SDK Handling HTTP 413 [Unity] #2494

Relay previously returned HTTP 400 Bad Request for oversized envelopes. This was changed in Relay #5474 to HTTP 413 (Content Too Large) to allow SDKs to distinguish size-related rejections from other errors. For more context on this decision, see the DACI: Relay Returns 413 for too-large envelopes.

The main benefit is for our users. With the HTTP 413 response, SDKs can now log specific, actionable error messages when envelopes are rejected due to size limits. Previously, users had no clear indication of why their data was being dropped when envelopes exceeded size limits. Now, they'll understand the cause and can take steps to resolve it.

Requirements

See the 413 section in Dealing With Network Failures in the SDK develop docs for the full specification.