Turbo (Hotwire)
Hotwire's main component — replacement for full-page navigation. Turbo Drive (fast page loads), Turbo Frames (partial updates), Turbo Streams (server push via WebSocket/SSE).
Turbo 8 (2024) adds morphdom-based page refresh for smooth state preservation. Differs from SPA frameworks: no JavaScript state, server renders HTML, client swaps in. Powers Basecamp, HEY, parts of GitHub (the PR view used Turbo Streams pre-2024).