Fix Moonshot Chat model toolcalling token usage

 - Accumulate the token usage when toolcalling is invoked
   - Fix both call() and stream() methods
     - Add `usage` field to the Chat completion choice as the usage is returned via Choice
 - Add Mootshot chatmodel ITs for functioncalling tests

Move the tests into MoonshotChatModelFunctionCallingIT

models/spring-ai-moonshot/src/main/java/org/springframework/ai/moonshot/MoonshotChatModel.java

@@ -36,6 +36,8 @@
 import org.springframework.ai.chat.metadata.ChatGenerationMetadata;
 import org.springframework.ai.chat.metadata.ChatResponseMetadata;
 import org.springframework.ai.chat.metadata.EmptyUsage;
+import org.springframework.ai.chat.metadata.Usage;
+import org.springframework.ai.chat.metadata.UsageUtils;
 import org.springframework.ai.chat.model.AbstractToolCallSupport;
 import org.springframework.ai.chat.model.ChatModel;
 import org.springframework.ai.chat.model.ChatResponse;
@@ -75,6 +77,7 @@
  *
  * @author Geng Rong
  * @author Alexandros Pappas
+ * @author Ilayaperumal Gopinathan
  */
 public class MoonshotChatModel extends AbstractToolCallSupport implements ChatModel, StreamingChatModel {
 
@@ -180,6 +183,10 @@ private static Generation buildGeneration(Choice choice, Map<String, Object> met
 
 	@Override
 	public ChatResponse call(Prompt prompt) {
+		return this.internalCall(prompt, null);
+	}
+
+	public ChatResponse internalCall(Prompt prompt, ChatResponse previousChatResponse) {
 		ChatCompletionRequest request = createRequest(prompt, false);
 
 		ChatModelObservationContext observationContext = ChatModelObservationContext.builder()
@@ -218,8 +225,11 @@ public ChatResponse call(Prompt prompt) {
 					// @formatter:on
 					return buildGeneration(choice, metadata);
 				}).toList();
-
-				ChatResponse chatResponse = new ChatResponse(generations, from(completionEntity.getBody()));
+				MoonshotApi.Usage usage = completionEntity.getBody().usage();
+				Usage currentUsage = (usage != null) ? MoonshotUsage.from(usage) : new EmptyUsage();
+				Usage cumulativeUsage = UsageUtils.getCumulativeUsage(currentUsage, previousChatResponse);
+				ChatResponse chatResponse = new ChatResponse(generations,
+						from(completionEntity.getBody(), cumulativeUsage));
 
 				observationContext.setResponse(chatResponse);
 
@@ -232,7 +242,7 @@ && isToolCall(response, Set.of(MoonshotApi.ChatCompletionFinishReason.TOOL_CALLS
 			var toolCallConversation = handleToolCalls(prompt, response);
 			// Recursively call the call method with the tool call message
 			// conversation that contains the call responses.
-			return this.call(new Prompt(toolCallConversation, prompt.getOptions()));
+			return this.internalCall(new Prompt(toolCallConversation, prompt.getOptions()), response);
 		}
 		return response;
 	}
@@ -244,6 +254,10 @@ public ChatOptions getDefaultOptions() {
 
 	@Override
 	public Flux<ChatResponse> stream(Prompt prompt) {
+		return this.internalStream(prompt, null);
+	}
+
+	public Flux<ChatResponse> internalStream(Prompt prompt, ChatResponse previousChatResponse) {
 		return Flux.deferContextual(contextView -> {
 			ChatCompletionRequest request = createRequest(prompt, true);
 
@@ -287,8 +301,11 @@ public Flux<ChatResponse> stream(Prompt prompt) {
 							// @formatter:on
 							return buildGeneration(choice, metadata);
 						}).toList();
+						MoonshotApi.Usage usage = chatCompletion2.usage();
+						Usage currentUsage = (usage != null) ? MoonshotUsage.from(usage) : new EmptyUsage();
+						Usage cumulativeUsage = UsageUtils.getCumulativeUsage(currentUsage, previousChatResponse);
 
