Cin's review feedback: the plugin contract was discoverable only
from the registry, not from the client files themselves. Reading
`youtube_client.py` cold gave no signal that the class participates
in the DownloadSourcePlugin contract.
Every download client class now inherits DownloadSourcePlugin
explicitly:
- SoulseekClient(DownloadSourcePlugin)
- YouTubeClient(DownloadSourcePlugin)
- TidalDownloadClient(DownloadSourcePlugin)
- QobuzClient(DownloadSourcePlugin)
- HiFiClient(DownloadSourcePlugin)
- DeezerDownloadClient(DownloadSourcePlugin)
- SoundcloudClient(DownloadSourcePlugin)
- LidarrDownloadClient(DownloadSourcePlugin)
Adjustments:
- core/download_plugins/base.py — moved TrackResult/AlbumResult/
DownloadStatus imports under TYPE_CHECKING since they're only
used in type annotations. Without this, clients inheriting the
contract create a circular import.
- core/download_plugins/__init__.py — drops DownloadPluginRegistry
re-export. Importing the package no longer triggers the registry's
eager client imports (which would also be circular for clients
that import from the package). Callers that need the registry
import it directly: `from core.download_plugins.registry import
DownloadPluginRegistry`.
Suite still green (335 download tests).
`core/download_plugins/` defines the canonical interface every
download source must satisfy and the registry that holds them.
Single source of truth replacing the orchestrator's hardcoded
`[self.soulseek, self.youtube, ...]` lists scattered across 6+
dispatch sites.
Pure additive — no consumers wired through the registry yet.
Broque Thomas