- Added Plugins API with `cypress/plugins/index.js` and first `file:preprocessor` event, enabling custom Node-side processing and preprocessor swapping.
- Extracted default Browserify preprocessor to @cypress/browserify and introduced @cypress/webpack preprocessor, allowing custom Babel config, CoffeeScript 2, and other language support.
- Fixed bugs (cy.contains regex handling, fixture formatting on Windows, cy.viewport resolution, auto‑reload on spec changes) and added extensive documentation updates.