Dvdsgl Claude Canvas Claude Canvas

Document Canvas

Display markdown documents with optional text selection and diff highlighting.

Example Prompts

Try asking Claude:

• "Draft an email to the marketing team about the Q1 product launch"
• "Help me edit this blog post — show it so I can highlight the parts to revise"
• "Write a project proposal and let me review it"
• "Show me the README so I can select sections to update"
• "Compose a response to this customer complaint"

Scenarios

display (default)

Read-only document view with markdown rendering. User can scroll but cannot select text.

bun run src/cli.ts show document --scenario display --config '{
  "content": "# Hello World\n\nThis is **markdown** content.",
  "title": "My Document"
}'

edit

Interactive document view with text selection. User can click and drag to select text, which is sent via IPC in real-time.

• Renders markdown with syntax highlighting (headers, bold, italic, code, links, lists, blockquotes)
• Diff highlighting: green background for additions, red for deletions
• Click and drag to select text
• Selection automatically sent via IPC

bun run src/cli.ts spawn document --scenario edit --config '{
  "content": "# My Blog Post\n\nThis is the **introduction** to my post.\n\n## Section One\n\n- Point one\n- Point two",
  "title": "Blog Post Draft",
  "diffs": [
    {"startOffset": 50, "endOffset": 62, "type": "add"}
  ]
}'

email-preview

Specialized view for email content display.

bun run src/cli.ts show document --scenario email-preview --config '{
  "content": "Dear Team,\n\nPlease review the attached document.\n\nBest regards,\nAlice",
  "title": "RE: Project Update"
}'

Configuration

interface DocumentConfig {
  content: string;        // Markdown content
  title?: string;         // Document title (shown in header)
  diffs?: DocumentDiff[]; // Optional diff markers for highlighting
  readOnly?: boolean;     // Disable selection (default: false for edit)
}

interface DocumentDiff {
  startOffset: number;    // Character offset in content
  endOffset: number;
  type: "add" | "delete";
}

Markdown Rendering

Supported markdown features:

• Headers (# H1, ## H2, etc.)
• Bold (**text**)
• Italic (*text*)
• Code (`inline` and fenced blocks)
• Links ([text](url))
• Lists (- or * bullets)
• Blockquotes (>)

Selection Result

interface DocumentSelection {
  selectedText: string;   // The selected text
  startOffset: number;    // Start character offset
  endOffset: number;      // End character offset
  startLine: number;      // Line number (1-based)
  endLine: number;
  startColumn: number;    // Column in start line
  endColumn: number;
}

Controls

• Mouse click and drag: Select text (edit scenario)
• ↑/↓ or scroll: Navigate document
• q or Esc: Close/cancel

API Usage

import { editDocument, displayDocument } from "${CLAUDE_PLUGIN_ROOT}/src/api";

// Display read-only document
await displayDocument({
  content: "# My Document\n\nContent here.",
  title: "View Mode",
});

// Interactive editing with selection
const result = await editDocument({
  content: "# My Document\n\nSelect some **text** here.",
  title: "Edit Mode",
  diffs: [{ startOffset: 20, endOffset: 30, type: "add" }],
});

if (result.success && result.data) {
  console.log(`Selected: "${result.data.selectedText}"`);
  console.log(`Position: ${result.data.startOffset}-${result.data.endOffset}`);
}

Source: dvdsgl/claude-canvas — distributed by TomeVault.