Can't drag to extend a text selection in the composer on iOS/iPadOS 18.x (touchmove selection frozen)

Contribute Bug
1

Summary

On iOS/iPadOS 18.x, it’s impossible to adjust a text selection inside the composer by dragging with a finger. Once a word is selected (e.g. by double-tap), dragging the selection handles does nothing: the selection stays frozen on the initially-selected word. This makes it very hard to select a phrase, a sentence, or an arbitrary range of text while editing a post.

Selecting text outside the composer (e.g. in a rendered post on the same page) works normally on the same device — so this is specific to the composer. It affects both the legacy composer and the new WYSIWYG (rich) editor, and reproduces in both Safari and Chrome on iOS/iPadOS (both use WebKit), so it isn’t browser-specific either.

Steps to reproduce

  1. On an iPhone or iPad running iOS/iPadOS 18.x, open Safari (or Chrome) and go to meta.discourse.org.
  2. Start a reply or a new topic to open the composer.
  3. Type a sentence.
  4. Double-tap a word to select it.
  5. Try to drag one of the selection handles (or touch-drag across the text) to extend the selection to neighbouring words.

Expected

The selection grows/shrinks to follow the finger, as it does in every other native text field / textarea on iOS, and as it does in rendered post text on the same page.

Actual

The selection remains fixed on the originally-selected word. Drag gestures on the handles have no effect; the range cannot be changed by touch.

Environment

  • Device / OS: iOS 18.x and iPadOS 18.x (latest 18 release) — reproducible on both.
  • Browsers: Safari and Chrome on iOS/iPadOS (both WebKit)
  • Site: meta.discourse.org
  • Scope: Composer only — both legacy and WYSIWYG. Selecting text outside the composer works fine on the same device.