test(vector): unit-test page-aware routing; clarify fallback comment

Address claude-review round 2 on PR #868:
- Extract the use_page_aware branching into a pure `should_use_page_aware`
  helper and cover the (doc_type, page_boundaries, page_aware_setting) matrix
  in tests/unit/test_processor_routing.py (file+boundaries+enabled, empty
  list, None, non-file doc types, disabled setting).
- Clarify the PageAwareChunker.chunk_text no-boundaries comment: the processor
  pre-filters via should_use_page_aware, so that branch is a direct-call safety
  net, not a production indexing path.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

nextcloud_mcp_server/vector/document_chunker.py

@@ -167,8 +167,11 @@ class PageAwareChunker:
         if not content:
             return [ChunkWithPosition(text="", start_offset=0, end_offset=0)]
 
-        # No page info (e.g. a non-PDF that reached this path) — degrade to the
-        # char-based behaviour so the caller still gets sensible chunks.
+        # No page info — degrade to char-based behaviour so the class is safe to
+        # call directly. The vector-sync processor pre-filters this case
+        # (``should_use_page_aware`` requires a truthy boundary list), so in
+        # production this branch is only reached by direct callers/tests, not
+        # the indexing path.
         if not page_boundaries:
             docs = await anyio.to_thread.run_sync(  # type: ignore[attr-defined]
                 self.splitter.create_documents,

nextcloud_mcp_server/vector/processor.py

@@ -92,6 +92,25 @@ def assign_page_numbers(chunks, page_boundaries):
             chunk.page_number = assigned_page
 
 
+def should_use_page_aware(
+    *, page_aware_enabled: bool, doc_type: str, page_boundaries: Any
+) -> bool:
+    """Decide whether the page-aware chunker applies to this document.
+
+    Page-aware chunking applies only to paginated files (PDFs) that actually
+    carry page boundaries. ``page_boundaries`` is tested for truthiness, not
+    just ``is not None``: an empty list carries no pages, so it routes through
+    the char-based path rather than the page-aware chunker's no-boundaries
+    fallback.
+
+    Args:
+        page_aware_enabled: ``settings.document_chunk_page_aware``.
+        doc_type: The document type (only ``"file"`` is paginated).
+        page_boundaries: The extractor's page-boundary list (or ``None``).
+    """
+    return page_aware_enabled and doc_type == "file" and bool(page_boundaries)
+
+
 async def processor_task(
     worker_id: int,
     receive_stream: MemoryObjectReceiveStream[DocumentTask],
@@ -690,13 +709,10 @@ async def _index_document(
     # which assigns page numbers inline; everything else uses the char-based
     # chunker followed by post-hoc page assignment.
     page_boundaries = file_metadata.get("page_boundaries")
-    use_page_aware = (
-        settings.document_chunk_page_aware
-        and doc_task.doc_type == "file"
-        # Truthy (not just "is not None"): an empty list carries no pages, so
-        # route it through the char-based path rather than the page-aware
-        # chunker's no-boundaries fallback.
-        and bool(page_boundaries)
+    use_page_aware = should_use_page_aware(
+        page_aware_enabled=settings.document_chunk_page_aware,
+        doc_type=doc_task.doc_type,
+        page_boundaries=page_boundaries,
     )
     with trace_operation(
         "vector_sync.chunk_text",

tests/unit/test_processor_routing.py

@@ -0,0 +1,62 @@
+"""Unit tests for the page-aware chunker routing decision (processor.py)."""
+
+import pytest
+
+from nextcloud_mcp_server.vector.processor import should_use_page_aware
+
+pytestmark = pytest.mark.unit
+
+_BOUNDARIES = [{"page": 1, "start_offset": 0, "end_offset": 10}]
+
+
+class TestShouldUsePageAware:
+    """Cover the (doc_type, page_boundaries, page_aware_setting) matrix."""
+
+    def test_pdf_with_boundaries_and_enabled_uses_page_aware(self):
+        assert (
+            should_use_page_aware(
+                page_aware_enabled=True,
+                doc_type="file",
+                page_boundaries=_BOUNDARIES,
+            )
+            is True
+        )
+
+    def test_empty_boundaries_falls_back_to_char_based(self):
+        """Empty list carries no pages -> char-based path."""
+        assert (
+            should_use_page_aware(
+                page_aware_enabled=True, doc_type="file", page_boundaries=[]
+            )
+            is False
+        )
+
+    def test_none_boundaries_falls_back_to_char_based(self):
+        assert (
+            should_use_page_aware(
+                page_aware_enabled=True, doc_type="file", page_boundaries=None
+            )
+            is False
+        )
+
+    @pytest.mark.parametrize("doc_type", ["note", "deck_card", "news_item"])
+    def test_non_file_doc_types_never_page_aware(self, doc_type):
+        """Only paginated files are page-aware, even with boundaries present."""
+        assert (
+            should_use_page_aware(
+                page_aware_enabled=True,
+                doc_type=doc_type,
+                page_boundaries=_BOUNDARIES,
+            )
+            is False
+        )
+
+    def test_disabled_setting_forces_char_based(self):
+        assert (
+            should_use_page_aware(
+                page_aware_enabled=False,
+                doc_type="file",
+                page_boundaries=_BOUNDARIES,
+            )
+            is False
+        )