Enhance sdist section handling in build configuration

This commit improves the logic for managing the sdist section in the build configuration by checking for the existence of the section and the 'only-include' setting before appending them. This ensures that the configuration is not duplicated and maintains clarity in the generated output, particularly for subfolder builds.

Author: alelom

src/python_package_folder/subfolder_build.py

@@ -742,18 +742,39 @@ def _modify_pyproject_string(
         # Use only-include for source distributions to ensure only the subfolder is included
         # This prevents including files from the project root
         if package_dirs:
-            result.append("")
-            result.append("[tool.hatch.build.targets.sdist]")
-            # Include only the subfolder directory and necessary files
-            only_include_paths = [package_dirs[0]]
-            # Also include pyproject.toml and README if they exist
-            only_include_paths.append("pyproject.toml")
-            only_include_paths.append("README.md")
-            only_include_paths.append("README.rst")
-            only_include_paths.append("README.txt")
-            only_include_paths.append("README")
-            only_include_str = ", ".join(f'"{p}"' for p in only_include_paths)
-            result.append(f"only-include = [{only_include_str}]")
+            # Check if sdist section already exists
+            sdist_section_exists = any(
+                line.strip().startswith("[tool.hatch.build.targets.sdist]")
+                for line in result
+            )
+            # Check if only-include is already set in the sdist section
+            only_include_set = False
+            if sdist_section_exists:
+                in_sdist_section = False
+                for line in result:
+                    if line.strip().startswith("[tool.hatch.build.targets.sdist]"):
+                        in_sdist_section = True
+                    elif line.strip().startswith("[") and in_sdist_section:
+                        in_sdist_section = False
+                    elif in_sdist_section and re.match(r"^\s*only-include\s*=", line):
+                        only_include_set = True
+                        break
+
+            if not sdist_section_exists or not only_include_set:
+                if not sdist_section_exists:
+                    result.append("")
+                    result.append("[tool.hatch.build.targets.sdist]")
+                # Include only the subfolder directory and necessary files
+                only_include_paths = [package_dirs[0]]
+                # Also include pyproject.toml and README if they exist
+                only_include_paths.append("pyproject.toml")
+                only_include_paths.append("README.md")
+                only_include_paths.append("README.rst")
+                only_include_paths.append("README.txt")
+                only_include_paths.append("README")
+                only_include_str = ", ".join(f'"{p}"' for p in only_include_paths)
+                if not only_include_set:
+                    result.append(f"only-include = [{only_include_str}]")
 
         # Add dependency group if specified
         if dependency_group: