The engine worker stores the encoded filename under the key 'filename'
(see worker.py dispatch). _record_to_status was reading 'original_filename',
which always returns "" — so every DownloadStatus emitted by
get_all_downloads/get_download_status had an empty filename string.
The download monitor builds lookup keys as
_make_context_key(download.username, download.filename). With filename=""
the key was always "amazon::" which never matched the task's
"amazon::B0B1234||Artist - Title" key. Monitor never detected Amazon
download completions, so tasks sat stuck at Downloading 0% forever even
though the files had actually downloaded.
Also fixes tests that had the same wrong key.
AmazonDownloadClient was missing set_engine() and set_shutdown_check().
The download engine auto-wires plugins by calling set_engine(self) at
registration time if the method exists (engine.py:136). Without it,
_engine stayed None forever, causing every download() call to raise
RuntimeError("_engine is not set") — silently failing and marking all
tracks not found.
All other streaming clients (Deezer, Qobuz, Tidal, HiFi, SoundCloud)
expose set_engine(); Amazon now matches the pattern.
Tests added: set_engine wires _engine, set_shutdown_check wires callback,
set_engine unblocks download dispatch (the exact live failure mode).
core/amazon_client.py — T2Tunes-backed metadata client following the
DeezerClient/iTunesClient contract. Exposes search_tracks, search_artists,
search_albums, get_track_details, get_album, get_album_tracks, get_artist,
get_artist_albums, get_track_features. T2TunesStreamInfo dataclass captures
the hex decryption key returned by the proxy (CENC/AES-128). Handles the
"stremeable" API typo. 0.5 s rate-limit guard + api_call_tracker.
core/amazon_download_client.py — DownloadSourcePlugin backed by the above
client. Codec waterfall: FLAC → Opus → EAC3. Downloads the encrypted MP4
container, decrypts with ffmpeg -decryption_key, yields the native audio
file (.flac / .opus / .eac3). Not yet wired into the app source registry —
validated in isolation only; see tests/tools/.
tools/t2tunes_probe.py + tools/t2tunes_media_plan.py — standalone CLI tools
used for live API exploration during development.
tests/tools/test_amazon_client.py — 72 unit tests (all mocked).
tests/tools/test_amazon_download_client.py — 52 unit tests (all mocked).
124 tests pass.
