Constant MAX_STALLED_RESUME_ATTEMPTS 

pub const MAX_STALLED_RESUME_ATTEMPTS: u32 = 3;

Consecutive resume attempts allowed at the same position before giving up.

A resume re-opens the same URL, so a server that is genuinely gone would otherwise end → resume → end forever. Progress past the last attempt resets the budget (see ResumeTracker), so this only bounds stuck retries.