支持 OpenAI Chat 兼容协议 (#99)

* feat: 完成 openai 接口兼容

* feat: 完成 openai 协议兼容

* fix: 修复测试用例

src/services/api/openai/convertMessages.ts

@@ -0,0 +1,184 @@
+import type {
+  BetaContentBlockParam,
+  BetaToolResultBlockParam,
+  BetaToolUseBlock,
+} from '@anthropic-ai/sdk/resources/beta/messages/messages.mjs'
+import type {
+  ChatCompletionAssistantMessageParam,
+  ChatCompletionMessageParam,
+  ChatCompletionSystemMessageParam,
+  ChatCompletionToolMessageParam,
+  ChatCompletionUserMessageParam,
+} from 'openai/resources/chat/completions/completions.mjs'
+import type { AssistantMessage, UserMessage } from '../../../types/message.js'
+import type { SystemPrompt } from '../../../utils/systemPromptType.js'
+
+/**
+ * Convert internal (UserMessage | AssistantMessage)[] to OpenAI-format messages.
+ *
+ * Key conversions:
+ * - system prompt → role: "system" message prepended
+ * - tool_use blocks → tool_calls[] on assistant message
+ * - tool_result blocks → role: "tool" messages
+ * - thinking blocks → silently dropped
+ * - cache_control → stripped
+ */
+export function anthropicMessagesToOpenAI(
+  messages: (UserMessage | AssistantMessage)[],
+  systemPrompt: SystemPrompt,
+): ChatCompletionMessageParam[] {
+  const result: ChatCompletionMessageParam[] = []
+
+  // Prepend system prompt as system message
+  const systemText = systemPromptToText(systemPrompt)
+  if (systemText) {
+    result.push({
+      role: 'system',
+      content: systemText,
+    } satisfies ChatCompletionSystemMessageParam)
+  }
+
+  for (const msg of messages) {
+    switch (msg.type) {
+      case 'user':
+        result.push(...convertInternalUserMessage(msg))
+        break
+      case 'assistant':
+        result.push(...convertInternalAssistantMessage(msg))
+        break
+      default:
+        break
+    }
+  }
+
+  return result
+}
+
+function systemPromptToText(systemPrompt: SystemPrompt): string {
+  if (!systemPrompt || systemPrompt.length === 0) return ''
+  return systemPrompt
+    .filter(Boolean)
+    .join('\n\n')
+}
+
+function convertInternalUserMessage(
+  msg: UserMessage,
+): ChatCompletionMessageParam[] {
+  const result: ChatCompletionMessageParam[] = []
+  const content = msg.message.content
+
+  if (typeof content === 'string') {
+    result.push({
+      role: 'user',
+      content,
+    } satisfies ChatCompletionUserMessageParam)
+  } else if (Array.isArray(content)) {
+    const textParts: string[] = []
+    const toolResults: BetaToolResultBlockParam[] = []
+
+    for (const block of content) {
+      if (typeof block === 'string') {
+        textParts.push(block)
+      } else if (block.type === 'text') {
+        textParts.push(block.text)
+      } else if (block.type === 'tool_result') {
+        toolResults.push(block as BetaToolResultBlockParam)
+      }
+      // Skip image, document, thinking, cache_edits, etc.
+    }
+
+    if (textParts.length > 0) {
+      result.push({
+        role: 'user',
+        content: textParts.join('\n'),
+      } satisfies ChatCompletionUserMessageParam)
+    }
+
+    for (const tr of toolResults) {
+      result.push(convertToolResult(tr))
+    }
+  }
+
+  return result
+}
+
+function convertToolResult(
+  block: BetaToolResultBlockParam,
+): ChatCompletionToolMessageParam {
+  let content: string
+  if (typeof block.content === 'string') {
+    content = block.content
+  } else if (Array.isArray(block.content)) {
+    content = block.content
+      .map(c => {
+        if (typeof c === 'string') return c
+        if ('text' in c) return c.text
+        return ''
+      })
+      .filter(Boolean)
+      .join('\n')
+  } else {
+    content = ''
+  }
+
+  return {
+    role: 'tool',
+    tool_call_id: block.tool_use_id,
+    content,
+  } satisfies ChatCompletionToolMessageParam
+}
+
+function convertInternalAssistantMessage(
+  msg: AssistantMessage,
+): ChatCompletionMessageParam[] {
+  const content = msg.message.content
+
+  if (typeof content === 'string') {
+    return [
+      {
+        role: 'assistant',
+        content,
+      } satisfies ChatCompletionAssistantMessageParam,
+    ]
+  }
+
+  if (!Array.isArray(content)) {
+    return [
+      {
+        role: 'assistant',
+        content: '',
+      } satisfies ChatCompletionAssistantMessageParam,
+    ]
+  }
+
+  const textParts: string[] = []
+  const toolCalls: NonNullable<ChatCompletionAssistantMessageParam['tool_calls']> = []
+
+  for (const block of content) {
+    if (typeof block === 'string') {
+      textParts.push(block)
+    } else if (block.type === 'text') {
+      textParts.push(block.text)
+    } else if (block.type === 'tool_use') {
+      const tu = block as BetaToolUseBlock
+      toolCalls.push({
+        id: tu.id,
+        type: 'function',
+        function: {
+          name: tu.name,
+          arguments:
+            typeof tu.input === 'string' ? tu.input : JSON.stringify(tu.input),
+        },
+      })
+    }
+    // Skip thinking, redacted_thinking, server_tool_use, etc.
+  }
+
+  const result: ChatCompletionAssistantMessageParam = {
+    role: 'assistant',
+    content: textParts.length > 0 ? textParts.join('\n') : null,
+    ...(toolCalls.length > 0 && { tool_calls: toolCalls }),
+  }
+
+  return [result]
+}