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README

llm-translate

Zero-dependency Go library for bidirectional protocol translation between the Anthropic Messages API, OpenAI Chat Completions, and the OpenAI Responses API.

Features

• Anthropic ↔ OpenAI Request & Response: Full fidelity translation of messages, tool definitions, tool results, thinking/reasoning blocks, system prompts, and multi-part vision content.
• SSE Stream Translation: Real-time translation between OpenAI chunk deltas and Anthropic SSE events (message_start, content_block_start, content_block_delta, message_delta, message_stop).
• OpenAI Responses ↔ Chat: Bidirectional translation for newer OpenAI Responses API backends to standard Chat completions.
• Pure Standard Library: Zero CGO, zero external dependencies.

Installation

go get github.com/xibodev/llm-translate

Quick Start

Convert Anthropic Messages Request to OpenAI

import "github.com/xibodev/llm-translate"

openaiMessages := translate.AnthropicMessagesToOpenAI(req.Messages, req.System)
tools := translate.AnthropicToolsToOpenAI(req.Tools)

Stream OpenAI Chunks as Anthropic SSE

translate.OpenAIStreamToAnthropicSSE(chunksIter, "claude-3-5-sonnet", func(sseEvent string) {
    w.Write([]byte(sseEvent))
    w.(http.Flusher).Flush()
})

License

MIT

Documentation

Overview

Package translate round-trips between the Anthropic Messages API and the OpenAI Chat Completions schema. The gateway speaks OpenAI natively; this is the single translator that lets Claude Code and other Anthropic clients talk to it, and lets the native Anthropic backend be called from OpenAI-shaped internals.

Faithful port of llmgw.api.anthropic_translate. JSON objects are modeled as map[string]any / []any to mirror the Python dict handling.

Index

• func AnthropicMessagesToOpenAI(messages []any, system any) []map[string]any
• func AnthropicRequestToOpenAI(payload map[string]any) ([]map[string]any, map[string]any, []string)
• func AnthropicResponseToOpenAI(response map[string]any, model string) map[string]any
• func AnthropicSSEToOpenAIChunks(lines func() (string, bool), model string, emit func(string))
• func AnthropicStopReasonToOpenAI(reason any) string
• func AnthropicToolChoiceToOpenAI(choice map[string]any) any
• func AnthropicToolsToOpenAI(tools []any) []any
• func ChatResponseToResponses(model string, chat map[string]any) map[string]any
• func ChatResponseToResponsesWithRequest(model string, chat map[string]any, request map[string]any) map[string]any
• func ChatToResponses(model string, messages []map[string]any, kw map[string]any, stream bool) map[string]any
• func FailedResponseEnvelope(model, id, code, message string, request map[string]any) map[string]any
• func NewResponseEnvelope(model, id, status string, output []any, request map[string]any) map[string]any
• func OpenAIFinishReasonToAnthropic(reason any) string
• func OpenAIMessagesToAnthropic(messages []map[string]any) (string, []map[string]any)
• func OpenAIResponseToAnthropic(response map[string]any, model string) map[string]any
• func OpenAIStreamToAnthropicSSE(chunks func() (string, bool), model string, emit func(string))
• func OpenAIToolsToAnthropic(tools []any) []any
• func PreferredEndpoint(supportedEndpoints []string) string
• func ResponsesRequestToChat(payload map[string]any) ([]map[string]any, map[string]any, error)
• func ResponsesToChat(model string, resp map[string]any) map[string]any
• func ResponsesToChatChunks(model string, resp map[string]any) []string

Functions

func AnthropicMessagesToOpenAI

func AnthropicMessagesToOpenAI(messages []any, system any) []map[string]any

AnthropicMessagesToOpenAI converts Anthropic messages + system into OpenAI messages.

func AnthropicRequestToOpenAI

func AnthropicRequestToOpenAI(payload map[string]any) ([]map[string]any, map[string]any, []string)

AnthropicRequestToOpenAI strictly converts the Messages core profile. The returned paths name every value that an OpenAI Chat target would lose.

func AnthropicResponseToOpenAI

func AnthropicResponseToOpenAI(response map[string]any, model string) map[string]any

