Scope Kimi tool call compatibility (#560)

Co-authored-by: James Grugett <jahooma@gmail.com>

Author: brandonkachen

web/src/llm-api/__tests__/kimi-tool-compat.test.ts

@@ -0,0 +1,112 @@
+import { describe, expect, it } from 'bun:test'
+
+import { addKimiToolCompatibilityFields, isKimiModel } from '../kimi-tool-compat'
+
+import type { ChatCompletionRequestBody } from '../types'
+
+describe('addKimiToolCompatibilityFields', () => {
+  it('adds declaration ids and tool-result names without mutating input', () => {
+    const body: ChatCompletionRequestBody = {
+      model: 'moonshotai/kimi-k2.6',
+      messages: [
+        {
+          role: 'assistant',
+          content: '',
+          tool_calls: [
+            {
+              id: 'call_123',
+              type: 'function',
+              function: {
+                name: 'read_files',
+                arguments: JSON.stringify({ paths: ['README.md'] }),
+              },
+            },
+          ],
+        },
+        {
+          role: 'tool',
+          tool_call_id: 'call_123',
+          content: JSON.stringify({ message: 'ok' }),
+        },
+      ],
+      tools: [
+        {
+          type: 'function',
+          function: {
+            name: 'read_files',
+            description: 'Read files',
+            parameters: { type: 'object' },
+          },
+        },
+      ],
+    }
+
+    const result = addKimiToolCompatibilityFields(body)
+
+    expect(result.tools?.[0]).toEqual({
+      id: 'tool_1',
+      type: 'function',
+      function: {
+        name: 'read_files',
+        description: 'Read files',
+        parameters: { type: 'object' },
+      },
+    })
+    expect(result.messages[1]).toEqual({
+      role: 'tool',
+      tool_call_id: 'call_123',
+      name: 'read_files',
+      content: JSON.stringify({ message: 'ok' }),
+    })
+    expect(body.tools?.[0]).not.toHaveProperty('id')
+    expect(body.messages[1]).not.toHaveProperty('name')
+  })
+
+  it('preserves existing ids and names', () => {
+    const body: ChatCompletionRequestBody = {
+      model: 'moonshotai/kimi-k2.6',
+      messages: [
+        {
+          role: 'assistant',
+          content: '',
+          tool_calls: [
+            {
+              id: 'call_456',
+              type: 'function',
+              function: {
+                name: 'write_todos',
+                arguments: JSON.stringify({ todos: [] }),
+              },
+            },
+          ],
+        },
+        {
+          role: 'tool',
+          tool_call_id: 'call_456',
+          name: 'existing_name',
+          content: '{}',
+        },
+      ],
+      tools: [
+        {
+          id: 'existing_tool_id',
+          type: 'function',
+          function: {
+            name: 'write_todos',
+            parameters: { type: 'object' },
+          },
+        },
+      ],
+    }
+
+    expect(addKimiToolCompatibilityFields(body)).toEqual(body)
+  })
+})
+
+describe('isKimiModel', () => {
+  it('matches only Moonshot model ids', () => {
+    expect(isKimiModel('moonshotai/kimi-k2.6')).toBe(true)
+    expect(isKimiModel('anthropic/claude-sonnet-4.5')).toBe(false)
+    expect(isKimiModel(undefined)).toBe(false)
+  })
+})

web/src/llm-api/canopywave.ts

@@ -9,6 +9,7 @@ import {
   extractRequestMetadata,
   insertMessageToBigQuery,
 } from './helpers'
+import { addKimiToolCompatibilityFields, isKimiModel } from './kimi-tool-compat'
 
 import type { UsageData } from './helpers'
 import type { InsertMessageBigqueryFn } from '@codebuff/common/types/contracts/bigquery'
@@ -88,8 +89,11 @@ function createCanopyWaveRequest(params: {
   fetch: typeof globalThis.fetch
 }) {
   const { body, originalModel, fetch } = params
+  const providerBody = isKimiModel(originalModel)
+    ? addKimiToolCompatibilityFields(body)
+    : body
   const canopywaveBody: Record<string, unknown> = {
-    ...body,
+    ...providerBody,
     model: getCanopyWaveModelId(originalModel),
   }
 

