🐛 Describe the bug

Singleton sensors are not tagging tracked objects with sensor data. When creating regions with singleton_type field, objects moving through these regions do not receive sensor readings despite MQTT messages being published to the sensor topics.

📋 To Reproduce

Steps to reproduce the behavior:

1. In the SceneScape UI, create a singleton sensor region using one of the out-of-box scenes

2. Set the singleton_type field to either "environmental" or "attribute"

3. Send MQTT sensor data when objects are in the sensor area

   mosquitto_pub -h localhost -t "scenescape/data/sensor/{sensor_id}" \
     -m '{"id":"sensor-id","timestamp":"2026-02-11T21:48:00Z","value":"72.5"}'

4. Subscribe to detection output and observe tracked objects

5. See that objects do NOT have sensors field despite being in the sensor region

💻 Expected behavior

Objects should be tagged with sensor data based on the singleton_type:

Environmental Sensors (ambient conditions)

Objects should receive transient sensor readings that are cleared when they exit.

On entry: Object is immediately tagged with the sensor's cached reading (if available).

During residence: Object receives updates as new MQTT sensor data arrives.

On exit: All sensor data is removed from the object.

{
  "id": "person-uuid",
  "type": "person",
  "regions": {
    "temp-sensor-01": {"entered": "2026-02-11T21:47:55.000Z"}
  },
  "sensors": {
    "temp-sensor-01": [
      ["2026-02-11T21:47:55.000Z", "72.0"],
      ["2026-02-11T21:48:00.000Z", "72.5"]
    ]
  }
}

Attribute Sensors (object-specific events)

Objects should receive persistent event data that remains after exit.

On entry: Object is added to sensor region but NOT tagged with any cached values.

During residence: Object is tagged only when MQTT sensor data arrives while object is present.

On exit: All sensor event data persists and remains on the object.

{
  "id": "person-uuid",
  "type": "person",
  "sensors": {
    "card-reader": [
      ["2026-02-11T21:48:39.983Z", "badge-12345"]
    ]
  }
}

🖥️ Screenshots or logs

Objects in singleton sensor regions show no sensors field in detection output despite MQTT messages arriving.

📦 Release version

• Version: 2026.0.0-dev (main branch)

🧩 Environment

• OS: Ubuntu 22.04
• Hardware: Gen 13 Core i7 NUC