AnthropicResponseToOpenAI converts a non-streaming Anthropic Message to an OpenAI completion.

func AnthropicSSEToOpenAIChunks

func AnthropicSSEToOpenAIChunks(lines func() (string, bool), model string, emit func(string))

AnthropicSSEToOpenAIChunks translates Anthropic SSE data lines into OpenAI chat.completion.chunk JSON strings, invoking emit for each.

func AnthropicStopReasonToOpenAI

func AnthropicStopReasonToOpenAI(reason any) string

AnthropicStopReasonToOpenAI maps an Anthropic stop_reason to an OpenAI finish_reason.

func AnthropicToolChoiceToOpenAI

func AnthropicToolChoiceToOpenAI(choice map[string]any) any

AnthropicToolChoiceToOpenAI converts Anthropic tool_choice to OpenAI's.

func AnthropicToolsToOpenAI

func AnthropicToolsToOpenAI(tools []any) []any

AnthropicToolsToOpenAI converts Anthropic tools to OpenAI function tools.

func ChatResponseToResponses

func ChatResponseToResponses(model string, chat map[string]any) map[string]any

ChatResponseToResponses converts the gateway's internal Chat Completions result back into the public Responses API envelope.

func ChatResponseToResponsesWithRequest

func ChatResponseToResponsesWithRequest(
	model string, chat map[string]any, request map[string]any,
) map[string]any

func ChatToResponses

func ChatToResponses(model string, messages []map[string]any, kw map[string]any, stream bool) map[string]any

ChatToResponses converts a Chat Completions request body into a Responses API request body.

func FailedResponseEnvelope

func FailedResponseEnvelope(
	model, id, code, message string, request map[string]any,
) map[string]any

func NewResponseEnvelope

func NewResponseEnvelope(
	model, id, status string, output []any, request map[string]any,
) map[string]any

NewResponseEnvelope creates the schema-complete Response shape used whenever the gateway adapts a Chat-only backend or synthesizes a terminal failure.

func OpenAIFinishReasonToAnthropic

func OpenAIFinishReasonToAnthropic(reason any) string

OpenAIFinishReasonToAnthropic maps an OpenAI finish_reason to Anthropic stop_reason.

func OpenAIMessagesToAnthropic

func OpenAIMessagesToAnthropic(messages []map[string]any) (string, []map[string]any)

OpenAIMessagesToAnthropic splits an OpenAI message list into Anthropic (system, messages).

func OpenAIResponseToAnthropic

func OpenAIResponseToAnthropic(response map[string]any, model string) map[string]any

OpenAIResponseToAnthropic converts a non-streaming OpenAI completion to an Anthropic Message.

func OpenAIStreamToAnthropicSSE

func OpenAIStreamToAnthropicSSE(chunks func() (string, bool), model string, emit func(string))

OpenAIStreamToAnthropicSSE translates OpenAI SSE chunk payloads (JSON strings, data: prefix already stripped) into Anthropic SSE event blocks, invoking emit for each output event.

func OpenAIToolsToAnthropic

func OpenAIToolsToAnthropic(tools []any) []any

OpenAIToolsToAnthropic converts OpenAI tools to Anthropic tool shape.

func PreferredEndpoint

func PreferredEndpoint(supportedEndpoints []string) string

PreferredEndpoint decides which OpenAI-family endpoint a model should use given its published supported_surfaces. Returns "responses" only when the model advertises /responses but NOT /chat/completions; otherwise "chat" (the safe default, including when the list is empty/unknown).

func ResponsesRequestToChat

func ResponsesRequestToChat(
	payload map[string]any,
) ([]map[string]any, map[string]any, error)

ResponsesRequestToChat converts supported Responses input/history/tools into the gateway's internal Chat representation. Built-in Responses-only tools fail explicitly instead of being silently flattened.

func ResponsesToChat

func ResponsesToChat(model string, resp map[string]any) map[string]any

ResponsesToChat converts a Responses API object into a chat.completion.

func ResponsesToChatChunks

func ResponsesToChatChunks(model string, resp map[string]any) []string

ResponsesToChatChunks renders a (buffered) Responses reply as a small sequence of chat.completion.chunk payloads for the streaming code path.