Mini-epic "Downloads correctness & UX" (S1–S3), on top of the iOS-AV1 + 720p fixes.
S1 — naming & titles:
- ASCII-fold on-disk dir/file names AND the served (Content-Disposition) filename: no
spaces (underscore-joined), no accents (á→a, ő→o, ß→ss), pure ASCII — portable and free
of the `?` mojibake accented names show in non-UTF-8 tools. (Forward-only; existing files
clean up via re-download.)
- Strip a leading social engagement prefix ("1.6M views · 66K reactions | …") from titles.
S2 — universal browser playability (generalizes the iOS re-encode):
- ensure_browser_playable guarantees the stored file is H.264 + AAC/MP3 in mp4 — the only
combo every browser decodes. Re-encode just the offending stream(s) (video for AV1/VP9/HEVC,
audio for Opus/etc), or remux when only the container is wrong. Gated on the mp4 compat
profile (an explicit vcodec / non-mp4 custom profile opts out).
S3 — force re-download (preserves share links):
- POST /downloads/{job_id}/redownload keeps the job row so its public DownloadLink survives
and resolves to the freshly-downloaded file; deletes the old file and re-fetches under the
current rules. A failed re-download leaves the job in error (the intended broken-link case).
- Library "Re-download" action (icon + confirm), api method, hu/en strings.
Tests: naming/title-strip (test_naming), browser_transcode_flags matrix; existing
download_filename expectation updated for the underscore policy.