Avoid redundant full scan after warm restart

docs/architecture.md

@@ -57,7 +57,8 @@ server. The daemon publishes complete folders atomically and increments a durabl
 revision; the reader polls that revision and refreshes changed manga after publication.
 The reader restores a disposable full-index snapshot at startup so browsing need not
 wait for a filesystem walk. Shallow directory stamps identify changed manga; a
-background and daily full reconciliation catches in-place manual edits.
+daily full reconciliation catches in-place manual edits. The last full-scan time
+survives restarts, so restarting does not itself force another complete walk.
 
 | Path | Lines | Responsibility |
 |------|------:|----------------|