filer.remote.sync: take the start time before the mount lookup

A bucket created between a not-found lookup and the end of the offset
read had its creation before a start taken afterwards, so the gateway
never created its remote bucket.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

weed/command/filer_remote_sync_dir.go

@@ -1108,6 +1108,7 @@ func collectLastSyncOffset(filerClient filer_pb.FilerClient, grpcDialOption grpc
 // retry loop instead of skipping every event since the failure. Only a
 // directory that does not exist yet, with no saved offset, starts now.
 func resolveLastSyncOffset(mountedDir string, timeAgo time.Duration, lookupMount func() (*filer_pb.Entry, error), readOffset func() (int64, error)) (time.Time, error) {
+	startedAt := time.Now()
 	var lastOffsetTs time.Time
 	if timeAgo == 0 {
 		mountedDirEntry, err := lookupMount()
@@ -1118,7 +1119,7 @@ func resolveLastSyncOffset(mountedDir string, timeAgo time.Duration, lookupMount
 				return time.Unix(0, lastOffsetTsNs), nil
 			}
 			if offsetErr == nil && errors.Is(err, filer_pb.ErrNotFound) {
-				return time.Now(), nil
+				return startedAt, nil
 			}
 			return time.Time{}, fmt.Errorf("get mounted directory %s: %w; no saved sync offset (%v)", mountedDir, err, offsetErr)
 		}
@@ -1135,10 +1136,10 @@ func resolveLastSyncOffset(mountedDir string, timeAgo time.Duration, lookupMount
 				lastOffsetTs = time.Unix(mountedDirEntry.Attributes.Crtime, 0)
 			}
 		} else {
-			lastOffsetTs = time.Now()
+			lastOffsetTs = startedAt
 		}
 	} else {
-		lastOffsetTs = time.Now().Add(-timeAgo)
+		lastOffsetTs = startedAt.Add(-timeAgo)
 		lastOffsetTsNs, err := readOffset()
 		if err != nil {
 			// an unread offset must not resolve to now minus timeAgo: the

weed/command/filer_remote_sync_dir_test.go

@@ -670,11 +670,17 @@ func TestResolveLastSyncOffsetReturnsTheErrorToTheRetryLoop(t *testing.T) {
 		t.Fatalf("got %v, want the lookup error: without a saved offset the caller's retry loop decides, not an exit", err)
 	}
 
-	// no directory and no saved offset yet: a first run starts now
+	// no directory and no saved offset yet: a first run starts no later than
+	// the lookup, so a bucket created while the offset is read is replayed
 	started := time.Now()
-	notFound := func() (*filer_pb.Entry, error) { return nil, fmt.Errorf("lookup /buckets: %w", filer_pb.ErrNotFound) }
-	if got, err := resolveLastSyncOffset("/buckets", 0, notFound, noOffset); err != nil || got.Before(started) {
-		t.Fatalf("got %v, %v; want now and no error before the directory exists", got, err)
+	var lookedUp time.Time
+	notFound := func() (*filer_pb.Entry, error) {
+		lookedUp = time.Now()
+		return nil, fmt.Errorf("lookup /buckets: %w", filer_pb.ErrNotFound)
+	}
+	slowNoOffset := func() (int64, error) { time.Sleep(10 * time.Millisecond); return 0, nil }
+	if got, err := resolveLastSyncOffset("/buckets", 0, notFound, slowNoOffset); err != nil || got.Before(started) || got.After(lookedUp) {
+		t.Fatalf("got %v, %v; want a start between %v and the lookup at %v", got, err, started, lookedUp)
 	}
 
 	// the mount answers but the saved offset is unreadable: never its creation time