feat(server): inline step ref + workflow validation

server/internal/services/validate.go

@@ -0,0 +1,19 @@
+package services
+
+import (
+	"fmt"
+
+	"github.com/mrhid6/vantage/server/internal/models"
+)
+
+// ValidateWorkflow checks each step ref sets exactly one of step_id / inline.
+func ValidateWorkflow(w models.Workflow) error {
+	for i, ref := range w.Steps {
+		hasLib := ref.StepID != ""
+		hasInline := ref.Inline != nil
+		if hasLib == hasInline {
+			return fmt.Errorf("step %d: exactly one of step_id or inline must be set", i)
+		}
+	}
+	return nil
+}

server/internal/services/validate_test.go

@@ -0,0 +1,29 @@
+package services
+
+import (
+	"testing"
+
+	"github.com/mrhid6/vantage/server/internal/models"
+)
+
+func TestValidateWorkflow(t *testing.T) {
+	inline := &models.WorkflowStep{Name: "x", Interpreter: "bash", Script: "echo hi"}
+	cases := []struct {
+		name    string
+		ref     models.WorkflowStepRef
+		wantErr bool
+	}{
+		{"library only", models.WorkflowStepRef{StepID: "abc"}, false},
+		{"inline only", models.WorkflowStepRef{Inline: inline}, false},
+		{"both set", models.WorkflowStepRef{StepID: "abc", Inline: inline}, true},
+		{"neither set", models.WorkflowStepRef{}, true},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			err := ValidateWorkflow(models.Workflow{Steps: []models.WorkflowStepRef{tc.ref}})
+			if (err != nil) != tc.wantErr {
+				t.Fatalf("got err=%v want wantErr=%v", err, tc.wantErr)
+			}
+		})
+	}
+}