.

wcfs/internal/xbtree/treediff.go

@@ -751,11 +751,10 @@ ABcov:
 					b.done = true
 				}
 
-				// stop if r coverage is complete
+				// continue with next right bucket until r coverage is complete
 				if r.hi_ <= b.hi_ {
 					break
 				}
-				// continue with next right bucket
 				lo = b.hi_ + 1
 			}
 		}

wcfs/internal/xbtree/δbtail.go

@@ -234,6 +234,7 @@ func (δBtail *ΔBtail) Tail() zodb.Tid { return δBtail.δZtail.Tail() }
 // XXX path -> []oid ?
 //
 // XXX catch cycles on add?
+// XXX no need to pass in key
 func (δBtail *ΔBtail) Track(key Key, nodePath []Node) error { // XXX Tree|Bucket; path[0] = root
 
 	path := nodePathToPath(nodePath)
@@ -339,20 +340,37 @@ func (δTtail *ΔTtail) rebuild(δZtail *zodb.ΔTail, db *zodb.DB) (δtrackSet P
 			// XXX update .KVAtTail, .lastRevOf
 		}
 
-		// an iteration closer to tail may turn out to add a key to the tracking set
-		// we have to recheck all entries past that revision for changes to that key
+		// an iteration closer to tail may turn out to add a key to the tracking set.
+		// We have to recheck all entries newer that revision for changes to that key
 		// for example:
 		//
 		//	XXX
 		//
-		// restart from head and cycle until set of tracked keys does not grow anymore
+		// Implement this via restarting from head and cycling until
+		// set of tracked keys does not grow anymore.
 		if δtkeycov.Empty() {
 			break
 		}
 
+		top := &nodeInRange{prefix: nil, lo: KeyMin, hi_: KeyMax, node: root}
+		V   := rangeSplit{top}
 		for _, r := δtkeycov.AllRanges() {
+			lo := r.lo
+			for {
+				b, err := V.GetToLeaf(ctx, lo)
+				if err != nil {
+					return nil, err
+				}
+
+				trackNew.AddPath(b.Path())
+
+				// continue with next right bucket until r coverage is complete
+				if r.hi_ <= b.hi_ {
+					break
+				}
+				lo = b.hi_ + 1
+			}
 		}
-
 	}