Subseq ADF Convert

version: 0.1.0 (first release)

This library provides lossless, round-trippable conversion between Atlassian Document Format (ADF), HTML, and Markdown, with strict fidelity to both the ADF specification and predictable Markdown generation.

It is designed as a strictly deterministic parser and renderer, capable of roundtripping:

Key Features

• ✅ ADF to HTML rendering
• ✅ HTML to ADF parsing
• ✅ ADF to Markdown conversion with custom handlers for complex edge cases (tables, media, expand, status, etc.)
• ✅ Markdown to ADF conversion via HTML bridging using markdown-rs and html5ever
• ✅ Custom handlers for ensuring consistency in tables, inline marks, and media rendering
• ✅ Robust HTML sanitizer post-processing to correct structural errors from Markdown parsers

Design Philosophy

• ADF-first model: ADF is the authoritative data model. HTML and Markdown are considered serialization formats only.
• Roundtrip Guarantee: All generated ADF must survive a full conversion cycle back to itself. Compromises are only accepted where Markdown format limitations make fidelity impossible.
• Markdown as supported input:
  Valid, standards-compliant Markdown is supported as input and will be parsed to ADF. However, features unique to ADF (e.g., mentions, emojis, statuses, inline cards) require either our tools or plugins to be produced and cannot be manually authored using standard Markdown syntax.
  Users are expected to edit the standard Markdown representation—we will correctly handle supported Markdown, and enhanced ADF features will be retained if present in the source ADF or inserted by compatible tooling.
• Clean sanitization: HTML produced by markdown-rs or third-party tools is automatically sanitized (e.g., nested <a> tags are flattened, invalid <p> wrappers are removed) to ensure valid roundtrip.
• Predictable fallback behavior: Where Markdown cannot express ADF features (e.g., task lists with state, decision lists), we will emit valid HTML blocks using custom tags.

Architecture

From	To	Notes
ADF	HTML	Fully custom renderer ensuring semantic correctness
HTML	Markdown	Uses htmd with extended element handlers
Markdown	HTML	Uses markdown-rs, followed by HTML5ever sanitization
HTML	ADF	Custom walker using html5ever::RcDom

Special Handling

• Tables: Custom renderer ensuring valid GFM tables with inline formatting and proper escaping.
• Media: Media nodes are wrapped and validated with link marks when necessary.
• Expand/Details: Uses <details><summary> and renders as block-level Markdown extensions.
• Inline complexity: Inline emojis, mentions, statuses, links, and inline cards are supported with proper mark serialization.

Known Limitations

• Standard Markdown input is supported where valid.
  Features specific to ADF cannot be expressed directly in standard Markdown without using custom syntax or extensions (e.g., <adf-status>, <adf-emoji>).
• Roundtrip guarantees are scoped to documents created via our rendering pipeline.
• Malformed or ambiguous user-authored Markdown outside of GFM or commonmark standards is not supported.
• Sanitizer ensures HTML correctness but does not attempt to repair semantically invalid Markdown.

Test Coverage

Roundtrip Tests

• ✅ Simple paragraphs and headings
• ✅ Mixed inline elements (emoji, mention, status, links)
• ✅ Decision and task lists with accurate state restoration
• ✅ Complex tables with inline formatting, emoji, and links
• ✅ Expand and nested expand blocks
• ✅ Full document structures with media, tables, blockquotes, and rules

Sanitizer Tests

• ✅ Flattening nested <a> inside <a>
• ✅ Removing invalid <p> wrappers around block elements
• ✅ Enforcing valid HTML output structure prior to ADF parsing

Usage Example

use subseq_adf_convert::html_to_adf::html_to_adf;
use subseq_adf_convert::adf_to_html::adf_to_html;
use subseq_adf_convert::markdown::{adf_to_markdown, markdown_to_adf};

// ADF -> HTML -> Markdown -> HTML -> ADF
let adf = my_custom_adf();
let html = adf_to_html(vec![adf.clone()]);
let markdown = adf_to_markdown(&[adf.clone()]);
let html_from_md = markdown_to_html(&markdown);
let adf_back = html_to_adf(&html_from_md);

assert_eq!(adf_back, adf);