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modelcontextprotocol--pytho…/scripts/docs/llms_txt.py
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chore: import upstream snapshot with attribution
2026-07-13 12:10:27 +08:00

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Python

"""Generate llms.txt, llms-full.txt, and per-page markdown (https://llmstxt.org/).
Zensical has no equivalent of MkDocs' build hooks, so this runs as a standalone
post-build step over the source tree (`mkdocs.yml` + `docs/`) and writes
three kinds of artifact into the built `site/`:
- `llms.txt`: a markdown index of the documentation, one link per page,
grouped by nav section.
- a `.md` rendition of every prose page next to its HTML (e.g.
`servers/tools/index.md`), which is what the llms.txt links point at.
- `llms-full.txt`: every prose page concatenated for single-fetch consumption.
Page markdown is the source markdown with YAML frontmatter stripped, `--8<--`
snippet includes resolved (so the `docs_src/` code examples appear inline) and
relative links rewritten to absolute URLs. The API reference pages under
`api/` are mkdocstrings stubs with no prose source, so they are linked as
rendered HTML from an Optional section instead of being embedded.
Usage:
python scripts/docs/llms_txt.py --site-dir site
"""
from __future__ import annotations
import argparse
import posixpath
import re
from pathlib import Path, PurePosixPath
from typing import Any
import yaml
ROOT = Path(__file__).parent.parent.parent
DOCS = ROOT / "docs"
# Pages with no markdown source, linked as HTML under "## Optional".
_OPTIONAL_PAGES = [
("api/mcp/index.md", "mcp API reference", "Auto-generated API reference for the mcp package (rendered HTML)"),
(
"api/mcp_types/index.md",
"mcp-types API reference",
"Auto-generated API reference for the mcp-types package (rendered HTML)",
),
]
_SNIPPET_LINE = re.compile(r'^(?P<indent>[ \t]*)--8<-- "(?P<path>[^"\n]+)"$', flags=re.MULTILINE)
# Every markdown link/image target: `](target#anchor "title")`. Each target is
# classified in `_rewrite_links` — there is deliberately no shape-based
# pre-filter here, so no link can dodge validation by its spelling. Zensical's
# own link validation only covers .md targets (a missing image or
# directory-style link builds green even under --strict; MkDocs failed the
# build), so everything else is validated here.
_LINK = re.compile(r'(\]\([ \t]*)([^)\s]+?)(#[^)\s]*)?( +(?:"[^"]*"|\'[^\']*\'|\([^()]*\)))?([ \t]*\))')
# CommonMark forms the classifier deliberately rejects rather than models:
# angle-bracket destinations `](<target>)` and reference-style definitions
# `[label]: target` (footnote definitions `[^label]:` are a different,
# supported syntax). Either would otherwise dodge validation by its spelling;
# failing loud keeps the guarantee without modelling unused syntax.
_ANGLE_LINK = re.compile(r"\]\([ \t]*<")
_REF_DEFINITION = re.compile(r"^[ \t]*\[(?!\^)[^\]]+\]:", flags=re.MULTILINE)
# Block HTML comments are inert in rendered output: python-markdown passes
# them through verbatim, so commented-out prose must not be validated.
_HTML_COMMENT = re.compile(r"<!--.*?-->", flags=re.DOTALL)
# A scheme-prefixed target (https:, mailto:, tel:, ...) is external — the
# `://` shorthand misses scheme-only URIs like mailto:.
_EXTERNAL = re.compile(r"[a-zA-Z][a-zA-Z0-9+.-]*:")
