Add safe historical configuration explanations

example_test.go

@@ -134,3 +134,17 @@ func ExampleOverride() {
 	fmt.Println(result.Config.Workers, result.Sources()[0].Label, err)
 	// Output: 0 --workers <nil>
 }
+
+func ExampleResult_Explain() {
+	type Config struct {
+		Workers int `yaml:"workers"`
+	}
+	result, err := configkit.Load(configkit.Bytes("config.yml", []byte("workers: 8\n")), configkit.Options[Config]{
+		Definition: configkit.Definition[Config]{Defaults: func() Config { return Config{Workers: 4} }},
+	})
+	explanation, ok := result.Explain(configkit.Keys("workers"))
+	fmt.Printf("%s -> %s known=%t error=%v\n",
+		strings.TrimSpace(explanation.History[0].After.YAML),
+		strings.TrimSpace(explanation.Effective.YAML), ok, err)
+	// Output: 4 -> 8 known=true error=<nil>
+}