- Plugins can now return a Promise and modify the yielded config, plus new `userAgent` and `blacklistHosts` options in `cypress.json` for browser UA control and request blocking.
- Enhanced TypeScript support: chai assertions for autocomplete, refreshed typings for Cypress APIs and bundled tools, and a breaking change to the `Chainer` interface for TypeScript extensions.
- Cypress.config() now returns the complete configuration set, env renamed to `env` in the GUI, and extensive documentation updates for configuration, plugins, and recipes.