# Fenced code blocks and inline code spans: their content is inert in the
# rendered HTML, so links inside them are illustrative text, neither validated
# nor rewritten. Fences are matched line-based in `_code_intervals` (closer at
# least as long as the opener, unclosed runs to EOF, per CommonMark) and spans
# only in the text between fences; a span cannot cross a blank line, so a
# stray unpaired backtick cannot swallow the paragraphs (and links) after it.
# Known approximations of the renderer's block model: 4-space-indented
# content is treated as prose, because in this corpus indentation is
# admonition/list body whose links must stay validated — a link in a true
# indented code block is over-validated (fails loud or gets rewritten in the
# rendition), never under-validated; and span pairing is bounded by blank
# lines rather than full block structure.
_FENCE = re.compile(r"^[ \t]*(`{3,}|~{3,})")
_CODE_SPAN = re.compile(r"(?s)(?<!`)(`+)(?!`)((?:(?!\n[ \t]*\n).)+?)(?<!`)\1(?!`)")
# A leading YAML frontmatter block, as MkDocs/Zensical parse it (mkdocs.utils.meta).
_FRONTMATTER = re.compile(r"\A---[ \t]*\n(?P<block>.*?)^(?:---|\.\.\.)[ \t]*(?:\n|\Z)", flags=re.MULTILINE | re.DOTALL)
class _BuildError(Exception):
"""A recoverable problem that should fail the docs build with a clear message."""
def _dest_md_uri(src_uri: str) -> str:
"""Map a source page (`servers/tools.md`) to its built rendition (`servers/tools/index.md`)."""
path = PurePosixPath(src_uri)
directory = path.parent if path.stem == "index" else path.parent / path.stem
return "index.md" if directory == PurePosixPath(".") else f"{directory}/index.md"
def _page_url(src_uri: str) -> str:
"""The directory URL of a page relative to the site root (`servers/tools/`, `""` for the home page)."""
return _dest_md_uri(src_uri).removesuffix("index.md")
def _split_frontmatter(text: str) -> tuple[dict[str, Any], str]:
"""Split a leading YAML frontmatter block from a page (mirrors mkdocs.utils.meta).
Hand-rolled deliberately: mkdocs is only a transitive dependency of this
toolchain, so the pipeline must not import it. The hook this replaced ran
post-frontmatter-extraction, so renditions never contained frontmatter and
`meta` fed the page title and llms.txt description. A leading block that
isn't a YAML mapping is page content, not frontmatter; an empty block is
frontmatter with no meta.
"""
match = _FRONTMATTER.match(text)
if match is None:
return {}, text
try:
meta = yaml.safe_load(match["block"])
except yaml.YAMLError:
return {}, text
if meta is not None and not isinstance(meta, dict):
return {}, text
return meta or {}, text[match.end() :].lstrip("\n")
def _collect_pages(items: list, prose: dict[str, str | None]) -> list[str]:
"""Collect the prose pages under a nav subtree, in nav order.
Records each page in `prose` (src_uri -> nav title, or `None` to fall
back to the page's H1). This is the single owner of the prose-page rule:
a page entry counts when it is a local .md path (external URLs render as
outbound nav links and are omitted, as the MkDocs pipeline did) and is not
part of the generated API reference.
"""
pages: list[str] = []
for entry in items:
title, value = next(iter(entry.items())) if isinstance(entry, dict) else (None, entry)
if isinstance(value, list):
pages.extend(_collect_pages(value, prose))
elif not _EXTERNAL.match(value) and value.endswith(".md") and not value.startswith("api/"):
# Contained values only: an escaping entry would write its
# rendition outside the built site.
if value.startswith("/") or posixpath.normpath(value).startswith(".."):
raise _BuildError(f"llms_txt: nav entry {value!r} escapes docs/")
prose[value] = title
pages.append(value)
return pages
def _walk_nav(nav: list, prose: dict[str, str | None], sections: list[tuple[str, list[str]]]) -> list[str]:
"""Split the nav into a flat list of top-level pages and titled sections.
Populates `sections` ((title, [src_uri]) in nav order) and returns the
top-level page src_uris; page collection itself is `_collect_pages`.
