Module shape_xlat 

Cross-shape translation Anthropic ↔ OpenAI (enterprise#16, feature shape-xlat).

Lets a Claude client (POST /v1/messages) transparently use an OpenAI-shape upstream (Azure AI Foundry, vLLM, Ollama, Groq…): the request is rewritten Messages→Chat-Completions before it leaves, and the response — streaming or not — is rewritten back so the caller’s Anthropic SDK never notices. Pure enabler for the router ([proxy.routing] cross-shape targets), deliberately not a headline feature (scope gate 12 §6).

Mapping summary:

Anthropic	OpenAI
system (string/blocks)	leading role:"system" message
tool_use block (assistant)	tool_calls[] entry
tool_result block (user)	role:"tool" message
image block (base64)	image_url part (data URL)
tools[].input_schema	tools[].function.parameters
tool_choice {auto,any,tool}	"auto", "required", function pick
stop_sequences	stop
metadata.user_id	user
cache_control	stripped (OpenAI caches implicitly)
response content[] / SSE events	choices[0].message / delta chunks
usage.prompt_tokens(_details.cached)	input_tokens / cache_read_…

Streaming is a stateful SSE-to-SSE rewrite (StreamXlat): OpenAI chat.completion.chunk deltas become message_start / content_block_start|delta|stop / message_delta / message_stop events. Usage metering does NOT read the translated stream — the forward path scans the raw upstream bytes with the OpenAI scanner before translation.

Structs

StreamXlat

Stateful OpenAI→Anthropic SSE translator. Feed raw upstream bytes, get translated Anthropic event bytes; call StreamXlat::finish at stream end to flush the closing events if the upstream never sent [DONE].

Functions

chat_to_messages

Translates a full OpenAI chat.completion body into an Anthropic message. None = body not recognizable (caller forwards it unchanged).

error_to_anthropic

Maps an OpenAI error envelope ({"error": {...}}) to the Anthropic one ({"type":"error","error":{...}}) so the caller’s SDK renders the message.

messages_to_chat

Translates a parsed Anthropic Messages request into an OpenAI Chat Completions body. None = not translatable (caller must fail open and forward natively).

to_anthropic_stream

Wraps an (already usage-teed) OpenAI SSE byte stream into the translated Anthropic SSE stream. Chunks that translate to nothing are skipped; on upstream end the closing events are flushed.