From b0991db7252091dfc8aae648ddddb3600b3e6dbb Mon Sep 17 00:00:00 2001 From: Ziyang Guo <121015044+RerankerGuo@users.noreply.github.com> Date: Wed, 28 Oct 2026 16:19:15 +0800 Subject: [PATCH] fix(frontmatter-read): put the frontmatter in the answer, not just a key count (#564) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit * fix(frontmatter-read): put the frontmatter in the answer, not just a key count `frontmatter_read` answered `Read frontmatter from (N key(s))` and left the frontmatter itself in `metadata["frontmatter"]`. MCP returns only `response.answer`, so the LLM that asked for a file's frontmatter learned how many keys exist and nothing else — the same shape of gap #379 describes for `list`, where the caller cannot act on the result. Render each key on its own line in the answer. Values are flattened to one line each so a multi-line description cannot break the line-per-key layout: lists join with commas and nested mappings render as compact JSON. An empty frontmatter says `(no keys)` rather than trailing off after the colon. The answer also names the probed path instead of the raw input, so a suffix-less request reports the `.md` file that was actually read and the caller can follow up with `read` without consulting metadata. Structured `metadata["frontmatter"]` is unchanged, so programmatic consumers see no difference. Towards #379. * docs(config): match the frontmatter_read description to the new answer The job description still advertised "Read a file's frontmatter as a dict", but the answer is now rendered `key: value` lines — the dict only survives in metadata. An LLM choosing between `frontmatter_read` and a whole-file `read` would expect a dict it can index into and get prose instead. This is the wording-alignment point raised on #397, applied here before review rather than after. * fix(frontmatter-read): never fail a valid YAML read on rendering Review on #564 found two rendering regressions plus boundary losses: - json.dumps(..., sort_keys=True) raised on datetime.date values (YAML timestamps) and on mixed-type mapping keys, turning a parseable frontmatter into a failed job with empty metadata - the base revision read those files fine. - Comma-joining lists lost item boundaries (["a, b", "c"] read back as one ambiguous string), [] was indistinguishable from an empty string, and the whitespace collapse also mangled spaces inside serialized values. _render_value is now a single tolerant renderer: bare strings keep their text but have line breaks escaped; everything else goes through json.dumps(ensure_ascii=False, default=str) (no key sort) so collections stay structured and YAML-only types serialize; anything JSON still cannot represent falls back to repr. Keys are rendered through the same path so a multiline key cannot break the one-key-per-line layout either. The structured metadata contract is untouched. Also aligns the benchmark.yaml job description with the textual answer (default.yaml already says 'one key: value per line') and the module docstring now distinguishes the textual answer from the structured payload in metadata. Regression coverage: nested dates, mixed mapping keys, empty lists, comma-containing items, significant whitespace, and a literal block scalar with a real newline. * fix(frontmatter-read): use json.dumps for all scalars to preserve string and mapping distinctions Follow-up to the @jinliyl review on #564 (10-15 round 2): - _render_value now sends every scalar through json.dumps rather than the str-only branch. The str-only branch collapsed a literal '\n' two-character sequence and an actual newline into the same rendered form ('\n') and lost the distinction between the string 'null' and YAML null. The JSON form preserves both. - Mixed mapping key types (int 1 vs string '1') now round-trip with their JSON-form distinction in the answer, matching the metadata. Callers that re-parse the answer body as JSON still discard one value (this is a YAML-side limitation, not a renderer one); pinned by a regression test. - Updated the three existing answer assertions to carry the new quoted scalar form, and added two regression tests: test_read_answer_distinguishes_newline_from_literal_backslash_n and test_read_answer_mixed_mapping_key_types_render_via_json. Note: the str-only branch's '\n' escape was the only reason the description: |- literal-block test in test_read_answer_tolerates_rich_yaml_types rendered as 'line one\\nline two'. With the change, the same description renders as '"line one\nline two"' (real newline, JSON- escaped), which is exactly the fix the review asked for. * fix(frontmatter-read): split key/value rendering so keys are not JSON-quoted The round-2 change sent every scalar (including string keys) through json.dumps, which added quotes around string keys. The rendered answer came out as '- "name": "Cobalt"' instead of '- name: "Cobalt"' on the round-2 head; the 5 new and updated tests in test_frontmatter_steps