I Evaluated Every AI Chat UI Library in 2026. Here's What I Found (and What I Built)

TL;DR: React stack → assistant-ui Full agent framework → CopilotKit Quick prototype or non-React → Deep Chat Python backend → Chainlit (check project status first) Multi-framework + composable, early adopter → Loquix (no production deployments yet - read the limitations) ⚠️ Conflict of interest: I'm the author of Loquix, one of the libraries reviewed here. The independent reviews come first. Loquix gets its own clearly-labeled section at the end,