Improve MistralAiApi Jackson mapping for message content

- Define different type of chunk instead of media content
- Introduce think chunk required by Magistral models and Mistral Small 4
- Introduce prompt_mode request parameter for Magistral models
- Introduce reasoning_effort request parameter for Mistral Small 4
- Improve existing Javadoc
- Polish integration tests and unit tests

Signed-off-by: Nicolas Krier <7557886+nicolaskrier@users.noreply.github.com>

Author: nicolaskrier

models/spring-ai-mistral-ai/pom.xml

@@ -80,8 +80,8 @@
 		</dependency>
 
 		<dependency>
-			<groupId>io.micrometer</groupId>
-			<artifactId>micrometer-observation-test</artifactId>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
 			<scope>test</scope>
 		</dependency>
 

models/spring-ai-mistral-ai/src/main/java/org/springframework/ai/mistralai/MistralAiChatModel.java

@@ -17,7 +17,6 @@
 package org.springframework.ai.mistralai;
 
 import java.util.ArrayList;
-import java.util.Base64;
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
@@ -350,7 +349,7 @@ private Flux<ChatResponse> internalStream(Prompt prompt, @Nullable ChatResponse
 			.doOnError(observation::error)
 			.doFinally(s -> observation.stop())
 			.contextWrite(ctx -> ctx.put(ObservationThreadLocalAccessor.KEY, observation));
-			// @formatter:on;
+			// @formatter:on
 
 			return new MessageAggregator().aggregate(chatResponseFlux, observationContext::setResponse);
 		});
@@ -366,7 +365,7 @@ private Generation buildGeneration(Choice choice, Map<String, Object> metadata)
 							toolCall.function().name(), toolCall.function().arguments()))
 					.toList();
 
-		var content = choice.message().content();
+		var content = choice.message().extractContent();
 		var assistantMessage = AssistantMessage.builder()
 			.content(content)
 			.properties(metadata)
@@ -507,14 +506,15 @@ private ChatCompletionMessage createSystemChatCompletionMessage(Message message)
 	}
 
 	private ChatCompletionMessage createUserChatCompletionMessage(Message message) {
-		Object content = message.getText();
+		var content = message.getText();
 		Assert.state(content != null, "content must not be null");
 
 		if (message instanceof UserMessage userMessage && !CollectionUtils.isEmpty(userMessage.getMedia())) {
-			List<ChatCompletionMessage.MediaContent> contentList = new ArrayList<>(
-					List.of(new ChatCompletionMessage.MediaContent((String) content)));
-			contentList.addAll(userMessage.getMedia().stream().map(this::mapToMediaContent).toList());
-			content = contentList;
+			var contentChunks = Stream.<ChatCompletionMessage.ContentChunk>concat(
+					Stream.of(new ChatCompletionMessage.TextChunk(content)), this.mapToImageUrlChunks(userMessage))
+				.toList();
+
+			return new ChatCompletionMessage(contentChunks, ChatCompletionMessage.Role.USER);
 		}
 
 		return new ChatCompletionMessage(content, ChatCompletionMessage.Role.USER);
@@ -526,24 +526,24 @@ private ToolCall mapToolCall(AssistantMessage.ToolCall toolCall) {
 		return new ToolCall(toolCall.id(), toolCall.type(), function, null);
 	}
 
-	private ChatCompletionMessage.MediaContent mapToMediaContent(Media media) {
-		return new ChatCompletionMessage.MediaContent(new ChatCompletionMessage.MediaContent.ImageUrl(
-				this.fromMediaData(media.getMimeType(), media.getData())));
+	private Stream<ChatCompletionMessage.ImageUrlChunk> mapToImageUrlChunks(UserMessage userMessage) {
+		return userMessage.getMedia().stream().map(this::mapToImageUrlChunk);
+	}
+
+	private ChatCompletionMessage.ImageUrlChunk mapToImageUrlChunk(Media media) {
+		return new ChatCompletionMessage.ImageUrlChunk(this.fromMediaData(media.getMimeType(), media.getData()));
 	}
 
-	private String fromMediaData(MimeType mimeType, Object mediaContentData) {
-		if (mediaContentData instanceof byte[] bytes) {
-			// Assume the bytes are an image. So, convert the bytes to a base64 encoded
-			// following the prefix pattern.
-			return String.format("data:%s;base64,%s", mimeType.toString(), Base64.getEncoder().encodeToString(bytes));
+	private ChatCompletionMessage.ImageUrlChunk.ImageUrl fromMediaData(MimeType mimeType, Object mediaData) {
+		if (mediaData instanceof byte[] bytes) {
+			return ChatCompletionMessage.ImageUrlChunk.ImageUrl.fromImageData(mimeType, bytes);
 		}
-		else if (mediaContentData instanceof String text) {
-			// Assume the text is a URLs or a base64 encoded image prefixed by the user.
-			return text;
+		else if (mediaData instanceof String text) {
+			// Assume the text is a URL or a base64 encoded image prefixed by the user.
+			return new ChatCompletionMessage.ImageUrlChunk.ImageUrl(text, null);
 		}
 		else {
-			throw new IllegalArgumentException(
-					"Unsupported media data type: " + mediaContentData.getClass().getSimpleName());
+			throw new IllegalArgumentException("Unsupported media data type: " + mediaData.getClass().getSimpleName());
 		}
 	}
 

models/spring-ai-mistral-ai/src/main/java/org/springframework/ai/mistralai/api/ContentLengthInterceptor.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2023-present 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.mistralai.api;
+
+import java.io.IOException;
+
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpRequest;
+import org.springframework.http.client.ClientHttpRequestExecution;
+import org.springframework.http.client.ClientHttpRequestInterceptor;
+import org.springframework.http.client.ClientHttpResponse;
+
+/**
+ * {@link ClientHttpRequestInterceptor} to apply a content length header based on the body
+ * length if this header was not present in the request headers.
+ *
+ * @author Nicolas Krier
+ */
+public class ContentLengthInterceptor implements ClientHttpRequestInterceptor {
+
+	// @formatter:off
+	// Temporary solution to fix the following error:
+	// org.springframework.ai.retry.NonTransientAiException: 411 - {
+	//		"message":"A valid Content-Length header is required",
+	//		"request_id":"5108031f4a1e0d3e6d66204d56b2ac60"
+	// }
+	// TODO: Discuss with Sébastien Deleuze the opportunity to add this class into Spring Framework if this solution is satisfying.
+	// @formatter:on
+	@Override
+	public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution)
+			throws IOException {
+		var headers = request.getHeaders();
+
+		if (!headers.containsHeader(HttpHeaders.CONTENT_LENGTH)) {
+			headers.setContentLength(body.length);
+		}
+
+		return execution.execute(request, body);
+	}
+
+}