sorting result: {old_sorted[0]} comes first")
+    print(f"  Semantic sorting result: {new_sorted[0]} comes first")
+    print()
+    
+    if new_sorted == ["5.2.5", "5.2rc1"]:
+        print("  ✅ SUCCESS: Semantic sorting correctly places 5.2.5 before 5.2rc1")
+        print("  ✅ This fixes the issue described in the task!")
+    else:
+        print("  ❌ FAILED: The issue is not resolved")
+    
+    print()
+    
+    # Test a more comprehensive example
+    comprehensive_test = [
+        "5.2.5", "5.2rc1", "5.2.0", "5.2a1", "5.2b1", 
+        "5.1.0", "5.3.0", "5.2.1"
+    ]
+    
+    old_comprehensive = sorted(comprehensive_test, reverse=True)
+    new_comprehensive = sort_versions_semantically(comprehensive_test, reverse=True)
+    
+    print("Comprehensive version sorting test:")
+    print(f"  Input: {comprehensive_test}")
+    print(f"  String sorted: {old_comprehensive}")
+    print(f"  Semantic sorted: {new_comprehensive}")
+    print()
+    
+    print("Expected semantic order (newest to oldest):")
+    print("  5.3.0 > 5.2.5 > 5.2.1 > 5.2.0 > 5.2rc1 > 5.2b1 > 5.2a1 > 5.1.0")
+
+
+if __name__ == "__main__":
+    test_specific_case()