{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://synacl.com/protocol/v1/schemas/data-backfill.json",
  "title": "Buffered telemetry replay",
  "description": "Telemetry a gateway buffered while its uplink was down, replayed in oldest-first batches on the GATEWAY-scoped topic `<prefix>/data/backfill`. The gateway's buffer is a single FIFO ring across all its devices, so one batch legitimately mixes devices and every record names its own `deviceId` — that is the only field a record adds over the live `data` schema, and ts/values/q/seq mean exactly what they mean there because the records feed the same telemetry store. Never replay on the live `data` topic: the live path rate-gates per device and would suspend a device replaying a backlog. Replayed records are stored only; they do not drive dashboards, rules or last-known values. The batch is capped at 40 records to bound parse cost (the reference firmware packs under 3,500 bytes). An over-long batch fails validation and the WHOLE message is dropped with a logged error — loud, not silently truncated. Unknown keys are silently stripped (Ajv `removeAdditional`), which is why every field is declared.",
  "type": "object",
  "required": [
    "batch"
  ],
  "properties": {
    "batch": {
      "description": "1 to 40 records, oldest first.",
      "type": "array",
      "minItems": 1,
      "maxItems": 40,
      "items": {
        "type": "object",
        "required": [
          "deviceId",
          "ts",
          "values"
        ],
        "properties": {
          "deviceId": {
            "description": "The device the record belongs to — its 24-hex-character id.",
            "type": "string",
            "pattern": "^[0-9a-fA-F]{24}$"
          },
          "ts": {
            "description": "When the values were read (epoch milliseconds) — the original read time, not the replay time.",
            "type": "integer",
            "minimum": 0
          },
          "values": {
            "description": "Tag name -> value, as in the live `data` message.",
            "type": "object",
            "minProperties": 1,
            "additionalProperties": {
              "type": [
                "number",
                "boolean",
                "string"
              ]
            }
          },
          "q": {
            "description": "Data quality. Omitted means `good`.",
            "type": "string",
            "enum": [
              "good",
              "bad",
              "uncertain",
              "stale"
            ],
            "default": "good"
          },
          "seq": {
            "description": "Optional per-device message counter, as in the live `data` message.",
            "type": "integer",
            "minimum": 0
          }
        },
        "additionalProperties": false
      }
    }
  },
  "additionalProperties": false
}