Prepare coalesced resolution replay

internal/engine/explain_test.go

@@ -520,3 +520,49 @@ func TestExplanationReplaysResolutionAdditionsAndOverlappingIntent(t *testing.T)
 		})
 	}
 }
+
+func TestExplanationReplayDescriptorsRemainDetachedAcrossQueries(t *testing.T) {
+	type config struct {
+		Count int `yaml:"count"`
+	}
+	result, err := testLoad(Bytes("resolution-explanation.yml", []byte("count: 1\n")), Options[config]{
+		Definition: Definition[config]{Resolve: func(value *config, resolution *Resolution) error {
+			value.Count = 2
+			resolution.Record(Keys("count"), ChangeNormalization, "normalized", Keys("count"))
+			return nil
+		}},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	first, ok := result.Explain(Keys("count"))
+	if !ok {
+		t.Fatal("missing explanation")
+	}
+	var firstResolution *ValueChange
+	for index := range first.History {
+		if first.History[index].Origin.Layer == LayerResolution {
+			firstResolution = &first.History[index]
+			break
+		}
+	}
+	if firstResolution == nil || len(firstResolution.Reasons) != 1 || len(firstResolution.Dependencies) != 1 {
+		t.Fatalf("resolution history = %#v", first.History)
+	}
+	firstResolution.Reasons[0] = "mutated"
+	firstResolution.Dependencies[0].segments[0].key = "mutated"
+
+	second, ok := result.Explain(Keys("count"))
+	if !ok {
+		t.Fatal("missing repeated explanation")
+	}
+	for _, change := range second.History {
+		if change.Origin.Layer == LayerResolution {
+			if !reflect.DeepEqual(change.Reasons, []string{"normalized"}) || len(change.Dependencies) != 1 || change.Dependencies[0].String() != "/count" {
+				t.Fatalf("repeated explanation observed caller mutation: %#v", change)
+			}
+			return
+		}
+	}
+	t.Fatalf("resolution change missing from repeated explanation: %#v", second.History)
+}