va-telephone-input: prevent cursor from jumping to end of input on edit

[it-harrison]

Chromatic

https://va-telephone-input-cursor-fix--65a6e2ed2314f7b8f98609d8.chromatic.com

Summary

This PR fixes a bug in va-telephone-input in which the cursor jumps to the end of an entered telephone number when the number is edited.

Description

When a user clicked into the middle of a formatted phone number and typed or deleted a character, the cursor would jump to the end of the string. This happened because the component reformats on every keystroke caused which lead to to re-render of the input with a new value prop, which resets the browser's caret position.

Related tickets and links

Link to any related issues, PRs, Slack conversations, or anything else relevant to documenting the changes.

Closes #5658

Screenshots

Before (note cursor jumps to end of input after first keystroke and this results in the wrong number being entered):

Screen.Recording.2026-04-17.at.1.01.42.PM.mov

After: (no cursor jump)

Screen.Recording.2026-04-17.at.12.59.50.PM.mov

Testing and review

local testing

Approvals

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• Engineering: platform-design-system-fe
• Accessibility: platform-design-system-a11y
• Design: platform-design-system-designer

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✨ New Component Added

• The PR has the minor label
• The component matches the Figma designs.
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• A new Storybook page has been added for the component
• Tested in all VA breakpoints.
• Chromatic UI Tests have run and snapshot changes have been accepted by the design reviewer
• Tested in vets-website using Verdaccio
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🌱 New Component Variation Added

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• Any Chromatic UI snapshot changes have been accepted by a design reviewer
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🐞 Component Fix

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  • Will any vets-website tests fail from the change?
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♿️ Component Fix - Accessibility

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🚨 Component Fix - Breaking API Change

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🔧 Component Update - Non-Breaking API Change

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📖 Storybook Update

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🎨 CSS-Library Update

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• Engineering has approved the PR

[RyanMunsch]

LGTM. Cursor position is behaving as expected on "with contact" story.