Set focus to the generated title text area upon modal open and completion

[Infinite-Null]

What?

Automatically sets focus to the generated title <textarea> inside the Title Generation modal when the modal opens and after a new title suggestion is regenerated.

Why?

When opening the Title Generation modal or clicking the "Regenerate" button, focus was not automatically placed on the generated title text field.

How?

1. Added focusOnMount="firstInputElement" to the WordPress Modal component in TitleToolbar.tsx.
2. Created a textAreaRef attached to the TextareaControl component.
3. In handleRegenerate(), scheduled textAreaRef.current?.focus() via setTimeout(..., 0) tracked in focusTimeoutRef.current so focus is set to the text area once state updates complete and the input is re-enabled.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude
Model(s): Sonnet 4.6
Used for: Code review, PR description

Testing Instructions

1. Open the post editor in WordPress with a post containing sufficient content.
2. Click the Generate button in the title toolbar to open the AI Title Generation modal.
3. Confirm that focus is automatically set inside the generated title text area upon opening.
4. Click the Regenerate button inside the modal.
5. Confirm that once title generation completes, focus is restored to the generated title text area.

Screencast:

Before:

Screen.Recording.2026-07-28.at.4.21.28.PM.mov

After:

Screen.Recording.2026-07-28.at.4.10.53.PM.mov

Changelog Entry

Fixed - Set focus to the generated title textarea when opening the title generation modal or regenerating a title.

[github-actions]

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Co-authored-by: Infinite-Null <ankitkumarshah@git.wordpress.org>

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.18%. Comparing base (5a1a1da) to head (f858db8).

Additional details and impacted files

@@            Coverage Diff             @@
##             develop     #901   +/-   ##
==========================================
  Coverage      80.18%   80.18%           
  Complexity      2526     2526           
==========================================
  Files            106      106           
  Lines          10240    10240           
==========================================
  Hits            8211     8211           
  Misses          2029     2029           

Flag	Coverage Δ
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