Move notice comment insertion to CSLPruner.save

Refactors the process of inserting the contribution notice comment so that it is handled in CSLPruner.save() based on a notice_comment attribute, rather than directly manipulating the XML in CSLBuilder. This centralizes comment insertion logic and simplifies the builder code.

Author: adunning

src/style_variant_builder/build.py

@@ -14,8 +14,6 @@
 from itertools import chain
 from pathlib import Path
 
-from lxml import etree
-
 from style_variant_builder.prune import CSLPruner
 
 logging.basicConfig(level=logging.INFO, format="%(message)s")
@@ -140,42 +138,13 @@ def _prune_variant(self, patched_file: Path, output_variant: Path) -> None:
         # Flatten single-macro layouts before pruning so wrapper macros can be removed
         pruner.flatten_layout_macros()
         pruner.prune_macros()
-        self._insert_notice_comment_xml(pruner)
-        pruner.save()
-
-    def _insert_notice_comment_xml(self, pruner: CSLPruner) -> None:
-        """Insert a contribution notice comment as the first child of the <style> element."""
-        if pruner.root is None:
-            logging.error("Cannot insert notice comment: XML root is None.")
-            return
-
-        comment_node = etree.Comment(
-            " This file was generated by the Style Variant Builder "
+        # Set notice comment to be inserted during save
+        pruner.notice_comment = (
+            "This file was generated by the Style Variant Builder "
             "<https://github.com/citation-style-language/style-variant-builder>. "
-            "To contribute changes, modify the template and regenerate variants. "
+            "To contribute changes, modify the template and regenerate variants."
         )
-        # Insert as the first child of the root <style> element
-        pruner.root.insert(0, comment_node)
-        # Insert a tail newline and indentation after the comment to ensure separation and correct indentation for <info>
-        # Detect the indentation used for children of <style>
-        if len(pruner.root) > 1:
-            # Try to infer indentation from the first real element (usually <info>)
-            next_elem = pruner.root[1]
-            # Find the preceding text (indentation) for the <info> element
-            # Default to 2 spaces if not found
-            indent = "  "
-            # Try to find the indentation from the previous tail or from the element itself
-            if next_elem.tail and next_elem.tail.lstrip("\n") != next_elem.tail:
-                # If tail starts with a newline, use the rest as indent
-                indent = next_elem.tail.split("\n")[-1]
-            elif (
-                pruner.root.text
-                and pruner.root.text.lstrip("\n") != pruner.root.text
-            ):
-                indent = pruner.root.text.split("\n")[-1]
-            pruner.root[0].tail = f"\n{indent}"
-        else:
-            pruner.root[0].tail = "\n  "
+        pruner.save()
 
     def build_variants(self) -> tuple[int, int]:
         try:

src/style_variant_builder/prune.py

@@ -34,6 +34,7 @@ class CSLPruner:
     modified: bool = field(
         default=False, init=False
     )  # Track whether changes have been made
+    notice_comment: str | None = field(default=None, init=False)
 
     def parse_xml(self) -> None:
         try:
@@ -280,6 +281,12 @@ def reindent_xml_bytes(self, xml_data: bytes) -> bytes:
     def save(self) -> None:
         if self.tree is not None:
             try:
+                # Insert notice comment if set
+                if self.notice_comment and self.root is not None:
+                    # Add spaces around comment text for proper XML comment formatting
+                    comment_text = f" {self.notice_comment.strip()} "
+                    self.root.insert(0, etree.Comment(comment_text))
+
                 # Serialize from the element root to avoid including any
                 # document-level processing instructions (e.g., xml-model)
                 xml_data = etree.tostring(