all failed for that reason on Unit Tests - py3.11 through py3.14. Split the renderer: - _render_key: pass-through str(key) so the answer reads as '- key:'. - _render_value: still json.dumps (with default=str and ensure_ascii=False) for the structural pinning the round-2 review asked for (literal '\n' vs actual newline, the string 'null' vs YAML null, mixed mapping key types). Caller formats the line as '- {key}: {value}'. Updated the three existing answer assertions to match the key-unchanged, value-quoted shape (e.g. '- name: "Cobalt"'). The two new tests added in the round-2 commit (newline, mixed keys) were already pinned on the right shape; the round-1 key-quote was the only bug. * fix(frontmatter-read): JSON-encode keys too so every answer entry stays on one line A multiline YAML key broke the one-key-per-line layout because keys were interpolated raw. Route keys through the same json.dumps renderer as values, update the expected answers to the quoted-key form, correct the renderer docstring and mixed-key test comments (JSON collapses int 1 and string "1" keys alike — the metadata keeps the distinction), and pin the rich-type answer to the quoted "created": "2026-10-12" rendering. * test(frontmatter-read): cover multiline keys, reseed YAML blocks as literal strings Add the multiline-key regression the review asked for, restate the mixed-mapping-key case as a documented presentation limitation (JSON stringifies both keys, so a re-parser keeps only the last value), and write the YAML seeds as triple-quoted literals so black stops joining the implicit concatenations and pylint's implicit-str-concat goes quiet. * refactor(frontmatter-read): simplify answer rendering --------- Co-authored-by: jinli.yl --- reme/config/benchmark.yaml | 2 +- reme/config/default.yaml | 2 +- reme/steps/file_io/frontmatter_read.py | 25 +++- tests/unit/test_frontmatter_steps.py | 183 +++++++++++++++++++++++++ 4 files changed, 206 insertions(+), 6 deletions(-) diff --git a/reme/config/benchmark.yaml b/reme/config/benchmark.yaml index 46d61455..743475ed 100644 --- a/reme/config/benchmark.yaml +++ b/reme/config/benchmark.yaml @@ -331,7 +331,7 @@ 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: diff --git a/reme/config/default.yaml b/reme/config/default.yaml index 19b4423d..2aa8f2da 100644 --- a/reme/config/default.yaml +++ b/reme/config/default.yaml @@ -583,7 +583,7 @@ 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: diff --git a/reme/steps/file_io/frontmatter_read.py b/reme/steps/file_io/frontmatter_read.py index fea6312d..93085fe7 100644 --- a/reme/steps/file_io/frontmatter_read.py +++ b/reme/steps/file_io/frontmatter_read.py @@ -1,13 +1,15 @@ -"""``frontmatter_read_step`` — return the frontmatter dict of a markdown file. +"""``frontmatter_read_step`` — surface a markdown file's frontmatter. Cheap structured read — frontmatter only, no body. Use ``body:read`` for the post-frontmatter content slice, or whole-file ``read`` when -you want both at once. Returns ``{exists: false}`` when the target -doesn't exist; otherwise ``{exists: true, frontmatter: {...}}``. +you want both at once. The answer has one ``- "key": value`` entry per +line; the parsed mapping is returned in ``metadata["frontmatter"]`` (and +``exists: false`` in metadata when the target doesn't exist). ``path`` is a path relative to the workspace. """ +import json from pathlib import Path import frontmatter @@ -18,6 +20,19 @@ from ..base_step import BaseStep from ...components import R +def _render_value(value) -> str: + """Render a key or value on one line using JSON with a ``repr`` fallback. + + YAML-only values such as dates use ``str``. Unsupported mapping keys + and recursive aliases fall back to ``repr``. JSON stringifies nested + mapping keys; only metadata preserves their original types. + """ + try: + return json.dumps(value, ensure_ascii=False, default=str) + except (TypeError, ValueError, RecursionError): + return repr(value) + + @R.register("frontmatter_read_step") class FrontmatterReadStep(BaseStep): """Read a Markdown file's frontmatter (YAML metadata only).""" @@ -71,6 +86,8 @@ 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))" + body = "\n".join(f"- {_render_value(key)}: {_render_value(value)}" for key, value in meta.items()) + self.context.response.answer = f"{header}:\n{body}" if body 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)}") diff --git a/tests/unit/test_frontmatter_steps.py b/tests/unit/test_frontmatter_steps.py index e742e6ff..6da209d5 100644 --- a/tests/unit/test_frontmatter_steps.py +++ b/tests/unit/test_frontmatter_steps.py @@ -12,6 +12,7 @@ probed path in not-found errors instead of the caller's raw input. from contextlib import chdir as temp_chdir import tempfile +from datetime import date from pathlib import Path import frontmatter @@ -246,3 +247,185 @@ 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_preserves_value_structure_and_reports_empty(): + """Multi-line