How to backup and restore MSAL Angular configuration with factory providers?

Because the provided sources do not contain information about MSAL Angular or factory providers, the following guidance is based on reasonable assumptions about how Angular dependency injection works. Treat it as a draft for review and adapt it to your specific implementation.

Assumptions

• The MSAL instance, guard config, and interceptor config are supplied via factory providers that return values from a central configuration service (e.g., MsalConfigService).
• You can read the current configuration values from that service at runtime.
• Persisting the configuration can be done with browser storage (e.g., sessionStorage) or a cookie, and restoring involves re‑providing the same values to the factory functions.
• After a restore, the application should re‑initialize the MSAL service (or reload the affected modules) to use the restored settings.

Numbered steps

1. Capture the current configuration
   • Inject your MsalConfigService (or wherever the factory reads its data) into a component or service that runs before logout or environment change.
   • Read the three configuration objects: msalInstanceConfig, msalGuardConfig, msalInterceptorConfig.
   • Serialize them (e.g., JSON.stringify) and store the string in sessionStorage.setItem('msalBackup', json).
2. Clear or change the environment (e.g., user logout)
   • Perform your logout logic, which may destroy the existing MSAL instance.
3. Restore the configuration
   • Retrieve the backup string: const backup = sessionStorage.getItem('msalBackup');
   • If the backup exists, parse it: const config = JSON.parse(backup);
   • Update the values in your MsalConfigService (or equivalent) so that the factory providers will return the restored objects when Angular’s DI resolves them.
4. Re‑initialize MSAL
   • If you have a wrapper service that creates the MSAL instance, call its initialization method again after the config service has been updated.
   • Alternatively, reload the Angular module that provides the MSAL factories (e.g., navigate to a dummy route and back) so that DI picks up the new values.
5. Verification
   • Check that acquiring a token silently or interactively does not throw errors.
   • Confirm that the guard and interceptor behave as expected (e.g., routes are protected, requests include the Authorization header).
6. Rollback (if restore fails)
   • If verification fails, clear the restored config and re‑apply the original backup (or fall back to a default configuration).
   • Repeat the re‑initialization step and verify again.

Notes and cautions

This approach assumes that the configuration objects are plain JSON‑serializable and that no hidden state (e.g., internal MSAL caches) needs to be preserved. If your factories rely on external services or mutable objects, you may need to deep‑clone or re‑inject those dependencies as well. Always test the backup/restore flow in a non‑production environment before relying on it for critical authentication flows.