Installation

DevSnoop has three components: a Chrome extension, a native host binary, and a skill file for your coding agent. The one-liner install handles everything except the Chrome extension.

Quick Install

One command installs the native host binary, writes the Chrome manifest, and downloads the coding agent skill file.

bash

curl -fsSL https://devsnoop.com/install.sh | bash

What this does:

1. Detects your OS and architecture
2. Downloads the native host binary to ~/.devsnoop/devsnoop-host
3. Writes the native messaging manifest so Chrome can find the host
4. Downloads SKILL.md to ~/.devsnoop/

Install the Chrome Extension

Get the extension from the Chrome Web Store. It adds the browser bridge that coding agents communicate with.

Add to Chrome

Chrome Web Store link will be added after extension review.

Install the Native Host

The native host bridges HTTP requests from your coding agent to the Chrome extension via Native Messaging. It's a self-contained binary — no Node, npm, or runtime needed.

bash

curl -fsSL https://devsnoop.com/install.sh | bash

This is the same one-liner from the quick install section above. If you already ran it, skip this step.

Configure Your Coding Agent

The install script downloads SKILL.md to ~/.devsnoop/. Copy or symlink it to your agent's skill/command location so it knows how to use DevSnoop.

Claude Code

Copy to your commands directory or add as a project skill:

cp ~/.devsnoop/SKILL.md ~/.claude/commands/devsnoop.md

Cursor

Add the file contents to your project's .cursorrules or reference it as context.

Other agents

Any agent that can make HTTP requests works — paste the contents of ~/.devsnoop/SKILL.md into your agent's system prompt or custom instructions.

Verify It Works

Open any page in Chrome, then run the ping command from your terminal.

bash

curl -s -X POST http://127.0.0.1:9400/ \
  -H 'Content-Type: application/json' \
  -d '{"command":"ping","params":{}}'

response

{"ok":true,"result":{"pong":true,"timestamp":1718...}}

If you see "pong": true, everything is connected. Your coding agent can now control the browser.

What Gets Installed

Component	Location	Purpose
devsnoop-host	~/.devsnoop/	HTTP server + native messaging bridge
com.devsnoop.agent.json	Chrome NativeMessagingHosts/	Tells Chrome where to find the host binary
SKILL.md	~/.devsnoop/	Teaches coding agents all available commands (copy to your agent's config)

Platform Support

macOSApple Silicon (arm64), Intel (x64)

supported

Linuxx64, arm64

supported

Windows—

planned

Manual Installation

If you prefer to install each component yourself, follow these steps.

Download the binary

bash

# Download the binary for your platform
# macOS Apple Silicon
curl -fSL https://github.com/nicepkg/devsnoop/releases/latest/download/devsnoop-host-darwin-arm64 \
  -o ~/.devsnoop/devsnoop-host

# macOS Intel
curl -fSL https://github.com/nicepkg/devsnoop/releases/latest/download/devsnoop-host-darwin-x64 \
  -o ~/.devsnoop/devsnoop-host

# Linux x64
curl -fSL https://github.com/nicepkg/devsnoop/releases/latest/download/devsnoop-host-linux-x64 \
  -o ~/.devsnoop/devsnoop-host

chmod +x ~/.devsnoop/devsnoop-host

Write the native messaging manifest

Replace YOUR_USERNAME with your actual username and EXTENSION_ID with the Chrome extension ID.

bash — macOS

# macOS
mkdir -p ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts

cat > ~/Library/Application\ Support/Google/Chrome/NativeMessagingHosts/com.devsnoop.agent.json << 'EOF'
{
  "name": "com.devsnoop.agent",
  "description": "DevSnoop Native Messaging Host",
  "path": "/Users/YOUR_USERNAME/.devsnoop/devsnoop-host",
  "type": "stdio",
  "allowed_origins": [
    "chrome-extension://EXTENSION_ID/"
  ]
}
EOF

bash — Linux

# Linux
mkdir -p ~/.config/google-chrome/NativeMessagingHosts

cat > ~/.config/google-chrome/NativeMessagingHosts/com.devsnoop.agent.json << 'EOF'
{
  "name": "com.devsnoop.agent",
  "description": "DevSnoop Native Messaging Host",
  "path": "/home/YOUR_USERNAME/.devsnoop/devsnoop-host",
  "type": "stdio",
  "allowed_origins": [
    "chrome-extension://EXTENSION_ID/"
  ]
}
EOF

Install the skill file

bash

# The install script downloads SKILL.md to ~/.devsnoop/SKILL.md
# Copy or symlink it to your coding agent's config location (see below)

Troubleshooting

"Connection failed" — ping returns nothing

- Make sure the Chrome extension is installed and enabled
- Open a page in Chrome (the extension needs at least one tab)
- Check that the native host binary exists at ~/.devsnoop/devsnoop-host
- Verify the manifest file is in the right location for your OS

"Permission needed" error

Click the DevSnoop extension icon in Chrome and grant access for the site you're inspecting. This is a one-time action per origin.

Extension installed but agent doesn't know commands

Make sure you've copied ~/.devsnoop/SKILL.md to your agent's config location (see step 3 above). Restart your coding agent after configuring.