feat(google-genai): add Gemini Text-to-Speech (TTS) implementation

auto-configurations/models/spring-ai-autoconfigure-model-google-genai/src/main/java/org/springframework/ai/model/google/genai/autoconfigure/tts/GoogleGenAiTtsAutoConfiguration.java

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2023-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.ai.model.google.genai.autoconfigure.tts;
+
+import org.springframework.ai.google.genai.tts.GeminiTtsModel;
+import org.springframework.ai.google.genai.tts.api.GeminiTtsApi;
+import org.springframework.ai.model.SpringAIModelProperties;
+import org.springframework.ai.model.SpringAIModels;
+import org.springframework.ai.retry.autoconfigure.SpringAiRetryAutoConfiguration;
+import org.springframework.boot.autoconfigure.AutoConfiguration;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
+import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.context.annotation.Bean;
+import org.springframework.core.retry.RetryTemplate;
+import org.springframework.util.Assert;
+import org.springframework.util.StringUtils;
+
+/**
+ * Auto-configuration for Google GenAI Text-to-Speech.
+ *
+ * @author Alexandros Pappas
+ * @since 1.1.0
+ */
+@AutoConfiguration(after = SpringAiRetryAutoConfiguration.class)
+@ConditionalOnClass({ GeminiTtsApi.class, GeminiTtsModel.class })
+@ConditionalOnProperty(name = SpringAIModelProperties.AUDIO_SPEECH_MODEL, havingValue = SpringAIModels.GOOGLE_GEN_AI,
+		matchIfMissing = false)
+@EnableConfigurationProperties({ GoogleGenAiTtsProperties.class, GoogleGenAiTtsConnectionProperties.class })
+public class GoogleGenAiTtsAutoConfiguration {
+
+	@Bean
+	@ConditionalOnMissingBean
+	public GeminiTtsApi geminiTtsApi(GoogleGenAiTtsConnectionProperties connectionProperties) {
+		Assert.hasText(connectionProperties.getApiKey(), "Google GenAI API key must be set!");
+
+		if (StringUtils.hasText(connectionProperties.getBaseUrl())) {
+			return new GeminiTtsApi(connectionProperties.getApiKey(), connectionProperties.getBaseUrl());
+		}
+
+		return new GeminiTtsApi(connectionProperties.getApiKey());
+	}
+
+	@Bean
+	@ConditionalOnMissingBean
+	public GeminiTtsModel geminiTtsModel(GeminiTtsApi geminiTtsApi, GoogleGenAiTtsProperties ttsProperties,
+			RetryTemplate retryTemplate) {
+
+		return GeminiTtsModel.builder()
+			.geminiTtsApi(geminiTtsApi)
+			.defaultOptions(ttsProperties.getOptions())
+			.retryTemplate(retryTemplate)
+			.build();
+	}
+
+}

auto-configurations/models/spring-ai-autoconfigure-model-google-genai/src/main/java/org/springframework/ai/model/google/genai/autoconfigure/tts/GoogleGenAiTtsConnectionProperties.java

@@ -0,0 +1,58 @@
+/*
+ * Copyright 2023-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.ai.model.google.genai.autoconfigure.tts;
+
+import org.springframework.boot.context.properties.ConfigurationProperties;
+
+/**
+ * Connection properties for Google GenAI TTS.
+ *
+ * @author Alexandros Pappas
+ * @since 1.1.0
+ */
+@ConfigurationProperties(GoogleGenAiTtsConnectionProperties.CONFIG_PREFIX)
+public class GoogleGenAiTtsConnectionProperties {
+
+	public static final String CONFIG_PREFIX = "spring.ai.google.genai";
+
+	/**
+	 * Google GenAI API Key for TTS.
+	 */
+	private String apiKey;
+
+	/**
+	 * Base URL for the Google GenAI TTS API.
+	 */
+	private String baseUrl = "https://generativelanguage.googleapis.com";
+
+	public String getApiKey() {
+		return this.apiKey;
+	}
+
+	public void setApiKey(String apiKey) {
+		this.apiKey = apiKey;
+	}
+
+	public String getBaseUrl() {
+		return this.baseUrl;
+	}
+
+	public void setBaseUrl(String baseUrl) {
+		this.baseUrl = baseUrl;
+	}
+
+}

auto-configurations/models/spring-ai-autoconfigure-model-google-genai/src/main/java/org/springframework/ai/model/google/genai/autoconfigure/tts/GoogleGenAiTtsProperties.java

