Firebase Remote Config Basics

---
name: firebase-remote-config-basics
description: >-
  Manages Firebase Remote Config templates, feature flags, loading strategies, and SDKs (Android, iOS). Use when downloading/deploying remoteconfig JSON templates, managing version history/feature flags, setting in-app defaults, fetchAndActivate(), real-time listeners, or SDK setup. Don't use for Firebase Hosting, Auth, Firestore, Data Connect, Crashlytics, or App Hosting.
compatibility: This skill is best used with the Firebase CLI, but does not require it. Firebase CLI can be accessed through `npx -y firebase-tools@latest`.
metadata:
  category: ApplicationDevelopment
---

# Remote Config

This skill provides a complete guide for getting started with Remote Config on
Android or iOS. Remote Config allows you to change the behavior and appearance
of your app without publishing an app update by maintaining a cloud-based
configuration template.

## Prerequisites

Provisioning Remote Config requires both a Firebase project and a Firebase app,
either Android or iOS. To manage the Remote Config template and conditions via
the command line, use the Firebase CLI. See the `firebase-basics` skill for
references on project initialization.

## Troubleshooting Execution

### Handling npx 403 Forbidden Errors

If `npx -y firebase-tools@latest` fails due to registry permissions (403 error):

1. **Inform the user**: "I am unable to fetch the latest Firebase tools via npx
   due to a registry error."
1. **Fallback**: Attempt to use the local `firebase` command directly if the
   user confirms it is installed globally (`npm install -g firebase-tools`).

### Handling Project Context Issues

If a command fails because "no active project is selected":

1. **Check login**: Run `npx -y firebase-tools@latest login:list`.
1. **Prompt for ID**: If logged in but no project is active, ask the user:
   "Please provide your Firebase Project ID to proceed."
1. **Use Flag**: Append `--project <PROJECT_ID>` to every subsequent command.

## SDK Setup

To learn how to set up Remote Config in your application code, choose your
platform:

- **Android**: [android_setup.md](references/android_setup.md)
- **iOS**: [ios_setup.md](references/ios_setup.md)

## Best Practices and Template Management

Follow these guidelines and use the associated CLI tools to ensure efficient and
safe use of Remote Config.

### Fetching Strategies

To optimize app performance and user experience, follow these recommended
patterns (see
[Loading Strategies](https://firebase.google.com/docs/remote-config/loading)):

- **Load new values for next startup**: The most effective pattern is to
  activate previously fetched values immediately on startup and fetch new values
  in the background to be used next time. This minimizes user wait time.
- **Real-time Updates**: Use the SDK's real-time listener to update the app
  instantly without a refresh when server-side configuration changes.

### Template Management via CLI

Use the following commands to manage your Remote Config template and version
history through the terminal:

### Template Management via CLI

Use the following commands to manage your Remote Config template and version
history through the terminal:

- **Get current template**: Save the remote template to a local JSON file for
  auditing or modification.

  ```bash
  npx -y firebase-tools@latest remoteconfig:get -o remote_config.json
  ```

- **Autonomous Editing & Discovery** : Modify the local `remote_config.json`
  directly. Determine the correct signal (e.g., device.country or percent) and
  update the "conditions" array and "parameters" map accordingly.

- **MANDATORY: User Review and Verification** : STOP and ask the user to verify
  your changes before proceeding to deployment.

  - Action: Inform the user: "I have prepared the changes in remote_config.json.
    Please review the file for accuracy. Once you are satisfied, tell me to
    'deploy' to make the changes live."

- **Deployment Orchestration** : To push changes, you must ensure the
  environment is configured for deployment.

  - Config Mapping: If a firebase.json file is missing, create one to map the
    local JSON to the Remote Config service:

  ```json
    { "remoteconfig": { "template": "remote_config.json" } }
  ```

  - Deploy: Execute the partial deployment command
    
    ```bash
    npx -y firebase-tools@latest deploy --only remoteconfig
    ```

- **Verification**: After deployment, verify the update by listing the version
  history.

  ```bash
  npx -y firebase-tools@latest remoteconfig:versions:list
  ```

The SDK provides a number of features to make your application dynamic and
responsive to user segments.

- **Set In-App Defaults**: Define baseline values to ensure the app functions
  offline or before the first fetch.
- **Fetch and Activate**: Retrieve values from the Firebase backend and apply
  them to the local UI/Logic.
- **Template Management**: Use the Firebase CLI to version-control, get, and
  deploy your config JSON files.