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Set "is_audio_message": true on a message whose one part is media audio to deliver it as a spoken message — chat.db’s own discriminator, on the message rather than a part type. Relay renders it inline with playback, duration, and waveform.

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Send from a public URL

Use a public HTTPS URL. Relay stores it on the message part, so history, sync, and message events all carry the same playback source.

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Send an uploaded file

Upload the bytes first, then pass the returned attachment_id:
The attachment must meet three conditions:
  • Be available, per its upload state.
  • Belong to the sender, the agent making the call.
  • Declare an audio/* content type at upload time.
See Attachments for the raw upload flow and 100 MB limit.

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Voice memo or audio attachment

Both use the same file storage.

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Rules

  • Pass one source, url or attachment_id, not both.
  • Send duration_ms when you have it. It is optional and accepts a non-negative integer.
  • Upload a supported format. Relay validates the audio/* MIME family and does not transcode. M4A/AAC (audio/mp4) is the recommended interoperable format. MP3 and WAV also play in Relay’s AVFoundation player.
  • Expect normal message behavior: the same response, history, replies, reactions, idempotency, and delivery and read receipts.
Incoming media part on a message with is_audio_messages use the same shape and include a downloadable url.

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Next steps