- C1: remove downloads/formats.py target_ext() — defined but never called (the
worker derives the real extension from the produced file's suffix).
- C2: the download-root containment+existence guard was copy-pasted 6× across the
file-serving endpoints (routes/downloads.py ×3, routes/public.py ×3). Extract
storage.safe_abs_path(root, rel) -> Path|None so this security-sensitive check
lives in one place; behavior identical (same containment test + messages). The
extraction also made `pathlib.Path` unused in both route modules (removed).
Two UAT findings:
1. The device download filename (Content-Disposition) kept emoji/symbols from the video title.
Add storage.display_filename (drops emoji/symbol/control unicode, keeps spaces + accents)
and use it for the download name — readable and clean ("…alapján!.mp4", no emoji).
2. Deleting/canceling a download removed the job but the shared MediaAsset (and its file) lingered
as cache, so 'Ready files' stayed inflated and disk wasn't freed. Rework: _release_asset drops
the hold and, once no job holds the asset, deletes the file + row immediately (the cache only
needs to span overlapping holders). Also fixes cancel never decrementing (it flipped status to
'canceled' before releasing, tripping the holding-state guard).
Verified: filename emoji-stripped; enqueue→delete removes the asset row + file from disk.
The .gitignore 'downloads/' pattern for the DOWNLOAD_ROOT bind mount also matched the
backend/app/downloads source package, so formats.py/storage.py/service.py never got
committed with M2. Anchor the ignore to '/downloads/' (repo root only) and add the package.
storage.sanitize() now handles arbitrarily messy titles (emoji, ZWJ, fullwidth, clickbait
punctuation): NFKC-normalize, drop emoji/symbol/control unicode categories, collapse
repeated punctuation, underscore-join words -> space-free paths. Accents (HU/DE) preserved,
no ASCII folding. Plex layout uses _-_ separators + Season_{year}.
