Records analytics events from a client SDK.

The client-surface counterpart of POST /v1/sdk/events, for SDKs that authenticate with a client key. The mobile SDKs (Swift, Android, Flutter) use this to report track() calls. Server SDKs keep using /v1/sdk/events.

A client that sends X-Featureflip-Reports-Evaluations: 1 on evaluate and identify reports the flags its code actually reads here, as Evaluation events (one per flag, variation and user is enough). For clients that don't send the header, this API records the evaluations it serves on their behalf.

Because a client key is public by design, this endpoint is rate limited per client IP, limits the size of a request, and caps the number of events in one request. An event that exceeds one of the following per-event limits is discarded on its own; the rest of the batch is still recorded, and the response is unchanged:

• its timestamp sits far outside the present;
• its flagKey is longer than 256 characters;
• it is a Custom event introducing more than 50 distinct event keys in one request. Repeats of a key already in the request are always recorded, so this bounds how many distinct event names a single batch can introduce, not how many events it may carry.