docling-project/docling

Markdown serialization of headings in rich table cells

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#2722 opened on Dec 4, 2025

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 (3 comments) (0 reactions) (1 assignee)Python (59,751 stars) (4,140 forks)batch import
buggood first issuemarkdown

Description

Bug

In docling-core, the MarkdownTableSerializer transforms DoclingDocument headings and titles into markdown headings (i.e., text with preceding # symbols). According to the markdown specs, you can’t use headings, blockquotes, lists, horizontal rules, images, or most HTML tags when formatting text within tables and most applications will not render those headings properly.

Steps to reproduce

Convert Docling's test file table_with_heading_02.html to markdown or check its ground truth file table_with_heading_02.html.md

Docling version

Docling version: 2.64.0 Docling Core version: 2.51.1 Docling IBM Models version: 3.10.2 Docling Parse version: 4.7.1 Python: cpython-313 (3.13.5) Platform: macOS-14.7.1-arm64-arm-64bit-Mach-O

Python version

Python 3.13.5

Contributor guide

Tech stack
python
Domain
backenddata
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
PythonMarkdown
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
The bug is in `docling core/transforms/serializer/markdown.py` where headings are serialized as `#` prefixed lines even within table cells, violating markdown specs. The issue is assigned and has recent comments; check if the assignee has a branch or plan. The fix likely involves detecting table context and replacing heading markup with plain text or bold inside tables. Reference the markdown spec link provided and the ground truth file to verify correct output.