.

wcfs/internal/xbtree/treediff.go

@@ -674,7 +674,9 @@ ABcov:
 							δtrack.Add.AddPath(bpath)
 							if nc := at.nchild; nc != 0 {
 								δtrack.δnchildNonLeafs[acOid] = nc
-							}
+								// XXX debugDiff δtrack [) ...
+							} else {
+								// adjust δtkeycov only if it was leaf bucket
 								ar := KeyRange{ac.lo, ac.hi_}
 								bc := Bv.Get(ac.lo)
 								br := KeyRange{bc.lo, bc.hi_}
@@ -683,6 +685,7 @@ ABcov:
 								debugfDiff("  δtrack - %s %v KKK\n", ar, apath)
 								debugfDiff("  δtrack + %s %v KKK\n", br, bpath)
 							}
+						}
 
 						continue
 					}
@@ -776,11 +779,17 @@ ABcov:
 					// δ <- δA
 					err = δMerge(δ, δA);	/*X*/if err != nil { return nil,nil,nil, err }
 					δtrack.Del.AddPath(a.Path())
-					// NOTE *no* δtkeycovADel change here - A keys reached in phase 2 were not originally tracked.
+					// NOTE adjust δtkeycovADel only if a was originally tracked
+					ar := KeyRange{a.lo, a.hi_}
+					_, tracked := trackSet[a.node.POid()]
+					if tracked {
+						δtkeycovADel.AddRange(ar)
+						debugfDiff("  δtrack - %s %v\n", ar, a.Path())
+					} else {
 						debugfDiff("  δtrack - [) %v\n", a.Path())
+					}
 
 					// Bkqueue <- a.range
-					ar := KeyRange{a.lo, a.hi_}
 					Akdone.AddRange(ar)
 					Bktodo(ar)