Add wtf_transcribe link for WTF transcription

server/links/wtf_transcribe/README.md

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+# WTF Transcription Link (vfun Integration)
+
+A link that sends vCon audio dialogs to a vfun transcription server and adds the results as WTF (World Transcription Format) analysis entries.
+
+## Overview
+
+This link integrates with the vfun transcription server to provide:
+- Multi-language speech recognition (English + auto-detect)
+- Speaker diarization (who spoke when)
+- GPU-accelerated processing with CUDA
+- WTF-compliant output format per IETF draft-howe-vcon-wtf-extension-01
+
+## Configuration
+
+```yaml
+wtf_transcribe:
+  module: links.wtf_transcribe
+  options:
+    # Required: URL of the vfun transcription server
+    vfun-server-url: http://localhost:8443/transcribe
+
+    # Optional: Enable speaker diarization (default: true)
+    diarize: true
+
+    # Optional: Request timeout in seconds (default: 300)
+    timeout: 300
+
+    # Optional: Minimum dialog duration to transcribe in seconds (default: 5)
+    min-duration: 5
+
+    # Optional: API key for vfun server authentication
+    api-key: your-api-key-here
+```
+
+## How It Works
+
+1. **Extract Audio**: Reads audio from vCon dialog (supports `body` with base64/base64url encoding, or `url` with file:// or http:// references)
+2. **Send to vfun**: POSTs audio file to vfun's `/transcribe` endpoint
+3. **Create WTF Analysis**: Formats the transcription result as a WTF analysis entry
+4. **Update vCon**: Adds the WTF analysis to the vCon and stores it back to Redis
+
+## Output Format
+
+The link adds analysis entries with the WTF format:
+
+```json
+{
+  "type": "wtf_transcription",
+  "dialog": 0,
+  "mediatype": "application/json",
+  "vendor": "vfun",
+  "product": "parakeet-tdt-110m",
+  "schema": "wtf-1.0",
+  "encoding": "json",
+  "body": {
+    "transcript": {
+      "text": "Hello, how can I help you today?",
+      "language": "en-US",
+      "duration": 30.0,
+      "confidence": 0.95
+    },
+    "segments": [
+      {
+        "id": 0,
+        "start": 0.0,
+        "end": 3.5,
+        "text": "Hello, how can I help you today?",
+        "confidence": 0.95,
+        "speaker": 0
+      }
+    ],
+    "metadata": {
+      "created_at": "2024-01-15T10:30:00Z",
+      "processed_at": "2024-01-15T10:30:05Z",
+      "provider": "vfun",
+      "model": "parakeet-tdt-110m"
+    },
+    "speakers": {
+      "0": {
+        "id": 0,
+        "label": "Speaker 0",
+        "segments": [0],
+        "total_time": 15.2
+      }
+    },
+    "quality": {
+      "average_confidence": 0.95,
+      "multiple_speakers": true,
+      "low_confidence_words": 0
+    }
+  }
+}
+```
+
+## Behavior
+
+- **Skips non-recording dialogs**: Only processes dialogs with `type: "recording"`
+- **Skips already transcribed**: Dialogs with existing WTF transcriptions are skipped
+- **Duration filtering**: Dialogs shorter than `min-duration` are skipped
+- **File URL support**: Can read audio from local `file://` URLs directly
+
+## Example Chain Configuration
+
+```yaml
+chains:
+  transcription_chain:
+    links:
+      - tag
+      - wtf_transcribe
+      - supabase_webhook
+    ingress_lists:
+      - transcribe
+    egress_lists:
+      - transcribed
+    enabled: 1
+```
+
+## vfun Server
+
+The vfun server provides GPU-accelerated transcription:
+
+```bash
+# Start vfun server
+cd /path/to/vfun
+./vfun server
+
+# Test health
+curl http://localhost:8443/ping
+
+# Manual transcription test
+curl -X POST http://localhost:8443/transcribe \
+  -H "Authorization: Bearer YOUR_API_KEY" \
+  -F "file=@audio.wav" \
+  -F "diarize=true"
+```
+
+## Related
+
+- [vfun](https://github.com/strolid/vfun) - GPU-accelerated transcription server
+- [draft-howe-vcon-wtf-extension](https://datatracker.ietf.org/doc/html/draft-howe-vcon-wtf-extension) - IETF WTF specification