feat: parse rustdoc item pages (decl, fields, variants, methods)

[fpt]

Problem

read_rustdoc (and the underlying parseDocsRsDocument) only understood module/index pages — title, overview, and dl.item-table lists. On item pages (struct.*, enum.*, fn.*, trait.*) the URL resolved and the page loaded, but the parser never looked at where the real content lives. Reading e.g. serde_json/struct.Map.html or rlua/struct.Lua.html returned just the title, a one-line overview, and a few empty section headers — forcing a raw HTML fetch to confirm method signatures.

Change

Additive matchers under the existing section#main-content root (verified against the live docs.rs DOM):

• pre.item-decl → fenced code block with the canonical declaration. Uniform across every item kind (struct/enum/fn/trait/type alias).
• Impl / trait methods — h3.code-header (impl header) + h4.code-header (method signature) + docblock, scoped to the inherent-impl and trait-impl lists. The auto-trait and blanket-impl lists (Send/Sync/From<T>/…) are skipped as noise, along with their now-empty section headers.
• Enum variants — div.variants > section.variant h3.code-header + variant docs.
• Struct fields — span.structfield code + the following div.docblock, gated on an inFields flag (HasPrefix "Fields", so #[non_exhaustive] Fields (Non-exhaustive) headers still match) since field spans and their docblocks are bare direct children of section#main-content.

Signatures use RawInnerText so punctuation from text nodes is preserved exactly, e.g. pub fn insert(&mut self, k: String, v: Value) -> Option<Value>.

Example (httparse::Request)

```

Fields

• `method: Option<&'buf str>`
  The request method, such as GET .
  ...

Implementations

impl<'h, 'b> Request<'h, 'b>

• `pub fn parse(&mut self, buf: &'b [u8]) -> Result`
  Try to parse a buffer of bytes into the Request.
  ```

Tests

• New golden fixtures: struct (serde_json::Map), function (serde_json::to_string), enum (serde_json::Value), and a documented-field struct (httparse::Request).
• Existing module-page goldens (serde/tokio/regex) are unchanged — module pages contain none of this markup, so there's no regression.
• make lint clean, make test green, plus live end-to-end reads of the affected pages.

🤖 Generated with Claude Code

[github-actions]

🤖 AI Review (klein) — turn 2

The change extends rustdoc parsing to item declarations, implementations, variants, fields, and richer nested documentation. The previously reported loss of headings, lists, and code examples in item docblocks is fixed by routing those blocks through writeRustDocBlock, and this was verified in the current parser. I found no additional verified correctness or regression issues in this incremental diff. The added golden output demonstrates preservation of examples across variants and implementation methods.

---

turn 2 (incremental review of e8b089f) · comments: total 1, active 0 (+0 new, −1 resolved) · verdict: approve

[github-actions]

klein AI review — details in the summary comment.

[github-actions]

[major] Do not limit impl/variant documentation to direct p elements; reuse the existing docblock content matchers (or add equivalent handling for headings, lists, and <pre> blocks) so the full docblock is emitted.

Rationale

Verified against the parser above: overview docblocks preserve headings, code blocks, and lists via docblockHeaderMatcher, docblockPreMatcher, and docblockListMatcher, but this matcher only visits p. Any method or enum-variant documentation containing an example, list, nested heading, or code block is therefore silently omitted; the new fixtures already show variant examples in the HTML (for example rustdoc_doc_serdejson_value.html:329-345).

[fpt]

Fixed in e8b089f. Added a shared writeRustDocBlock helper that renders the full docblock — paragraphs, <pre> code blocks, lists, and headings — for method, enum-variant, and struct-field docs, indented to nest under each item. Headings are emitted as bold text to avoid clashing with the document's ## section structure. Overview matchers are untouched, so module-page goldens are unchanged. The serde_json::Value golden now carries 104 method/variant example code blocks that were previously dropped.

Superseded: the latest AI review no longer requests changes.