# 03 — Prefill/decode wire protocol

Status: ready-for-agent

## Goal

Define and implement the activation protocol needed by both PyTorch and future GGUF backends.

## Scope

- Add route/session lifecycle headers.
- Separate `prefill` from `decode-step`.
- Keep binary bfloat16 activation bodies.
- Preserve relay compatibility.
- Add route id and model artifact hash validation.

## Draft Endpoints

- `POST /sessions/{session_id}/prefill`
- `POST /sessions/{session_id}/decode-step`
- `DELETE /sessions/{session_id}`
- `GET /sessions/{session_id}/status`

## Acceptance

- Old `/forward` remains temporarily or fails with clear version message.
- Tests cover relay preservation of session headers.
- Decode-step payload is independent of prompt length.