fix: extend render fallback normalization guards to all tail and candidate roles

paperforge/worker/ocr_render.py

@@ -707,9 +707,22 @@ def render_fulltext_markdown(
         for i, block in enumerate(structured_blocks):
             old_role = block.get("role")
             new_role = new_blocks[i].get("role") if i < len(new_blocks) else old_role
-            # Never demote backmatter/reference headings — those are explicit
+            # Never demote tail/candidate roles — those are explicit
             # test-level decisions, not normalization targets.
-            if old_role in ("backmatter_heading", "backmatter_boundary_heading", "reference_heading"):
+            _PROTECTED = frozenset({
+                "backmatter_heading",
+                "backmatter_boundary_heading",
+                "backmatter_body",
+                "reference_heading",
+                "reference_item",
+                "figure_caption_candidate",
+                "backmatter_heading_candidate",
+                "backmatter_boundary_candidate",
+                "non_body_insert",
+                "subsection_heading",
+                "sub_subsection_heading",
+            })
+            if old_role in _PROTECTED:
                 continue
             if old_role != new_role:
                 block["role"] = new_role

tests/test_ocr_render_stabilization.py

@@ -846,6 +846,27 @@ def test_stabilize_tail_zone_references_kept_separate() -> None:
     assert "<!-- page 23" in md, "Page marker for page 23 should be present"
 
 
+def test_fallback_preserves_tail_roles():
+    from paperforge.worker.ocr_render import render_fulltext_markdown
+
+    blocks = [
+        {"paper_id": "KEY", "page": 5, "block_id": "b1", "role": "backmatter_heading", "text": "Funding", "render_default": True, "bbox": [80, 200, 320, 240], "page_width": 1200, "page_height": 1700},
+        {"paper_id": "KEY", "page": 5, "block_id": "b2", "role": "backmatter_body", "text": "This work was supported by Grant A.", "render_default": True, "bbox": [80, 280, 520, 340], "page_width": 1200, "page_height": 1700},
+        {"paper_id": "KEY", "page": 5, "block_id": "b3", "role": "reference_item", "text": "Smith J. (2023)", "render_default": True, "bbox": [80, 400, 520, 440], "page_width": 1200, "page_height": 1700},
+    ]
+
+    md = render_fulltext_markdown(
+        structured_blocks=blocks,
+        resolved_metadata={},
+        figure_inventory={},
+        table_inventory={},
+    )
+
+    assert "## Funding" in md, "backmatter_heading should be preserved"
+    assert "This work was supported" in md, "backmatter_body should be preserved"
+    assert "Smith J." in md, "reference_item should be preserved"
+
+
 def test_normalize_ocr_math_text_delimiter_spacing() -> None:
     from paperforge.worker.ocr_math import normalize_ocr_math_text
     assert normalize_ocr_math_text("$ ^{8,49} $") == "$^{8,49}$"