Changelog

v0.3.0 — Strict output formats, telephony & clearer limits

output_format is now strictly validated — unsupported values return 400 instead of silently falling back. Supported: container raw/wav, encoding pcm_s16le/pcm_mulaw/pcm_alaw, sample_rate 8000/16000/22050.
Telephony encodings added — 8 kHz μ-law (pcm_mulaw) and A-law (pcm_alaw) for Twilio/SIP media streams.
Removed formats — mp3, pcm_f32le, and sample rates 24000/44100/48000 are no longer accepted.
Streaming is raw-only — wav is available on /tts/bytes only; /tts/sse and /tts/websocket require raw.
Limits clarified as per-org — rate and concurrency limits are shared across all of an org’s API keys; extra keys don’t add capacity. Concurrency is measured per active-speech turn, not per call.
Dutch voices are now tagged nl-NL (BCP-47 dialect) instead of bare nl.

Cartesia-compatible surface: POST /tts/bytes, POST /tts/sse, GET /tts/websocket, /voices CRUD, POST /voices/clone
Model: gepard-1.0
Real-time WebSocket streaming with per-transcript billing
Voice cloning and the full Cartesia voice library
API keys now use the sk_996_<prefix>_<secret> format, scoped to a project
Prepaid credits: 1 credit per character, $5 per 1M characters, credits never expire
Per-project tiers (rate + concurrency): tier1 / tier2 / tier3, with auto-upgrade to tier2 at $50 lifetime spend

OpenAI-compatible TTS API (deprecated; replaced by the Cartesia-compatible surface above)