Load backend smoke-test metadata

construction_contract_test.go

@@ -1,6 +1,7 @@
 package promptkit_test
 
 import (
+	"bytes"
 	"context"
 	"errors"
 	"io"
@@ -208,6 +209,66 @@ func TestPublicConstructionCanOverlayMaintainedBackend(t *testing.T) {
 	}
 }
 
+func TestBackendSourceOwnsSmokeTestValuesAndDefersDefaultLookup(t *testing.T) {
+	backendEndpoint := "https://backend.example/v1"
+	defaultProfile := "not-yet-listed"
+	reachabilityEndpoint := " https://probe.example/ready?check=1 "
+	authenticationKind := " OPENROUTER_KEY "
+	authenticationEndpoint := "https://probe.example/key?scope=current"
+	source := promptkit.BackendSource("diagnostic backend", map[string]promptkit.BackendConfig{
+		"local": {
+			Endpoint: &backendEndpoint,
+			SmokeTests: &promptkit.BackendSmokeTestConfig{
+				DefaultProfile: &defaultProfile,
+				Reachability:   &promptkit.ReachabilityProbeConfig{Endpoint: &reachabilityEndpoint},
+				Authentication: &promptkit.AuthenticationProbeConfig{
+					Kind: &authenticationKind, Endpoint: &authenticationEndpoint,
+				},
+			},
+		},
+	})
+	backendEndpoint = "https://mutated.example/v1"
+	defaultProfile = "mutated-profile"
+	reachabilityEndpoint = "https://mutated.example/ready"
+	authenticationKind = "none"
+	authenticationEndpoint = "https://mutated.example/key"
+
+	engine, err := promptkit.NewEngine(promptkit.Config{Sources: promptkit.ConfigurationSources{
+		Underlays: []configkit.Underlay{{Inputs: []configkit.Input{{Source: source}}}},
+	}})
+	if err != nil {
+		t.Fatalf("construct engine with dangling diagnostic default: %v", err)
+	}
+	inspection, err := engine.InspectConfiguration()
+	if err != nil {
+		t.Fatal(err)
+	}
+	var effective bytes.Buffer
+	if err := inspection.WriteEffective(&effective); err != nil {
+		t.Fatal(err)
+	}
+	contents := effective.String()
+	for _, want := range []string{
+		"https://backend.example/v1",
+		"not-yet-listed",
+		"https://probe.example/ready?check=1",
+		"openrouter_key",
+		"https://probe.example/key?scope=current",
+	} {
+		if !strings.Contains(contents, want) {
+			t.Errorf("effective configuration does not contain %q:\n%s", want, contents)
+		}
+	}
+	for _, unwanted := range []string{
+		"mutated.example",
+		"mutated-profile",
+	} {
+		if strings.Contains(contents, unwanted) {
+			t.Errorf("effective configuration unexpectedly contains %q:\n%s", unwanted, contents)
+		}
+	}
+}
+
 func TestPreparationRejectsAmbiguousPromptVersion(t *testing.T) {
 	definition := func(content string) map[string]any {
 		return map[string]any{