3.8 KiB
Voice Conversation API (v1)
/api/v1/voice is a server-side device API for native iOS and Echo-style clients. It is separate from the browser voice feature. Azure credentials remain on the PI WEB host.
Security and provisioning
Create a device token on the PI WEB host:
pi-web voice-token create \
--project project-id --workspace workspace-id \
--model openai-codex/gpt-5.6-terra --thinking high
Each restriction flag may be repeated. Omitting a category grants * for that category. A restricted model or thinking scope requires the client to explicitly select an allowed value; it cannot inherit a server default. Project and workspace scopes are both enforced. Token records contain a SHA-256 token hash only and are persisted at mode 0600 in ~/.config/pi-web/voice-api.json; the plaintext (pwv1_...) is printed only once.
pi-web voice-token list
pi-web voice-token revoke <token-id>
Use Authorization: Bearer pwv1_... on every HTTP and WebSocket connection. The API requires HTTPS, except loopback for local development/testing. A conversation is owned by the creating token: other valid device tokens receive 404 when they try to inspect, delete, or attach it. A client may select only a registered workspace id, never a filesystem path.
HTTP
GET /api/v1/voice/targets returns only the caller's authorized registered workspaces plus effective scopes.
POST /api/v1/voice/conversations
{
"workspaceId": "registered-workspace-id",
"model": "openai-codex/gpt-5.6-terra",
"thinking": "high",
"context": "You are helping with the home-automation project."
}
The response is 201 and includes the opaque conversation id, session id, selected workspace, and input-ready status. GET and DELETE /api/v1/voice/conversations/:id inspect and close the API conversation handle.
WebSocket wire protocol
Connect to wss://host/api/v1/voice/stream with the Bearer header. The server first sends:
{
"type":"hello",
"protocol":"pi-web.voice.v1",
"pcm":{"input":"s16le/16000/mono","output":"s16le/24000/mono"},
"binary":{"version":1,"headerBytes":8,"kind":"audio"}
}
Attach an owned conversation and wait for input.ready before sending a turn:
{"type":"attach","conversationId":"..."}
Text fallback
Send exactly one JSON input while input-ready:
{"type":"input.text","text":"Turn on the kitchen lights."}
Audio input
For speech input, send binary WebSocket frames containing raw signed little-endian 16-bit, 16 kHz, mono PCM (no WAV header). Frames must be nonempty, <=64 KiB, aligned to two bytes, and an utterance is limited to two minutes. Finish with:
{"type":"input.end"}
Azure push-stream recognition emits transcript.partial and transcript.final JSON events. The final transcript is submitted to Pi. This Voice API never returns an Azure token or key to a device.
Turn output and lifecycle
For either input form, the server emits agent.working, then agent.accepted after Pi accepted the prompt. It subscribes to the session event stream before submission and waits for Pi's native agent.settled event (not merely agent.end), with a two-minute turn timeout. assistant.delta is streamed while Pi answers; assistant.final contains only assistant text, never STT transcript.
Azure synthesis output is signed little-endian 16-bit, 24 kHz, mono PCM. Every binary server frame has this eight-byte header followed by PCM:
| Bytes | Meaning |
|---|---|
| 0 | protocol version: 1 |
| 1 | kind: 1 (audio) |
| 2–3 | reserved: 0 (big endian) |
| 4–7 | monotonically increasing frame sequence (uint32 big endian) |
The server then emits {"type":"audio.end"} and a fresh input.ready. Send {"type":"close"} or close the WebSocket to end; disconnecting closes STT/event resources and clears the handle's working state.