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Ziyang Guo 2026-10-10 11:43:36 +08:00 • committed by GitHub
commit eb39e76df4
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3 changed files with 72 additions and 2 deletions

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@ -549,7 +549,7 @@ jobs:
frontmatter_read:
backend: base
description: "Read a file's frontmatter as a dict."
description: "Read a file's frontmatter, one key: value per line."
parameters:
type: object
properties:

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@ -8,6 +8,7 @@ doesn't exist; otherwise ``{exists: true, frontmatter: {...}}``.
``path`` is a path relative to the workspace.
"""
import json
from pathlib import Path
import frontmatter
@ -18,6 +19,28 @@ from ..base_step import BaseStep
from ...components import R
def _render_value(value) -> str:
"""Flatten one frontmatter value onto a single answer line."""
if isinstance(value, (list, tuple)):
rendered = ", ".join(str(item) for item in value)
elif isinstance(value, dict):
rendered = json.dumps(value, ensure_ascii=False, sort_keys=True)
else:
rendered = str(value)
return " ".join(rendered.split())
def _render_frontmatter(meta: dict) -> list[str]:
"""Render each frontmatter key on its own ``- key: value`` line.
``frontmatter_read`` is served straight to the LLM, so the answer has to
carry the frontmatter itself; a key count alone leaves the caller with
nothing to act on. Values are flattened to one line each so a multi-line
description cannot break the line-per-key layout.
"""
return [f"- {key}: {_render_value(value)}" for key, value in meta.items()]
@R.register("frontmatter_read_step")
class FrontmatterReadStep(BaseStep):
"""Read a Markdown file's frontmatter (YAML metadata only)."""
@ -71,6 +94,8 @@ class FrontmatterReadStep(BaseStep):
self.logger.info(f"[{self.name}] path={path} parse_error={exc!r}")
return
self.context.response.success = True
self.context.response.answer = f"Read frontmatter from {path} ({len(meta)} key(s))"
header = f"Read frontmatter from {probed} ({len(meta)} key(s))"
rendered = _render_frontmatter(meta)
self.context.response.answer = f"{header}:\n" + "\n".join(rendered) if rendered else f"{header}: (no keys)"
self.context.response.metadata.update({"path": path, "exists": True, "frontmatter": meta, **resolved})
self.logger.info(f"[{self.name}] path={path} keys={len(meta)}")

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@ -262,3 +262,48 @@ async def test_explicit_md_path_has_no_resolved_path():
assert resp.success is True
assert "resolved_path" not in resp.metadata
await store.close()
@pytest.mark.asyncio
async def test_read_answer_carries_the_frontmatter_itself():
"""The answer must contain the frontmatter, not just a key count.
``frontmatter_read`` is served straight to the LLM and MCP returns only
``response.answer``, so a count alone leaves the caller with nothing to
act on. The suffix-less substitution is disclosed in the answer too.
"""
with tempfile.TemporaryDirectory() as tmp, temp_chdir(tmp):
_seed(Path(tmp), NOTE, BODY)
store = await _make_store()
resp = await _run(FrontmatterReadStep, store, path="notes/post")
assert resp.success is True
assert resp.answer == "Read frontmatter from notes/post.md (2 key(s)):\n- name: n\n- tags: a"
assert resp.metadata["frontmatter"] == {"name": "n", "tags": ["a"]}
await store.close()
@pytest.mark.asyncio
async def test_read_answer_flattens_values_and_reports_empty():
"""Multi-line, list and nested values stay on one line each; empty says so."""
with tempfile.TemporaryDirectory() as tmp, temp_chdir(tmp):
_seed(
Path(tmp),
"notes/rich.md",
"---\nname: Cobalt\ndescription: line one\n line two\ntags:\n- a\n- b\nnested:\n x: 1\n---\nbody\n",
)
_seed(Path(tmp), "notes/empty.md", "---\n---\nbody\n")
store = await _make_store()
resp = await _run(FrontmatterReadStep, store, path="notes/rich.md")
assert resp.answer == (
"Read frontmatter from notes/rich.md (4 key(s)):\n"
"- name: Cobalt\n"
"- description: line one line two\n"
"- tags: a, b\n"
'- nested: {"x": 1}'
)
resp = await _run(FrontmatterReadStep, store, path="notes/empty.md")
assert resp.answer == "Read frontmatter from notes/empty.md (0 key(s)): (no keys)"
assert resp.metadata["frontmatter"] == {}
await store.close()