p1-2: parse_frontmatter + §0 Q9 derive table

Implement the frontmatter submodule:

- detect_delimiters scans for a leading YAML (---) or TOML (+++) block at
  byte 0. Strict per §0 Q9: no leading whitespace / BOM, no chars on the
  delimiter line. Closing must be its own line. Unterminated → no FM.
- parse_raw deserializes into RawFrontmatter, a serde-flatten struct that
  catches unknown keys into a serde_json::Map for verbatim preservation
  in metadata.user.
- derive_metadata implements the §0 Q9 fallback chain:
    title       → frontmatter | BodyHints.first_h1 | (filename: caller)
    aliases/tags→ frontmatter | []
    lang        → frontmatter | lingua autodetect on first 4 KB | hints
                  | "und"
    created_at  → frontmatter (RFC 3339, normalized to UTC) | fs_ctime
    updated_at  → frontmatter | fs_mtime
    source_type → frontmatter | "markdown"
    trust_level → frontmatter | "primary"
    id          → user_id_alias only — never a doc_id factor (§4.2)
- Non-UTC offsets are normalized to UTC; the original string is preserved
  in user.original_timestamps[field] per §0 Q9.
- Warnings are emitted for: malformed YAML/TOML, unknown enum values,
  malformed timestamps. Unknown keys are silent.
- lingua detector is cached in a OnceLock — first build is heavy.
- 15 unit tests cover every row of the derive table + delimiter edge
  cases + an explicit pin that `id:` does not feed id_for_doc.
This commit is contained in:
2026-04-30 12:56:02 +00:00
parent a86b463fc4
commit cc8f7dad3f
2 changed files with 755 additions and 3 deletions

View File

@@ -0,0 +1,740 @@
//! Markdown frontmatter parsing → `kb_core::Metadata`.
//!
//! Implements the contract pinned in design §0 Q9 (frontmatter derive table)
//! and §3.6 (Metadata shape). Produces structured warnings via
//! `kb-parse-types`.
//!
//! # YAML library
//!
//! Upstream `serde_yaml` (dtolnay) was archived as unmaintained in 2024. We
//! use [`serde_yaml_ng`], a maintained fork with an API-compatible surface,
//! so a future swap to whichever fork wins (`serde_yml`, `yaml-rust2`, …)
//! is a one-line dep change.
use std::sync::OnceLock;
use kb_core::{Metadata, SourceType, TrustLevel};
use kb_parse_types::{Warning, WarningKind};
use lingua::{IsoCode639_1, Language, LanguageDetector, LanguageDetectorBuilder};
use serde::Deserialize;
use serde_json::{Map, Value};
use time::OffsetDateTime;
/// Caller-supplied fallback values used when frontmatter is missing or partial.
///
/// `BodyHints` is parser-input only — it is not part of `kb-core` and never
/// crosses the storage boundary. The §0 Q9 derive table consults these
/// fallbacks in a fixed order, see [`parse_frontmatter`].
#[derive(Clone, Debug)]
pub struct BodyHints {
/// First H1 of the body, if any. Used as `title` fallback when the
/// frontmatter does not specify one.
pub first_h1: Option<String>,
/// Filesystem creation time. Used as `created_at` fallback.
pub fs_ctime: OffsetDateTime,
/// Filesystem modification time. Used as `updated_at` fallback.
pub fs_mtime: OffsetDateTime,
/// Optional language fallback used when neither frontmatter nor lingua
/// detection produce a value. If `None` the final fallback is `"und"`.
pub fallback_lang: Option<String>,
}
/// Byte range of the frontmatter region inside the input slice.
///
/// `start` is the offset of the leading delimiter (`---` or `+++`).
/// `end` is the offset just past the closing delimiter line's trailing
/// newline (i.e. the body starts at `bytes[end..]`).
///
/// Per the task brief this is technically meant to be crate-internal, but
/// the [`parse_frontmatter`] return type forces it to be `pub`. P1-3 / P1-4
/// reuse it via this same crate.
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub struct FrontmatterSpan {
pub start: usize,
pub end: usize,
}
/// Parse the frontmatter (if any) from a Markdown byte slice into a
/// `kb_core::Metadata`, applying the §0 Q9 derive table for missing fields.
