feat: add usage tracking and token extraction for Anthropic messages

Author: NoOne7135

index.ts

@@ -43,6 +43,7 @@ type AnthropicMessageLike = {
   content?: Array<any>;
   stop_reason?: string | null;
   parsed_output?: unknown;
+  usage?: AnthropicUsage;
 };
 
 type AnthropicToolUseBlock = {
@@ -67,6 +68,19 @@ type LangChainModelCallRequest = {
   messages: LangChainMessageLike[];
 };
 
+type AnthropicUsage = {
+  input_tokens?: number;
+  cache_creation_input_tokens?: number | null;
+  cache_read_input_tokens?: number | null;
+  output_tokens?: number;
+};
+
+type UsedTokens = {
+  input_uncached: number;
+  input_cached: number;
+  output: number;
+};
+
 function getApiKey(options: AdapterOptions): string | undefined {
   return options.anthropicApiKey || options.antropicApiKey;
 }
@@ -112,6 +126,21 @@ function extractReasoning(data: AnthropicMessageLike): string | undefined {
   return reasoning || undefined;
 }
 
+function extractUsedTokens(data: AnthropicMessageLike): UsedTokens | undefined {
+  const usage = data.usage;
+  if (!usage) return undefined;
+
+  const inputTokens = usage.input_tokens ?? 0;
+  const cacheWriteTokens = usage.cache_creation_input_tokens ?? 0;
+  const cacheReadTokens = usage.cache_read_input_tokens ?? 0;
+
+  return {
+    input_uncached: inputTokens + cacheWriteTokens,
+    input_cached: cacheReadTokens,
+    output: usage.output_tokens ?? 0,
+  };
+}
+
 function extractToolUse(data: AnthropicMessageLike): AnthropicToolUseBlock | undefined {
   for (const block of data.content ?? []) {
     if (block?.type === "tool_use") {
@@ -323,6 +352,7 @@ export default class CompletionAdapterAnthropicMessages
     content?: string;
     finishReason?: string;
     error?: string;
+    used_tokens?: UsedTokens;
   }> => {
     const request =
       typeof requestOrContent === "string"
@@ -386,6 +416,7 @@ export default class CompletionAdapterAnthropicMessages
             ? extractOutputText(parsedMessage)
             : JSON.stringify(parsedMessage.parsed_output);
         const parsedReasoning = extractReasoning(parsedMessage);
+        const usedTokens = extractUsedTokens(parsedMessage);
 
         if (parsedReasoning && isStreaming) {
           await streamChunkCallback?.(parsedReasoning, {
@@ -417,25 +448,29 @@ export default class CompletionAdapterAnthropicMessages
             return {
               content: toolResult,
               finishReason: "tool_call",
+              used_tokens: usedTokens,
             };
           } catch (error) {
             return {
               error: getErrorMessage(error),
               finishReason: "tool_call",
+              used_tokens: usedTokens,
             };
           }
         }
 
         return {
           content: parsedOutput || undefined,
           finishReason: parsedMessage.stop_reason || undefined,
+          used_tokens: usedTokens,
         };
       }
 
       if (!isStreaming) {
         const message = (await this.getClient().messages.create(
           body as any,
         )) as AnthropicMessageLike;
+        const usedTokens = extractUsedTokens(message);
 
         const toolUse = extractToolUse(message);
         if (toolUse) {
@@ -444,18 +479,21 @@ export default class CompletionAdapterAnthropicMessages
             return {
               content: toolResult,
               finishReason: "tool_call",
+              used_tokens: usedTokens,
             };
           } catch (error) {
             return {
               error: getErrorMessage(error),
               finishReason: "tool_call",
+              used_tokens: usedTokens,
             };
           }
         }
 
         return {
           content: extractOutputText(message) || undefined,
           finishReason: message.stop_reason || undefined,
+          used_tokens: usedTokens,
         };
       }
 
@@ -492,6 +530,7 @@ export default class CompletionAdapterAnthropicMessages
       const message = (await stream.finalMessage()) as AnthropicMessageLike;
       const finalContent = extractOutputText(message);
       const finalReasoning = extractReasoning(message) || "";
+      const usedTokens = extractUsedTokens(message);
 
       if (finalReasoning && finalReasoning !== fullReasoning) {
         const delta = finalReasoning.startsWith(fullReasoning)
@@ -541,19 +580,22 @@ export default class CompletionAdapterAnthropicMessages
           return {
             content: toolResult,
             finishReason: "tool_call",
+            used_tokens: usedTokens,
           };
         } catch (error) {
           return {
             error: getErrorMessage(error),
             content: fullContent || undefined,
             finishReason: "tool_call",
+            used_tokens: usedTokens,
           };
         }
       }
 
       return {
         content: fullContent || undefined,
         finishReason: message.stop_reason || undefined,
+        used_tokens: usedTokens,
       };
     } catch (error) {
       return {