The next change is in a critical part of the app, so proceed with utmost caution. - Carefully examine all related code and dependencies *before* making changes. - Avoid any modifications to unrelated components or files. - If there’s any uncertainty, pause and explain your thought process before continuing. - Ensure thorough testing after the change to confirm nothing else is affected. Task: Update the user authentication logic to support OAuth login via Google, on top of existing email/password without breaking either flow. *(Be extremely careful and double-check each step during implementation.)*