documents: exports read through MarkdownReader, one fresh stack per area; reading helpers close again

The writer in ElyMark kept its own copy of the inline reading, which drifted
from the drawing. Reader goes public as MarkdownReader with block, inline,
note and label, and its blocks as MarkdownBlock. Shortcodes, InlineTag,
inline_tag and html_block_text close back to the tree; headings(text) goes.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

AGENTS.md

@@ -13,7 +13,7 @@ Ely GPUI Component. A component library for GPUI, in light and dark.
 - Web views: `wry` 0.57 (Apache-2.0 OR MIT, default features off, macOS only) lays a child WKWebView over the window.
 - Terminal: `alacritty_terminal` 0.26 (Apache-2.0, default features off, native only) for the grid, its parser and the pseudo-terminal; `futures` carries its events. `vte` 0.15 (Apache-2.0 OR MIT), the parser it re-exports, reads `AnsiText`'s codes alone, so colored output builds for wasm32.
 - Diffs: `similar` 3.2 (Apache-2.0) for line and word diffs and three-way merges; its `unicode` feature splits words at punctuation.
-- Markdown: `markdown` 1.0.0 (markdown-rs, MIT) reads GitHub's flavor and math into a syntax tree with byte positions for `MarkdownRenderer`, `MarkdownEditor`, the highlights, block ranges and outline. `MarkdownRenderer` draws display math through `typography::Latex`, a ```` ```mermaid ```` block through `documents::Diagram`, and pictures from the owner's folder (`base`) or `data:` addresses (`base64` 0.22, MIT OR Apache-2.0); web pictures stay unloaded. Inline math shows as TeX: gpui text carries no inline pictures. Inline it reads as Typora's defaults: `:shortcode:` turns to its emoji as GitHub reads it (the `emojis` crate's names, GitHub's today, so `:cricket:` is the insect; read after escapes and references, so `\:smile:` turns too; inside an autolink or `<code>` it stays text; within one DOM text node, which filtered tags do not split, the first `:name:`-shaped run decides for all: blank text or a space before it turns every shortcode, else none, so `x:smile: :smile:` stays), inline HTML's `u`, `b`/`strong`, `i`/`em`, `s`/`del`/`strike`, `code`/`kbd`, `mark`, `br` and `a href` draw as what they mean GFM's filtered tags (`script`, `style`, `title`, `textarea`, `iframe`, `xmp`, `noembed`, `noframes`, `plaintext`) show as text, and other tags, hyphenated names too, vanish, leaving their text; a tag's name runs to white space or `/`, as HTML5 reads it; attribute values split on ASCII whitespace alone and decode as HTML decodes them; each Markdown container is the element GitHub writes (`em`, `strong`, `del`, `a`), on one stack with the tags and repaired as HTML5 repairs: an end tag closes the innermost element of its name and all above it, of which only formatting elements (`a`, `b`, `code`, `em`, `i`, `s`, `strike`, `strong`, `u`) reopen, a new `a` ends the open one and an `a` without `href` links nothing; other tags are not tracked, and `</br>` breaks as `<br>` does; and a footnote reference is its number in superscript, numbered by first reference, as its definition is; one `~` still strikes. At the root, blocks read as GitHub shows them: a quote whose first line is plain text reading `[!NOTE]`, `[!TIP]`, `[!IMPORTANT]`, `[!WARNING]` or `[!CAUTION]` in any case, after escapes and references, spaces and tabs around it, with more after it, is an alert under its title (Important in the palette's violet, `syntax.keyword`, read at 4.5:1); a paragraph that is `[toc]` alone, as Typora reads it, lists every heading by depth, and a press on one reveals it as a link press does (`MarkdownDocument`'s `reveal`), the heading found where `CodeEditor` anchors carried it through each edit since the read, gone if an edit or an undo took it, and a secondary press acts on press, since a block writing back moves the list; front matter shows in a box without its fences; an HTML block shows its text with the inline tags above, white space collapsed and owed as a browser lays it, block elements breaking lines and closing what opened inside them, HTML5's start tags ending an open `p`, `fieldset` and `menu` too, and an `li` start an `li`, a `dd` or `dt` start either, as HTML5 ends them, comments dropped, the filtered tags shown as text, and an unclosed tag dropping the rest; a rule is a 2px `border_strong` line; bullets go •, ◦, ▪ by list depth, ordered lists counted. `MarkdownDocument` holds a whole file in one `CodeEditor` (text and undo, colored by `CodeEditor::highlighter` with `markdown_highlights`): visual draws the file's top-level blocks in a gpui `list`, a pressed block opening as its source in a `TextInput` whose typing is the document's text at once and whose write-back is one undo step; source is the editor; preview draws without presses. A written-back block, a mode switch or a new text is read at once up to 128 KiB, longer ones on the background executor; typing in source or split reads 300 ms after the last key, off the main thread (markdown-rs grows with the square of a paragraph's lines: 40,000 lines take 0.9 s). Texts past `LARGEST_READ` (2 MiB) are never read: no blocks, no outline. A new read keeps the list's blocks alike at both ends. One caret serves every mode: the editor's selection, which a written-back block moves; `set_caret` and `set_top_line` set caret and view apart; a top line asked (numbered, so a late frame callback finishes only its own ask; new text places it again, clamped to the text as it then is) waits for the read, lands on its block, then a frame later at its share of the block's height; `reveal` is such an ask with the caret at its line; a switch between source and the list keeps the top line, one between visual and preview keeps the list's scroll as it is. A block opens only when the read is of the text as it is now. A pressed block keeps its identity across the write-back of the one before it. Blocks are Tab stops that Enter or Space opens; preview takes no presses, undo or redo. `CodeEditor` keeps at most 64 MiB of undo and redo text, dropping the oldest undo and then the fartLine truncated
