References

Specs, libraries, and prior art that shaped PEN.

Core Specifications

Chrome DevTools Protocol

The CDP spec covers every domain PEN talks to:

Domain	Purpose	Reference
`Runtime`	Console messages, JS evaluation	Runtime
`Network`	Request/response interception, waterfall	Network
`Page`	Navigation, screenshots, lifecycle	Page
`HeapProfiler`	Heap snapshots, allocation tracking	HeapProfiler
`Profiler`	CPU profiling	Profiler
`Debugger`	Source maps, script sources	Debugger
`Tracing`	Performance traces	Tracing
`Audits`	Lighthouse-style audits	Audits
`Target`	Tab management, target discovery	Target

Model Context Protocol

Specification: spec.modelcontextprotocol.io/2025-03-26
Transport: stdio (stdin/stdout JSON-RPC 2.0)
Capabilities used: Tools (ListTools, CallTool)
SDK: github.com/modelcontextprotocol/go-sdk

Go Libraries

Library	Version	Purpose
`github.com/modelcontextprotocol/go-sdk`	v1.3.1	MCP server implementation
`github.com/chromedp/chromedp`	v0.13.6	Chrome DevTools Protocol client
`github.com/chromedp/cdproto`	(transitive)	CDP type definitions
`github.com/charmbracelet/huh`	v1.0.0	Interactive terminal wizard (`pen init`)
`github.com/charmbracelet/lipgloss`	v1.1.0	Terminal output styling

All versions pulled from go.mod. Requires Go 1.24.2+.

Prior Art

Tools and projects that influenced PEN:

Tool	Relationship to PEN
Chrome DevTools	PEN exposes the same browser internals, but over MCP instead of a GUI
Puppeteer	Node.js CDP library; PEN uses chromedp (Go) for the same protocol
Playwright	Multi-browser automation; PEN is Chrome-only, MCP-native
Lighthouse CLI	PEN shells out to the Lighthouse CLI via `exec.CommandContext` rather than wrapping CDP audit domains directly
web-vitals	Client-side metrics library; PEN grabs the same data server-side via CDP

Architecture References

Go concurrency: sync.Mutex for operation locks, context.Context for cancellation, goroutines for event listeners
Graceful degradation: Partial results over hard failures (see Error Handling)
Token-aware output: Everything shaped for LLM context windows (see Output Design)

Project Links

Resource	URL
Source code	github.com/edbnme/pen
Documentation	pen-docs (this site)
Go module	`github.com/edbnme/pen`
License	MIT