Add fallback support for public hifi-api instances that expose playback through /track/ instead of /trackManifests/. The capability checker now accepts either manifest shape, and downloads can use direct URLs decoded from the legacy base64 manifest.
Tests cover legacy instance capability detection and download-manifest fallback while preserving the newer trackManifests path.
Probe public HiFi instances with the same trackManifests endpoint used by real downloads instead of the legacy /track endpoint. This prevents compatible instances from being falsely labeled search-only in Settings.
Centralize HiFi instance capability checks in HiFiClient and reuse manifest URI parsing with the download path.
Tests cover manifest-based capability detection, no legacy /track probe, and limited instances without a manifest URI.
Two findings from JohnBaumb on the engine refactor.
(1) Every download client returned None when self._engine was None,
just logging an error. The orchestrator's download_with_fallback
treated None as "source declined", so the user got no feedback —
download silently disappeared. Now each client raises a RuntimeError
on the engine-not-wired path. download_with_fallback already catches
plugin exceptions, logs a warning, and tries the next source — so
the visible behavior is "real error in logs + fallback to next
source" instead of "silent drop". Six clients touched (deezer, hifi,
qobuz, soundcloud, tidal, youtube). Pinning tests updated to expect
raise.
(2) Monitor's engine.get_all_downloads() walked every plugin
including soulseek, but the same monitor loop already pulled slskd
transfers via the transfers/downloads endpoint a few lines earlier —
soulseek's records were being fetched twice per tick. Same issue in
web_server.py's get_cached_transfer_data path. Added an exclude
parameter to engine.get_all_downloads(); both call sites now pass
('soulseek',). New test pins the exclude semantic.
Also fixed a stray 8-space over-indent on the for-loop body in
get_cached_transfer_data (cosmetic, JohnBaumb flagged the same
pattern in monitor.py earlier).
Same pattern as C2/C3/C4. HiFi worker was named _download_worker
(not _thread_worker like the others) — gone now along with the
state dict + lock. Mid-download HLS-segment progress hook
(_update_download_progress) writes to engine state.
Pinning tests updated. Suite still green (318 download tests).
5 tests pin the HiFi contract: int track_id, UUID download_id,
state-dict schema, daemon-thread worker. Note: target method is
`_download_worker` (NOT `_thread_worker` like Tidal/Qobuz) and
worker signature is 3-arg (download_id, track_id, display_name).
Engine refactor's plugin contract must accommodate or normalize.
