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Subscribe to a Server-Sent Events (SSE) stream that pushes your current flag configuration immediately on connect, then re-pushes the full configuration whenever any flag for your tenant is created, updated, toggled, or deleted (including targeting rule changes).
The iOS SDK (2.0.6+) manages this connection for you, including automatic reconnection. You typically only call this endpoint directly from server-side consumers.

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Request

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Headers

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Query parameters

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Response

The stream stays open and emits a single event type, flags. Each event carries the full flag configuration for the requested environment (the same shape as GET /api/v1/flags) — replace your cached config wholesale on every event, no diffing required:
Flag values are typed (boolean, integer, double, string, or JSON), resolved for the requested environment.

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Keepalives

Every 20 seconds the server writes an SSE comment line:
Comment lines (prefixed with :) are ignored by spec-compliant SSE parsers. They exist purely to defeat idle timeouts at every hop between your client and the server — including the iOS SDK’s 75-second URLSession idle timeout (SDK 2.0.6) and CDN proxy idle cutoffs. If you write your own SSE client, make sure it tolerates comment lines and does not treat them as events.

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Reconnection

Connections can still drop (network changes, deploys, proxy resets). Reconnect with exponential backoff; on reconnect the first flags event immediately restores the current configuration, so no state is lost.
SDK 2.0.6+ handles all of this automatically — keepalive tolerance, the 75s idle timeout, and reconnection with backoff. If flag streaming silently stalls on older SDK versions, upgrade to 2.0.6 or later.

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See also