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Switch markdown conversion from Python-Markdown to cmark-gfm #13448

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Merged
svgeesus merged 1 commit into from
Feb 6, 2026
Merged

Switch markdown conversion from Python-Markdown to cmark-gfm #13448

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3 changes: 2 additions & 1 deletion .github/workflows/build-specs.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -33,7 +33,8 @@ jobs:
python-version: "3.14"
cache: 'pip'

- run: pip install bikeshed markdown
- run: sudo apt-get install -y cmark-gfm
- run: pip install bikeshed
- run: bikeshed update

# The following chunk of code all stolen from andeubotella
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54 changes: 48 additions & 6 deletions bin/build-markdown.py
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@@ -1,11 +1,17 @@
#!/usr/bin/env python3
"""Convert markdown files in spec directories to HTML."""
"""Convert markdown files in spec directories to HTML.

Uses cmark-gfm for full GitHub Flavored Markdown rendering, then
post-processes the output to convert GFM alert syntax (> [!NOTE], etc.)
into styled admonition blocks.
"""

import glob
import os
import re
import subprocess

import markdown
ADMONITION_TYPES = {"NOTE", "TIP", "IMPORTANT", "WARNING", "CAUTION"}

TEMPLATE = """\
<!doctype html>
Expand All @@ -17,19 +23,56 @@
pre {{ background: #f4f4f4; padding: 1em; overflow: auto; border-radius: 3px; }}
pre code {{ background: none; padding: 0; }}
img {{ max-width: 100%; }}
.admonition {{ border-left: 4px solid #888; padding: 0.5em 1em; margin: 1em 0; background: #f8f9fa; border-radius: 3px; }}
.admonition-title {{ font-weight: bold; margin: 0 0 0.25em; }}
.admonition.note, .admonition.tip {{ border-color: #0969da; }}
.admonition.important {{ border-color: #8250df; }}
.admonition.warning, .admonition.caution {{ border-color: #d1242f; }}
</style>
{body}
"""

# cmark-gfm renders > [!NOTE]\n> text as:
# <blockquote>\n<p>[!NOTE]\ntext</p>\n</blockquote>
# We convert these to styled admonition divs.
ADMONITION_RE = re.compile(
r"<blockquote>\n<p>\[!(NOTE|TIP|IMPORTANT|WARNING|CAUTION)\]\n"
r"(.*?)</p>\n</blockquote>",
re.DOTALL,
)


def convert_admonitions(html):
def replace(m):
kind = m.group(1).lower()
body = m.group(2)
title = m.group(1).capitalize()
return (
f'<div class="admonition {kind}">\n'
f'<p class="admonition-title">{title}</p>\n'
f"<p>{body}</p>\n"
f"</div>"
)
return ADMONITION_RE.sub(replace, html)


def extract_title(text):
m = re.search(r"^#\s+(.+)", text, re.MULTILINE)
return m.group(1).strip() if m else "Untitled"


def main():
md = markdown.Markdown(extensions=["fenced_code", "tables"])
def render_markdown(text):
proc = subprocess.run(
["cmark-gfm", "--extension", "table", "--extension", "autolink",
"--extension", "strikethrough", "--extension", "tasklist"],
input=text, capture_output=True, encoding="utf-8",
)
if proc.returncode != 0:
raise RuntimeError(f"cmark-gfm failed: {proc.stderr}")
return convert_admonitions(proc.stdout)


def main():
for md_file in sorted(glob.glob("*/*.md")):
if md_file.startswith("."):
continue
Expand All @@ -42,8 +85,7 @@ def main():
text = f.read()

title = extract_title(text)
body = md.convert(text)
md.reset()
body = render_markdown(text)

with open(html_file, "w", encoding="utf-8") as f:
f.write(TEMPLATE.format(title=title, body=body))
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