feat(googeai): add withBaseURL func option

llms/googleai/googleai_test.go

@@ -168,6 +168,35 @@ func TestGoogleAIGenerateContentWithSystemMessage(t *testing.T) {
 	assert.NotEmpty(t, resp.Choices)
 }
 
+func TestGoogleAIGenerateContentWithCustomBaseURL(t *testing.T) {
+	// This proves the option is accepted and doesn't break the SDK's path construction.
+	officialBaseURL := "https://generativelanguage.googleapis.com"
+
+	llm := newHTTPRRClient(t, WithBaseURL(officialBaseURL))
+
+	ctx := context.Background()
+	content := []llms.MessageContent{
+		{
+			Role: llms.ChatMessageTypeHuman,
+			Parts: []llms.ContentPart{
+				llms.TextPart("Hey! How are you doing?"),
+			},
+		},
+	}
+
+	resp, err := llm.GenerateContent(ctx, content)
+	if err != nil {
+		// Check if this is a recording mismatch error
+		if strings.Contains(err.Error(), "cached HTTP response not found") {
+			t.Skip("Recording format has changed or is incompatible. Hint: Re-run tests with -httprecord=. to record new HTTP interactions")
+		}
+		require.NoError(t, err)
+	}
+
+	require.NoError(t, err)
+	require.NotNil(t, resp)
+}
+
 func TestGoogleAICall(t *testing.T) {
 
 	llm := newHTTPRRClient(t)

llms/googleai/googleai_unit_test.go

@@ -138,6 +138,12 @@ func TestOptions(t *testing.T) { //nolint:funlen // comprehensive test //nolint:
 		assert.Len(t, opts.ClientOptions, 1)
 	})
 
+	t.Run("WithBaseURL", func(t *testing.T) {
+		opts := &Options{}
+		WithBaseURL("https://custom.endpoint.com")(opts)
+		assert.Len(t, opts.ClientOptions, 1)
+	})
+
 	t.Run("WithHTTPClient", func(t *testing.T) {
 		opts := &Options{}
 		WithHTTPClient(nil)(opts)

llms/googleai/option.go

@@ -92,6 +92,16 @@ func WithRest() Option {
 	}
 }
 
+// WithBaseURL appends a ClientOption that configures the underlying Google AI
+// client to use a custom base URL (endpoint). This is useful for directing
+// requests to proxy servers, local development environments, or alternative
+// regional endpoints not automatically handled by the default client setup.
+func WithBaseURL(baseURL string) Option {
+	return func(opts *Options) {
+		opts.ClientOptions = append(opts.ClientOptions, option.WithEndpoint(baseURL))
+	}
+}
+
 // WithHTTPClient append a ClientOption that uses the provided HTTP client to
 // make requests.
 // This is useful for vertex clients.