{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id": "urn:shiin:schema:checkpoint:v1",
  "title": "Shiin signed audit checkpoint payload",
  "type": "object",
  "required": ["schema", "key_id", "seq", "head", "signed_at"],
  "properties": {
    "schema": { "type": "string", "const": "shiin.checkpoint/v1-draft.1" },
    "key_id": { "$ref": "urn:shiin:schema:common:v1#/$defs/sha256" },
    "seq": { "type": "integer", "minimum": 0 },
    "head": { "$ref": "urn:shiin:schema:common:v1#/$defs/sha256" },
    "signed_at": { "type": "string", "format": "date-time" }
  },
  "additionalProperties": false
}