+- Markdown: `markdown` 1.0.0 (markdown-rs, MIT) reads GitHub's flavor and math into a syntax tree with byte positions for `MarkdownRenderer`, `MarkdownEditor`, the highlights, block ranges and outline. `MarkdownRenderer` draws display math through `typography::Latex`, a ```` ```mermaid ```` block through `documents::Diagram`, and pictures from the owner's folder (`base`) or `data:` addresses (`base64` 0.22, MIT OR Apache-2.0); web pictures stay unloaded. Inline math shows as TeX: gpui text carries no inline pictures. Inline it reads as Typora's defaults: `:shortcode:` turns to its emoji as GitHub reads it (the `emojis` crate's names, GitHub's today, so `:cricket:` is the insect; read after escapes and references, so `\:smile:` turns too; inside an autolink or `<code>` it stays text; within one DOM text node, which filtered tags do not split, the first `:name:`-shaped run decides for all: blank text or a space before it turns every shortcode, else none, so `x:smile: :smile:` stays), inline HTML's `u`, `b`/`strong`, `i`/`em`, `s`/`del`/`strike`, `code`/`kbd`, `mark`, `br` and `a href` draw as what they mean GFM's filtered tags (`script`, `style`, `title`, `textarea`, `iframe`, `xmp`, `noembed`, `noframes`, `plaintext`) show as text, and other tags, hyphenated names too, vanish, leaving their text; a tag's name runs to white space or `/`, as HTML5 reads it; attribute values split on ASCII whitespace alone and decode as HTML decodes them; each Markdown container is the element GitHub writes (`em`, `strong`, `del`, `a`), on one stack with the tags and repaired as HTML5 repairs: an end tag closes the innermost element of its name and all above it, of which only formatting elements (`a`, `b`, `code`, `em`, `i`, `s`, `strike`, `strong`, `u`) reopen, a new `a` ends the open one and an `a` without `href` links nothing; other tags are not tracked, and `</br>` breaks as `<br>` does; and a footnote reference is its number in superscript, numbered by first reference, as its definition is; one `~` still strikes. At the root, blocks read as GitHub shows them: a quote whose first line is plain text reading `[!NOTE]`, `[!TIP]`, `[!IMPORTANT]`, `[!WARNING]` or `[!CAUTION]` in any case, after escapes and references, spaces and tabs around it, with more after it, is an alert under its title (Important in the palette's violet, `syntax.keyword`, read at 4.5:1); a paragraph that is `[toc]` alone, as Typora reads it, lists every heading by depth, and a press on one reveals it as a link press does (`MarkdownDocument`'s `reveal`), the heading found where `CodeEditor` anchors carried it through each edit since the read, gone if an edit or an undo took it, and a secondary press acts on press, since a block writing back moves the list; front matter shows in a box without its fences; an HTML block shows its text with the inline tags above, white space collapsed and owed as a browser lays it, block elements breaking lines and closing what opened inside them, HTML5's start tags ending an open `p`, `fieldset` and `menu` too, and an `li` start an `li`, a `dd` or `dt` start either, as HTML5 ends them, comments dropped, the filtered tags shown as text, and an unclosed tag dropping the rest; a rule is a 2px `border_strong` line; bullets go •, ◦, ▪ by list depth, ordered lists counted. Exports read a tree as the drawing does through `MarkdownReader` (`block` gives its `MarkdownBlock`s, `inline` its text, `note` and `label` its footnotes, `headings` the `[toc]` list), one fresh stack per paragraph, heading or cell. `MarkdownDocument` holds a whole file in one `CodeEditor` (text and undo, colored by `CodeEditor::highlighter` with `markdown_highlights`): visual draws the file's top-level blocks in a gpui `list`, a pressed block opening as its source in a `TextInput` whose typing is the document's text at once and whose write-back is one undo step; source is the editor; preview draws without presses. A written-back block, a mode switch or a new text is read at once up to 128 KiB, longer ones on the background executor; typing in source or split reads 300 ms after the last key, off the main thread (markdown-rs grows with the square of a paragraph's lines: 40,000 lines take 0.9 s). Texts past `LARGEST_READ` (2 MiB) are never read: no blocks, no outline. A new read keeps the list's blocks alike at both ends. One caret serves every mode: the editor's selection, which a written-back block moves; `set_caret` and `set_top_line` set caret and view apart; a top line asked (numbered, so a late frame callback finishes only its own ask; new text places it again, clamped to the text as it then is) waits for the read, lands on its block, then a frame later at its share of the block's height; `reveal` is such an ask with the caret at its line; a switch between source and the list keeps the top line, one between visual and preview keeps the list's scroll as it is. A block opens only when the read is of the text as it is now. A pressed block keeps its identitLine truncated
 - Pictures: `image` 0.25 (MIT OR Apache-2.0), the crate gpui decodes with, default features off; it turns decoded frames and rims map tiles.
 - Math and diagrams: RaTeX 0.1.14 (`ratex-parser`, `ratex-layout`, `ratex-svg` with `embed-fonts`, `ratex-types`; MIT, KaTeX's fonts OFL) typesets `Latex` to SVG with outlined glyphs; `mermaid-rs-renderer` 0.3.1 (MIT, default features off) draws `Diagram`. Both go through gpui's `SvgRenderer` at the window's scale, loaded as gpui assets off the main thread; `usvg` 0.46, gpui's own, reads a diagram's size. A RaTeX or Mermaid panic on parsed input becomes the element's error. Each element holds its picture through `primitives::held`: a new source, or the element leaving the window, removes the old asset from gpui's cache and drops its image from the atlas after the frame.
 - Maps: Natural Earth's 110m countries (public domain). `assets/maps/countries.geojson`, trimmed by `scripts/countries.py` to an ISO code, a name and positions to 0.01°, backs `maps::WorldMap`; the gallery's tiles are cut from the same file, z0 to z3, by `scripts/tiles.py` with Pillow.

