Fix Firebase Referral Commission

The referral flow in my JavaScript-based Firebase back end has stopped rewarding the referrer. A new user can still sign up with a code or link, the record shows in Firestore, yet the commission field in the referrer’s wallet document remains unchanged and no error is thrown.

My priority is the commission-crediting logic. I would like you to trace the current Cloud Functions (or client-side writes, if that’s where it lives), verify the database rules, and patch whatever is preventing the wallet balance from updating. The app itself is delivered as a mobile build, so please keep an eye on any latency or permission issues that might arise on that platform.

Acceptance criteria
• When a user registers with a valid referral code or link, the referrer’s wallet balance reflects the commission instantly and persists after page refresh or app relaunch.
• Your fix is committed with clear comments and a brief note explaining what was wrong and how you resolved it.
• No other wallet or registration features break in the process; basic regression testing passes.

Tech in use: Firebase Authentication, Firestore, Cloud Functions, vanilla HTML/JS front end that compiles into the mobile build (Cordova). Access to the repository and Firebase console will be provided as soon as we kick off.