Avoid redundant full scan after warm restart

docs/import.md

@@ -33,6 +33,11 @@ MangaCircus does not copy or convert anything. "Import" means **indexing the lib
 | **Rescan** (Settings → Admin, or `POST /api/admin/rescan {}`) | On demand; the request returns when the scan is done | used |
 | **Full rescan** (`POST /api/admin/rescan {"full":true}`) | On demand | ignored: every image header is read again |
 
+The saved index records when its last full reconciliation finished. A warm restart
+does a shallow check but does not reset the daily full-scan clock; if that scan is
+overdue, the reader schedules it within a minute. Set `FULL_SCAN_INTERVAL=0` to
+disable automatic full reconciliations, while retaining admin Rescan.
+
 Scans are **single-flight**. A trigger during a scan queues one coalesced follow-up,
 with a full reconciliation taking precedence over a shallow check. Publication
 revisions trigger a shallow check; if no changed directory is visible, the reader