@@ -0,0 +1,51 @@
+/*
+ * Copyright 2025-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.ai.model.google.genai.autoconfigure.tts;
+
+import org.springframework.ai.google.genai.tts.GeminiTtsOptions;
+import org.springframework.boot.context.properties.ConfigurationProperties;
+import org.springframework.boot.context.properties.NestedConfigurationProperty;
+
+/**
+ * Configuration properties for Google GenAI Text-to-Speech.
+ *
+ * @author Alexandros Pappas
+ * @since 1.1.0
+ */
+@ConfigurationProperties(GoogleGenAiTtsProperties.CONFIG_PREFIX)
+public class GoogleGenAiTtsProperties {
+
+	public static final String CONFIG_PREFIX = "spring.ai.google.genai.tts";
+
+	public static final String DEFAULT_MODEL = "gemini-2.5-flash-preview-tts";
+
+	public static final String DEFAULT_VOICE = "Kore";
+
+	/**
+	 * Google GenAI TTS options.
+	 */
+	@NestedConfigurationProperty
+	private final GeminiTtsOptions options = GeminiTtsOptions.builder()
+		.model(DEFAULT_MODEL)
+		.voice(DEFAULT_VOICE)
+		.build();
+
+	public GeminiTtsOptions getOptions() {
+		return this.options;
+	}
+
+}

auto-configurations/models/spring-ai-autoconfigure-model-google-genai/src/main/resources/META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports

@@ -16,3 +16,4 @@
 org.springframework.ai.model.google.genai.autoconfigure.chat.GoogleGenAiChatAutoConfiguration
 org.springframework.ai.model.google.genai.autoconfigure.embedding.GoogleGenAiEmbeddingConnectionAutoConfiguration
 org.springframework.ai.model.google.genai.autoconfigure.embedding.GoogleGenAiTextEmbeddingAutoConfiguration
+org.springframework.ai.model.google.genai.autoconfigure.tts.GoogleGenAiTtsAutoConfiguration

auto-configurations/models/spring-ai-autoconfigure-model-google-genai/src/test/java/org/springframework/ai/model/google/genai/autoconfigure/tts/GoogleGenAiTtsAutoConfigurationIT.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright 2025-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.ai.model.google.genai.autoconfigure.tts;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.condition.EnabledIfEnvironmentVariable;
+
+import org.springframework.ai.google.genai.tts.GeminiTtsModel;
+import org.springframework.ai.utils.SpringAiTestAutoConfigurations;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Integration tests for the {@link GoogleGenAiTtsAutoConfiguration}.
+ *
+ * @author Alexandros Pappas
+ */
+@EnabledIfEnvironmentVariable(named = "GOOGLE_API_KEY", matches = ".*")
+public class GoogleGenAiTtsAutoConfigurationIT {
+
+	private static final org.apache.commons.logging.Log logger = org.apache.commons.logging.LogFactory
+		.getLog(GoogleGenAiTtsAutoConfigurationIT.class);
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+		.withPropertyValues("spring.ai.google.genai.api-key=" + System.getenv("GOOGLE_API_KEY"),
+				"spring.ai.model.audio.speech=google-genai")
+		.withConfiguration(SpringAiTestAutoConfigurations.of(GoogleGenAiTtsAutoConfiguration.class));
+
+	@Test
+	void ttsModelBeanCreation() {
+		this.contextRunner.run(context -> {
+			assertThat(context).hasSingleBean(GeminiTtsModel.class);
+			GeminiTtsModel ttsModel = context.getBean(GeminiTtsModel.class);
+			assertThat(ttsModel).isNotNull();
+		});
+	}
+
+	@Test
+	void ttsModelApiCall() {
+		this.contextRunner.run(context -> {
+			GeminiTtsModel ttsModel = context.getBean(GeminiTtsModel.class);
+			byte[] response = ttsModel.call("Hello");
+
+			assertThat(response).isNotNull();
+			assertThat(response).isNotEmpty();
+			// PCM audio should be substantial (24kHz * 2 bytes/sample * ~1 second)
+			assertThat(response.length).isGreaterThan(1000);
+
+			logger.debug("PCM audio response size: " + response.length + " bytes");
+		});
+	}
+
+	@Test
+	void ttsModelWithCustomVoice() {
+		this.contextRunner
+			.withPropertyValues("spring.ai.google.genai.tts.options.voice=Puck",
+					"spring.ai.google.genai.tts.options.model=gemini-2.5-flash-preview-tts")
+			.run(context -> {
+				GeminiTtsModel ttsModel = context.getBean(GeminiTtsModel.class);
+				byte[] response = ttsModel.call("Testing custom voice");
+
+				assertThat(response).isNotNull();
+				assertThat(response).isNotEmpty();
+				assertThat(response.length).isGreaterThan(1000);
+			});
+	}
+
+}