web/src/llm-api/kimi-tool-compat.ts

@@ -0,0 +1,67 @@
+import type { ChatCompletionRequestBody } from './types'
+
+export function isKimiModel(model: unknown): model is string {
+  return typeof model === 'string' && model.startsWith('moonshotai/')
+}
+
+function getToolCallNamesById(
+  messages: ChatCompletionRequestBody['messages'],
+): Map<string, string> {
+  const namesById = new Map<string, string>()
+
+  for (const message of messages) {
+    if (message.role !== 'assistant') {
+      continue
+    }
+    for (const toolCall of message.tool_calls ?? []) {
+      if (toolCall.id && toolCall.function.name) {
+        namesById.set(toolCall.id, toolCall.function.name)
+      }
+    }
+  }
+
+  return namesById
+}
+
+/**
+ * Kimi-compatible providers require two OpenAI-compatible extensions that are
+ * not part of the strict Chat Completions schema: ids on tool declarations and
+ * names on tool-result messages.
+ */
+export function addKimiToolCompatibilityFields(
+  body: ChatCompletionRequestBody,
+): ChatCompletionRequestBody {
+  const namesByToolCallId = getToolCallNamesById(body.messages)
+
+  return {
+    ...body,
+    tools: body.tools?.map((tool, index) => {
+      if (tool.type !== 'function' || tool.id) {
+        return tool
+      }
+      return {
+        ...tool,
+        id: `tool_${index + 1}`,
+      }
+    }),
+    messages: body.messages.map((message) => {
+      if (
+        message.role !== 'tool' ||
+        message.name ||
+        typeof message.tool_call_id !== 'string'
+      ) {
+        return message
+      }
+
+      const name = namesByToolCallId.get(message.tool_call_id)
+      if (!name) {
+        return message
+      }
+
+      return {
+        ...message,
+        name,
+      }
+    }),
+  }
+}

web/src/llm-api/openrouter.ts

@@ -9,6 +9,7 @@ import {
   extractRequestMetadata,
   insertMessageToBigQuery,
 } from './helpers'
+import { addKimiToolCompatibilityFields, isKimiModel } from './kimi-tool-compat'
 import {
   OpenRouterErrorResponseSchema,
   OpenRouterStreamChatCompletionChunkSchema,
@@ -61,6 +62,10 @@ function createOpenRouterRequest(params: {
   fetch: typeof globalThis.fetch
 }) {
   const { body, openrouterApiKey, fetch } = params
+  const providerBody = isKimiModel(body.model)
+    ? addKimiToolCompatibilityFields(body)
+    : body
+
   return fetch('https://openrouter.ai/api/v1/chat/completions', {
     method: 'POST',
     headers: {
@@ -69,7 +74,7 @@ function createOpenRouterRequest(params: {
       'X-Title': 'Codebuff',
       'Content-Type': 'application/json',
     },
-    body: JSON.stringify(body),
+    body: JSON.stringify(providerBody),
     // Use custom agent with extended headers timeout for deep-thinking models
     // @ts-expect-error - dispatcher is a valid undici option not in fetch types
     dispatcher: openrouterAgent,

web/src/llm-api/types.ts

@@ -28,9 +28,21 @@ export interface ChatMessage {
   tool_call_id?: string
 }
 
+export interface ChatCompletionTool {
+  id?: string
+  type: string
+  function?: {
+    name: string
+    description?: string
+    parameters?: unknown
+    strict?: boolean
+  }
+}
+
 export interface ChatCompletionRequestBody {
   model: string
   messages: ChatMessage[]
+  tools?: ChatCompletionTool[]
   stream?: boolean
   temperature?: number
   max_tokens?: number