Probot is a framework for building GitHub Apps in Node.js/TypeScript. It abstracts away the complexity of receiving and validating webhooks, authenticating as a GitHub App, and making API calls via an authenticated Octokit client. The system provides a `Probot` class that manages webhook event handling, an `Octokit` instance with plugins for throttling, retry, pagination, and enterprise compatibility, and a `Server` class for HTTP routing. Key entry points include the `run()` function for CLI usage, `createNodeMiddleware()` for serverless or custom server integration, and direct use of the `Probot` class for programmatic control. The architecture is modular: the `Probot` class initializes webhooks and Octokit, the `Server` class handles HTTP requests and proxies webhooks via Smee.io for local development, and the `Context` class provides helpers for extracting repository, issue, and pull request information from webhook payloads. External dependencies include the Octokit ecosystem, pino for logging, bottleneck for rate limiting, and ioredis for optional Redis-backed throttling. The codebase is well-structured with extensive test coverage and supports multiple runtimes (Node.js, Deno, Bun).