Agentic Frontends
Streaming tokens, tool progress, citations, cancellation and partial failure — plus the rule that a model suggesting an action is never the same as the action being authorized.
The model runs elsewhere. The client is a UI for an operation that streams, takes tools, fails halfway and must never be trusted with authority.
Tokens arrive dozens of times a second on a thread that also has to paint. What you do per chunk decides whether the answer feels alive or the page feels broken.
Observable states — searching, retrieving, calling, processing — reported honestly. Not a dramatisation of thinking the system cannot actually show you.
A source the user can actually check, and an answer that admits what it is missing. Both are interface problems before they are model problems.
Cancellation is two-sided and retry is not free: a run that already called a tool has already changed something.
The model proposes; structured validation, a permission check and the backend decide. The UI shows only what was actually confirmed.