Add xfyun asr service

README.md

@@ -115,6 +115,7 @@ Returned bot audio:
 Returned transcripts and assistant text:
 
 ```json
+{"type": "input.transcript.interim", "text": "What's the"}
 {"type": "input.transcript.final", "text": "What's the weather?", "user_id": "...", "timestamp": "..."}
 {"type": "response.text.started"}
 {"type": "response.text.delta", "text": "It's "}
@@ -131,6 +132,32 @@ the TTS in the pipeline. `response.text.final` fires when the turn ends,
 carrying the full concatenated assistant text and an `interrupted` flag
 (true when an `input.text` or barge-in cut the turn short).
 
+### Xfyun ASR
+
+The STT provider can be switched to iFlytek/Xfyun's streaming voice dictation
+WebSocket API. The engine sends PCM chunks as `encoding: "raw"` and emits
+`input.transcript.interim` events with the current full interim transcript as
+Xfyun results arrive, followed by the existing `input.transcript.final` event.
+
+```json
+"stt": {
+  "provider": "xfyun",
+  "app_id": "your_xfyun_app_id",
+  "api_key": "your_xfyun_api_key",
+  "api_secret": "your_xfyun_api_secret",
+  "base_url": "wss://iat-api.xfyun.cn/v2/iat",
+  "language": "zh_cn",
+  "domain": "iat",
+  "accent": "mandarin",
+  "encoding": "raw",
+  "frame_size": 1280,
+  "timeout_sec": 10.0
+}
+```
+
+Credentials may also be provided through `XFYUN_APP_ID`, `XFYUN_API_KEY`, and
+`XFYUN_API_SECRET`.
+
 ### Xfyun TTS
 
 The TTS provider can be switched to iFlytek/Xfyun's online TTS WebSocket API.