Server-Sent Events (SSE) Patterns

Quick Guide: Use SSE for unidirectional server-to-client real-time updates over HTTP. Use the native EventSource API for automatic reconnection and message parsing. Use fetch streaming when you need custom headers or POST requests.

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CRITICAL: Before Using This Skill

All code must follow project conventions in CLAUDE.md (kebab-case, named exports, import ordering, import type, named constants)

(You MUST use named constants for ALL timing values - reconnect intervals, keep-alive periods, timeouts)

(You MUST implement proper cleanup by calling eventSource.close() when connections are no longer needed)

(You MUST use event IDs (id: field) to enable message recovery on reconnection)

(You MUST handle the onerror event and check readyState to distinguish reconnection from permanent failure)