Streamtty

A drop-in replacement for markdown rendering in TTY environments, designed for AI-powered streaming with blessed.

Streamtty is inspired by Streamdown but built specifically for terminal/TTY environments using blessed. It handles the unique challenges of streaming Markdown content from AI models in terminals, providing seamless formatting even with incomplete or unterminated Markdown blocks.

✨ Features

Core Features

• 🚀 Streaming-optimized - Handles incomplete Markdown gracefully during real-time generation
• 🎨 Unterminated block parsing - Styles incomplete bold, italic, code, links, and headings
• 📊 GitHub Flavored Markdown - Tables, task lists, and strikethrough support
• 📝 Rich formatting - Headers, lists, blockquotes, links, and more
• ⚡ Performance optimized - Debounced rendering for efficient updates
• 🎮 Interactive - Built-in keyboard navigation and scrolling

Enhanced Features (Streamdown Parity) ✨ NEW

• 📐 Math Rendering - LaTeX math expressions converted to Unicode (inline and block)
• 📊 Mermaid Diagrams - Flowcharts, sequence diagrams, and more rendered as ASCII art
• 🎨 Shiki Syntax Highlighting - Advanced code highlighting with multiple themes
• 📋 Advanced Tables - Full table support with alignment, borders, and navigation
• 🛡️ Security Layer - ANSI sanitization, input validation, and injection prevention
• ⌨️ Interactive Controls - Copy code, export diagrams, navigate with keyboard shortcuts
• 🔌 Plugin System - Remark/Rehype compatible plugin architecture
• 🎭 Theme Support - Light/dark themes with auto-detection
• 🧩 Component Overrides - Customize rendering for any token type

📦 Installation

npm install streamtty
# or
yarn add streamtty
# or
pnpm add streamtty

Note: blessed is included as a dependency and will be installed automatically.

🚀 Quick Start

Basic Usage

import { Streamtty } from 'streamtty';

const markdown = `
# Hello World

This is **bold** and this is *italic*.

\`\`\`typescript
console.log('Hello, Streamtty!');
\`\`\`
`;

const streamtty = new Streamtty();
streamtty.setContent(markdown);

Streaming Usage (AI-like)

import { Streamtty } from 'streamtty';

const streamtty = new Streamtty({
  parseIncompleteMarkdown: true,
  autoScroll: true,
});

// Simulate AI streaming
const chunks = ['# Hello ', '**World**', '!\n\nThis is ', '`streaming`'];
for (const chunk of chunks) {
  streamtty.stream(chunk);
  await new Promise(resolve => setTimeout(resolve, 100));
}

Interactive Chat Example

import blessed from 'blessed';
import { Streamtty } from 'streamtty';

const screen = blessed.screen({
  smartCSR: true,
  title: 'AI Chat',
});

const streamtty = new Streamtty({ screen });

// Stream AI response character by character
function streamResponse(response: string) {
  let index = 0;
  const interval = setInterval(() => {
    if (index < response.length) {
      streamtty.stream(response[index]);
      index++;
    } else {
      clearInterval(interval);
    }
  }, 50);
}

streamResponse('# AI Response\n\nHere is some **formatted** text!');

Enhanced Features Usage

import { Streamtty } from 'streamtty';

// Enable all enhanced features
const streamtty = new Streamtty({
  syntaxHighlight: true,
  theme: 'dark',
  shikiLanguages: ['typescript', 'python', 'bash'],
  enhancedFeatures: {
    math: true,              // LaTeX math rendering
    mermaid: true,           // Mermaid diagrams
    shiki: true,             // Advanced syntax highlighting
    security: true,          // ANSI sanitization & validation
    interactiveControls: true, // Keyboard shortcuts
    advancedTables: true,    // Enhanced table rendering
  },
  controls: {
    code: true,    // Press 'c' to copy code blocks
    table: true,   // Arrow keys to navigate tables
    mermaid: true, // Press 'e' to export diagrams
    math: true,    // Copy math expressions
  },
  security: {
    enabled: true,
    stripDangerousAnsi: true,
    allowedLinkPrefixes: ['https://'],
  },
});

// Math rendering
const mathContent = `
Inline math: $E = mc^2$

Block math:
$$
\\int_0^\\infty e^{-x^2} dx = \\frac{\\sqrt{\\pi}}{2}
$$
`;
streamtty.setContent(mathContent);

// Mermaid diagrams
const diagramContent = `
\`\`\`mermaid
graph TD
    A[Start] --> B{Decision}
    B -->|Yes| C[Success]
    B -->|No| D[Retry]
\`\`\`
`;
streamtty.stream(diagramContent);

// Advanced tables
const tableContent = `
| Feature | Status | Priority |
|---------|:------:|----------|
| Math    | ✅     | High     |
| Mermaid | ✅     | High     |
| Tables  | ✅     | Medium   |
`;
streamtty.stream(tableContent);

Plugin System

import { Streamtty, RemarkPlugin, RehypePlugin } from 'streamtty';

