YouTube gates media formats behind signature / "n" JS challenges that
yt-dlp's bundled solver can't reliably crack. Without the EJS
remote-component solver script yt-dlp warns "Signature/n challenge
solving failed: Some formats may be missing" and downloads break — even
with valid cookies, so it masquerades as a cookie/auth problem.
Pass --remote-components ejs:github by default (env/CLI overridable) on
all four yt-dlp call sites. Needs a recent yt-dlp + deno present; set
YTDLP_REMOTE_COMPONENTS / --remote-components '' to disable.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>