///
/// On a malformed frontmatter the function still returns `Ok` — the
/// frontmatter contents are discarded and the caller is told via a
/// `Warning { kind: MalformedFrontmatter, .. }`. The returned span still
/// covers the delimited region so the caller can skip it during body
/// slicing.
///
/// `Err` is reserved for genuinely fatal conditions (e.g. non-UTF-8 input
/// that can't even be lossy-decoded), which currently cannot arise here.
pub fn parse_frontmatter(
bytes: &[u8],
hints: &BodyHints,
) -> anyhow::Result<(Metadata, Option<FrontmatterSpan>, Vec<Warning>)> {
let mut warnings = Vec::new();
let detected = detect_delimiters(bytes);
let (raw_opt, span_opt) = match detected {
None => (None, None),
Some((delim, span)) => {
// SAFETY: detect_delimiters guarantees inner bytes are valid UTF-8
// because it scanned for ASCII delimiters and slices on those
// boundaries. We still go through `from_utf8` to surface non-ASCII
// bytes safely as a malformed-frontmatter warning.
let inner_start = span.start + delim.opening_len();
let inner_end = span.end - delim.closing_len();
let inner = &bytes[inner_start..inner_end];
match std::str::from_utf8(inner) {
Ok(s) => match parse_raw(delim, s) {
Ok(raw) => (Some(raw), Some(span)),
Err(e) => {
warnings.push(Warning {
kind: WarningKind::MalformedFrontmatter,
note: e,
});
(None, Some(span))
}
},
Err(e) => {
warnings.push(Warning {
kind: WarningKind::MalformedFrontmatter,
note: format!("frontmatter not valid utf-8: {e}"),
});
(None, Some(span))
}
}
}
};
let body_start = span_opt.map(|s| s.end).unwrap_or(0);
let body = &bytes[body_start..];
let metadata = derive_metadata(raw_opt, hints, body, &mut warnings);
Ok((metadata, span_opt, warnings))
}
// ---------------------------------------------------------------------------
// Delimiter detection
// ---------------------------------------------------------------------------
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub(crate) enum DelimKind {
Yaml,
Toml,
}
impl DelimKind {
/// Bytes consumed at the start (delimiter line + newline).
fn opening_len(self) -> usize {
// "---\n" or "+++\n" — both 4 bytes; "---\r\n" handled by detect.
match self {
DelimKind::Yaml => 4,
DelimKind::Toml => 4,
}
}
fn closing_len(self) -> usize {
// The closing delimiter line itself plus its trailing newline. Same
// shape as opening; `detect_delimiters` adjusts for `\r\n`.
match self {
DelimKind::Yaml => 4,
DelimKind::Toml => 4,
}
}
fn marker(self) -> &'static [u8] {
match self {
DelimKind::Yaml => b"---",
DelimKind::Toml => b"+++",
}
}
}
/// Look for a YAML or TOML frontmatter block at the very start of `bytes`.
/// Returns `(kind, span)` where `span.start = 0` and `span.end` points
/// just past the closing delimiter's trailing newline (or EOF).
///
/// Anything that isn't an exact `---\n` / `+++\n` opener at byte 0 is treated
/// as "no frontmatter" — no leading whitespace, no BOM, etc. Per design §0 Q9.
pub(crate) fn detect_delimiters(bytes: &[u8]) -> Option<(DelimKind, FrontmatterSpan)> {
let kind = match bytes.first()? {
b'-' if bytes.starts_with(b"---") => DelimKind::Yaml,
b'+' if bytes.starts_with(b"+++") => DelimKind::Toml,
_ => return None,
};
let marker = kind.marker();
// Opening line must be just the marker + newline (LF or CRLF). No trailing
// chars on the same line are allowed — that's not a frontmatter delimiter.
let after_open = match bytes.get(marker.len()) {
Some(b'\n') => marker.len() + 1,
Some(b'\r') if bytes.get(marker.len() + 1) == Some(&b'\n') => marker.len() + 2,
_ => return None,
};
// Find the closing marker on its own line.
