{
  "$schema": "http://json-schema.org/draft-07/schema#",
  "$id": "https://adcontextprotocol.org/schemas/3.3.0-beta.1/core/assignment-tracker.json",
  "title": "Assignment Tracker",
  "description": "A renderer-fired HTTP GET measurement tracker for one creative-to-package assignment, in addition to the creative's own trackers. Uses the pixel_tracker event vocabulary with image-pixel semantics; it is not a click destination, JavaScript include, or advertiser-site conversion pixel. The seller MUST fire every accepted tracker at its declared event or reject the assignment, including unrecognized custom events; silent no-op behavior is not permitted for assignment trackers.",
  "x-added-in": "3.3.0",
  "type": "object",
  "properties": {
    "event": {
      "$ref": "https://adcontextprotocol.org/schemas/3.3.0-beta.1/enums/pixel-tracking-event.json",
      "description": "Measurement event, with the same timing as pixel_tracker. An event the seller cannot fire on the assigned format MUST cause assignment rejection."
    },
    "custom_event_name": {
      "type": "string",
      "minLength": 1,
      "description": "Required when event is custom; MUST be absent otherwise. The seller must recognize and fire this event or reject the assignment."
    },
    "url": {
      "$ref": "https://adcontextprotocol.org/schemas/3.3.0-beta.1/core/macro-bearing-url.json",
      "description": "Tracker URL template, preserved on readback. AdCP macros follow the creative tracker rules without declarations, including existing 3.x compatibility behavior. Creative asset macro_declarations do not transfer to this URL, and assignment tracker support does not promise resolution of any particular token."
    }
  },
  "required": [
    "event",
    "url"
  ],
  "allOf": [
    {
      "if": {
        "properties": {
          "event": {
            "const": "custom"
          }
        },
        "required": [
          "event"
        ]
      },
      "then": {
        "required": [
          "custom_event_name"
        ]
      },
      "else": {
        "not": {
          "required": [
            "custom_event_name"
          ]
        }
      }
    }
  ],
  "not": {
    "anyOf": [
      {
        "required": [
          "asset_type"
        ]
      },
      {
        "required": [
          "method"
        ]
      },
      {
        "required": [
          "macro_declarations"
        ]
      }
    ]
  },
  "additionalProperties": true,
  "examples": [
    {
      "event": "impression",
      "url": "https://measurement.example/imp?mb=mb_1&pkg=pkg_1&cb={CACHEBUSTER}"
    },
    {
      "event": "custom",
      "custom_event_name": "start",
      "url": "https://measurement.example/start?mb=mb_1"
    }
  ]
}