Stalest collection first. The sweep paces itself from CSFloat's own rate limit — it spends each window evenly, parks when the budget is gone, and picks up from exactly where it stopped when the window refills, so a full pass can take days without ever earning a 429. Runs only while this tab is open; results are kept in this browser, keyed by listing id, so a re-scan updates rows rather than duplicating them.
Every saved listing whose float clears the thresholds below. Change one and the whole archive is re-judged in this browser; none of it costs a CSFloat request.
These start strict, so roughly 1 saved listing in 30 counts as rare. Mirrored blocks and near-palindromes start off: switched on at their loosest they flag about half of everything.