Add Test & Download button for diarization model, clickable links

- Add diarize.download IPC handler that downloads the pyannote model
  and returns user-friendly error messages (missing license, bad token)
- Add download_diarize_model Tauri command
- Add "Test & Download Model" button in Speakers settings tab
- Update instructions to list both required model licenses
  (speaker-diarization-3.1 AND segmentation-3.0)
- Make all HuggingFace URLs clickable (opens in system browser)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

python/voice_to_notes/ipc/handlers.py

@@ -88,6 +88,57 @@ def make_diarize_handler() -> HandlerFunc:
     return handler
 
 
+def make_diarize_download_handler() -> HandlerFunc:
+    """Create a handler that downloads/validates the diarization model."""
+
+    def handler(msg: IPCMessage) -> IPCMessage:
+        payload = msg.payload
+        hf_token = payload.get("hf_token")
+
+        try:
+            from pyannote.audio import Pipeline
+
+            print("[sidecar] Downloading diarization model...", file=sys.stderr, flush=True)
+            pipeline = Pipeline.from_pretrained(
+                "pyannote/speaker-diarization-3.1",
+                token=hf_token,
+            )
+            print("[sidecar] Diarization model downloaded successfully", file=sys.stderr, flush=True)
+            return IPCMessage(
+                id=msg.id,
+                type="diarize.download.result",
+                payload={"ok": True},
+            )
+        except Exception as e:
+            error_msg = str(e)
+            # Make common errors more user-friendly
+            if "403" in error_msg and "gated" in error_msg.lower():
+                # Extract which model needs access
+                if "segmentation" in error_msg:
+                    error_msg = (
+                        "Access denied for pyannote/segmentation-3.0. "
+                        "Please visit huggingface.co/pyannote/segmentation-3.0 "
+                        "and accept the license agreement."
+                    )
+                elif "speaker-diarization" in error_msg:
+                    error_msg = (
+                        "Access denied for pyannote/speaker-diarization-3.1. "
+                        "Please visit huggingface.co/pyannote/speaker-diarization-3.1 "
+                        "and accept the license agreement."
+                    )
+                else:
+                    error_msg = (
+                        "Access denied. Please accept the license agreements at: "
+                        "huggingface.co/pyannote/speaker-diarization-3.1 and "
+                        "huggingface.co/pyannote/segmentation-3.0"
+                    )
+            elif "401" in error_msg:
+                error_msg = "Invalid token. Please check your HuggingFace token."
+            return error_message(msg.id, "download_error", error_msg)
+
+    return handler
+
+
 def make_pipeline_handler() -> HandlerFunc:
     """Create a full pipeline handler (transcribe + diarize + merge)."""
     from voice_to_notes.services.pipeline import PipelineService, pipeline_result_to_payload

python/voice_to_notes/main.py

@@ -15,6 +15,7 @@ from voice_to_notes.ipc.handlers import (  # noqa: E402
     HandlerRegistry,
     hardware_detect_handler,
     make_ai_chat_handler,
+    make_diarize_download_handler,
     make_diarize_handler,
     make_export_handler,
     make_pipeline_handler,
@@ -32,6 +33,7 @@ def create_registry() -> HandlerRegistry:
     registry.register("transcribe.start", make_transcribe_handler())
     registry.register("hardware.detect", hardware_detect_handler)
     registry.register("diarize.start", make_diarize_handler())
+    registry.register("diarize.download", make_diarize_download_handler())
     registry.register("pipeline.start", make_pipeline_handler())
     registry.register("export.start", make_export_handler())
     registry.register("ai.chat", make_ai_chat_handler())