Firebase plan upgrade

I’m building a mobile app that relies on Firebase and I need a second pair of eyes on my database plan—specifically the security rules. The collections and data flow are largely mapped out, but I want to be certain the access logic is airtight before we ship.

Here’s what I’m looking for:
• A collaborative review of my current structure (Firestore or Realtime Database).
• Hands-on drafting or refinement of `.rules` / `.json` files, using best-practice patterns.
• Live testing in the Firebase Emulator to prove that read/write privileges are scoped exactly as intended.
• Clear, commented rules plus a short recap of the decisions we made so I can maintain everything confidently.

If you’ve hardened Firebase backends for production mobile apps and are fluent with Authentication, custom claims, and the emulator suite, I’d love your help figuring this out and locking it down.