agentviewer

name	agentviewer
description	Display rich content (markdown, code, diffs, mermaid diagrams) to users in a browser viewer. Use when you need to show complex content that benefits from rich rendering - reports, documentation, code with syntax highlighting, git diffs, or diagrams.
allowed-tools	Read,Bash(curl:*,agentviewer:*)
version	0.1.0
author	Peter Engelbrecht <https://github.com/pengelbrecht>
license	MIT

Agentviewer

Display rich content in a browser-based tabbed viewer. Perfect for showing users:

• Markdown documents with rendered formatting
• Code with syntax highlighting (180+ languages)
• Git diffs with side-by-side comparison
• Mermaid diagrams and LaTeX math

Prerequisites

The agentviewer CLI must be installed and available in your PATH.

Installation Options

macOS/Linux (Homebrew):

brew install pengelbrecht/tap/agentviewer

Windows (Scoop):

scoop bucket add agentviewer https://github.com/pengelbrecht/scoop-agentviewer
scoop install agentviewer

Windows (Winget):

winget install pengelbrecht.agentviewer

Linux (deb - Debian/Ubuntu):

curl -LO https://github.com/pengelbrecht/agentviewer/releases/latest/download/agentviewer_amd64.deb
sudo dpkg -i agentviewer_amd64.deb

Linux (rpm - Fedora/RHEL):

curl -LO https://github.com/pengelbrecht/agentviewer/releases/latest/download/agentviewer_x86_64.rpm
sudo rpm -i agentviewer_x86_64.rpm

Go:

go install github.com/pengelbrecht/agentviewer@latest

Binary: Download from GitHub Releases

Verify Installation

agentviewer --version

Quick Start

Start the server (runs in background, opens browser):

agentviewer serve --open &

Create a tab with content:

curl -X POST localhost:3333/api/tabs \
  -d '{"title": "Report", "type": "markdown", "content": "# Hello\n\nContent here..."}'

API Reference

Base URL: http://localhost:3333

Create/Update Tab

# Markdown (renders GFM with diagrams and math)
curl -X POST localhost:3333/api/tabs \
  -d '{"title": "Notes", "type": "markdown", "content": "# My Notes\n\n- Item 1\n- Item 2"}'

# Code with syntax highlighting
curl -X POST localhost:3333/api/tabs \
  -d '{"title": "main.go", "type": "code", "content": "package main\n\nfunc main() {}", "language": "go"}'

# From file path (auto-detects type, enables live reload)
curl -X POST localhost:3333/api/tabs \
  -d '{"title": "Config", "file": "/path/to/config.yaml"}'

# Git diff (side-by-side comparison)
curl -X POST localhost:3333/api/tabs \
  -d '{"type": "diff", "diff": {"left": "old.go", "right": "new.go"}}'

# With explicit ID (for updates)
curl -X POST localhost:3333/api/tabs \
  -d '{"id": "my-report", "title": "Report", "type": "markdown", "content": "..."}'

Tab Management

# List all tabs
curl localhost:3333/api/tabs

# Get tab content
curl localhost:3333/api/tabs/{id}

# Delete specific tab
curl -X DELETE localhost:3333/api/tabs/{id}

# Delete all tabs
curl -X DELETE localhost:3333/api/tabs

# Activate (switch to) tab
curl -X POST localhost:3333/api/tabs/{id}/activate

Server Status

# Check if server is running
curl localhost:3333/api/status

Content Types

Type	Description	Features
markdown	Rendered markdown	GFM, Mermaid diagrams, LaTeX math, code blocks
code	Source code	Syntax highlighting for 180+ languages
diff	File comparison	Side-by-side view with line numbers

Markdown Features

Agentviewer renders GitHub-flavored markdown with extensions:

# Mermaid Diagrams
\`\`\`mermaid
graph TD
    A[Start] --> B{Decision}
    B -->|Yes| C[Action]
    B -->|No| D[End]
\`\`\`

# LaTeX Math
Inline: $E = mc^2$

Block:
$$
\frac{-b \pm \sqrt{b^2 - 4ac}}{2a}
$$

# Code Blocks (with syntax highlighting)
\`\`\`python
def hello():
    print("Hello, world!")
\`\`\`

Common Workflows

Show Analysis Results

# Start server
agentviewer serve --open &

# Show a markdown report
curl -X POST localhost:3333/api/tabs -d '{
  "title": "Analysis",
  "type": "markdown",
  "content": "# Code Analysis\n\n## Summary\n- 10 files analyzed\n- 2 issues found\n\n## Issues\n\n### Issue 1\n```go\n// problematic code\nfunc foo() {}\n```\n"
}'

Show Code with Live Reload

# Show a code file (changes reload automatically)
curl -X POST localhost:3333/api/tabs -d '{
  "title": "main.go",
  "file": "./main.go"
}'

Show Git Diff

# Get current changes
git diff HEAD > /tmp/changes.diff

# Display in viewer
curl -X POST localhost:3333/api/tabs -d '{
  "title": "Changes",
  "type": "diff",
  "file": "/tmp/changes.diff"
}'

Create Architecture Diagram

curl -X POST localhost:3333/api/tabs -d '{
  "title": "Architecture",
  "type": "markdown",
  "content": "# System Architecture\n\n```mermaid\ngraph TB\n    subgraph Frontend\n        A[React App]\n    end\n    subgraph Backend\n        B[API Server]\n        C[Database]\n    end\n    A --> B\n    B --> C\n```"
}'

Best Practices

1. Start server once at the beginning of a session
2. Use file paths when showing existing files (enables auto-reload)
3. Use meaningful titles - they appear in the tab bar
4. Clean up - delete tabs when no longer needed
5. Use markdown for complex documents - renders beautifully with diagrams
6. Use explicit IDs when updating content to avoid creating duplicate tabs

Error Handling

# Check if server is running
if ! curl -s localhost:3333/api/status > /dev/null 2>&1; then
    agentviewer serve --open &
    sleep 1
fi

CLI Reference

# Start server
agentviewer serve [--port 3333] [--open]

# Show version
agentviewer --version
agentviewer -v