streamdown 0.0.1

Flicker-free streaming markdown renderer for Flutter AI apps. Drop-in replacement for flutter_markdown with no flash on partial code fences, tables, or LaTeX.

Changelog

All notable changes to this project will be documented in this file.

The format is based on Keep a Changelog, and this project adheres to Semantic Versioning.

0.0.1

Initial pre-release. Flicker-free streaming markdown for Flutter AI apps.

Added

Streaming engine

• Append-only incremental block tokenizer — never re-tokenizes the prefix when new chunks arrive.
• Append-only parser builds an AST where only the trailing open node mutates; closed nodes are frozen.
• Provisional rendering: a half-finished ```dart becomes a code block immediately; tables grow row-by-row with stable column widths.
• Stable monotonic node IDs used as Flutter widget keys — Flutter's element diff never tears down already-rendered blocks.
• Stream cancellation on widget dispose; lifecycle-aware finalization.

Public widget API

• Streamdown(stream: ...) — incremental constructor for AI chat use cases.
• Streamdown.text(...) — static constructor for cached or full-text markdown.
• selectable (default true) — wraps the rendered tree in SelectionArea.
• onLinkTap — callback fired when a link or autolink is tapped.
• textStyle, padding — basic styling hooks.
• syntaxTheme — code-block color scheme; defaults to SyntaxTheme.auto.
• codeBlockBuilder — full override for code rendering (line numbers, custom themes, etc.).
• latex (default false) — enable $...$ and $$...$$ math via flutter_math_fork. Disabled by default so dollar amounts ($10) don't trigger math mode.
• errorBuilder — fallback widget when the stream errors.

Markdown coverage

• ATX headings H1–H6 using Material's text theme.
• Paragraphs with soft and hard line breaks.
• Ordered, unordered, and task lists (- [ ] / - [x]).
• Blockquotes.
• Horizontal rules.
• Fenced code blocks with syntax highlighting via flutter_highlight (200+ languages, GitHub-light / atom-one-dark / auto themes).
• Code block copy-to-clipboard button with a 2-second confirmation state.
• GFM tables with left / center / right alignment and inline markdown inside cells.
• Inline formatting: bold, italic, strikethrough, inline code, links, autolinks (<https://…> and bare https://…), images (![alt](url)).
• LaTeX math via flutter_math_fork when latex: true.

Quality

• 224 tests covering tokenizer, parser, widget rendering, streaming stability, and a flutter_markdown-equivalence benchmark.
• Headline benchmark: ~188× faster than naive re-parse on every chunk (5 KB markdown, 4-char chunks).
• 100 KB markdown stream parsed end-to-end in single-digit milliseconds.
• GitHub Actions CI: dart format, flutter analyze --fatal-warnings, flutter test --coverage on every push and PR.

Limitations (planned for v0.2)

• Single-level blockquotes only (nested >> flattened to depth 1 in the AST).
• Lists close on any blank line — no CommonMark loose-list distinction.
• Stack-based delimiter pairing for **/*/~~ — not fully CommonMark-spec compliant for pathological cases like *foo**bar*baz**.
• Hero demo GIF lives in example/screenshots/ and is recorded manually by the maintainer before each marketing push.