Replay added configuration paths in explanations

explain_test.go

@@ -365,3 +365,48 @@ func TestExplanationReconcilesDefaultsAfterInputReplacement(t *testing.T) {
 		}
 	}
 }
+
+func TestExplanationReplaysResolutionAdditionsAndOverlappingIntent(t *testing.T) {
+	type cfg struct {
+		M map[string]any `yaml:"m"`
+	}
+	for _, overlap := range []bool{false, true} {
+		t.Run(fmt.Sprint(overlap), func(t *testing.T) {
+			result, err := Load(Bytes("base", []byte("m: {old: 1}\n")), Options[cfg]{Definition: Definition[cfg]{Resolve: func(c *cfg, r *Resolution) error {
+				c.M["new"] = map[string]any{"child": int64(7)}
+				delete(c.M, "old")
+				r.Record(Keys("m", "new"), ChangeDerivedDefault, "add nested", Keys("m", "old"))
+				r.Record(Keys("m", "old"), ChangeNormalization, "remove old")
+				if overlap {
+					r.Record(Keys("m"), ChangeNormalization, "update container")
+				}
+				return nil
+			}}})
+			if err != nil {
+				t.Fatal(err)
+			}
+			for _, path := range []Path{Keys("m"), Keys("m", "new"), Keys("m", "new", "child"), Keys("m", "old")} {
+				x, ok := result.Explain(path)
+				if !ok {
+					t.Fatal("missing known history")
+				}
+				var count int
+				for _, v := range x.History {
+					if v.Origin.Layer == LayerResolution {
+						count++
+						if overlap && len(v.Reasons) != 3 {
+							t.Fatal("lost overlapping intent")
+						}
+					}
+				}
+				if overlap && count != 1 {
+					t.Fatalf("overlapping records applied %d times", count)
+				}
+				last := x.History[len(x.History)-1]
+				if last.After != x.Effective {
+					t.Fatalf("incorrect replay for %s: %#v", path, x)
+				}
+			}
+		})
+	}
+}