New extension/lib/repoScan.ts resolves the target DID's PDS via its didDoc, calls com.atproto.repo.describeRepo, and returns the set of collection NSIDs on the repo. Results cached in chrome.storage.local keyed by DID with a 1h TTL (LRU-capped at 50 entries). Popup's Ready view fires the scan when pdsRecordScan is enabled, then hands the resulting Set down to each WaypointButton plus the recommendedForType ranking pass: - Confirmed-present waypoints sort to the top of the "Recommended" section (and inside any user-defined group). - Absent waypoints render dimmed with a "No records found on this repo" caption (still clickable — the dimming explains itself without locking the user out of the link). - Unknown waypoints render as before. Cached collections render immediately on warm cache opens; the live scan refreshes in the background without flicker. Profiles that arrive without a DID get one resolveHandleToDid call up-front so the scan can proceed.