GitHub-Style Callouts

Overview

Support for GitHub-style admonition blocks (> [!NOTE], > [!TIP], etc.) with color-coded rendering, custom titles, and collapsible state.

Key Files

• src/markdown/parser.rs - Callout detection, CalloutType enum, blockquote-to-callout conversion
• src/markdown/editor.rs - Styled rendering with colors, icons, collapse toggle
• src/markdown/widgets.rs - Serialization back to markdown syntax

Syntax

> [!NOTE]
> Basic note content

> [!TIP] Custom Title
> Tip with a custom title

> [!WARNING]-
> Collapsed by default, click to expand

Supported Types

Type	Color	Icon
NOTE	Blue	ℹ
TIP	Green	💡
WARNING	Orange	⚠
CAUTION	Yellow	◆
IMPORTANT	Red	❗

Implementation Details

Parser (parser.rs)

• CalloutType enum with from_str (case-insensitive), display_name(), and icon() methods.
• MarkdownNodeType::Callout AST node with callout_type, title (Option), and collapsed (bool) fields.
• Processing order: convert_callout_blockquotes runs before merge_consecutive_blockquotes to prevent distinct callouts from being merged into one blockquote.
• split_and_convert_blockquote: Handles a single BlockQuote containing multiple [!TYPE] markers by splitting it into separate Callout nodes.
• extract_callout_info: Parses the [!TYPE], optional - suffix (collapsed), and optional custom title from the first paragraph's text content.

Renderer (editor.rs)

• callout_colors(): Returns (border_color, bg_color, title_color) per type using Color32::from_rgba_unmultiplied with low alpha (20-25) for subtle backgrounds.
• Collapse toggle: Uses ui.allocate_rect() over the title row with Sense::click() for reliable click detection. State is persisted via egui::Id keyed on (start_line, end_line).
• Pointer cursor: Shows CursorIcon::PointingHand on hover over the title.
• ID uniqueness: Each callout is wrapped in ui.push_id(("callout_...", start_line, end_line)) to prevent egui widget ID collisions.
• Both render_callout_with_structural_keys and render_callout implement the same rendering logic for their respective render paths.

Serializer (widgets.rs)

Reconstructs the original markdown syntax from the AST:

• > [!TYPE] for basic callouts
• > [!TYPE]- for collapsed
• > [!TYPE] Custom Title for custom titles

Tests

8 parser tests in parser.rs:

• test_callout_note_basic - Basic NOTE callout
• test_callout_custom_title - Custom title parsing
• test_callout_collapsed - Collapsed state (- suffix)
• test_callout_all_types - All 5 types recognized
• test_callout_case_insensitive - Case-insensitive matching
• test_regular_blockquote_not_callout - Regular blockquotes unchanged
• test_unknown_callout_type - Unknown types stay as blockquotes
• test_callout_multiline_content - Multi-paragraph content

Known Considerations

• Consecutive callouts (separated by blank lines) are correctly parsed as separate blocks.
• Unknown [!TYPE] values are left as regular blockquotes.
• Collapse state persists across frames via egui's persistent data store.