Design an Embeddable Streaming Chat Interface

# Design an Embeddable Streaming Chat Interface Design an embeddable chat-agent widget. Cover the host-page integration, streaming responses over SSE or gRPC, long-conversation virtualization, chat-history caching, and core product and reliability metrics. ### Constraints & Assumptions - The widget may run inside a host application with its own authentication and styles. - Assistant output arrives incrementally and may fail or be cancelled. - Long histories cannot all remain mounted in the browser. ### Clarifying Questions to Ask - Is the widget an iframe, web component, or library integrated into the host DOM? - Must conversations synchronize across devices? - Which guarantees apply to message ordering and resuming a broken stream? ```hint Define message states Represent pending, streaming, complete, failed, retried, and cancelled messages explicitly before choosing UI components. ``` ### What a Strong Answer Covers - Embedding boundary, authentication, accessibility, and style isolation. - Streaming protocol, sequence numbers, retry or resume behavior, and cancellation. - Virtualized history, pagination, caching, optimistic UI, and consistency. - Metrics for latency, completion, errors, engagement, and user correction. ### Follow-up Questions 1. How would tool-call approval appear without allowing duplicate actions? 2. How would you avoid losing partially streamed content during navigation?