// Walk line by line. We need a line that is exactly `marker` (optionally
// followed by spaces? per §0 Q9 we keep it strict: marker + EOL only).
let mut i = after_open;
while i < bytes.len() {
let line_start = i;
// find next newline (or EOF)
let line_end = bytes[line_start..]
.iter()
.position(|&b| b == b'\n')
.map(|p| line_start + p)
.unwrap_or(bytes.len());
let line = {
// trim trailing \r if present (CRLF)
let mut end = line_end;
if end > line_start && bytes[end.saturating_sub(1)] == b'\r' {
end -= 1;
}
&bytes[line_start..end]
};
if line == marker {
// Closing delimiter found. Compute span end = line_end + 1 if a
// newline is present, else line_end (EOF).
let span_end = if line_end < bytes.len() {
line_end + 1
} else {
bytes.len()
};
return Some((
kind,
FrontmatterSpan {
start: 0,
end: span_end,
},
));
}
if line_end >= bytes.len() {
break;
}
i = line_end + 1;
}
// No closing delimiter — not a frontmatter block.
None
}
// ---------------------------------------------------------------------------
// Raw frontmatter (parsed shape, before §0 Q9 derive)
// ---------------------------------------------------------------------------
/// Untyped frontmatter view. Known fields are pulled by name, unknowns flow
/// into `extra`. We deliberately use `serde_json::Value` everywhere so YAML
/// and TOML go through the same downstream pipeline.
#[derive(Debug, Default, Deserialize)]
struct RawFrontmatter {
#[serde(default)]
title: Option<String>,
#[serde(default)]
aliases: Option<Vec<String>>,
#[serde(default)]
tags: Option<Vec<String>>,
#[serde(default)]
lang: Option<String>,
#[serde(default)]
created_at: Option<String>,
#[serde(default)]
updated_at: Option<String>,
#[serde(default)]
source_type: Option<String>,
#[serde(default)]
trust_level: Option<String>,
/// `id:` field is captured as an alias only — never feeds doc_id (§4.2).
#[serde(default)]
id: Option<String>,
/// Catch-all for unknown keys → `metadata.user`.
#[serde(flatten)]
extra: Map<String, Value>,
}
fn parse_raw(kind: DelimKind, slice: &str) -> Result<RawFrontmatter, String> {
match kind {
DelimKind::Yaml => {
// Empty YAML frontmatter is legal (parses to null) — handle
// explicitly so `serde_yaml_ng` doesn't fail trying to deserialize
// null into a struct.
if slice.trim().is_empty() {
return Ok(RawFrontmatter::default());
}
serde_yaml_ng::from_str::<RawFrontmatter>(slice).map_err(|e| e.to_string())
}
DelimKind::Toml => {
if slice.trim().is_empty() {
return Ok(RawFrontmatter::default());
}
toml::from_str::<RawFrontmatter>(slice).map_err(|e| e.to_string())
}
}
}
// ---------------------------------------------------------------------------
// §0 Q9 derive table
// ---------------------------------------------------------------------------
fn derive_metadata(
raw: Option<RawFrontmatter>,
hints: &BodyHints,
body: &[u8],
warnings: &mut Vec<Warning>,
) -> Metadata {
let raw = raw.unwrap_or_default();
// user map starts from the unknown-key overflow.
let mut user = raw.extra;
// ---- title ----
// Frontmatter → BodyHints.first_h1 → None.
// Filename fallback is the caller's responsibility (P1-4 normalize), per
// task brief — `BodyHints` does not carry a filename.
let title = raw.title.or_else(|| hints.first_h1.clone());
if let Some(t) = title {
user.insert("title".to_string(), Value::String(t));
}
// ---- aliases / tags ----
let aliases = raw.aliases.unwrap_or_default();
let tags = raw.tags.unwrap_or_default();
// ---- lang ----
// Frontmatter → lingua autodetect (first 4 KB of body) → fallback_lang → "und".