src/documents/mod.rs

@@ -58,8 +58,7 @@ pub use thumbs::PageThumbnailList;
 pub use todo::{Checklist, TodoItem};
 pub use toolbar::FixedFormatToolbar;
 pub use tree::{
-    AlertKind, Inline, InlineTag, Shortcodes, Style, alert, headings, html_block_text, inline_tag,
-    is_toc,
+    AlertKind, Inline, Node as MarkdownBlock, Reader as MarkdownReader, Style, alert, is_toc,
 };
 pub(crate) use viewer::step as zoom_step;
 pub use viewer::{DocPage, DocumentViewer, PageHit, PageNote};

src/documents/tree/blocks.rs

@@ -1,7 +1,7 @@
 use markdown::mdast;
 
 use super::{Inline, Node, Reader, Run, html};
-use crate::documents::markdown::{file_tree, span};
+use crate::documents::markdown::span;
 
 /// A heading anywhere in the file.
 #[derive(Clone, Debug, PartialEq)]
@@ -77,7 +77,7 @@ impl Reader<'_> {
 }
 
 /// An HTML block's text, as a browser shows it.
-pub fn html_block_text(written: &str) -> Inline {
+pub(super) fn html_block_text(written: &str) -> Inline {
     let mut run = Run::default();
     let mut rest = written;
     while let Some(at) = rest.find('<') {
@@ -232,11 +232,6 @@ pub fn is_toc(node: &mdast::Node, source: &str) -> bool {
         && source[span(node)].trim().eq_ignore_ascii_case("[toc]")
 }
 
-/// Every heading in `text`, as `[toc]` lists them.
-pub fn headings(text: &str) -> Vec<DocumentHeading> {
-    Reader::new(text, &file_tree(text)).headings
-}
-
 /// A plain first line naming a kind, and what follows.
 fn marker(children: &[mdast::Node]) -> Option<(AlertKind, Vec<mdast::Node>)> {
     let mut line = String::new();

src/documents/tree/emoji.rs

@@ -49,7 +49,7 @@ fn candidate(text: &str) -> Option<usize> {
 
 /// One DOM text node's shortcodes, as GitHub reads them.
 #[derive(Default)]
-pub struct Shortcodes {
+pub(super) struct Shortcodes {
     /// Settled by the node's first `:name:`.
     reads: Option<bool>,
     /// Text before it held more than white space.
@@ -59,12 +59,12 @@ pub struct Shortcodes {
 
 impl Shortcodes {
     /// A new DOM text node starts.
-    pub fn split(&mut self) {
+    pub(super) fn split(&mut self) {
         *self = Self::default();
     }
 
