fix: select a phone format that can hold the typed digits (NANP 310 numbers were truncated to 7 digits)

[jamesacklin]

Summary

PhoneNumberTransformer silently drops every digit after the seventh for +1 numbers with area code 310 (Los Angeles), so a full 10-digit 310 number can never be entered, in both national mode (country: 'US') and international mode.

Cause

The generated NANP country data lists two formats for every +1 country, in this order:

1. (\d{3})(\d{4}) → $1-$2, leading digits 310 (Canada's 7-digit 310-XXXX service numbers)
2. (\d{3})(\d{3})(\d{4}) → ($1) $2-$3, leading digits [2-9]

selectFormat returns the first format whose leadingDigits matches and never considers the number of digits typed, and applyFormat then clamps the input to that format's capacity via getFormatMaxDigits. Any national number starting with 310 is therefore truncated to seven digits:

'+13102705123' → '+1 310-2705'   (expected '+1 (310) 270-5123')

Fix

selectFormat now passes over a leading-digits match whose pattern cannot hold every digit typed so far and continues to the next match. If every matching format overflows, it falls back to the widest match, so overlong input is still clamped exactly as before (the existing "limits to 10 national digits" test is unchanged). This mirrors libphonenumber's AsYouTypeFormatter, which re-chooses a format once the current template is exhausted:

'+1 310-2705'  →  '+1 (310) 270-51'  on the eighth digit

selectFormat moves below getFormatMaxDigits, which it now calls, so the worklet plugin's eager closure capture never sees a const in its temporal dead zone.

Behaviour only changes when a leading-digits match cannot hold the digits typed so far; previously those digits were dropped. In the bundled data 310 is the only prefix whose format shadows a longer one, and every pattern uses plain \d{n} / \d{n,m} groups, so the capacity check is exact.

Tests

Added a formats sharing a leading-digits prefix (NANP 310) block to PhoneNumberTransformer.test.ts covering national and international mode, the genuine 7-digit 310-2705 case, the 7-to-10-digit transition with cursor position, and the 10-digit cap. yarn test, yarn lint, and yarn format:prettier:check pass locally.

Context

Found via a signup form in Tlon Messenger where users with 310 numbers could not register; we are shipping this as a pnpm patch on 0.4.1 in the meantime (tloncorp/tlon-apps#6613).

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