Beacon protocol

{
  "s": "<siteId>",
  "u": "<userId>",
  "v": <configVersion>,
  "t": <clientTimestampMs>,
  "nr": "n" | "r",
  "rf": "<trafficChannel>",
  "uc": "<utmCampaign>",
  "p": { "lcp": <ms>, "a": { "<expId>": <ms> } },
  "e": [
    { "i": "<experimentId>", "k": "<variantKey>", "bn": "l" | "s", "gn": <generation> }
  ],
  "g": [
    {
      "i": "<experimentId>",
      "k": "<variantKey>",
      "gi": "<goalId>",
      "v": <value>,
      "bn": "l" | "s",
      "gn": <generation>,
      "oid": "<orderId>",
      "cur": "<currency>",
      "rt": "refund",
      "rid": "<refundId>",
      "eid": "<eventId>"
    }
  ]
}

{ "accepted": true, "reason": null }

{ "accepted": false, "reason": "location_not_matched" | "audience_not_matched" | "not_eligible_by_bucket" }

{
  "s": "<siteId>",
  "v": <configVersion>,
  "t": <clientTimestampMs>,
  "errors": [
    {
      "e": "<experimentId>",
      "vk": "<variantKey>",
      "ph": "apply" | "cleanup" | "route-handler" | "variant-js" | "async" | "global-js",
      "m": "<messageString>",
      "st": "<stackString>",
      "u": "<pageUrl>"
    }
  ]
}

{
  "s": "<siteId>",
  "e": "<experimentId>",
  "vk": "<variantKey>",
  "lib": "<libraryKey>",
  "phase": "load-start" | "load-end" | "load-error",
  "t": <clientTimestampMs>,
  "dur": <durationMs>
}

{ "country": "US", "region": "CA", "city": "San Francisco" }