auto-configurations/models/spring-ai-autoconfigure-model-google-genai/src/test/java/org/springframework/ai/model/google/genai/autoconfigure/tts/GoogleGenAiTtsPropertiesTests.java

@@ -0,0 +1,89 @@
+/*
+ * Copyright 2025-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.ai.model.google.genai.autoconfigure.tts;
+
+import org.junit.jupiter.api.Test;
+
+import org.springframework.boot.context.properties.EnableConfigurationProperties;
+import org.springframework.boot.test.context.runner.ApplicationContextRunner;
+import org.springframework.context.annotation.Configuration;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Unit tests for Google GenAI TTS properties binding.
+ *
+ * @author Alexandros Pappas
+ */
+public class GoogleGenAiTtsPropertiesTests {
+
+	private final ApplicationContextRunner contextRunner = new ApplicationContextRunner()
+		.withUserConfiguration(PropertiesTestConfiguration.class);
+
+	@Test
+	void connectionPropertiesBinding() {
+		this.contextRunner
+			.withPropertyValues("spring.ai.google.genai.api-key=test-tts-key",
+					"spring.ai.google.genai.base-url=https://test.api.google.com")
+			.run(context -> {
+				GoogleGenAiTtsConnectionProperties connectionProperties = context
+					.getBean(GoogleGenAiTtsConnectionProperties.class);
+				assertThat(connectionProperties.getApiKey()).isEqualTo("test-tts-key");
+				assertThat(connectionProperties.getBaseUrl()).isEqualTo("https://test.api.google.com");
+			});
+	}
+
+	@Test
+	void ttsPropertiesBinding() {
+		this.contextRunner
+			.withPropertyValues("spring.ai.google.genai.tts.options.model=gemini-2.5-pro-preview-tts",
+					"spring.ai.google.genai.tts.options.voice=Puck", "spring.ai.google.genai.tts.options.speed=1.2")
+			.run(context -> {
+				GoogleGenAiTtsProperties ttsProperties = context.getBean(GoogleGenAiTtsProperties.class);
+				assertThat(ttsProperties.getOptions().getModel()).isEqualTo("gemini-2.5-pro-preview-tts");
+				assertThat(ttsProperties.getOptions().getVoice()).isEqualTo("Puck");
+				assertThat(ttsProperties.getOptions().getSpeed()).isEqualTo(1.2);
+			});
+	}
+
+	@Test
+	void ttsDefaultValuesBinding() {
+		// Test that defaults are applied when not specified
+		this.contextRunner.run(context -> {
+			GoogleGenAiTtsProperties ttsProperties = context.getBean(GoogleGenAiTtsProperties.class);
+			assertThat(ttsProperties.getOptions().getModel()).isEqualTo("gemini-2.5-flash-preview-tts");
+			assertThat(ttsProperties.getOptions().getVoice()).isEqualTo("Kore");
+			assertThat(ttsProperties.getOptions().getFormat()).isEqualTo("pcm");
+		});
+	}
+
+	@Test
+	void connectionDefaultBaseUrl() {
+		this.contextRunner.withPropertyValues("spring.ai.google.genai.api-key=test-key").run(context -> {
+			GoogleGenAiTtsConnectionProperties connectionProperties = context
+				.getBean(GoogleGenAiTtsConnectionProperties.class);
+			assertThat(connectionProperties.getBaseUrl()).isEqualTo("https://generativelanguage.googleapis.com");
+		});
+	}
+
+	@Configuration
+	@EnableConfigurationProperties({ GoogleGenAiTtsConnectionProperties.class, GoogleGenAiTtsProperties.class })
+	static class PropertiesTestConfiguration {
+
+	}
+
+}