documents: format always reads apart; read cutoff back to 128 KiB

The format command never parses on the UI thread; refusals past the
size checks come by event. The document's at-once read returns to
128 KiB, so a visual opening between the cutoffs starts at the top.
Timing test takes web_time::Instant.

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. 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 16 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 its nodes, not its bytes: in release, 128 KiB of one-letter paragraphs takes 1.7 s, 16 KiB 42 ms, while 128 KiB of prose takes 20 ms). 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 Line 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 its nodes, not its bytes: in release, 128 KiB of one-letter paragraphs takes 1.7 s, 16 KiB 42 ms, while 128 KiB of prose takes 20 ms; a block-heavy text under the cutoff can still hold the UI thread past 100 ms, a known limit). 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 listLine 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/document/format/apply.rs

@@ -7,7 +7,7 @@ use gpui::{AppContext as _, Context};
 use super::{Change, FormatRefusal, InlineFormat, toggle};
 use crate::documents::{
     MarkdownMode,
-    document::{AT_ONCE, DocumentEvent, LARGEST_READ, MarkdownDocument},
+    document::{DocumentEvent, LARGEST_READ, MarkdownDocument},
     modes::joint,
 };
 
@@ -15,7 +15,7 @@ use crate::documents::{
 type Snapshot = (String, usize, Range<usize>);
 
 impl MarkdownDocument {
-    /// `format` at the selection; long texts refuse by event.
+    /// `format` at the selection, read apart; refusals by event.
     pub fn format(
         &mut self,
         format: InlineFormat,
@@ -36,12 +36,6 @@ impl MarkdownDocument {
             log::info!("markdown document: format {format:?} refused: one runs");
             return Err(FormatRefusal::Busy);
         }
-        if full.len() <= AT_ONCE {
-            let change = toggle(&full, selection, format).inspect_err(|why| {
-                log::info!("markdown document: format {format:?} refused: {why:?}");
-            })?;
-            return self.apply(format, change, &full, offset, cx);
-        }
         log::info!(
             "markdown document: format {format:?} reads {} bytes apart",
             full.len()

src/documents/document/mod.rs

@@ -41,7 +41,7 @@ use crate::{
 };
 
 /// Texts this long parse at once; longer ones elsewhere.
-const AT_ONCE: usize = 16 << 10;
+const AT_ONCE: usize = 128 << 10;
 
 /// Longer texts are never read: source alone.
 pub const LARGEST_READ: usize = 2 << 20;

src/documents/document/tests/format.rs

@@ -1,15 +1,15 @@
 //! Inline formats toggle as Typora's (R4.6).
 
-use std::{cell::RefCell, rc::Rc, time::Instant};
+use std::{cell::RefCell, rc::Rc};
 
 use gpui::{Entity, Modifiers, TestAppContext, VisualTestContext};
 use markdown::mdast::Node;
+use web_time::Instant;
 
 use super::{open, opened, press, text};
 use crate::documents::{
     DocumentEvent, FormatRefusal, InlineFormat, LARGEST_READ, MarkdownDocument, MarkdownMode,
     document::{
-        AT_ONCE,
         format::{toggle, toggle_tree},
         visual,
     },
@@ -145,6 +145,7 @@ fn an_open_block_stays_open_and_undoes_as_one_step(cx: &mut TestAppContext) {
             .format(InlineFormat::Strong, cx)
             .expect("formatted");
     });
+    cx.run_until_parked();
     assert_eq!(
         opened(&document, cx),
         "alpha **beta**",
@@ -172,6 +173,7 @@ fn the_source_takes_a_format_as_one_step(cx: &mut TestAppContext) {
             .update(cx, |editor, cx| editor.select(std::iter::once(2..2), cx));
         document.format(InlineFormat::Code, cx).expect("formatted");
     });
+    cx.run_until_parked();
     assert_eq!(text(&document, cx), "`alpha` beta\n");
     document.update(cx, |document, cx| {
         document.editor.update(cx, |editor, cx| editor.undo(cx));
@@ -221,8 +223,8 @@ fn underline_comes_off_past_other_tags() {
     assert_eq!(ok("<u>a <em>b‸c</em> d</u>", Underline), "a <em>b‸c</em> d");
 }
 
-/// A source document of one long word, caret at 1.
-fn long(cx: &mut TestAppContext, len: usize) -> (Entity<MarkdownDocument>, &mut VisualTestContext) {
+/// A source document of one word, caret at 1.
+fn word(cx: &mut TestAppContext, len: usize) -> (Entity<MarkdownDocument>, &mut VisualTestContext) {
     let (document, cx) = open(&"x".repeat(len), MarkdownMode::Source, cx);
     document.update(cx, |document, cx| {
         document
@@ -233,8 +235,8 @@ fn long(cx: &mut TestAppContext, len: usize) -> (Entity<MarkdownDocument>, &mut
 }
 
 #[gpui::test]
-fn a_long_text_formats_once_read_apart(cx: &mut TestAppContext) {
-    let (document, cx) = long(cx, AT_ONCE + 1);
+fn a_format_reads_apart(cx: &mut TestAppContext) {
+    let (document, cx) = word(cx, 64);
     document.update(cx, |document, cx| {
         document.format(InlineFormat::Strong, cx).expect("taken")
     });
@@ -248,7 +250,7 @@ fn a_long_text_formats_once_read_apart(cx: &mut TestAppContext) {
 
