Home Assistant Blueprint: Stale sensor detection

stale-sensor-detection-for-sensors.yaml

blueprint:
  name: Stale "Last seen" Sensor Report
  description: >
    Checks timestamp sensors ending in " Last seen". Lists those older than the threshold 
    or marked as "unavailable", stripping the suffix and adding the days ago.
  domain: automation
  input:
    days_threshold:
      name: Days Offline Threshold
      description: Sensors older than this many days will be reported.
      default: 7
      selector:
        number:
          min: 1
          max: 30
          unit_of_measurement: 'days'
          mode: slider
          step: 1
    time:
      name: Time to test on
      default: '08:00:00'
      selector:
        time: {}
    exclude:
      name: Excluded Entities
      default: {entity_id: []}
      selector:
        target:
          entity:
            device_class: timestamp
    actions:
      name: Actions
      description: '{{sensors}} will be replaced with the list (e.g., "Sensor Name (7d)").'
      selector:
        action: {}

variables:
  days_threshold: !input 'days_threshold'
  exclude: !input 'exclude'
  threshold_seconds: "{{ days_threshold | int * 86400 }}"
  sensors: >-
    {% set result = namespace(sensors=[]) %}
    {% set timestamp_sensors = states.sensor 
      | selectattr('attributes.device_class', 'defined') 
      | selectattr('attributes.device_class', 'eq', 'timestamp') 
      | list %}
    
    {% for state in timestamp_sensors %}
      {% if state.name.endswith(' Last seen') and not state.entity_id in exclude.entity_id %}
        {% set clean_name = state.name | replace(' Last seen', '') %}
        
        {% if state.state == 'unavailable' or state.state == 'unknown' %}
          {# Handle unavailable sensors separately #}
          {% set result.sensors = result.sensors + [clean_name ~ ' (unknown)'] %}
        {% else %}
          {# Calculate time difference for valid timestamps #}
          {% set last_seen_ts = as_timestamp(state.state, 0) %}
          {% set diff_seconds = as_timestamp(now()) - last_seen_ts %}
          
          {% if diff_seconds > threshold_seconds %}
            {% set days_ago = (diff_seconds / 86400) | int %}
            {% set result.sensors = result.sensors + [clean_name ~ ' (' ~ days_ago ~ 'd)'] %}
          {% endif %}
        {% endif %}
      {% endif %}
    {% endfor %}
    {{ result.sensors | join('\n') }}

trigger:
  - platform: time
    at: !input 'time'

condition:
  - "{{ sensors != '' }}"

action:
  - choose: []
    default: !input 'actions'

mode: single