fix(api): harden SDK generator inputs

Co-Authored-By: Virgil <virgil@lethean.io>

codegen.go

@@ -11,6 +11,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"slices"
+	"strings"
 
 	coreio "dappco.re/go/core/io"
 	coreerr "dappco.re/go/core/log"
@@ -54,20 +55,40 @@ type SDKGenerator struct {
 //
 //	err := gen.Generate(context.Background(), "go")
 func (g *SDKGenerator) Generate(ctx context.Context, language string) error {
+	if g == nil {
+		return coreerr.E("SDKGenerator.Generate", "generator is nil", nil)
+	}
+	if ctx == nil {
+		return coreerr.E("SDKGenerator.Generate", "context is nil", nil)
+	}
+
+	language = strings.TrimSpace(language)
 	generator, ok := supportedLanguages[language]
 	if !ok {
 		return coreerr.E("SDKGenerator.Generate", fmt.Sprintf("unsupported language %q: supported languages are %v", language, SupportedLanguages()), nil)
 	}
 
-	if _, err := os.Stat(g.SpecPath); os.IsNotExist(err) {
-		return coreerr.E("SDKGenerator.Generate", "spec file not found: "+g.SpecPath, nil)
+	specPath := strings.TrimSpace(g.SpecPath)
+	if specPath == "" {
+		return coreerr.E("SDKGenerator.Generate", "spec path is required", nil)
+	}
+	if _, err := os.Stat(specPath); err != nil {
+		if os.IsNotExist(err) {
+			return coreerr.E("SDKGenerator.Generate", "spec file not found: "+specPath, nil)
+		}
+		return coreerr.E("SDKGenerator.Generate", "stat spec file", err)
+	}
+
+	outputBase := strings.TrimSpace(g.OutputDir)
+	if outputBase == "" {
+		return coreerr.E("SDKGenerator.Generate", "output directory is required", nil)
 	}
 
 	if !g.Available() {
 		return coreerr.E("SDKGenerator.Generate", "openapi-generator-cli not installed", nil)
 	}
 
-	outputDir := filepath.Join(g.OutputDir, language)
+	outputDir := filepath.Join(outputBase, language)
 	if err := coreio.Local.EnsureDir(outputDir); err != nil {
 		return coreerr.E("SDKGenerator.Generate", "create output directory", err)
 	}

codegen_test.go

@@ -59,6 +59,67 @@ func TestSDKGenerator_Bad_MissingSpec(t *testing.T) {
 	}
 }
 
+func TestSDKGenerator_Bad_EmptySpecPath(t *testing.T) {
+	gen := &api.SDKGenerator{
+		OutputDir: t.TempDir(),
+	}
+
+	err := gen.Generate(context.Background(), "go")
+	if err == nil {
+		t.Fatal("expected error for empty spec path, got nil")
+	}
+	if !strings.Contains(err.Error(), "spec path is required") {
+		t.Fatalf("expected error to contain 'spec path is required', got: %v", err)
+	}
+}
+
+func TestSDKGenerator_Bad_EmptyOutputDir(t *testing.T) {
+	specDir := t.TempDir()
+	specPath := filepath.Join(specDir, "spec.json")
+	if err := os.WriteFile(specPath, []byte(`{"openapi":"3.1.0"}`), 0o644); err != nil {
+		t.Fatalf("failed to write spec file: %v", err)
+	}
+
+	gen := &api.SDKGenerator{
+		SpecPath: specPath,
+	}
+
+	err := gen.Generate(context.Background(), "go")
+	if err == nil {
+		t.Fatal("expected error for empty output directory, got nil")
+	}
+	if !strings.Contains(err.Error(), "output directory is required") {
+		t.Fatalf("expected error to contain 'output directory is required', got: %v", err)
+	}
+}
+
+func TestSDKGenerator_Bad_NilContext(t *testing.T) {
+	gen := &api.SDKGenerator{
+		SpecPath:  filepath.Join(t.TempDir(), "nonexistent.json"),
+		OutputDir: t.TempDir(),
+	}
+
+	err := gen.Generate(nil, "go")
+	if err == nil {
+		t.Fatal("expected error for nil context, got nil")
+	}
+	if !strings.Contains(err.Error(), "context is nil") {
+		t.Fatalf("expected error to contain 'context is nil', got: %v", err)
+	}
+}
+
+func TestSDKGenerator_Bad_NilReceiver(t *testing.T) {
+	var gen *api.SDKGenerator
+
+	err := gen.Generate(context.Background(), "go")
+	if err == nil {
+		t.Fatal("expected error for nil generator, got nil")
+	}
+	if !strings.Contains(err.Error(), "generator is nil") {
+		t.Fatalf("expected error to contain 'generator is nil', got: %v", err)
+	}
+}
+
 func TestSDKGenerator_Bad_MissingGenerator(t *testing.T) {
 	t.Setenv("PATH", t.TempDir())