Add Analytics Label Support for FCM Messages in Parse Server Push Adapter

New Feature / Enhancement Checklist

• I am not disclosing a vulnerability.
• I am not just asking a question.
• I have searched through existing issues.

Current Limitation

Currently, the Parse Server push adapter does not support adding analytics labels to FCM messages. Without an analytics label, Firebase’s delivery statistics for data messages are limited and cannot be fully filtered or analyzed in the Firebase console.

Feature / Enhancement Description

This feature request proposes adding support for analytics labels in the FCM payload generated by the push adapter. Specifically, the adapter should:

• Allow developers to include an analytics_label field in their push notification request data.
• Validate the provided label against the regex pattern ^[a-zA-Z0-9-_.~%]{1,50}$ (ensuring it contains only letters, numbers, and the symbols -_.~% with a maximum length of 50 characters).
• If valid, inject the label into the outgoing payload under fcm_options.analytics_label.

This change would help align the adapter’s behavior with Firebase’s HTTP v1 API requirements and enable developers to filter and view detailed delivery statistics for their push notifications in the Firebase console.

Example Use Case

1. A developer wants to monitor push delivery for a new feature update.
2. They include analytics_label: "feature_update_v1" in the push notification payload.
3. The push adapter processes the request, validates the label, and adds it under the fcm_options.analytics_label field.
4. Firebase records and displays delivery statistics for messages with this label, enabling the developer to filter reports and analyze the campaign’s performance.

Alternatives / Workarounds

I haven't found an alternative or workarounds

3rd Party References

• Firebase documentation on analytics labels: Adding analytics labels to messages
• Stackoverflow discussion: FCM not showing any data in reports

Start by locating the FCM payload construction and any existing validation or payload tests in the adapter. Add support for the requested analytics_label input, validate the specified pattern and length, and confirm valid labels appear under fcm_options.analytics_label while invalid labels are rejected or ignored according to existing behavior.