"""
top_level: list[str] = []
for entry in nav:
title, value = next(iter(entry.items())) if isinstance(entry, dict) else (None, entry)
if isinstance(value, list):
pages = _collect_pages(value, prose)
if pages:
assert title is not None
sections.append((title, pages))
else:
top_level.extend(_collect_pages([entry], prose))
return top_level
def _resolve_snippets(markdown: str, src_uri: str) -> str:
def include(match: re.Match[str]) -> str:
indent, path = match["indent"], match["path"]
# Reject snippet paths that escape the repo root (mirrors the snippets
# extension's restrict_base_path).
resolved = (ROOT / path).resolve()
if not resolved.is_relative_to(ROOT.resolve()):
raise _BuildError(f"llms_txt: snippet path {path!r} in {src_uri} escapes the repo root")
try:
content = resolved.read_text(encoding="utf-8").rstrip("\n")
except OSError as exc:
raise _BuildError(f"llms_txt: cannot read snippet {path!r} in {src_uri}") from exc
if path.endswith(".py"):
content = f"# {path}\n{content}"
if indent:
content = "\n".join(indent + line if line else line for line in content.split("\n"))
return content
resolved, substitutions = _SNIPPET_LINE.subn(include, markdown)
if substitutions != sum("--8<--" in line for line in markdown.splitlines()):
raise _BuildError(f"llms_txt: unresolved snippet include in {src_uri}")
return resolved
def _in_code(code: list[tuple[int, int]], position: int) -> bool:
"""Whether `position` falls inside any code interval."""
return any(start <= position < end for start, end in code)
def _prose_h1(markdown: str) -> re.Match[str] | None:
"""The first ATX H1 outside code (at most 3 spaces of indent, per CommonMark).
Code-awareness matters: every resolved `.py` snippet starts with a
`# path` pointer line that must never win over the page's real H1.
"""
code = _code_intervals(markdown)
for match in re.finditer(r"^ {0,3}# (.+)$", markdown, flags=re.MULTILINE):
if not _in_code(code, match.start()):
return match
return None
def _code_intervals(markdown: str) -> list[tuple[int, int]]:
"""The character spans of fenced code blocks and inline code spans."""
fences: list[tuple[int, int]] = []
opener = ""
start = offset = 0
for line in markdown.splitlines(keepends=True):
if not opener:
if match := _FENCE.match(line):
opener, start = match[1], offset
elif (stripped := line.strip()).startswith(opener) and set(stripped) == {opener[0]}:
fences.append((start, offset + len(line)))
opener = ""
offset += len(line)
if opener:
fences.append((start, len(markdown)))
intervals = list(fences)
previous_end = 0
for fence_start, fence_end in [*fences, (len(markdown), len(markdown))]:
segment = markdown[previous_end:fence_start]
for pattern in (_CODE_SPAN, _HTML_COMMENT):
intervals += [(previous_end + m.start(), previous_end + m.end()) for m in pattern.finditer(segment)]
previous_end = fence_end
return intervals
def _rewrite_links(markdown: str, src_uri: str, site_url: str, prose: dict[str, str | None]) -> str:
src_dir = posixpath.dirname(src_uri)
code = _code_intervals(markdown)
rejected = ((_ANGLE_LINK, "angle-bracket link destination"), (_REF_DEFINITION, "reference-style link definition"))
for pattern, form in rejected:
for match in pattern.finditer(markdown):
if not _in_code(code, match.start()):
raise _BuildError(f"llms_txt: {form} in {src_uri} is not supported here; use a plain inline link")
def rewrite(match: re.Match[str]) -> str:
opening, target, anchor, title, closing = match.groups()
if target.startswith("#") or _EXTERNAL.match(target):
return match.group(0) # in-page anchor or external URL (https:, mailto:, ...)
if _in_code(code, match.start()):
return match.group(0) # illustrative link inside a code block/span
if target.startswith("/"):
raise _BuildError(f"llms_txt: absolute link target {target!r} in {src_uri}: link the .md source instead")
linked = posixpath.normpath(posixpath.join(src_dir, target))
if linked == ".." or linked.startswith("../"):
raise _BuildError(f"llms_txt: link target {target!r} in {src_uri} escapes docs/")
if (DOCS / linked).is_dir():
raise _BuildError(
f"llms_txt: directory-style link target {target!r} in {src_uri}: link the page's .md source instead"
)
if not (DOCS / linked).is_file():
raise _BuildError(f"llms_txt: cannot resolve link target {target!r} in {src_uri}")
if linked.endswith(".md"):
