.

wcfs/δbtail.go

@@ -246,10 +246,7 @@ func (δBtail *ΔBtail) Track(key Key, keyPresent bool, path []Node, flags Track
 		// XXX check for InvalidOid  (e.g. T/B1:a with bucket not having its own oid.
 		track, ok := δBtail.trackIdx[oid]
 		if !ok {
-			track = nodeTrack{parent: parent}
-			if parent != zodb.InvalidOid {
-				track.trackedKeys = SetKey{}
-			}
+			track = nodeTrack{parent: parent, trackedKeys: SetKey{}}
 			δBtail.trackIdx[oid] = track
 			// XXX .trackNew += oid
 		}
@@ -528,6 +525,9 @@ func diffT(ctx context.Context, a, b *Tree, δZTC SetOid, trackIdx map[zodb.Oid]
 		}
 		δtqkeys.Update(track.trackedKeys)
 	}
+	if a != nil && len(av) == 0 { // ø tree - fetch tracked keys from it directly
+		δtqkeys.Update(trackIdx[a.POid()].trackedKeys)
+	}
 	fmt.Printf("  δtqkeys:   %s\n", δtqkeys)
 
 	// b -> {bChildren} : coverage ∩ "might be changed" tracked keys