agent-ui

An interface with a model behind it has one extra state everything else lacks: in progress, with partial output, of unknown length. Every pattern here follows from handling that state honestly.

Principles

1. Show the work, collapsed. Reasoning, tool calls and sources are visible on demand, never hidden and never forced open.
2. The user can always stop. Every generation has a stop control in the same place, reachable by Escape.
3. Never fake progress. No spinners that mean nothing, no "thinking" that is a timer, no typewriter effect slower than the real stream.
4. The input is always available. Composing the next message while the current one streams is normal.
5. Output is a document, not a log. Rendered markdown, real code blocks, stable layout.

The composer