Add opt-in configuration overrides

integrations/ckprompt/examples/composed/main.go

@@ -32,8 +32,9 @@ type inspectionInput struct {
 }
 
 type applicationCacheKey struct {
-	selection ckconfig.Selection
-	campaign  commandkit.Supplied[string]
+	config   commandkit.Supplied[string]
+	overlay  commandkit.Supplied[string]
+	campaign commandkit.Supplied[string]
 }
 
 // runCache belongs to one invocation and is shared only where the application
@@ -80,7 +81,7 @@ func loadApplicationConfig(ctx context.Context, selection ckconfig.Selection, in
 	if input != nil {
 		campaignInput = input.Campaign
 	}
-	key := applicationCacheKey{selection: selection, campaign: campaignInput}
+	key := applicationCacheKey{config: selection.Config, overlay: selection.Overlay, campaign: campaignInput}
 	if cache != nil {
 		if cached, ok := cache.applications[key]; ok {
 			return cached, nil

integrations/ckprompt/examples/composed/main_test.go

@@ -266,7 +266,7 @@ func TestBuildValidationRequestDefaultsOnlyAbsentVariables(t *testing.T) {
 	if !reflect.DeepEqual(got.Inputs, inputs) || !reflect.DeepEqual(seed.Request.Vars, explicit) {
 		t.Fatalf("seed bindings changed: built=%#v seed=%#v", got.Inputs, explicit)
 	}
-	key := applicationCacheKey{selection: seed.Selection, campaign: input.Campaign}
+	key := applicationCacheKey{config: seed.Selection.Config, overlay: seed.Selection.Overlay, campaign: input.Campaign}
 	cached := cache.applications[key]
 	if cached == nil {
 		t.Fatal("builder did not load application configuration into invocation state")