{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://synacl.com/protocol/v1/schemas/image-meta.json",
  "title": "Event image header (experimental)",
  "description": "EXPERIMENTAL — may change without a version bump. A fog node relaying an event-triggered camera frame publishes this header on `<prefix>/devices/{deviceId}/image/meta` first, then `chunks` ordered image-chunk messages under the same `imageId`. Bounded so a misbehaving node cannot exhaust memory: at most 1024 chunks (about 1.5 MB of image at 2048 base64 characters per chunk).",
  "type": "object",
  "required": [
    "imageId",
    "chunks"
  ],
  "properties": {
    "imageId": {
      "description": "Unique per image; every chunk repeats it.",
      "type": "string",
      "maxLength": 96
    },
    "ts": {
      "description": "Epoch milliseconds.",
      "type": "integer",
      "minimum": 0
    },
    "trigger": {
      "description": "What caused the capture.",
      "type": "string",
      "maxLength": 64
    },
    "samples": {
      "description": "Sensor readings around the trigger, at most 16.",
      "type": "array",
      "maxItems": 16,
      "items": {
        "type": "number"
      }
    },
    "format": {
      "type": "string",
      "enum": [
        "jpeg",
        "jpg",
        "png"
      ]
    },
    "width": {
      "type": "integer",
      "minimum": 0,
      "maximum": 10000
    },
    "height": {
      "type": "integer",
      "minimum": 0,
      "maximum": 10000
    },
    "size": {
      "description": "Decoded image size in bytes, at most 8 MiB.",
      "type": "integer",
      "minimum": 0,
      "maximum": 8388608
    },
    "chunks": {
      "description": "How many image-chunk messages follow (1-1024).",
      "type": "integer",
      "minimum": 1,
      "maximum": 1024
    }
  },
  "additionalProperties": false
}