// Custom remark plugin (pre-parse)
const customRemarkPlugin: RemarkPlugin = {
  name: 'custom-remark',
  type: 'remark',
  priority: 50,
  async process(markdown, context) {
    // Transform markdown before parsing
    return markdown.replace(/TODO:/g, '📝 TODO:');
  },
};

// Custom rehype plugin (post-parse)
const customRehypePlugin: RehypePlugin = {
  name: 'custom-rehype',
  type: 'rehype',
  priority: 50,
  async process(tokens, context) {
    // Transform tokens after parsing
    return tokens.map(token => {
      if (token.type === 'text' && token.content.includes('IMPORTANT')) {
        token.style = { fg: 'red', bold: true };
      }
      return token;
    });
  },
};

const streamtty = new Streamtty({
  remarkPlugins: [customRemarkPlugin],
  rehypePlugins: [customRehypePlugin],
});

📖 API Reference

Streamtty

Main class for rendering streamed markdown in TTY.

Constructor Options

interface StreamttyOptions {
  parseIncompleteMarkdown?: boolean;  // Default: true
  styles?: Partial<MarkdownStyles>;
  syntaxHighlight?: boolean;          // Default: true
  showLineNumbers?: boolean;          // Default: false
  maxWidth?: number;                  // Default: 120
  gfm?: boolean;                      // Default: true
  screen?: Widgets.Screen;            // Custom blessed screen
  autoScroll?: boolean;               // Default: true
}

Methods

stream(chunk: string): void

Stream a chunk of markdown content. Handles incomplete markdown gracefully.

streamtty.stream('# Hello ');
streamtty.stream('**World**');

setContent(markdown: string): void

Set complete markdown content all at once.

streamtty.setContent('# Complete Document\n\nWith **multiple** paragraphs.');

render(): void

Manually trigger a render. Usually not needed as rendering is automatic.

clear(): void

Clear all content from the display.

streamtty.clear();

startAutoRender(intervalMs?: number): void

Start auto-rendering at specified interval (default: 50ms).

stopAutoRender(): void

Stop auto-rendering.

getScreen(): Widgets.Screen

Get the blessed screen instance.

getContainer(): Widgets.BoxElement

Get the blessed container box.

getContent(): string

Get current buffer content.

destroy(): void

Cleanup and destroy the instance.

🎨 Styling

Streamtty uses blessed's styling system. You can customize styles for different markdown elements:

const streamtty = new Streamtty({
  styles: {
    h1: { fg: 'cyan', bold: true },
    h2: { fg: 'blue', bold: true },
    code: { fg: 'green', bold: true },
    codeBlock: { fg: 'white', bg: 'black' },
    blockquote: { fg: 'gray', italic: true },
    link: { fg: 'blue', underline: true },
  },
});

⌨️ Keyboard Shortcuts

Built-in keyboard navigation:

• ↑ / k - Scroll up
• ↓ / j - Scroll down
• Page Up - Scroll up one page
• Page Down - Scroll down one page
• Home / g - Go to top
• End / G - Go to bottom
• Escape / q / Ctrl+C - Exit

📚 Examples

Check out the examples/ directory for complete examples:

Basic Example

yarn tsx examples/basic.ts

Shows static markdown rendering with various elements.

Streaming Example

yarn tsx examples/streaming.ts

Simulates AI-like streaming of markdown content.

Chat Example

yarn tsx examples/chat.ts

Interactive chat interface with streaming AI responses.

🔧 Development

# Install dependencies
yarn install

# Build
yarn build

# Watch mode
yarn dev

# Run examples
yarn example:basic
yarn example:streaming
yarn example:chat

📝 Markdown Support

Streamtty supports a wide range of markdown features:

Basic Formatting

• Bold: **text** or __text__
• Italic: *text* or _text_
• Inline code: `code`
• ~~Strikethrough~~: ~~text~~

Headers

# H1
## H2
### H3
#### H4
##### H5
###### H6

Lists

- Unordered list
- Items

1. Ordered list
2. Items

Code Blocks

```typescript
function hello(): void {
  console.log('Hello!');
}
```

Blockquotes

> This is a blockquote
> Multiple lines supported

Links

[Link text](https://example.com)

Tables

| Column 1 | Column 2 |
|----------|----------|
| Data 1   | Data 2   |

Horizontal Rules

---

Task Lists

- [x] Completed task
- [ ] Pending task

🆚 Streamdown vs Streamtty

| Feature | Streamdown | Streamtty | |---------|-----------|-----------| | Environment | React / Web | TTY / Terminal | | Rendering | React Components | Blessed Widgets | | Output | HTML/JSX | ANSI/Terminal | | Use Case | Web Apps | CLI Tools / TUIs | | Dependencies | React, ReactDOM | Blessed, Marked |

🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

📄 License

MIT © [Your Name]

🙏 Credits

• Inspired by Streamdown by Vercel
• Built with blessed
• Markdown parsing by marked

🔗 Links

• Streamdown - The web/React version
• blessed - Terminal UI library
• marked - Markdown parser

Made with ❤️ for the terminal