chore: configure gin mode

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pkg/config/config_test.go

@@ -179,3 +179,54 @@ func TestLoadAppliesFileEnvironmentOverride(t *testing.T) {
 		t.Fatalf("got %d", cfg.File.MaxWriteBytes)
 	}
 }
+
+func TestDefaultIncludesGinConfig(t *testing.T) {
+	cfg := Default()
+	if cfg.Gin.Mode != "release" {
+		t.Fatalf("Gin.Mode = %q, want release", cfg.Gin.Mode)
+	}
+}
+
+func TestLoadParsesGinConfigFromYAML(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.yaml")
+	data := []byte(`gin:
+  mode: "debug"
+`)
+	if err := os.WriteFile(path, data, 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	cfg, err := Load(path)
+	if err != nil {
+		t.Fatalf("Load returned error: %v", err)
+	}
+	if cfg.Gin.Mode != "debug" {
+		t.Fatalf("Gin.Mode = %q, want debug", cfg.Gin.Mode)
+	}
+}
+
+func TestLoadAppliesGinModeEnvironmentOverride(t *testing.T) {
+	t.Setenv("CODESPACE_GIN_MODE", "test")
+	cfg, err := Load(filepath.Join(t.TempDir(), "missing.yaml"))
+	if err != nil {
+		t.Fatalf("Load returned error: %v", err)
+	}
+	if cfg.Gin.Mode != "test" {
+		t.Fatalf("Gin.Mode = %q, want test", cfg.Gin.Mode)
+	}
+}
+
+func TestLoadRejectsInvalidGinMode(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "config.yaml")
+	data := []byte(`gin:
+  mode: "verbose"
+`)
+	if err := os.WriteFile(path, data, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := Load(path); err == nil {
+		t.Fatal("expected invalid gin mode error")
+	}
+}