fix: Handle null, empty, and string 'None' title in markdown frontmatter (#387) (#389)

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>
Co-authored-by: Paul Hernandez <phernandez@users.noreply.github.com>

src/basic_memory/markdown/entity_parser.py

@@ -129,8 +129,13 @@ class EntityParser:
         file_stats = absolute_path.stat()
         metadata = post.metadata
 
-        # Ensure required fields have defaults (issue #184)
-        metadata["title"] = post.metadata.get("title", absolute_path.stem)
+        # Ensure required fields have defaults (issue #184, #387)
+        # Handle title - use default if missing, None/null, empty, or string "None"
+        title = post.metadata.get("title")
+        if not title or title == "None":
+            metadata["title"] = absolute_path.stem
+        else:
+            metadata["title"] = title
         # Handle type - use default if missing OR explicitly set to None/null
         entity_type = post.metadata.get("type")
         metadata["type"] = entity_type if entity_type is not None else "note"

tests/markdown/test_entity_parser_error_handling.py

@@ -183,6 +183,84 @@ async def test_parse_file_with_null_entity_type(tmp_path):
     assert result.frontmatter.title == "Test File"
 
 
+@pytest.mark.asyncio
+async def test_parse_file_with_null_title(tmp_path):
+    """Test that files with explicit null title get default from filename (issue #387)."""
+    # Create a file with null title
+    test_file = tmp_path / "null_title.md"
+    content = dedent(
+        """
+        ---
+        title: null
+        type: note
+        ---
+        # Content
+        """
+    ).strip()
+    test_file.write_text(content)
+
+    # Parse the file
+    parser = EntityParser(tmp_path)
+    result = await parser.parse_file(test_file)
+
+    # Should have default title from filename even when explicitly set to null
+    assert result is not None
+    assert result.frontmatter.title == "null_title"  # Default from filename
+    assert result.frontmatter.type == "note"
+
+
+@pytest.mark.asyncio
+async def test_parse_file_with_empty_title(tmp_path):
+    """Test that files with empty title get default from filename (issue #387)."""
+    # Create a file with empty title
+    test_file = tmp_path / "empty_title.md"
+    content = dedent(
+        """
+        ---
+        title:
+        type: note
+        ---
+        # Content
+        """
+    ).strip()
+    test_file.write_text(content)
+
+    # Parse the file
+    parser = EntityParser(tmp_path)
+    result = await parser.parse_file(test_file)
+
+    # Should have default title from filename when title is empty
+    assert result is not None
+    assert result.frontmatter.title == "empty_title"  # Default from filename
+    assert result.frontmatter.type == "note"
+
+
+@pytest.mark.asyncio
+async def test_parse_file_with_string_none_title(tmp_path):
+    """Test that files with string 'None' title get default from filename (issue #387)."""
+    # Create a file with string "None" as title (common in templates)
+    test_file = tmp_path / "template_file.md"
+    content = dedent(
+        """
+        ---
+        title: "None"
+        type: note
+        ---
+        # Content
+        """
+    ).strip()
+    test_file.write_text(content)
+
+    # Parse the file
+    parser = EntityParser(tmp_path)
+    result = await parser.parse_file(test_file)
+
+    # Should have default title from filename when title is string "None"
+    assert result is not None
+    assert result.frontmatter.title == "template_file"  # Default from filename
+    assert result.frontmatter.type == "note"
+
+
 @pytest.mark.asyncio
 async def test_parse_valid_file_still_works(tmp_path):
     """Test that valid files with proper frontmatter still parse correctly."""