feat(tokens): enhance token estimation and refactor count_tokens endpoint for improved handling

src/main/apiServer/routes/messages.ts

@@ -46,20 +46,11 @@ const providerRouter = express.Router({ mergeParams: true })
 
 /**
  * Estimate token count from messages
- * Uses tokenx library for accurate token estimation and supports images
+ * Uses tokenx library for accurate token estimation and supports images, tools
  */
 interface CountTokensInput {
-  messages: Array<{
-    role: string
-    content:
-      | string
-      | Array<{
-          type: string
-          text?: string
-          source?: { type: string; media_type?: string; data?: string }
-        }>
-  }>
-  system?: string | Array<{ type: string; text?: string }>
+  messages: MessageCreateParams['messages']
+  system?: MessageCreateParams['system']
 }
 
 function estimateTokenCount(input: CountTokensInput): number {
@@ -89,14 +80,40 @@ function estimateTokenCount(input: CountTokensInput): number {
           totalTokens += approximateTokenSize(block.text)
         } else if (block.type === 'image') {
           // Image token estimation (consistent with TokenService)
-          // Base64 images: estimate from data length
-          if (block.source?.data) {
+          if (block.source.type === 'base64') {
+            // Base64 images: estimate from data length
             const dataSize = block.source.data.length * 0.75 // base64 to bytes
             totalTokens += Math.floor(dataSize / 100)
           } else {
-            // Default image token estimate
+            // URL images: use default estimate
             totalTokens += 1000
           }
+        } else if (block.type === 'tool_use') {
+          // Tool use token estimation: name + input JSON
+          if (block.name) {
+            totalTokens += approximateTokenSize(block.name)
+          }
+          if (block.input) {
+            const inputJson = JSON.stringify(block.input)
+            totalTokens += approximateTokenSize(inputJson)
+          }
+          // Add overhead for tool use structure
+          totalTokens += 10
+        } else if (block.type === 'tool_result') {
+          // Tool result token estimation
+          if (typeof block.content === 'string') {
+            totalTokens += approximateTokenSize(block.content)
+          } else if (Array.isArray(block.content)) {
+            for (const item of block.content) {
+              if (typeof item === 'string') {
+                totalTokens += approximateTokenSize(item)
+              } else if (item.type === 'text' && item.text) {
+                totalTokens += approximateTokenSize(item.text)
+              }
+            }
+          }
+          // Add overhead for tool result structure
+          totalTokens += 10
         }
       }
     }
@@ -127,6 +144,70 @@ async function validateRequestBody(req: Request): Promise<{ valid: boolean; erro
   return { valid: true }
 }
 
+/**
+ * Shared handler for count_tokens endpoint
+ * Validates request and returns token count estimation
+ */
+async function handleCountTokens(
+  req: Request,
+  res: Response,
+  options: {
+    requireModel?: boolean
+    logContext?: Record<string, any>
+  } = {}
+): Promise<Response> {
+  try {
+    const { model, messages, system } = req.body
+    const { requireModel = false, logContext = {} } = options
+
+    // Validate model parameter if required
+    if (requireModel && !model) {
+      return res.status(400).json({
+        type: 'error',
+        error: {
+          type: 'invalid_request_error',
+          message: 'model parameter is required'
+        }
+      })
+    }
+
+    // Validate messages parameter
+    if (!messages || !Array.isArray(messages)) {
+      return res.status(400).json({
+        type: 'error',
+        error: {
+          type: 'invalid_request_error',
+          message: 'messages parameter is required'
+        }
+      })
+    }
+
+    // Estimate token count
+    const estimatedTokens = estimateTokenCount({ messages, system })
+
+    // Log with context
+    logger.debug('Token count estimated', {
+      model,
+      messageCount: messages.length,
+      estimatedTokens,
+      ...logContext
+    })
+
+    return res.json({
+      input_tokens: estimatedTokens
+    })
+  } catch (error: any) {
+    logger.error('Token counting error', { error })
+    return res.status(500).json({
+      type: 'error',
+      error: {
+        type: 'api_error',
+        message: error.message || 'Internal server error'
+      }
+    })
+  }
+}
+
 interface HandleMessageProcessingOptions {
   res: Response
   provider: Provider
@@ -650,91 +731,17 @@ providerRouter.post('/', async (req: Request, res: Response) => {
  *         description: Bad request
  */
 router.post('/count_tokens', async (req: Request, res: Response) => {
-  try {
-    const { model, messages, system } = req.body
-
-    if (!model) {
-      return res.status(400).json({
-        type: 'error',
-        error: {
-          type: 'invalid_request_error',
-          message: 'model parameter is required'
-        }
-      })
-    }
-
-    if (!messages || !Array.isArray(messages)) {
-      return res.status(400).json({
-        type: 'error',
-        error: {
-          type: 'invalid_request_error',
-          message: 'messages parameter is required'
-        }
-      })
-    }
-
-    const estimatedTokens = estimateTokenCount({ messages, system })
-
-    logger.debug('Token count estimated', {
-      model,
-      messageCount: messages.length,
-      estimatedTokens
-    })
-
-    return res.json({
-      input_tokens: estimatedTokens
-    })
-  } catch (error: any) {
-    logger.error('Token counting error', { error })
-    return res.status(500).json({
-      type: 'error',
-      error: {
-        type: 'api_error',
-        message: error.message || 'Internal server error'
-      }
-    })
-  }
+  return handleCountTokens(req, res, { requireModel: true })
 })
 
 /**
  * Provider-specific count_tokens endpoint
  */
 providerRouter.post('/count_tokens', async (req: Request, res: Response) => {
-  try {
-    const { model, messages, system } = req.body
-
-    if (!messages || !Array.isArray(messages)) {
-      return res.status(400).json({
-        type: 'error',
-        error: {
-          type: 'invalid_request_error',
-          message: 'messages parameter is required'
-        }
-      })
-    }
-
-    const estimatedTokens = estimateTokenCount({ messages, system })
-
-    logger.debug('Token count estimated (provider route)', {
-      providerId: req.params.provider,
-      model,
-      messageCount: messages.length,
-      estimatedTokens
-    })
-
-    return res.json({
-      input_tokens: estimatedTokens
-    })
-  } catch (error: any) {
-    logger.error('Token counting error', { error })
-    return res.status(500).json({
-      type: 'error',
-      error: {
-        type: 'api_error',
-        message: error.message || 'Internal server error'
-      }
-    })
-  }
+  return handleCountTokens(req, res, {
+    requireModel: false,
+    logContext: { providerId: req.params.provider }
+  })
 })
 
 export { providerRouter as messagesProviderRoutes, router as messagesRoutes }