Backplane.AiProtocol

backplane_ai_protocol is a standalone production package for provider-neutral AI protocol contracts and bounded native protocol observation.

It contains canonical contracts, validation/serialization boundaries, pure translation and wire preflight, SSE framing, and an OpenAI Responses observer. It intentionally contains no provider transport, credential handling, database, Phoenix, Backplane host process, or network startup.

Backplane proxy boundary

Same-protocol traffic uses native passthrough. Cross-protocol traffic uses backplane_ai_protocol translation. Logging and usage collection are isolated observations.

Native selection is based on the concrete client wire protocol and the selected provider API's declared native_protocols, not its provider name or broad compatibility family. Native requests, responses, streaming events, and upstream errors bypass canonical conversion. Model alias mapping is the sole routing exception: when needed, only the semantic model value changes; otherwise the original request bytes are forwarded.

A cross-protocol route may be enabled only when the package has complete request, non-streaming response, streaming-event lifecycle, tool, usage, and error codecs for that directed pair. The current package provides compatibility preflight but no complete cross-protocol HTTP codec pair, so the host rejects mismatches with unsupported_protocol_translation before submission.

Source notices

See SOURCE_NOTES.md for the pinned extraction candidates and current non-extraction boundary.