Identity overrides don't work in offline local evaluation mode

Start in flagsmith/flagsmith.py at the offline-handler loading path around line 117 and the API-update path around line 273; trace how identity_overrides are represented in the local file. Verify that offline local evaluation applies the override for identifier 146433 while preserving normal feature-state behavior, and add or run regression coverage for the case.

I'm using version 3.8.0 and have identity overrides enabled for my environment.

I'm using a copy of a config for local development and initialize Flagsmith as follows:

local_file_handler = LocalFileHandler(
    environment_document_path=f"./feature_flags_configuration.local.json"
)
flagsmith = Flagsmith(
    environment_key=settings.FLAGSMITH_API_KEY,
    enable_local_evaluation=True,
    offline_handler=local_file_handler,
    offline_mode=True,
)

I have following settings on my config:

  "feature_states": [
    {
      "feature": {
        "id": 103972,
        "name": "ipqs_geo_ip",
        "type": "STANDARD"
      },
      "enabled": true,
      "django_id": 576867,
      "feature_segment": null,
      "featurestate_uuid": "04dcc7d5-b387-4668-8264-d30a2da2e111",
      "feature_state_value": null,
      "multivariate_feature_state_values": []
    }
  ],
  "identity_overrides": [
    {
      "identifier": "146433",
      "environment_api_key": ...,
      "created_date": "2024-08-26T17:45:31.959128Z",
      "identity_features": [
        {
          "feature": {
            "id": 103972,
            "name": "ipqs_geo_ip",
            "type": "STANDARD"
          },
          "enabled": false,
          "django_id": null,
          "feature_segment": null,
          "featurestate_uuid": "964dd1e9-b34a-4bf7-9984-937abbba3f0e",
          "feature_state_value": null,
          "multivariate_feature_state_values": []
        }
      ],
      "identity_traits": [],
      "identity_uuid": "8fd6de03-b834-41d2-b5ec-7076d00e6cd3",
      "django_id": null,
      "composite_key": "cfWNJQwEQkcAiKxSPFL2rv_146433"
    }
  ],

However, identity overrides are ignored unless I disable offline mode.

The root cause must be that it is updated only here when API request is made and are not loaded from offline handler here.

In production, I'm also using the local file as a fallback for the case when Flagsmith is unavailable during app start, so it might become a problem in production in rare cases.