fix(serializer): serialize table footnotes in Markdown and HTML

docling_core/transforms/serializer/html.py

@@ -443,6 +443,11 @@ def serialize(
         text_res = "".join([r.text for r in res_parts])
         text_res = f"<table>{text_res}</table>" if text_res else ""
 
+        ftn_res = doc_serializer.serialize_footnotes(item=item, **kwargs)
+        if ftn_res.text:
+            text_res = f"{text_res}{ftn_res.text}" if text_res else ftn_res.text
+            res_parts.append(ftn_res)
+
         return create_ser_result(text=text_res, span_source=res_parts)
 
     @override
@@ -1276,6 +1281,33 @@ def serialize_captions(
             text_res = f"<{tag}>{text_res}</{tag}>"
         return create_ser_result(text=text_res, span_source=results)
 
+    @override
+    def serialize_footnotes(
+        self,
+        item: FloatingItem,
+        **kwargs: Any,
+    ) -> SerializationResult:
+        """Serialize the item's footnotes."""
+        params = self.params.merge_with_patch(patch=kwargs)
+        results: list[SerializationResult] = []
+        excluded_refs = self.get_excluded_refs(**kwargs)
+
+        if DocItemLabel.FOOTNOTE in params.labels:
+            for ftn in item.footnotes:
+                if isinstance(it := ftn.resolve(self.doc), TextItem) and it.self_ref not in excluded_refs:
+                    text_ftn = it.text
+                    text_dir = get_text_direction(text_ftn)
+                    dir_str = f' dir="{text_dir}"' if text_dir == "rtl" else ""
+                    results.append(
+                        create_ser_result(
+                            text=(f'<div class="footnote"{dir_str}>{html.escape(text_ftn)}</div>'),
+                            span_source=it,
+                        )
+                    )
+
+        text_res = params.caption_delim.join([r.text for r in results])
+        return create_ser_result(text=text_res, span_source=results)
+
     def _generate_head(self) -> str:
         """Generate the HTML head section with metadata and styles."""
         params = self.params

docling_core/transforms/serializer/markdown.py

@@ -576,6 +576,10 @@ def serialize(
             if table_text:
                 res_parts.append(create_ser_result(text=table_text, span_source=item))
 
+            ftn_res = doc_serializer.serialize_footnotes(item=item, **kwargs)
+            if ftn_res.text:
+                res_parts.append(ftn_res)
+
         text_res = "\n\n".join([r.text for r in res_parts])
 
         return create_ser_result(text=text_res, span_source=res_parts)

test/test_serialization.py

@@ -1103,3 +1103,36 @@ def test_html_meta_emits_xhtml_compatible_attributes():
     assert 'data-meta-name="entities"' in html_out
     # Output must be parseable by a strict XML parser.
     ET.fromstring(html_out)
+
+
+def test_table_footnotes_serialized_to_markdown_and_html():
+    """Regression test for #496: table footnotes must not be dropped by the
+    Markdown and HTML serializers (they are delegated to the parent TableItem)."""
+    doc = DoclingDocument(name="t")
+
+    td = TableData(num_rows=0, num_cols=2)
+    td.add_row(["Header 1", "Header 2"])
+    td.add_row(["Data 1", "Data 2"])
+    table = doc.add_table(data=td)
+
+    fn1 = doc.add_text(label=DocItemLabel.FOOTNOTE, text="First footnote.")
+    fn2 = doc.add_text(label=DocItemLabel.FOOTNOTE, text="Second footnote.")
+    table.footnotes.append(fn1.get_ref())
+    table.footnotes.append(fn2.get_ref())
+
+    # footnotes are stored on the table in the document model ...
+    assert [fn.resolve(doc).text for fn in table.footnotes] == [
+        "First footnote.",
+        "Second footnote.",
+    ]
+
+    # ... and must survive Markdown serialization
+    md_out = doc.export_to_markdown()
+    assert "First footnote." in md_out
+    assert "Second footnote." in md_out
+
+    # ... and HTML serialization (as escaped footnote divs after the table)
+    html_out = doc.export_to_html()
+    assert "First footnote." in html_out
+    assert "Second footnote." in html_out
+    assert '<div class="footnote">First footnote.</div>' in html_out