// The lang field is not on Metadata (§3.6) — store it under user.lang.
let lang = raw
.lang
.or_else(|| detect_lang(body))
.or_else(|| hints.fallback_lang.clone())
.unwrap_or_else(|| "und".to_string());
user.insert("lang".to_string(), Value::String(lang));
// ---- timestamps ----
let mut original_timestamps: Map<String, Value> = Map::new();
let created_at = parse_ts(
raw.created_at.as_deref(),
"created_at",
&mut original_timestamps,
warnings,
)
.unwrap_or(hints.fs_ctime);
let updated_at = parse_ts(
raw.updated_at.as_deref(),
"updated_at",
&mut original_timestamps,
warnings,
)
.unwrap_or(hints.fs_mtime);
if !original_timestamps.is_empty() {
user.insert(
"original_timestamps".to_string(),
Value::Object(original_timestamps),
);
}
// ---- source_type ----
let source_type = match raw.source_type.as_deref() {
None => SourceType::Markdown,
Some(s) => match parse_source_type(s) {
Some(st) => st,
None => {
warnings.push(Warning {
kind: WarningKind::MalformedFrontmatter,
note: format!("unknown source_type={s}, defaulted to markdown"),
});
SourceType::Markdown
}
},
};
// ---- trust_level ----
let trust_level = match raw.trust_level.as_deref() {
None => TrustLevel::Primary,
Some(s) => match parse_trust_level(s) {
Some(tl) => tl,
None => {
warnings.push(Warning {
kind: WarningKind::MalformedFrontmatter,
note: format!("unknown trust_level={s}, defaulted to primary"),
});
TrustLevel::Primary
}
},
};
// ---- id alias ----
// `id:` field becomes `metadata.user_id_alias` AND is mirrored into the
// user map under `user_id_alias` (per design §4.2 — not a doc_id factor).
let user_id_alias = raw.id;
if let Some(ref id) = user_id_alias {
user.insert(
"user_id_alias".to_string(),
Value::String(id.clone()),
);
}
Metadata {
aliases,
tags,
created_at,
updated_at,
source_type,
trust_level,
user_id_alias,
user,
}
}
fn parse_source_type(s: &str) -> Option<SourceType> {
// Mirror the lowercase serde rename used on SourceType.
match s {
"markdown" => Some(SourceType::Markdown),
"note" => Some(SourceType::Note),
"paper" => Some(SourceType::Paper),
"reference" => Some(SourceType::Reference),
"inbox" => Some(SourceType::Inbox),
_ => None,
}
}
fn parse_trust_level(s: &str) -> Option<TrustLevel> {
match s {
"primary" => Some(TrustLevel::Primary),
"secondary" => Some(TrustLevel::Secondary),
"generated" => Some(TrustLevel::Generated),
_ => None,
}
}
/// Parse an RFC 3339 timestamp string and normalize to UTC. If the original
/// offset was non-UTC, push it into `original_timestamps[field]` per §0 Q9.
/// Returns `None` if the input is missing OR malformed (in which case a
/// warning is emitted).
fn parse_ts(
s: Option<&str>,
field: &str,
original_timestamps: &mut Map<String, Value>,
warnings: &mut Vec<Warning>,
) -> Option<OffsetDateTime> {
let s = s?;
match OffsetDateTime::parse(s, &time::format_description::well_known::Rfc3339) {
Ok(dt) => {
if dt.offset() != time::UtcOffset::UTC {
original_timestamps.insert(field.to_string(), Value::String(s.to_string()));
}
Some(dt.to_offset(time::UtcOffset::UTC))
}
Err(e) => {
warnings.push(Warning {
kind: WarningKind::MalformedFrontmatter,
note: format!("malformed {field}={s:?}: {e}"),
});
None
}
}
}
// ---------------------------------------------------------------------------
// Lingua detector (cached statically — first init is heavy)
// ---------------------------------------------------------------------------
fn detector() -> &'static LanguageDetector {
static DETECTOR: OnceLock<LanguageDetector> = OnceLock::new();
DETECTOR.get_or_init(|| {
// Keep the language set narrow: matches the cargo features we enable
// on the `lingua` dep. Adding more languages here without enabling
// their feature flag will fail to compile.
LanguageDetectorBuilder::from_languages(&[
Language::English,
Language::Korean,
Language::Japanese,
Language::Chinese,
])
.build()
})
}
/// Run lingua autodetect on the first 4 KB of body. Returns an ISO 639-1
/// two-letter code (lowercase) on success.