-						return new ChatResponse(generations, from(chatCompletion2));
+						return new ChatResponse(generations, from(chatCompletion2, cumulativeUsage));
 					}
 					catch (Exception e) {
 						logger.error("Error processing chat completion", e);
@@ -303,7 +320,7 @@ public Flux<ChatResponse> stream(Prompt prompt) {
 					var toolCallConversation = handleToolCalls(prompt, response);
 					// Recursively call the stream method with the tool call message
 					// conversation that contains the call responses.
-					return this.stream(new Prompt(toolCallConversation, prompt.getOptions()));
+					return this.internalStream(new Prompt(toolCallConversation, prompt.getOptions()), response);
 				}
 				return Flux.just(response);
 			})
@@ -325,6 +342,16 @@ private ChatResponseMetadata from(ChatCompletion result) {
 			.build();
 	}
 
+	private ChatResponseMetadata from(ChatCompletion result, Usage usage) {
+		Assert.notNull(result, "Moonshot ChatCompletionResult must not be null");
+		return ChatResponseMetadata.builder()
+			.id(result.id() != null ? result.id() : "")
+			.usage(usage)
+			.model(result.model() != null ? result.model() : "")
+			.keyValue("created", result.created() != null ? result.created() : 0L)
+			.build();
+	}
+
 	/**
 	 * Convert the ChatCompletionChunk into a ChatCompletion. The Usage is set to null.
 	 * @param chunk the ChatCompletionChunk to convert
@@ -336,10 +363,11 @@ private ChatCompletion chunkToChatCompletion(ChatCompletionChunk chunk) {
 			if (delta == null) {
 				delta = new ChatCompletionMessage("", ChatCompletionMessage.Role.ASSISTANT);
 			}
-			return new ChatCompletion.Choice(cc.index(), delta, cc.finishReason());
+			return new ChatCompletion.Choice(cc.index(), delta, cc.finishReason(), cc.usage());
 		}).toList();
-
-		return new ChatCompletion(chunk.id(), "chat.completion", chunk.created(), chunk.model(), choices, null);
+		// Get the usage from the latest choice
+		MoonshotApi.Usage usage = choices.get(choices.size() - 1).usage();
+		return new ChatCompletion(chunk.id(), "chat.completion", chunk.created(), chunk.model(), choices, usage);
 	}
 
 	/**

models/spring-ai-moonshot/src/main/java/org/springframework/ai/moonshot/api/MoonshotApi.java

@@ -532,7 +532,8 @@ public record Choice(
 		// @formatter:off
 			@JsonProperty("index") Integer index,
 			@JsonProperty("message") ChatCompletionMessage message,
-			@JsonProperty("finish_reason") ChatCompletionFinishReason finishReason) {
+			@JsonProperty("finish_reason") ChatCompletionFinishReason finishReason,
+			@JsonProperty("usage") Usage usage) {
 			 // @formatter:on
 		}
 

models/spring-ai-moonshot/src/main/java/org/springframework/ai/moonshot/api/MoonshotStreamFunctionCallingHelper.java

@@ -64,8 +64,10 @@ private ChunkChoice merge(ChunkChoice previous, ChunkChoice current) {
 				: previous.finishReason());
 		Integer index = (current.index() != null ? current.index() : previous.index());
 
+		MoonshotApi.Usage usage = current.usage() != null ? current.usage() : previous.usage();
+
 		ChatCompletionMessage message = merge(previous.delta(), current.delta());
-		return new ChunkChoice(index, message, finishReason, null);
+		return new ChunkChoice(index, message, finishReason, usage);
 	}
 
 	private ChatCompletionMessage merge(ChatCompletionMessage previous, ChatCompletionMessage current) {

models/spring-ai-moonshot/src/test/java/org/springframework/ai/moonshot/MoonshotRetryTests.java

@@ -80,7 +80,7 @@ public void beforeEach() {
 	public void moonshotChatTransientError() {
 
 		var choice = new ChatCompletion.Choice(0, new ChatCompletionMessage("Response", Role.ASSISTANT),
-				ChatCompletionFinishReason.STOP);
+				ChatCompletionFinishReason.STOP, null);
 		ChatCompletion expectedChatCompletion = new ChatCompletion("id", "chat.completion", 789L, "model",
 				List.of(choice), new MoonshotApi.Usage(10, 10, 10));
 

models/spring-ai-moonshot/src/test/java/org/springframework/ai/moonshot/chat/MoonshotChatModelFunctionCallingIT.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2024 the original author or authors.
+ * 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.
@@ -17,6 +17,7 @@
 package org.springframework.ai.moonshot.chat;
 
