Centralize runtime config setup

internal/app/validate_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"encoding/json"
+	"os"
 	"path/filepath"
 	"strings"
 	"testing"
@@ -183,6 +184,51 @@ pipelines:
 	}
 }
 
+func TestValidateConfiguredSourcePrintsSecretConflictWarningWithoutValues(t *testing.T) {
+	name := "DISTRIBUTOR_TEST_VALIDATE_SECRET"
+	t.Setenv(name, "process-value")
+	sourceRoot := t.TempDir()
+	destinationRoot := t.TempDir()
+	secretsRoot := t.TempDir()
+	if err := os.WriteFile(filepath.Join(secretsRoot, name), []byte("secret-value\n"), 0o600); err != nil {
+		t.Fatalf("write secret: %v", err)
+	}
+	testutil.WriteSourceBundle(t, sourceRoot, "", testutil.BundleOptions{})
+	configPath := writeConfigFile(t, `
+secrets:
+  directory: `+secretsRoot+`
+pipelines:
+  - id: reports
+    source:
+      backend: local
+      path: `+sourceRoot+`
+    destinations:
+      - id: archive
+        backend: local
+        path: `+destinationRoot+`
+`)
+
+	var stdout bytes.Buffer
+	err := Validate(context.Background(), ValidateOptions{
+		ConfigPath: configPath,
+		PipelineID: "reports",
+		Stdout:     &stdout,
+	})
+	if err != nil {
+		t.Fatalf("Validate() error = %v", err)
+	}
+	output := stdout.String()
+	if !strings.Contains(output, "secret "+name+" ignored because the real environment already has that variable") {
+		t.Fatalf("stdout = %q, want secret conflict warning", output)
+	}
+	if !strings.Contains(output, "Validated 1 bundle(s) for pipeline reports source local") {
+		t.Fatalf("stdout = %q, want validate summary", output)
+	}
+	if strings.Contains(output, "process-value") || strings.Contains(output, "secret-value") {
+		t.Fatalf("stdout exposed secret values: %q", output)
+	}
+}
+
 func TestValidateConfiguredSourceRequiresPipeline(t *testing.T) {
 	sourceRoot := t.TempDir()
 	destinationRoot := t.TempDir()