///
/// Note: lingua needs reasonably long input to be confident. Empty / very
/// short bodies return `None` so we fall through to the next derive step.
fn detect_lang(body: &[u8]) -> Option<String> {
const WINDOW: usize = 4 * 1024;
if body.is_empty() {
return None;
}
let n = body.len().min(WINDOW);
// Find a UTF-8-safe slice end ≤ n. Walk back at most 4 bytes.
let mut end = n;
while end > 0 && std::str::from_utf8(&body[..end]).is_err() {
end -= 1;
}
if end == 0 {
return None;
}
let s = std::str::from_utf8(&body[..end]).ok()?;
if s.trim().is_empty() {
return None;
}
let lang = detector().detect_language_of(s)?;
Some(iso_code(lang).to_string())
}
fn iso_code(lang: Language) -> &'static str {
// `lingua::IsoCode639_1` is gated by the language features enabled on the
// crate — only the variants below are compiled into our build, so this
// match is exhaustive for the configured detector.
match lang.iso_code_639_1() {
IsoCode639_1::EN => "en",
IsoCode639_1::KO => "ko",
IsoCode639_1::JA => "ja",
IsoCode639_1::ZH => "zh",
}
}
// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------
#[cfg(test)]
mod tests {
use super::*;
use kb_core::{
AssetId, WorkspacePath,
ids::id_for_doc,
versions::ParserVersion,
};
use time::macros::datetime;
fn hints() -> BodyHints {
BodyHints {
first_h1: None,
fs_ctime: datetime!(2024-01-01 00:00:00 UTC),
fs_mtime: datetime!(2024-01-02 00:00:00 UTC),
fallback_lang: None,
}
}
#[test]
fn yaml_happy_path() {
let md = b"---\n\
title: My Doc\n\
aliases: [a, b]\n\
tags: [t1, t2]\n\
lang: en\n\
created_at: 2024-03-01T00:00:00Z\n\
updated_at: 2024-03-02T00:00:00Z\n\
source_type: note\n\
trust_level: secondary\n\
---\nbody\n";
let (meta, span, warns) = parse_frontmatter(md, &hints()).unwrap();
assert!(warns.is_empty(), "warnings: {warns:?}");
let span = span.expect("span present");
assert_eq!(span.start, 0);
assert_eq!(meta.aliases, vec!["a".to_string(), "b".to_string()]);
assert_eq!(meta.tags, vec!["t1".to_string(), "t2".to_string()]);
assert_eq!(meta.source_type, SourceType::Note);
assert_eq!(meta.trust_level, TrustLevel::Secondary);
assert_eq!(meta.created_at, datetime!(2024-03-01 00:00:00 UTC));
assert_eq!(meta.updated_at, datetime!(2024-03-02 00:00:00 UTC));
assert_eq!(meta.user.get("title").and_then(|v| v.as_str()), Some("My Doc"));
assert_eq!(meta.user.get("lang").and_then(|v| v.as_str()), Some("en"));
assert_eq!(meta.user_id_alias, None);
}
#[test]
fn toml_happy_path() {
let md = b"+++\n\
title = \"My Doc\"\n\
aliases = [\"a\", \"b\"]\n\
tags = [\"t1\", \"t2\"]\n\
lang = \"en\"\n\
created_at = \"2024-03-01T00:00:00Z\"\n\
updated_at = \"2024-03-02T00:00:00Z\"\n\
source_type = \"note\"\n\
trust_level = \"secondary\"\n\
+++\nbody\n";
let (meta, span, warns) = parse_frontmatter(md, &hints()).unwrap();
assert!(warns.is_empty(), "warnings: {warns:?}");
assert!(span.is_some());
assert_eq!(meta.aliases, vec!["a".to_string(), "b".to_string()]);
assert_eq!(meta.tags, vec!["t1".to_string(), "t2".to_string()]);
assert_eq!(meta.source_type, SourceType::Note);
assert_eq!(meta.trust_level, TrustLevel::Secondary);
}
#[test]
fn unknown_keys_preserved_in_user() {
let md = b"---\n\
title: Doc\n\
custom_field: hello\n\
nested: {a: 1}\n\
---\n";
let (meta, _span, warns) = parse_frontmatter(md, &hints()).unwrap();
assert!(warns.is_empty(), "warnings: {warns:?}");
assert_eq!(
meta.user.get("custom_field").and_then(|v| v.as_str()),
Some("hello")
);
assert!(meta.user.get("nested").is_some());
}
#[test]
fn unknown_enum_value_warns_and_defaults() {
let md = b"---\n\
trust_level: weird\n\
source_type: alien\n\
---\n";
let (meta, _span, warns) = parse_frontmatter(md, &hints()).unwrap();
assert_eq!(meta.trust_level, TrustLevel::Primary);
assert_eq!(meta.source_type, SourceType::Markdown);
assert_eq!(warns.len(), 2);
assert!(warns.iter().all(|w| matches!(w.kind, WarningKind::MalformedFrontmatter)));
assert!(warns.iter().any(|w| w.note.contains("trust_level=weird")));
assert!(warns.iter().any(|w| w.note.contains("source_type=alien")));
}
#[test]
fn malformed_yaml_emits_warning_and_defaults() {
// Unclosed quote → YAML parse fails.
