Function translateToAnthropic

src/routes/messages/non-stream-translation.ts:281–327

(
  response: ChatCompletionResponse,
)

// Response translation

export function translateToAnthropic(
  response: ChatCompletionResponse,
): AnthropicResponse {
  // Merge content from all choices
  const allTextBlocks: Array<AnthropicTextBlock> = []
  const allToolUseBlocks: Array<AnthropicToolUseBlock> = []
  let stopReason: "stop" | "length" | "tool_calls" | "content_filter" | null =
    null // default
  stopReason = response.choices[0]?.finish_reason ?? stopReason

  // Process all choices to extract text and tool use blocks
  for (const choice of response.choices) {
    const textBlocks = getAnthropicTextBlocks(choice.message.content)
    const toolUseBlocks = getAnthropicToolUseBlocks(choice.message.tool_calls)

    allTextBlocks.push(...textBlocks)
    allToolUseBlocks.push(...toolUseBlocks)

    // Use the finish_reason from the first choice, or prioritize tool_calls
    if (choice.finish_reason === "tool_calls" || stopReason === "stop") {
      stopReason = choice.finish_reason
    }
  }

  // Note: GitHub Copilot doesn't generate thinking blocks, so we don't include them in responses

  return {
    id: response.id,
    type: "message",
    role: "assistant",
    model: response.model,
    content: [...allTextBlocks, ...allToolUseBlocks],
    stop_reason: mapOpenAIStopReasonToAnthropic(stopReason),
    stop_sequence: null,
    usage: {
      input_tokens:
        (response.usage?.prompt_tokens ?? 0)
        - (response.usage?.prompt_tokens_details?.cached_tokens ?? 0),
      output_tokens: response.usage?.completion_tokens ?? 0,
      ...(response.usage?.prompt_tokens_details?.cached_tokens
        !== undefined && {
        cache_read_input_tokens:
          response.usage.prompt_tokens_details.cached_tokens,
      }),
    },
  }
}

function getAnthropicTextBlocks(
  messageContent: Message["content"],