values stay on one line each; lists keep their shape; 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.success is True + 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}' + ) + assert resp.metadata["frontmatter"] == { + "name": "Cobalt", + "description": "line one line two", + "tags": ["a", "b"], + "nested": {"x": 1}, + } + + resp = await _run(FrontmatterReadStep, store, path="notes/empty.md") + assert resp.success is True + assert resp.answer == "Read frontmatter from notes/empty.md (0 key(s)): (no keys)" + assert resp.metadata["frontmatter"] == {} + await store.close() + + +@pytest.mark.asyncio +async def test_read_answer_tolerates_rich_yaml_types(): + """Rendering must never turn a parseable frontmatter into a failed job. + + Regression test for the review findings: YAML dates (``datetime.date``) + crashed ``json.dumps``, mixed mapping keys crashed ``sort_keys``, and + comma-joined lists / collapsed whitespace lost value boundaries. All of + these stay successful reads with the structured ``metadata`` untouched. + """ + rich = """--- +created: 2026-10-12 +schedule: + 1: one + label: two +tags: [] +aliases: + - "a, b" + - c +command: "echo a b" +description: |- + line one + line two +--- +body +""" + with tempfile.TemporaryDirectory() as tmp, temp_chdir(tmp): + _seed(Path(tmp), "notes/types.md", rich) + store = await _make_store() + resp = await _run(FrontmatterReadStep, store, path="notes/types.md") + assert resp.success is True + expected_lines = [ + "Read frontmatter from notes/types.md (6 key(s)):", + '- "created": "2026-10-12"', + '- "schedule": {"1": "one", "label": "two"}', + '- "tags": []', + '- "aliases": ["a, b", "c"]', + '- "command": "echo a b"', + '- "description": "line one\\nline two"', + ] + assert resp.answer == "\n".join(expected_lines) + assert resp.metadata["frontmatter"] == { + "created": date(2026, 10, 12), + "schedule": {1: "one", "label": "two"}, + "tags": [], + "aliases": ["a, b", "c"], + "command": "echo a b", + "description": "line one\nline two", + } + await store.close() + + +@pytest.mark.asyncio +async def test_read_answer_distinguishes_newline_from_literal_backslash_n(): + """Strings go through json.dumps, so an actual newline and a + two-character ``"\\n"`` sequence render as different escape + sequences. Review follow-up: pin the answer so this distinction + survives future refactors. + """ + body = r"""--- +real_newline: "line one\nline two" +literal_seq: "a\\nb" +--- +body +""" + with tempfile.TemporaryDirectory() as tmp, temp_chdir(tmp): + _seed(Path(tmp), "notes/newline.md", body) + store = await _make_store() + resp = await _run(FrontmatterReadStep, store, path="notes/newline.md") + assert resp.success is True + assert '- "real_newline": "line one\\nline two"' in resp.answer + # Literal two-character \n renders as a JSON-escaped backslash-n + # (the JSON string contains a backslash + an n). + assert '- "literal_seq": "a\\\\nb"' in resp.answer + await store.close() + + +@pytest.mark.asyncio +async def test_read_answer_escapes_multiline_keys(): + """Keys go through the same JSON renderer as values, so a multiline + YAML key stays a single ``- "key": value`` entry instead of breaking + the one-key-per-line layout. Review finding: a key like + ``first\\n- forged`` used to render as two lines and look like a + second entry. The metadata keeps the original key. + """ + body = r"""--- +"first\n- forged": "value" +--- +body +""" + with tempfile.TemporaryDirectory() as tmp, temp_chdir(tmp): + _seed(Path(tmp), "notes/keys.md", body) + store = await _make_store() + resp = await _run(FrontmatterReadStep, store, path="notes/keys.md") + assert resp.success is True + assert resp.answer == 'Read frontmatter from notes/keys.md (1 key(s)):\n- "first\\n- forged": "value"' + assert resp.metadata["frontmatter"] == {"first\n- forged": "value"} + await store.close() + + +@pytest.mark.asyncio +async def test_read_answer_mixed_mapping_key_types_render_via_json(): + """An int 1 and a string "1" stay distinct in YAML and in the + metadata, but the JSON-rendered answer collapses both keys to the + string "1": the fragment textually keeps both entries, while + re-parsing it as JSON keeps only the latter value. Documented + presentation limitation — the structured metadata is the source of + truth for key types. + """ + body = """--- +mixed: + 1: "number" + "1": "string" +--- +body +""" + with tempfile.TemporaryDirectory() as tmp, temp_chdir(tmp): + _seed(Path(tmp), "notes/mixed_keys.md", body) + store = await _make_store() + resp = await _run(FrontmatterReadStep, store, path="notes/mixed_keys.md") + assert resp.success is True + # Both entries render textually; JSON's key coercion means a + # re-parser sees only the last "1". The metadata keeps the types. + assert '- "mixed": {"1": "number", "1": "string"}' in resp.answer + assert resp.metadata["frontmatter"] == { + "mixed": {1: "number", "1": "string"}, + } + await store.close()