# Pages without a markdown rendition (the api/ stubs) link to their HTML instead.
url = _dest_md_uri(linked) if linked in prose else _page_url(linked)
else:
url = linked # assets are published at their docs-relative path
return f"{opening}{site_url}{url}{anchor or ''}{title or ''}{closing}"
return _LINK.sub(rewrite, markdown)
def _title(src_uri: str, nav_title: str | None, meta: dict[str, Any], body: str) -> str:
if nav_title is not None:
return nav_title
if isinstance(meta_title := meta.get("title"), str):
return meta_title
if match := _prose_h1(body):
return match.group(1).strip()
raise _BuildError(f"llms_txt: page {src_uri} has no nav title, no title frontmatter, and no H1")
def generate(site_dir: Path) -> None:
if not (DOCS / "api").is_dir():
raise _BuildError("llms_txt: docs/api not found (run gen_ref_pages first)")
config = yaml.safe_load((ROOT / "mkdocs.yml").read_text(encoding="utf-8"))
site_url = config["site_url"].rstrip("/") + "/"
prose: dict[str, str | None] = {}
sections: list[tuple[str, list[str]]] = []
top_level = _walk_nav(config["nav"], prose, sections)
ordered: list[tuple[str, list[str]]] = ([("Docs", top_level)] if top_level else []) + sections
rendered: dict[str, str] = {}
metas: dict[str, dict[str, Any]] = {}
for src_uri in prose:
metas[src_uri], markdown = _split_frontmatter((DOCS / src_uri).read_text(encoding="utf-8"))
markdown = _resolve_snippets(markdown, src_uri)
rendered[src_uri] = _rewrite_links(markdown, src_uri, site_url, prose)
index = [f"# {config['site_name']}", "", f"> {config['site_description']}", ""]
full: list[str] = []
for section_title, pages in ordered:
index += [f"## {section_title}", ""]
for src_uri in pages:
markdown = rendered[src_uri]
md_uri = _dest_md_uri(src_uri)
(site_dir / md_uri).parent.mkdir(parents=True, exist_ok=True)
(site_dir / md_uri).write_text(markdown, encoding="utf-8")
title = _title(src_uri, prose[src_uri], metas[src_uri], markdown)
description = metas[src_uri].get("description")
tail = f": {description}" if description else ""
index.append(f"- [{title}]({site_url}{md_uri}){tail}")
# `full` re-titles every page, so drop its first prose H1 (the
# same one `_title` falls back to).
h1 = _prose_h1(markdown)
body = markdown if h1 is None else markdown[: h1.start()] + markdown[h1.end() :]
full += [f"# {title}", "", f"Source: {site_url}{_page_url(src_uri)}", "", body.strip(), ""]
index.append("")
index += ["## Optional", ""]
# _OPTIONAL_PAGES must match the generated package indexes exactly: a
# package added to gen_ref_pages.PACKAGES without an entry here would be
# published on the site but silently missing from llms.txt, and a stale
# entry would link a page that no longer exists.
generated = {f"api/{path.name}/index.md" for path in (DOCS / "api").iterdir() if path.is_dir()}
listed = {src_uri for src_uri, _, _ in _OPTIONAL_PAGES}
if generated != listed:
raise _BuildError(
f"llms_txt: _OPTIONAL_PAGES out of sync with docs/api:"
f" missing {sorted(generated - listed)}, stale {sorted(listed - generated)}"
)
for src_uri, title, description in _OPTIONAL_PAGES:
index.append(f"- [{title}]({site_url}{_page_url(src_uri)}): {description}")
index.append("")
(site_dir / "llms.txt").write_text("\n".join(index), encoding="utf-8")
(site_dir / "llms-full.txt").write_text("\n".join(full), encoding="utf-8")
def main() -> None:
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument("--site-dir", default=str(ROOT / "site"), help="The built site directory to write into.")
args = parser.parse_args()
try:
generate(Path(args.site_dir))
except _BuildError as exc:
raise SystemExit(str(exc)) from exc
except OSError as exc:
raise SystemExit(f"llms_txt: {exc}") from exc
if __name__ == "__main__":
main()