HISTORY_REACH_KINDS

const HISTORY_REACH_KINDS: readonly ["full", "window", "recent-only"];

How much of an upstream’s history is reachable at all.

A property of the upstream, not of the adapter: window is an RSS feed carrying its publisher’s most recent N posts, recent-only is a headline feed holding roughly a day, and full is an archive that can be walked to the beginning. Recorded so a stalled backfill can be explained rather than retried against a wall.