{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://synacl.com/protocol/v1/schemas/source-status.json",
  "title": "Gateway presence (heartbeat + last will)",
  "description": "The gateway's presence on `<prefix>/status`, published RETAINED. Two uses of one schema: (1) the MQTT last will, set at connect time, is exactly `{\"online\":false}` so the broker announces an ungraceful disconnect; (2) a heartbeat `{\"online\":true, …}` on connect and then every 60 s. The platform treats a gateway whose last heartbeat is older than 180 s as offline, so a missing heartbeat is itself evidence. An `online:false` also marks every device behind the gateway offline. Every field but `online` is optional and self-reported; the ones present are stored on the gateway record and shown in the app. Unknown keys are silently stripped (Ajv `removeAdditional`), so an undeclared field never reaches the handler.",
  "type": "object",
  "required": [
    "online"
  ],
  "properties": {
    "online": {
      "type": "boolean"
    },
    "ts": {
      "description": "Epoch milliseconds.",
      "type": "integer",
      "minimum": 0
    },
    "ip": {
      "description": "The gateway's local IP address (self-reported).",
      "type": "string"
    },
    "fw": {
      "description": "Firmware version string.",
      "type": "string"
    },
    "rssi": {
      "description": "Wi-Fi (or cellular) signal strength in dBm. A number — fractional values are accepted.",
      "type": "number"
    },
    "simMode": {
      "description": "The gateway is running in simulation mode (synthetic readings).",
      "type": "boolean"
    },
    "uplink": {
      "description": "Which interface carries the internet connection right now.",
      "type": "string",
      "enum": [
        "wifi",
        "ethernet",
        "cellular"
      ]
    },
    "ethIp": {
      "description": "The Ethernet interface's own address; present when Ethernet is used only for a local segment (LAN mode) rather than as the uplink.",
      "type": "string",
      "maxLength": 64
    },
    "bufRam": {
      "description": "Store-and-forward buffer: records currently held in RAM. The buffer fields are absent on firmware without the `buffering` capability.",
      "type": "integer",
      "minimum": 0
    },
    "bufFlash": {
      "description": "Store-and-forward buffer: records currently held on flash.",
      "type": "integer",
      "minimum": 0
    },
    "bufDropped": {
      "description": "Cumulative records dropped (ring overflow, no valid clock, identity mismatch).",
      "type": "integer",
      "minimum": 0
    },
    "flashErrors": {
      "description": "Cumulative flash write-verify / mount failures. Greater than 0 is the replace-this-unit signal.",
      "type": "integer",
      "minimum": 0
    },
    "flashWearPct": {
      "description": "Estimated flash erase-cycle consumption, 0-100.",
      "type": "integer",
      "minimum": 0,
      "maximum": 100
    }
  },
  "additionalProperties": false
}