feat(app): add model_install_download_started event

Previously, we used `model_install_download_progress` for both download starting and progressing. When handling this event, we don't know which actual thing it represents.

Add `model_install_download_started` event to explicitly represent a model download started event.

invokeai/app/services/events/events_base.py

@@ -22,6 +22,7 @@ from invokeai.app.services.events.events_common import (
     ModelInstallCompleteEvent,
     ModelInstallDownloadProgressEvent,
     ModelInstallDownloadsCompleteEvent,
+    ModelInstallDownloadStartedEvent,
     ModelInstallErrorEvent,
     ModelInstallStartedEvent,
     ModelLoadCompleteEvent,
@@ -144,6 +145,10 @@ class EventServiceBase:
 
     # region Model install
 
+    def emit_model_install_download_started(self, job: "ModelInstallJob") -> None:
+        """Emitted at intervals while the install job is started (remote models only)."""
+        self.dispatch(ModelInstallDownloadStartedEvent.build(job))
+
     def emit_model_install_download_progress(self, job: "ModelInstallJob") -> None:
         """Emitted at intervals while the install job is in progress (remote models only)."""
         self.dispatch(ModelInstallDownloadProgressEvent.build(job))

invokeai/app/services/events/events_common.py

@@ -417,6 +417,42 @@ class ModelLoadCompleteEvent(ModelEventBase):
         return cls(config=config, submodel_type=submodel_type)
 
 
+@payload_schema.register
+class ModelInstallDownloadStartedEvent(ModelEventBase):
+    """Event model for model_install_download_started"""
+
+    __event_name__ = "model_install_download_started"
+
+    id: int = Field(description="The ID of the install job")
+    source: str = Field(description="Source of the model; local path, repo_id or url")
+    local_path: str = Field(description="Where model is downloading to")
+    bytes: int = Field(description="Number of bytes downloaded so far")
+    total_bytes: int = Field(description="Total size of download, including all files")
+    parts: list[dict[str, int | str]] = Field(
+        description="Progress of downloading URLs that comprise the model, if any"
+    )
+
+    @classmethod
+    def build(cls, job: "ModelInstallJob") -> "ModelInstallDownloadStartedEvent":
+        parts: list[dict[str, str | int]] = [
+            {
+                "url": str(x.source),
+                "local_path": str(x.download_path),
+                "bytes": x.bytes,
+                "total_bytes": x.total_bytes,
+            }
+            for x in job.download_parts
+        ]
+        return cls(
+            id=job.id,
+            source=str(job.source),
+            local_path=job.local_path.as_posix(),
+            parts=parts,
+            bytes=job.bytes,
+            total_bytes=job.total_bytes,
+        )
+
+
 @payload_schema.register
 class ModelInstallDownloadProgressEvent(ModelEventBase):
     """Event model for model_install_download_progress"""

invokeai/app/services/model_install/model_install_default.py

@@ -822,7 +822,7 @@ class ModelInstallService(ModelInstallServiceBase):
                 install_job.download_parts = download_job.download_parts
                 install_job.bytes = sum(x.bytes for x in download_job.download_parts)
                 install_job.total_bytes = download_job.total_bytes
-                self._signal_job_downloading(install_job)
+                self._signal_job_download_started(install_job)
 
     def _download_progress_callback(self, download_job: MultiFileDownloadJob) -> None:
         with self._lock:
@@ -874,6 +874,13 @@ class ModelInstallService(ModelInstallServiceBase):
         if self._event_bus:
             self._event_bus.emit_model_install_started(job)
 
+    def _signal_job_download_started(self, job: ModelInstallJob) -> None:
+        if self._event_bus:
+            assert job._multifile_job is not None
+            assert job.bytes is not None
+            assert job.total_bytes is not None
+            self._event_bus.emit_model_install_download_started(job)
+
     def _signal_job_downloading(self, job: ModelInstallJob) -> None:
         if self._event_bus:
             assert job._multifile_job is not None