fix: Remove legacy backward compatibility code and comments (#37)

Removed backward compatibility code sections and comments from the
codebase as the tool now has a single stable interface with no
historic dependencies.

Changes:
- bibtex_parser.py: Removed unused wrapper methods _extract_authors()
  and _get_field() that were marked for backward compatibility
- bibtex_parser.py: Updated reference to use _get_field_safely()
  directly
- cache.py: Removed "BACKWARD COMPATIBILITY" section headers and
  comments
- cache.py: Updated docstrings to remove backward compatibility
  language while maintaining current functionality
- cache.py: Changed misleading comments to accurately describe the
  current purpose of methods

All tests pass and functionality is preserved. These methods are
actively used by the codebase and have been retained with updated
documentation.

Fixes #13

Co-authored-by: florath-ai-assistant[bot] <Andreas.Florath@telekom.de>

Author: coding-ai-assistant[bot]

src/aletheia_probe/bibtex_parser.py

@@ -220,7 +220,7 @@ def _extract_journal_name(entry: Entry) -> str | None:
         journal_fields = ["journal", "journaltitle"]
 
         for field in journal_fields:
-            journal_name = BibtexParser._get_field(entry, field)
+            journal_name = BibtexParser._get_field_safely(entry, field)
             if journal_name:
                 return journal_name
 
@@ -298,15 +298,6 @@ def _extract_authors_safely(entry: Entry) -> str | None:
             detail_logger.debug(f"Error extracting authors: {e}")
             return None
 
-    @staticmethod
-    def _extract_authors(entry: Entry) -> str | None:
-        """Extract author information from a BibTeX entry.
-
-        This is the original method, kept for backward compatibility.
-        New code should use _extract_authors_safely.
-        """
-        return BibtexParser._extract_authors_safely(entry)
-
     @staticmethod
     def _get_field_safely(entry: Entry, field_name: str) -> str | None:
         """Get a field value from a BibTeX entry with error handling.
@@ -346,12 +337,3 @@ def _get_field_safely(entry: Entry, field_name: str) -> str | None:
         except Exception as e:
             detail_logger.debug(f"Error getting field '{field_name}': {e}")
             return None
-
-    @staticmethod
-    def _get_field(entry: Entry, field_name: str) -> str | None:
-        """Get a field value from a BibTeX entry.
-
-        This is the original method, kept for backward compatibility.
-        New code should use _get_field_safely.
-        """
-        return BibtexParser._get_field_safely(entry, field_name)

src/aletheia_probe/cache.py

@@ -484,7 +484,7 @@ def search_journals(
                 # Get URLs from pre-fetched data
                 journal_dict["urls"] = urls_by_journal.get(journal_id, [])
 
-                # Get source-specific data for backward compatibility
+                # Get source-specific data when filtering by source
                 if source_name:
                     source_cursor = conn.execute(
                         """
@@ -499,7 +499,7 @@ def search_journals(
 
                     source_data = source_cursor.fetchall()
                     if source_data:
-                        # Add backward compatibility fields
+                        # Add convenience aliases for common fields
                         journal_dict["journal_name"] = journal_dict["display_name"]
                         journal_dict["list_type"] = source_data[0][0]  # assessment
 
@@ -571,7 +571,6 @@ def find_conflicts(self) -> list[dict[str, Any]]:
 
             return [dict(row) for row in cursor.fetchall()]
 
-    # Backward compatibility methods
     def cache_assessment_result(
         self,
         query_hash: str,
@@ -668,9 +667,6 @@ def get_source_last_updated(self, source_name: str) -> datetime | None:
                 return datetime.fromisoformat(row[0])
             return None
 
-    # ===== BACKWARD COMPATIBILITY METHODS =====
-    # These methods provide compatibility with the old CacheManager interface
-
     def add_journal_list_entry(
         self,
         source_name: str,
@@ -683,9 +679,9 @@ def add_journal_list_entry(
         metadata: dict[str, Any] | None = None,
     ) -> None:
         """
-        Backward compatibility method for add_journal_list_entry.
+        Add a journal entry using list-based nomenclature.
 
-        Maps the old interface to the new normalized add_journal_entry method.
+        Maps list-based parameters (list_type) to assessment-based parameters.
         """
         # Register the data source if not exists (use generic "mixed" type to avoid conflicts)
         with sqlite3.connect(self.db_path) as conn:
@@ -854,15 +850,15 @@ def get_cached_value(self, key: str) -> str | None:
 
     def get_source_stats(self) -> dict[str, dict[str, Any]]:
         """
-        Get statistics for all data sources (backward compatibility).
+        Get statistics for all data sources.
 
         Returns:
-            Dictionary with source statistics in old format
+            Dictionary with source statistics
         """
-        # Get the new statistics format
+        # Get the base statistics
         stats = self.get_source_statistics()
 
-        # Convert to old format expected by tests
+        # Convert to structured format
         result = {}
         for source_name, source_stats in stats.items():
             result[source_name] = {