feat(client-go): accept gateway cert by default over TLS

clients/go/mxgateway/client.go

@@ -222,10 +222,24 @@ func resolveTransportCredentials(opts Options) (credentials.TransportCredentials
 		return credentials.NewTLS(cfg), nil
 	}
 
-	return credentials.NewTLS(&tls.Config{
+	return credentials.NewTLS(tlsConfigForOptions(opts)), nil
+}
+
+// tlsConfigForOptions returns the *tls.Config for the no-CA, no-custom-config TLS path.
+// It returns nil when the caller should use a different credentials path (CA file or custom TLSConfig).
+// Exposed as an internal helper so unit tests can assert the InsecureSkipVerify posture.
+func tlsConfigForOptions(opts Options) *tls.Config {
+	// CA file and custom TLSConfig take their own paths in resolveTransportCredentials.
+	if opts.CACertFile != "" || opts.TLSConfig != nil {
+		return nil
+	}
+	return &tls.Config{
 		MinVersion: tls.VersionTLS12,
 		ServerName: opts.ServerNameOverride,
-	}), nil
+		//nolint:gosec // internal tool; self-signed cert is the expected gateway default;
+		// opt-in to strict verification via RequireCertificateValidation.
+		InsecureSkipVerify: !opts.RequireCertificateValidation,
+	}
 }
 
 // OpenSessionOptions describes fields used to create an OpenSessionRequest.

clients/go/mxgateway/client_tls_test.go

@@ -0,0 +1,59 @@
+package mxgateway
+
+import (
+	"crypto/tls"
+	"testing"
+)
+
+// tlsConfigFromOptions is the internal helper under test.
+// It extracts the *tls.Config from the no-CA TLS path of resolveTransportCredentials.
+// We exercise it directly to avoid needing a real dial target.
+
+func TestTLSInsecureSkipVerify_DefaultTrue(t *testing.T) {
+	cfg := tlsConfigForOptions(Options{
+		Endpoint: "localhost:5120",
+	})
+	if cfg == nil {
+		t.Fatal("expected non-nil tls.Config")
+	}
+	if !cfg.InsecureSkipVerify {
+		t.Error("InsecureSkipVerify should be true by default when no CA is pinned")
+	}
+}
+
+func TestTLSInsecureSkipVerify_FalseWhenRequireCertificateValidation(t *testing.T) {
+	cfg := tlsConfigForOptions(Options{
+		Endpoint:                     "localhost:5120",
+		RequireCertificateValidation: true,
+	})
+	if cfg == nil {
+		t.Fatal("expected non-nil tls.Config")
+	}
+	if cfg.InsecureSkipVerify {
+		t.Error("InsecureSkipVerify should be false when RequireCertificateValidation is true")
+	}
+}
+
+func TestTLSInsecureSkipVerify_FalseWhenCACertFileSet(t *testing.T) {
+	// When a CA file is pinned, the CA-verification path is taken instead.
+	// tlsConfigForOptions should return nil (the CA path does not use our helper).
+	cfg := tlsConfigForOptions(Options{
+		Endpoint:   "localhost:5120",
+		CACertFile: "/some/ca.pem",
+	})
+	if cfg != nil {
+		t.Error("expected nil tls.Config when CACertFile is set (CA path taken)")
+	}
+}
+
+func TestTLSInsecureSkipVerify_FalseWhenCustomTLSConfig(t *testing.T) {
+	// When TLSConfig is supplied explicitly, our default skip-verify must not overwrite it.
+	custom := &tls.Config{MinVersion: tls.VersionTLS13}
+	cfg := tlsConfigForOptions(Options{
+		Endpoint:  "localhost:5120",
+		TLSConfig: custom,
+	})
+	if cfg != nil {
+		t.Error("expected nil tls.Config when TLSConfig is already set (custom config path taken)")
+	}
+}

clients/go/mxgateway/options.go

@@ -34,6 +34,10 @@ type Options struct {
 	TransportCredentials credentials.TransportCredentials
 	// DialOptions are appended to the gRPC dial options after the defaults.
 	DialOptions []grpc.DialOption
+	// RequireCertificateValidation forces TLS certificate verification even when
+	// no CACertFile is pinned. Default false: the gateway's self-signed cert is
+	// accepted without verification (internal-tool posture).
+	RequireCertificateValidation bool
 }
 
 // BrowseChildrenOptions configures lazy Galaxy hierarchy walks performed by