Push events into a running session with channels - Claude Code Docs
Use channels to push messages, alerts, and webhooks into your Claude Code session from an MCP server. Forward CI results, chat messages, and monitorin...
Real-Time Web Infrastructure
Summary
Explores why chatbot UIs like Claude lose in-progress responses on page refresh due to stateless SSE streaming, and proposes WebSockets with Pub/Sub as a more resilient alternative for real-time token delivery.
Highlights
- Claude's UI uses SSE via EventSource; refreshing the page disconnects the stream and loses all in-progress tokens until generation completes and saves to a database
- The core problem: SSE is stateless and one-directional, so previous events are inaccessible after disconnection
- Proposed solution: WebSockets combined with Ably's Pub/Sub enables stream resumption, multi-device sync, and presence awareness without persistent storage
- The author frames this as a broader infrastructure gap: model performance has advanced dramatically while the delivery layer has not kept pace
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Context
Audience
Frontend developers and architects building real-time chat interfaces or streaming UIs
DomainReal-Time Web Infrastructure
FormatLong-form technical blog post with GIF demonstrations
AccessFree online blog post
Source Overview
Page refresh disrupts chatbot UIs like Claude's, which use stateless SSE for token streaming, causing lost responses until generation completes and history loads from a database.
A minimal UI demo using WebSockets and Ably's Pub/Sub resumes streams seamlessly on refresh without persistent storage. Pub/Sub platforms enable reconnection, multi-device support, presence awareness, and efficient token appending, surpassing SSE limitations.
Topics
Related
Server-Sent Events (SSE)WebSocketsAbly Pub/SubEventSource APIReal-time streaming UIs