     /// Blank or spaced text before the first reads them all.
-    pub fn read(&mut self, text: &str) -> String {
+    pub(super) fn read(&mut self, text: &str) -> String {
         if self.reads.is_none() {
             let at = candidate(text);
             let lead = &text[..at.unwrap_or(text.len())];

src/documents/tree/html.rs

@@ -98,7 +98,7 @@ pub(crate) fn breaks(name: &str) -> bool {
 
 /// What one inline HTML tag does, as GitHub shows it.
 #[derive(Clone, Debug, PartialEq)]
-pub enum InlineTag {
+pub(super) enum InlineTag {
     /// Opens `name`; an anchor styles only with an address.
     Open {
         name: String,
@@ -114,7 +114,7 @@ pub enum InlineTag {
 }
 
 /// What the inline HTML `written` does.
-pub fn inline_tag(written: &str) -> InlineTag {
+pub(super) fn inline_tag(written: &str) -> InlineTag {
     let Some(tag) = tag(written) else {
         return InlineTag::Gone;
     };

src/documents/tree/mod.rs

@@ -8,9 +8,9 @@ mod blocks;
 mod emoji;
 mod html;
 
-pub use blocks::{AlertKind, DocumentHeading, alert, headings, html_block_text, is_toc};
-pub use emoji::Shortcodes;
-pub use html::{InlineTag, inline_tag};
+use blocks::html_block_text;
+pub use blocks::{AlertKind, DocumentHeading, alert, is_toc};
+use html::InlineTag;
 
 /// How a stretch of inline text prints.
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
@@ -80,11 +80,12 @@ pub enum Node {
 }
 
 /// A tree read against its source and its link definitions.
-pub(crate) struct Reader<'a> {
+pub struct Reader<'a> {
     source: &'a str,
     urls: HashMap<String, String>,
     /// Footnotes numbered by their first reference.
     notes: HashMap<String, usize>,
+    /// Every heading, as `[toc]` lists them.
     pub headings: Vec<DocumentHeading>,
 }
 
@@ -243,7 +244,7 @@ pub fn parse(markdown: &str) -> Vec<Node> {
 
 impl<'a> Reader<'a> {
     /// A reader of `root`, parsed from `source`.
-    pub(crate) fn new(source: &'a str, root: &mdast::Node) -> Self {
+    pub fn new(source: &'a str, root: &mdast::Node) -> Self {
         let mut nodes = Vec::new();
         walk(root, &mut nodes);
         let (mut urls, mut notes, mut headings) = (HashMap::new(), HashMap::new(), Vec::new());
@@ -298,7 +299,8 @@ impl<'a> Reader<'a> {
             .expect("a reference names a definition")
     }
 
-    pub(crate) fn block(&self, node: &mdast::Node, out: &mut Vec<Node>) {
+    /// `node`'s blocks, as the drawing reads them.
+    pub fn block(&self, node: &mdast::Node, out: &mut Vec<Node>) {
         match node {
             mdast::Node::Paragraph(paragraph) => self.paragraph(node, &paragraph.children, out),
             mdast::Node::Heading(heading) => {
@@ -350,13 +352,7 @@ impl<'a> Reader<'a> {
             }
             mdast::Node::ThematicBreak(_) => out.push(Node::Rule),
             mdast::Node::FootnoteDefinition(note) => out.push(Node::Footnote {
-                label: match self.notes.get(&note.identifier) {
-                    Some(number) => number.to_string(),
-                    None => note
-                        .label
-                        .clone()
-                        .unwrap_or_else(|| note.identifier.clone()),
-                },
+                label: self.label(note),
                 body: self.nested(&note.children),
             }),
             mdast::Node::Html(html) => text_block(html_block_text(&html.value), out),
@@ -381,8 +377,21 @@ impl<'a> Reader<'a> {
         text_block(run.cut(), out);
     }
 
+    /// A footnote's number, by its first reference.
+    pub fn note(&self, identifier: &str) -> Option<usize> {
+        self.notes.get(identifier).copied()
+    }
+
+    /// A note's label: its number, once referenced.
+    pub fn label(&self, note: &mdast::FootnoteDefinition) -> String {
+        match self.note(&note.identifier) {
+            Some(number) => number.to_string(),
+            None => note.label.clone().unwrap_or_else(|| note.identifier.clone()),
+        }
+    }
+
     /// Inline text where images draw as their alt text.
-    pub(crate) fn inline(&self, nodes: &[mdast::Node]) -> Inline {
+    pub fn inline(&self, nodes: &[mdast::Node]) -> Inline {
         let mut run = Run::default();
         for node in nodes {
             self.inline_into(node, &mut run, &mut Images::Alt);