Docker report (HellRa1SeR, 2.7.8): pasting YouTube cookies threw
`ERROR: unsupported browser: "custom"`. the 'Paste cookies.txt' dropdown value is the sentinel
'custom', and youtube_client built `cookiesfrombrowser=('custom',)` from it — yt-dlp rejects
that since 'custom' isn't a browser. (server/Docker users have no local browser, so pasted
cookies.txt is the ONLY way to authenticate yt-dlp — e.g. for private 'Liked Music'.)
the correct precedence already existed in core.youtube_cookies.build_youtube_cookie_opts
('custom' -> cookiefile, browser name -> cookiesfrombrowser, falsy -> anonymous) and the web
layer used it — but youtube_client never got migrated and kept 5 inline cookiesfrombrowser
sites. route all of them through a shared _resolve_cookie_opts() that delegates to the tested
helper (reads youtube.cookies_browser + youtube.cookies_file, checks the file exists). also:
the no-cookies download retry now drops cookiefile too (not just cookiesfrombrowser), and
removed 3 now-dead config_manager imports.
3 regression tests (custom->cookiefile, browser unchanged, custom+missing-file->anonymous);
97 youtube tests green.
Private YT Music playlists (a user's Liked Music, list=LM) need auth, but the
only cookie option was cookiesfrombrowser — a browser on the same machine as
SoulSync, useless on a headless/Docker box (and locked to whatever account that
browser happens to be signed into). Add a 'Paste cookies.txt' mode so users can
supply the exact session they want from any machine.
- core/youtube_cookies.py: pure seam — build_youtube_cookie_opts (cookiefile vs
cookiesfrombrowser precedence, mutually exclusive, fail-safe on a missing file),
looks_like_cookiefile (needs a real cookie row; rejects junk/header-only),
write_pasted_cookiefile (validate + 0600 write; blank/junk never clobbers a saved file).
- _youtube_cookie_opts() delegates to the seam, so every yt-dlp call site gets it.
- /api/settings pops cookies_paste before the generic persist, validates (400 on
junk), writes config/youtube_cookies.txt, stores only the path (blob never hits config.json).
- Settings dropdown gains 'Paste cookies.txt'; selecting it reveals a textarea.
- tests/test_youtube_cookies.py: precedence, validation, fail-safe write (11 tests).
