refactor: move _coerce_bool to index/utils as the shared home

Both indexing paths and the CLI now use it; page_index_md re-exports it
for existing importers.

pageindex/index/page_index.py

@@ -1089,7 +1089,7 @@ async def tree_parser(page_list, opt, doc=None, logger=None):
 
 def page_index_main(doc, opt=None):
     # accept legacy 'yes'/'no' string flags (a bare 'no' is truthy)
-    from .page_index_md import _coerce_bool
+    from .utils import _coerce_bool
     for flag in ('if_add_node_id', 'if_add_node_text',
                  'if_add_node_summary', 'if_add_doc_description'):
         if hasattr(opt, flag):

pageindex/index/page_index_md.py

@@ -3,6 +3,7 @@ import json
 import re
 import os
 from .utils import *
+from .utils import _coerce_bool  # underscore names aren't star-exported
 
 async def get_node_summary(node, summary_token_threshold=200, model=None):
     node_text = node.get('text')
@@ -243,13 +244,6 @@ def clean_tree_for_output(tree_nodes):
     return cleaned_nodes
 
 
-def _coerce_bool(value):
-    """Coerce a legacy 'yes'/'no' string flag to bool (a bare 'no' is truthy)."""
-    if isinstance(value, str):
-        return value.strip().lower() in ("yes", "true", "1", "y", "on")
-    return bool(value)
-
-
 async def md_to_tree(md_path, if_thinning=False, min_token_threshold=None, if_add_node_summary=False, summary_token_threshold=None, model=None, if_add_doc_description=False, if_add_node_text=False, if_add_node_id=True):
     # Accept legacy 'yes'/'no' string flags — a bare 'no' would otherwise be
     # truthy and wrongly enable the option.

pageindex/index/utils.py

@@ -941,6 +941,13 @@ def add_node_text_with_labels(node, pdf_pages):
     return
 
 
+def _coerce_bool(value):
+    """Coerce a legacy 'yes'/'no' string flag to bool (a bare 'no' is truthy)."""
+    if isinstance(value, str):
+        return value.strip().lower() in ("yes", "true", "1", "y", "on")
+    return bool(value)
+
+
 class ConfigLoader:
     """Legacy 0.2.x config helper. Defaults now come from IndexConfig; this
     class no longer reads the packaged ``config.yaml`` (the CLI still uses it

run_pageindex.py

@@ -6,7 +6,8 @@ from pageindex.index.page_index import *
 # a bare ``--flag`` (no value) resolves to True via argparse's ``const``; an
 # explicit value keeps the legacy yes/no style working, so ``--flag no`` turns
 # it off. argparse only ever passes a str here (const/default bypass type=).
-from pageindex.index.page_index_md import md_to_tree, _coerce_bool as _cli_bool
+from pageindex.index.page_index_md import md_to_tree
+from pageindex.index.utils import _coerce_bool as _cli_bool
 from pageindex.config import IndexConfig