{
  "kind": "payload_envelope",
  "expect": "valid",
  "description": "pre_prompt_frame placement, preferred requirement, body_ref instead of inline body",
  "data": {
    "schema_version": "lifeloop.v0.2",
    "payload_id": "pay-pre-1",
    "client_id": "ccd",
    "payload_kind": "instruction_frame",
    "format": "client-defined",
    "content_encoding": "utf8",
    "body_ref": "blob://pay-pre-1",
    "byte_size": 1024,
    "content_digest": "sha256:0000",
    "acceptable_placements": [
      { "placement": "pre_prompt_frame", "requirement": "preferred" },
      { "placement": "side_channel_context", "requirement": "optional" }
    ]
  }
}
