Emulator firestore UI Defaults to the literal name `default` Project Even with `.firebaserc` has 'default' parameter set to something else

[ventisep]

❗ Emulator UI Defaults to default Project Even with .firebaserc Set

🗭 Context

I'm using the Firebase Local Emulator Suite with a .firebaserc configured like:

{
  "projects": {
    "default": "my-project-local",
    "my-firebase-project": "my-project-cfbe5"
  }
}

From the root directory (same place as .firebaserc), I run:

firebase emulators:start

💨 Unexpected Behavior

• The Emulator UI defaults to showing /firestore/default/data, not /firestore/my-project-local/data.
• Data written via scripts using @google-cloud/firestore (or firebase-admin) targeting my-project-local did not show up, and:
  • No errors were thrown
  • Try/catch blocks did not catch anything
  • Emulator logs showed no write activity
  • Data was not persisted in any database (live or emulator)

This leads to extremely confusing debugging. The developer assumes the projectId is correct and the emulator is running — but the Emulator UI and underlying Firestore instances are misaligned.

✅ Workaround

The only way to get the emulator and UI to align correctly is:

firebase emulators:start --project my-project-local

Which causes the UI to properly route to:

/firestore/my-project-local/data

❗ Request

Please consider:

• Making Emulator UI respect .firebaserc’s "default" project
• Adding visible warnings or logs when the emulator receives writes with mismatched project IDs
• Logging when data is silently discarded due to unrecognized projectId

🔍 Why This Matters

Without visible errors or logs, this creates hours of confusion and the risk of:

• Developers unknowingly thinking data was persisted
• Assuming bugs in their write logic
• Worse: accidentally writing to the live database

Thanks for your incredible work on Firebase — and hope this helps make emulator behavior safer and clearer!