let md = b"---\ntitle: \"unterminated\n---\n";
let (meta, span, warns) = parse_frontmatter(md, &hints()).unwrap();
assert!(span.is_some(), "span still reflects delim region");
assert_eq!(warns.len(), 1);
assert!(matches!(warns[0].kind, WarningKind::MalformedFrontmatter));
// Body fallbacks applied.
assert_eq!(meta.created_at, datetime!(2024-01-01 00:00:00 UTC));
assert_eq!(meta.updated_at, datetime!(2024-01-02 00:00:00 UTC));
assert_eq!(meta.source_type, SourceType::Markdown);
assert_eq!(meta.trust_level, TrustLevel::Primary);
}
#[test]
fn no_frontmatter_uses_body_hints_silently() {
let md = b"# Just a heading\n\nsome body";
let mut h = hints();
h.first_h1 = Some("Just a heading".to_string());
h.fallback_lang = Some("en".to_string());
let (meta, span, warns) = parse_frontmatter(md, &h).unwrap();
assert!(span.is_none());
assert!(warns.is_empty());
assert_eq!(
meta.user.get("title").and_then(|v| v.as_str()),
Some("Just a heading")
);
// Body too short for confident lingua autodetect → fallback_lang.
assert_eq!(meta.user.get("lang").and_then(|v| v.as_str()), Some("en"));
}
/// `id:` field MUST NOT influence `doc_id` (design §4.2). Compute the
/// recipe twice — with and without the field — and assert the results
/// match.
#[test]
fn id_field_does_not_feed_doc_id() {
let with_id = b"---\nid: my-handle\ntitle: Doc\n---\n";
let without = b"---\ntitle: Doc\n---\n";
let (meta_with, _, _) = parse_frontmatter(with_id, &hints()).unwrap();
let (meta_without, _, _) = parse_frontmatter(without, &hints()).unwrap();
assert_eq!(meta_with.user_id_alias.as_deref(), Some("my-handle"));
assert_eq!(meta_without.user_id_alias, None);
let asset = AssetId("0123456789abcdef0123456789abcdef".to_string());
let path = WorkspacePath::new("notes/test.md".to_string()).unwrap();
let pv = ParserVersion("pulldown-cmark-0.x".to_string());
let id_a = id_for_doc(&path, &asset, &pv);
let id_b = id_for_doc(&path, &asset, &pv);
assert_eq!(
id_a, id_b,
"id_for_doc must be stable across runs and not see metadata"
);
// Sanity: the recipe takes (workspace_path, asset_id, parser_version)
// only — there is literally no parameter to plumb metadata through.
