1 files changed, 30 insertions, 12 deletions

diff --git a/internal/engine/property_test.go b/internal/engine/property_test.go
index 39589da..135c20a 100644
--- a/internal/engine/property_test.go
+++ b/internal/engine/property_test.go
@@ -102,27 +102,41 @@ func propertySeeds(t *testing.T) []int64 {
 // chain loses no content - every file's content is still somewhere under
 // the home directory, the Trash included - and undoing the run then puts
 // the home directory back exactly: every file's content, mode and
-// modification time, and nothing extra. A failing subtest names its seed.
+// modification time, every directory, and nothing extra. A failing subtest
+// names its seed. It also fails when fewer than half the cases applied
+// anything, so a broken Apply cannot make it pass vacuously (review undo
+// F7).
 func TestApplyUndoProperty(t *testing.T) {
-	for _, seed := range propertySeeds(t) {
+	seeds := propertySeeds(t)
+	applied := 0
+	for _, seed := range seeds {
 		t.Run(fmt.Sprintf("seed=%d", seed), func(t *testing.T) {
-			checkApplyUndo(t, genCase(rand.New(rand.NewSource(seed))))
+			if checkApplyUndo(t, genCase(rand.New(rand.NewSource(seed)))) {
+				applied++
+			}
 		})
 	}
+	if len(seeds) >= 20 && applied*2 < len(seeds) {
+		t.Errorf("only %d of %d cases applied anything; the property is not being exercised", applied, len(seeds))
+	}
 }
 
-// contentCounts counts the files of a snapshot by content hash.
+// contentCounts counts the files of a snapshot by content hash; directory
+// entries have no content and are not counted.
 func contentCounts(snap map[string]string) map[string]int {
 	counts := map[string]int{}
 	for _, v := range snap {
-		counts[strings.Fields(v)[0]]++
+		if v != "dir" {
+			counts[strings.Fields(v)[0]]++
+		}
 	}
 	return counts
 }
 
 // checkApplyUndo builds c in a sandbox, applies every chain, checks nothing
-// was lost, undoes the run and checks the home directory is as it was.
-func checkApplyUndo(t *testing.T, c propertyCase) {
+// was lost, undoes the run and checks the home directory - files and
+// directories - is as it was. It reports whether any file was applied.
+func checkApplyUndo(t *testing.T, c propertyCase) bool {
 	h := sandbox(t)
 	old := time.Date(2026, 3, 1, 12, 0, 0, 0, time.UTC)
 	put := func(p, body string) {
@@ -147,12 +161,15 @@ func checkApplyUndo(t *testing.T, c propertyCase) {
 		put(filepath.Join(h, rel), body)
 	}
 	main := writeConfig(t, h, `(include "dl")`, map[string]string{"dl": c.rules})
-	// userTree is the home directory without krino's own config and state.
+	// userTree is the home directory, files and directories, without
+	// krino's own config, state, Trash and cache.
 	userTree := func() map[string]string {
-		snap := snapshot(t, h)
+		snap := treeSnapshot(t, h)
 		for rel := range snap {
-			if strings.HasPrefix(rel, ".config/") || strings.HasPrefix(rel, ".local/") {
-				delete(snap, rel)
+			for _, own := range []string{".config/", ".local/", ".cache/"} {
+				if strings.HasPrefix(rel, own) {
+					delete(snap, rel)
+				}
 			}
 		}
 		return snap
@@ -193,7 +210,7 @@ func checkApplyUndo(t *testing.T, c propertyCase) {
 		if after := userTree(); !reflect.DeepEqual(after, before) {
 			t.Fatalf("nothing was applied, yet the tree changed")
 		}
-		return
+		return false
 	}
 
 	have := contentCounts(snapshot(t, h))
@@ -236,4 +253,5 @@ func checkApplyUndo(t *testing.T, c propertyCase) {
 			}
 		}
 	}
+	return true
 }