Validate user input

Users can submit the profile form with empty phone numbers. Add client-side validation that checks phone is numeric and 10 digits, shows the error message under the field, and blocks submission until corrected. Coordinate with Priya in UX for the error copy and deploy the change by Tuesday.

Before I hand this to QA, make the input validation reviewer-friendly: put the validation rules at the top of the module, show the exact error strings next to each rule, and highlight any validators that accept malformed input like leading plus signs or spaces.

I added a validator to the signup form and now some international users report their phone numbers are rejected. I wrote a strict 10-digit numeric rule because legal asked for consistency, but I don't know which countries we must accept. I can't change policy alone. What's the likely compromise that preserves compliance but doesn't block legitimate users, and how should I present this to legal and product?

We repeatedly lose time because validation rules live in many components, producing inconsistent error copy and duplicate bugs. Which habit should we adopt to centralize validation, how to version rules, and a lightweight gating step so changes don't break client or server expectations?