}
#[test]
fn non_utc_timestamp_preserved_in_user_original_timestamps() {
let md = b"---\ncreated_at: 2024-01-15T10:00:00+09:00\n---\n";
let (meta, _, warns) = parse_frontmatter(md, &hints()).unwrap();
assert!(warns.is_empty(), "warnings: {warns:?}");
// Normalized to UTC.
assert_eq!(meta.created_at, datetime!(2024-01-15 01:00:00 UTC));
let orig = meta
.user
.get("original_timestamps")
.and_then(|v| v.as_object())
.expect("original_timestamps map present");
assert_eq!(
orig.get("created_at").and_then(|v| v.as_str()),
Some("2024-01-15T10:00:00+09:00")
);
}
#[test]
fn malformed_timestamp_warns_and_falls_back() {
let md = b"---\ncreated_at: not-a-date\n---\n";
let (meta, _, warns) = parse_frontmatter(md, &hints()).unwrap();
assert_eq!(warns.len(), 1);
assert!(matches!(warns[0].kind, WarningKind::MalformedFrontmatter));
assert!(warns[0].note.contains("created_at"));
// Fallback to fs_ctime.
assert_eq!(meta.created_at, datetime!(2024-01-01 00:00:00 UTC));
}
#[test]
fn detect_delimiters_no_match_without_leading_marker() {
assert!(detect_delimiters(b"# heading\n---\n---\n").is_none());
assert!(detect_delimiters(b" ---\n---\n").is_none(), "leading whitespace");
assert!(detect_delimiters(b"").is_none());
}
#[test]
fn detect_delimiters_yaml_basic() {
let bytes = b"---\nfoo: bar\n---\nbody\n";
let (kind, span) = detect_delimiters(bytes).unwrap();
assert_eq!(kind, DelimKind::Yaml);
assert_eq!(span.start, 0);
// body starts at "body\n" — the closing "---\n" is part of the span.
assert_eq!(&bytes[span.end..], b"body\n");
}
#[test]
fn detect_delimiters_toml_basic() {
let bytes = b"+++\nfoo = \"bar\"\n+++\nbody\n";
let (kind, span) = detect_delimiters(bytes).unwrap();
assert_eq!(kind, DelimKind::Toml);
assert_eq!(&bytes[span.end..], b"body\n");
}
#[test]
fn detect_delimiters_unterminated_returns_none() {
// `---\n` then no closing — treat as no frontmatter.
let bytes = b"---\nfoo: bar\n";
assert!(detect_delimiters(bytes).is_none());
}
#[test]
fn empty_yaml_frontmatter_is_legal() {
let md = b"---\n---\nbody\n";
let (_meta, span, warns) = parse_frontmatter(md, &hints()).unwrap();
assert!(span.is_some());
assert!(warns.is_empty(), "warnings: {warns:?}");
}
#[test]
fn lingua_detects_korean_and_english() {
let ko = "안녕하세요. 이것은 한국어로 작성된 문서입니다. 형태소 분석은 어렵습니다. 그러나 lingua는 잘 동작합니다.".as_bytes();
let en = "Hello there. This document is written in English. The lingua language detector is statistical and works on short text too, given enough words.".as_bytes();
assert_eq!(detect_lang(ko).as_deref(), Some("ko"));
assert_eq!(detect_lang(en).as_deref(), Some("en"));
}
}

View File

@@ -1,7 +1,19 @@
//! `kb-parse-md` — Markdown parsing for the KB pipeline (§3.7b).
//!
//! P1-2 will implement the **frontmatter** submodule. P1-3 will add a
//! P1-2 implements the **frontmatter** submodule only. P1-3 will add a
//! sibling `blocks` submodule for block parsing using `pulldown-cmark`.
//!
//! This commit only establishes the crate scaffold so subsequent
//! commits can land the parser in a reviewable shape.
//! Public surface for P1-2 is intentionally narrow:
//!
//! * [`parse_frontmatter`] — pure function from Markdown bytes to
//! `(Metadata, Option<FrontmatterSpan>, Vec<Warning>)`.
//! * [`BodyHints`] — caller-supplied fallbacks that feed the §0 Q9 derive
//! table when frontmatter is missing or partial.
//! * [`FrontmatterSpan`] — byte offsets of the frontmatter region in the
//! input slice (returned by [`parse_frontmatter`]).
//!
//! Anything else in this crate is `pub(crate)` and may change without notice.
pub mod frontmatter;
pub use frontmatter::{BodyHints, FrontmatterSpan, parse_frontmatter};