Long narration and long recordings now route instead of hitting a limit

Status: scheduled. Synthesis past a vendor’s character cap answered with the vendor’s own refusal, and a recording past 8 MiB answered 413 on the route the OpenAI SDK reaches. Long text is now split at sentence boundaries and narrated on one voice, and a transcription upload is allowed the 25 MiB OpenAI documents plus the first-byte budget the bytes actually need.