 #[gpui::test]
 fn many_short_paragraphs_format_apart(cx: &mut TestAppContext) {
-    let source = "a\n\n".repeat(AT_ONCE / 3 + 1);
+    let source = "a\n\n".repeat(100);
     let (document, cx) = open(&source, MarkdownMode::Source, cx);
     document.update(cx, |document, cx| {
         document
@@ -262,8 +264,8 @@ fn many_short_paragraphs_format_apart(cx: &mut TestAppContext) {
 }
 
 #[gpui::test]
-fn a_long_format_lapses_when_the_text_moves(cx: &mut TestAppContext) {
-    let (document, cx) = long(cx, AT_ONCE + 1);
+fn a_format_lapses_when_the_text_moves(cx: &mut TestAppContext) {
+    let (document, cx) = word(cx, 64);
     document.update(cx, |document, cx| {
         document.format(InlineFormat::Strong, cx).expect("taken");
         document
@@ -296,8 +298,8 @@ fn refusals(
 }
 
 #[gpui::test]
-fn a_long_lapse_comes_by_event(cx: &mut TestAppContext) {
-    let (document, cx) = long(cx, AT_ONCE + 1);
+fn a_lapse_comes_by_event(cx: &mut TestAppContext) {
+    let (document, cx) = word(cx, 64);
     let heard = refusals(&document, cx);
     document.update(cx, |document, cx| {
         document.format(InlineFormat::Strong, cx).expect("taken");
@@ -351,8 +353,8 @@ fn many_paragraphs_format_in_linear_time() {
 }
 
 #[gpui::test]
-fn a_second_long_format_refuses_while_one_runs(cx: &mut TestAppContext) {
-    let (document, cx) = long(cx, AT_ONCE + 1);
+fn a_second_format_refuses_while_one_runs(cx: &mut TestAppContext) {
+    let (document, cx) = word(cx, 64);
     let second = document.update(cx, |document, cx| {
         document.format(InlineFormat::Strong, cx).expect("taken");
         document.format(InlineFormat::Emphasis, cx)
@@ -372,8 +374,8 @@ fn a_second_long_format_refuses_while_one_runs(cx: &mut TestAppContext) {
 }
 
 #[gpui::test]
-fn a_long_refusal_comes_by_event(cx: &mut TestAppContext) {
-    let source = format!("`code` {}", "x".repeat(AT_ONCE));
+fn a_refusal_comes_by_event(cx: &mut TestAppContext) {
+    let source = format!("`code` {}", "x".repeat(64));
     let (document, cx) = open(&source, MarkdownMode::Source, cx);
     let heard = refusals(&document, cx);
     let taken = document.update(cx, |document, cx| {
@@ -389,8 +391,8 @@ fn a_long_refusal_comes_by_event(cx: &mut TestAppContext) {
 }
 
 #[gpui::test]
-fn a_long_format_drops_once_preview_shows(cx: &mut TestAppContext) {
-    let (document, cx) = long(cx, AT_ONCE + 1);
+fn a_format_drops_once_preview_shows(cx: &mut TestAppContext) {
+    let (document, cx) = word(cx, 64);
     let heard = refusals(&document, cx);
     document.update_in(cx, |document, window, cx| {
         document.format(InlineFormat::Strong, cx).expect("taken");
@@ -403,7 +405,25 @@ fn a_long_format_drops_once_preview_shows(cx: &mut TestAppContext) {
 
 #[gpui::test]
 fn a_text_past_the_largest_read_refuses(cx: &mut TestAppContext) {
-    let (document, cx) = long(cx, LARGEST_READ + 1);
+    let (document, cx) = word(cx, LARGEST_READ + 1);
     let refused = document.update(cx, |document, cx| document.format(InlineFormat::Strong, cx));
     assert_eq!(refused, Err(FormatRefusal::TooLong));
 }
+
+#[gpui::test]
+fn a_visual_format_reads_apart(cx: &mut TestAppContext) {
+    let (document, cx) = open("word\n\nmore\n", MarkdownMode::Visual, cx);
+    document.update(cx, |document, cx| {
+        document
+            .editor
+            .update(cx, |editor, cx| editor.select(std::iter::once(1..1), cx));
+        document.format(InlineFormat::Strong, cx).expect("taken");
+    });
+    assert_eq!(
+        text(&document, cx),
+        "word\n\nmore\n",
+        "not on the UI thread"
+    );
+    cx.run_until_parked();
+    assert_eq!(text(&document, cx), "**word**\n\nmore\n");
+}

src/documents/document/tests/place.rs

@@ -229,3 +229,11 @@ fn the_selection_reads_in_source_and_in_an_open_block(cx: &mut TestAppContext) {
         "words"
     );
 }
+
+#[gpui::test]
+fn a_visual_opening_starts_at_the_top(cx: &mut TestAppContext) {
+    let source = format!("alpha beta\n\n{}", "x".repeat(20000));
+    let (document, cx) = open(&source, MarkdownMode::Visual, cx);
+    cx.run_until_parked();
+    assert_eq!(landed(&document, cx), 0);
+}