generated: '2026-07-21'
method: searched
source: https://maas.unisound.com/docs/api/overview
authentication:
  style: bearer-api-key
  header: 'Authorization: Bearer <api_key>'
  anthropic_compatible_header: 'x-api-key: <api_key>'
  artifact: authentication/unisound-authentication.yml
compatibility:
  - surface: OpenAI Chat Completions
    endpoint: POST https://maas-api.unisound.com/v1/chat/completions
    docs: https://maas.unisound.com/docs/api/text/openai-compatible
  - surface: Anthropic Messages
    endpoint: POST https://maas-api.unisound.com/anthropic/v1/messages
    docs: https://maas.unisound.com/docs/api/text/anthropic-compatible
async_pattern:
  style: task-polling
  description: 'Long-running work (long-audio transcription, long-text synthesis,
    document parsing) is submitted as a task returning a task_id; clients poll a GET
    task-status endpoint until completion. Result URLs from long-text synthesis expire
    9 hours (32400 s) after being returned. Inputs are staged through the file API
    (POST /v1/files/upload with a purpose such as a2t_async_input) which returns a
    file_id.'
streaming:
  - style: sse
    description: 'Chat endpoints support stream: true for incremental deltas; the
      Anthropic-compatible endpoint emits message_start / content_block_start / content_block_delta
      / content_block_stop / message_delta / message_stop events.'
  - style: websocket
    description: 'One-shot and real-time speech recognition use WSS endpoints; the
      legacy Open Platform ASR is ws[s]://ws-osasr.hivoice.cn/v1/asr.'
model_capabilities:
  - name: context-cache
    docs: https://maas.unisound.com/docs/guide/capability/context-cache
    note: Cache hits are billed at a discounted input rate (e.g. U2 0.02 vs 1 CNY per
      million tokens).
  - name: prefix-continuation
    docs: https://maas.unisound.com/docs/guide/capability/prefix-continuation
  - name: structured-output
    docs: https://maas.unisound.com/docs/guide/capability/structured-output
  - name: function-calling
    docs: https://maas.unisound.com/docs/guide/capability/function-calling
error_envelope:
  description: HTTP status plus business error code with documented meaning and resolution;
    legacy Open Platform responses carry errorCode (0 = success).
  artifact: errors/unisound-problem-types.yml
rate_limits:
  docs: https://maas.unisound.com/docs/api/rate-limit
  signaling: 'Open Platform code 20206 signals concurrency limit exceeded; 20207 signals
    quota exhausted.'
idempotency:
  supported: false
  note: No idempotency-key mechanism is documented on either platform.
pagination:
  note: File list endpoints exist (GET /v1/files); no cross-cutting pagination convention
    is documented.
versioning:
  artifact: lifecycle/unisound-lifecycle.yml
  style: uri-path
  current: v1 (Token Hub), rest/v1.1 (UniGPT WebAPI)