Add PhoneNumberInput component with libphonenumber-js formatting

Uses AsYouType for real-time phone number formatting as user types.
Implements digit-based cursor positioning to handle formatting changes
without cursor jumping.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/publisher-dashboard/src/lib/components/ui/phone-number-input/index.ts

@@ -0,0 +1,7 @@
+import Root from "./phone-number-input.svelte";
+
+export {
+  Root,
+  //
+  Root as PhoneNumberInput,
+};

apps/publisher-dashboard/src/lib/components/ui/phone-number-input/phone-number-input.svelte

@@ -0,0 +1,111 @@
+<script lang="ts">
+import type { HTMLInputAttributes } from "svelte/elements";
+import { AsYouType, type CountryCode } from "libphonenumber-js";
+import { cn, type WithElementRef } from "$lib/utils.js";
+
+type Props = WithElementRef<
+  Omit<HTMLInputAttributes, "type" | "value"> & {
+    value?: string;
+    defaultCountry?: CountryCode;
+  }
+>;
+
+let {
+  ref = $bindable(null),
+  value = $bindable(""),
+  defaultCountry = "US",
+  class: className,
+  "data-slot": dataSlot = "phone-input",
+  oninput,
+  ...restProps
+}: Props = $props();
+
+// Format initial value on mount
+let formattedValue = $state("");
+
+$effect(() => {
+  // Only format if value changed externally (not from our own input)
+  if (value && value !== formattedValue) {
+    const formatter = new AsYouType(defaultCountry);
+    formattedValue = formatter.input(value);
+    value = formattedValue;
+  } else if (!value) {
+    formattedValue = "";
+  }
+});
+
+/**
+ * Count the number of digit characters before a given position in a string.
+ */
+function countDigitsBefore(str: string, position: number): number {
+  let count = 0;
+  for (let i = 0; i < position && i < str.length; i++) {
+    if (/\d/.test(str[i])) {
+      count++;
+    }
+  }
+  return count;
+}
+
+/**
+ * Find the position in a string where a given number of digits have been seen.
+ */
+function findPositionAfterDigits(str: string, digitCount: number): number {
+  let count = 0;
+  for (let i = 0; i < str.length; i++) {
+    if (/\d/.test(str[i])) {
+      count++;
+      if (count === digitCount) {
+        return i + 1;
+      }
+    }
+  }
+  return str.length;
+}
+
+function handleInput(e: Event) {
+  const input = e.target as HTMLInputElement;
+  const cursorPosition = input.selectionStart ?? 0;
+  const rawValue = input.value;
+
+  // Count digits before cursor in the raw input
+  const digitsBefore = countDigitsBefore(rawValue, cursorPosition);
+
+  // Format the input
+  const formatter = new AsYouType(defaultCountry);
+  const formatted = formatter.input(rawValue);
+
+  // Update state
+  formattedValue = formatted;
+  value = formatted;
+
+  // Calculate new cursor position: find where the same number of digits ends up
+  const newPosition = findPositionAfterDigits(formatted, digitsBefore);
+
+  // Set cursor position synchronously after updating the input
+  // We need to wait for Svelte to update the DOM
+  queueMicrotask(() => {
+    input.setSelectionRange(newPosition, newPosition);
+  });
+
+  // Call the original oninput if provided
+  if (oninput) {
+    oninput(e as Event & { currentTarget: HTMLInputElement });
+  }
+}
+</script>
+
+<input
+  bind:this={ref}
+  data-slot={dataSlot}
+  class={cn(
+    "border-input bg-background selection:bg-primary dark:bg-input/30 selection:text-primary-foreground ring-offset-background placeholder:text-muted-foreground flex h-9 w-full min-w-0 rounded-md border px-3 py-1 text-base shadow-xs transition-[color,box-shadow] outline-none disabled:cursor-not-allowed disabled:opacity-50 md:text-sm",
+    "focus-visible:border-ring focus-visible:ring-ring/50 focus-visible:ring-[3px]",
+    "aria-invalid:ring-destructive/20 dark:aria-invalid:ring-destructive/40 aria-invalid:border-destructive",
+    className
+  )}
+  type="tel"
+  value={formattedValue}
+  oninput={handleInput}
+  {...restProps}
+/>

apps/publisher-dashboard/src/routes/account/+page.svelte

@@ -16,6 +16,7 @@ import {
 } from "$lib/components/ui/card";
 import { Input } from "$lib/components/ui/input";
 import { Label } from "$lib/components/ui/label";
+import { PhoneNumberInput } from "$lib/components/ui/phone-number-input";
 import { LoadingButton } from "$lib/components/ui/loading-button";
 import { Separator } from "$lib/components/ui/separator";
 import { cn } from "$lib/utils";
@@ -224,9 +225,8 @@ function getInitials(name: string | null | undefined): string {
 
             <div class="space-y-2">
               <Label for="phoneNumber">Phone number</Label>
-              <Input
+              <PhoneNumberInput
                 id="phoneNumber"
-                type="tel"
                 placeholder="+1 555 123 4567"
                 bind:value={phoneNumber}
                 onblur={handlePhoneBlur}