Init() created a new SynologyClient and logged in for every download. A
many-file download opened dozens of near-simultaneous sessions for one DSM
account; DSM invalidates older session IDs, so in-flight File Station calls
failed with error 119 "SID not found".
Add SynologyClientProvider: a thread-safe cache that authenticates once and
shares the client across downloads (concurrent first calls collapse to a
single login; later calls reuse it; a credential change re-authenticates).
Wrap every Synology call in a session-retry that drops the session and
re-authenticates once on a session error (119/106/107) so an expired SID
self-heals, reading credentials fresh from settings so edits take effect live.
Adds provider unit tests and a downloader test covering the 119 re-auth path.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The DownloadStation downloader left downloads stuck or silently failing.
This fixes the core flow and documents setup:
- Create the per-download destination folder via File Station (force_parent)
before creating the task; DownloadStation does not create it for a
direct-file task, which otherwise fails with "Destination does not exist".
- Auto-set the account's default destination when it has none (DSM leaves
every task "Waiting" otherwise), preserving the other server settings.
- Detect completion across the terminal states (Finished/Downloaded/Seeding/
PreSeeding or fully transferred), then verify the file is visible at the
container path before signalling success, so a path-mapping mismatch is a
clear error instead of a silent import failure.
- Surface DownloadStation errors (status_extra.error_detail, captcha) instead
of polling progress forever.
- Harden task-list / get-info / delete handling against responses that fail
to deserialize (upstream #723/#792) so one bad task can't abort a download.
- Make task creation idempotent: adopt an existing task instead of throwing
"already added", which previously bricked every retry.
Adds unit tests, fixes a settings description typo, and documents Download
Station setup and the path-mapping requirement in the README.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
