- Autoplay toggle button in the Up Next header (defaults Off, persisted
in localStorage as ytpAutoplay_solo)
- When autoplay is On and video ends (_plOnVideoEnd hook), automatically
loads the first recommended video via SPA — no page refresh
- Clicking any recommended video uses recGoTo() → recTransitionTo()
instead of window.location.href: swaps video source, resets progress
bar, updates title, then background-swaps description, channel row,
comments, and the entire sidebar with fresh recommendations from the
next page
- First card gets a red ▶ indicator while autoplay is On so the user
can see what will play next
- Browser back/forward work via popstate
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
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