StepFun stepaudio-2.5-asr Transcribe audio with StepFun's (released 2026-04, verified 2026-04-23). Long audio in one call, no chunking — but only if the request hits the right endpoint with the right body shape. The wrong endpoint returns an error that looks identical to "model doesn't exist", which is the #1 reason this skill exists. Companion: for TTS with (the sibling model), use the skill — they share an API key but live on different endpoints with different body shapes. Why this skill exists — three traps that cost hours 1. Wrong endpoint, wrong error . does not live on (that endpoint se…