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Objects;
 import java.util.stream.Collectors;
@@ -53,6 +54,33 @@ class MoonshotChatModelFunctionCallingIT {
 	@Autowired
 	ChatModel chatModel;
 
+	private static final MoonshotApi.FunctionTool FUNCTION_TOOL = new MoonshotApi.FunctionTool(
+			MoonshotApi.FunctionTool.Type.FUNCTION, new MoonshotApi.FunctionTool.Function(
+					"Get the weather in location. Return temperature in 30°F or 30°C format.", "getCurrentWeather", """
+							{
+								"type": "object",
+								"properties": {
+									"location": {
+										"type": "string",
+										"description": "The city and state e.g. San Francisco, CA"
+									},
+									"lat": {
+										"type": "number",
+										"description": "The city latitude"
+									},
+									"lon": {
+										"type": "number",
+										"description": "The city longitude"
+									},
+									"unit": {
+										"type": "string",
+										"enum": ["C", "F"]
+									}
+								},
+								"required": ["location", "lat", "lon", "unit"]
+							}
+							"""));
+
 	@Test
 	void functionCallTest() {
 
@@ -89,6 +117,7 @@ void streamFunctionCallTest() {
 			.functionCallbacks(List.of(FunctionCallback.builder()
 				.function("getCurrentWeather", new MockWeatherService())
 				.description("Get the weather in location")
+				.inputType(MockWeatherService.Request.class)
 				.build()))
 			.build();
 
@@ -108,4 +137,47 @@ void streamFunctionCallTest() {
 		assertThat(content).contains("30", "10", "15");
 	}
 
+	@Test
+	public void toolFunctionCallWithUsage() {
+		var promptOptions = MoonshotChatOptions.builder()
+			.model(MoonshotApi.ChatModel.MOONSHOT_V1_8K.getValue())
+			.tools(Arrays.asList(FUNCTION_TOOL))
+			.functionCallbacks(List.of(FunctionCallback.builder()
+				.function("getCurrentWeather", new MockWeatherService())
+				.description("Get the weather in location. Return temperature in 36°F or 36°C format.")
+				.inputType(MockWeatherService.Request.class)
+				.build()))
+			.build();
+		Prompt prompt = new Prompt("What's the weather like in San Francisco? Return the temperature in Celsius.",
+				promptOptions);
+
+		ChatResponse chatResponse = this.chatModel.call(prompt);
+		assertThat(chatResponse).isNotNull();
+		assertThat(chatResponse.getResult().getOutput());
+		assertThat(chatResponse.getResult().getOutput().getText()).contains("San Francisco");
+		assertThat(chatResponse.getResult().getOutput().getText()).contains("30.0");
+		assertThat(chatResponse.getMetadata().getUsage().getTotalTokens()).isLessThan(450).isGreaterThan(280);
+	}
+
+	@Test
+	public void testStreamFunctionCallUsage() {
+		var promptOptions = MoonshotChatOptions.builder()
+			.model(MoonshotApi.ChatModel.MOONSHOT_V1_8K.getValue())
+			.tools(Arrays.asList(FUNCTION_TOOL))
+			.functionCallbacks(List.of(FunctionCallback.builder()
+				.function("getCurrentWeather", new MockWeatherService())
+				.description("Get the weather in location. Return temperature in 36°F or 36°C format.")
+				.inputType(MockWeatherService.Request.class)
+				.build()))
+			.build();
+		Prompt prompt = new Prompt("What's the weather like in San Francisco? Return the temperature in Celsius.",
+				promptOptions);
+
+		ChatResponse chatResponse = this.chatModel.stream(prompt).blockLast();
+		assertThat(chatResponse).isNotNull();
+		assertThat(chatResponse.getMetadata()).isNotNull();
+		assertThat(chatResponse.getMetadata().getUsage()).isNotNull();
+		assertThat(chatResponse.getMetadata().getUsage().getTotalTokens()).isLessThan(450).isGreaterThan(280);
+	}
+
 }