feat: 实现 Anthropic 兼容的 count_tokens API

- 在 KiroApiService 中添加 countTokens 方法，支持计算 messages、system、tools 的 token 数
- 使用 @anthropic-ai/tokenizer 进行准确的 token 计算
- 支持 text、tool_use、tool_result、image、document 等内容类型
- 修改 request-handler.js 处理 POST /v1/messages/count_tokens 请求
- 返回格式与 Anthropic 官方 API 一致：{ input_tokens: number }

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/claude/claude-kiro.js

@@ -1776,6 +1776,73 @@ async initializeAuth(forceRefresh = false) {
         }
     }
 
+    /**
+     * Count tokens for a message request (compatible with Anthropic API)
+     * POST /v1/messages/count_tokens
+     * @param {Object} requestBody - The request body containing model, messages, system, tools, etc.
+     * @returns {Object} { input_tokens: number }
+     */
+    countTokens(requestBody) {
+        let totalTokens = 0;
+
+        // Count system prompt tokens
+        if (requestBody.system) {
+            const systemText = this.getContentText(requestBody.system);
+            totalTokens += this.countTextTokens(systemText);
+        }
+
+        // Count all messages tokens
+        if (requestBody.messages && Array.isArray(requestBody.messages)) {
+            for (const message of requestBody.messages) {
+                if (message.content) {
+                    if (typeof message.content === 'string') {
+                        totalTokens += this.countTextTokens(message.content);
+                    } else if (Array.isArray(message.content)) {
+                        for (const block of message.content) {
+                            if (block.type === 'text' && block.text) {
+                                totalTokens += this.countTextTokens(block.text);
+                            } else if (block.type === 'tool_use') {
+                                // Count tool use block tokens
+                                totalTokens += this.countTextTokens(block.name || '');
+                                totalTokens += this.countTextTokens(JSON.stringify(block.input || {}));
+                            } else if (block.type === 'tool_result') {
+                                // Count tool result block tokens
+                                const resultContent = this.getContentText(block.content);
+                                totalTokens += this.countTextTokens(resultContent);
+                            } else if (block.type === 'image') {
+                                // Images have a fixed token cost (approximately 1600 tokens for a typical image)
+                                // This is an estimation as actual cost depends on image size
+                                totalTokens += 1600;
+                            } else if (block.type === 'document') {
+                                // Documents - estimate based on content if available
+                                if (block.source?.data) {
+                                    // For base64 encoded documents, estimate tokens
+                                    const estimatedChars = block.source.data.length * 0.75; // base64 to bytes ratio
+                                    totalTokens += Math.ceil(estimatedChars / 4);
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+        }
+
+        // Count tools definitions tokens if present
+        if (requestBody.tools && Array.isArray(requestBody.tools)) {
+            for (const tool of requestBody.tools) {
+                // Count tool name and description
+                totalTokens += this.countTextTokens(tool.name || '');
+                totalTokens += this.countTextTokens(tool.description || '');
+                // Count input schema
+                if (tool.input_schema) {
+                    totalTokens += this.countTextTokens(JSON.stringify(tool.input_schema));
+                }
+            }
+        }
+
+        return { input_tokens: totalTokens };
+    }
+
     /**
      * 获取用量限制信息
      * @returns {Promise<Object>} 用量限制信息

src/request-handler.js

@@ -8,6 +8,24 @@ import { MODEL_PROVIDER } from './common.js';
 import { PROMPT_LOG_FILENAME } from './config-manager.js';
 import { handleOllamaRequest, handleOllamaShow } from './ollama-handler.js';
 
+/**
+ * Parse request body as JSON
+ */
+function parseRequestBody(req) {
+    return new Promise((resolve, reject) => {
+        let body = '';
+        req.on('data', chunk => { body += chunk.toString(); });
+        req.on('end', () => {
+            try {
+                resolve(body ? JSON.parse(body) : {});
+            } catch (e) {
+                reject(new Error('Invalid JSON in request body'));
+            }
+        });
+        req.on('error', reject);
+    });
+}
+
 /**
  * Main request handler. It authenticates the request, determines the endpoint type,
  * and delegates to the appropriate specialized handler function.
@@ -95,16 +113,6 @@ export function createRequestHandler(config, providerPoolManager) {
             }
         }
 
-        // Ignore count_tokens requests
-        if (path.includes('/count_tokens')) {
-            console.log(`[Server] Ignoring count_tokens request: ${path}`);
-            res.writeHead(200, { 'Content-Type': 'application/json' });
-            res.end(JSON.stringify({
-                tokens: 0,
-                message: 'Token counting is not supported'
-            }));
-            return true;
-        }
 
         // Handle API requests
         // Allow overriding MODEL_PROVIDER via request header
@@ -152,6 +160,37 @@ export function createRequestHandler(config, providerPoolManager) {
             return;
         }
 
+        // Handle count_tokens requests (Anthropic API compatible)
+        if (path.includes('/count_tokens') && method === 'POST') {
+            try {
+                const body = await parseRequestBody(req);
+                console.log(`[Server] Handling count_tokens request for model: ${body.model}`);
+
+                // Check if apiService has countTokens method
+                if (apiService && typeof apiService.countTokens === 'function') {
+                    const result = apiService.countTokens(body);
+                    res.writeHead(200, { 'Content-Type': 'application/json' });
+                    res.end(JSON.stringify(result));
+                } else {
+                    // Fallback: use estimateInputTokens if available
+                    if (apiService && typeof apiService.estimateInputTokens === 'function') {
+                        const inputTokens = apiService.estimateInputTokens(body);
+                        res.writeHead(200, { 'Content-Type': 'application/json' });
+                        res.end(JSON.stringify({ input_tokens: inputTokens }));
+                    } else {
+                        // Last resort: return 0 with a message
+                        res.writeHead(200, { 'Content-Type': 'application/json' });
+                        res.end(JSON.stringify({ input_tokens: 0 }));
+                    }
+                }
+                return true;
+            } catch (error) {
+                console.error(`[Server] count_tokens error: ${error.message}`);
+                handleError(res, { statusCode: 500, message: `Failed to count tokens: ${error.message}` });
+                return;
+            }
+        }
+
         try {
             // Handle Ollama request (normalize path and route to appropriate endpoints)
             const { handled, normalizedPath } = await handleOllamaRequest(method, path, requestUrl, req, res, apiService, currentConfig, providerPoolManager);