Post Title: Add fit text support

docs/reference-guides/core-blocks/README.md

@@ -745,7 +745,7 @@ Displays the title of a post, page, or any other content-type.
 
 -	**Name:** [core/post-title](https://developer.wordpress.org/block-editor/reference-guides/core-blocks/core-blocks-theme/core-block-post-title/)
 -	**Category:** [theme](https://developer.wordpress.org/block-editor/reference-guides/core-blocks/core-blocks-theme/)
--	**Supports:** align (full, wide), anchor, background (backgroundImage, backgroundSize, gradient), color (background, gradients, link, text), dimensions (minHeight, minWidth), interactivity (clientNavigation), shadow, spacing (margin, padding), typography (fontSize, lineHeight, textAlign), ~~html~~
+-	**Supports:** align (full, wide), anchor, background (backgroundImage, backgroundSize, gradient), color (background, gradients, link, text), dimensions (minHeight, minWidth), interactivity (clientNavigation), shadow, spacing (margin, padding), typography (fitText, fontSize, lineHeight, textAlign), ~~html~~
 -	**Attributes:** isLink, level, levelOptions, linkTarget, placeholder, rel
 
 ## Preformatted

packages/block-library/CHANGELOG.md

@@ -15,6 +15,7 @@
 -   Cover: Stop an uploaded background video on the front end when the visitor prefers reduced motion ([#83853](https://github.com/WordPress/gutenberg/pull/83853)).
 -   Image: Animate touch-swipe navigation in the gallery lightbox so the image follows the finger and slides off on commit, with a quick fade-in for the next image ([#79114](https://github.com/WordPress/gutenberg/pull/79114)).
 -   Post Navigation Link: Add background image, size, and gradient support, withheld from the empty wrapper the same way as border, shadow and spacing ([#83940](https://github.com/WordPress/gutenberg/pull/83940)).
+-   Post Title: Add Fit text support, so the title can resize to fill its container ([#83036](https://github.com/WordPress/gutenberg/pull/83036)).
 
 ### Bug Fixes
 

packages/block-library/src/post-title/README.md

@@ -46,6 +46,7 @@ _Defined via the [`supports`](https://developer.wordpress.org/block-editor/refer
   - [`fontSize`](https://developer.wordpress.org/block-editor/reference-guides/block-api/block-supports/#typography-fontsize): `true`
   - [`lineHeight`](https://developer.wordpress.org/block-editor/reference-guides/block-api/block-supports/#typography-lineheight): `true`
   - [`textAlign`](https://developer.wordpress.org/block-editor/reference-guides/block-api/block-supports/#typography-textalign): `true`
+  - `fitText`: `true`
 - [`interactivity`](https://developer.wordpress.org/block-editor/reference-guides/block-api/block-supports/#interactivity):
   - `clientNavigation`: `true`
 

packages/block-library/src/post-title/block.json

@@ -79,6 +79,7 @@
 			"__experimentalTextTransform": true,
 			"__experimentalTextDecoration": true,
 			"__experimentalLetterSpacing": true,
+			"fitText": true,
 			"__experimentalDefaultControls": {
 				"fontSize": true
 			}

packages/block-library/src/post-title/edit.jsx

@@ -20,7 +20,15 @@ import { createInterpolateElement } from '@wordpress/element';
 import { useToolsPanelDropdownMenuProps } from '../utils/hooks';
 
 export default function PostTitleEdit( {
-	attributes: { level, levelOptions, isLink, rel, linkTarget, placeholder },
+	attributes: {
+		level,
+		levelOptions,
+		isLink,
+		rel,
+		linkTarget,
+		placeholder,
+		fitText,
+	},
 	setAttributes,
 	context: { postType, postId, queryId },
 } ) {
@@ -98,6 +106,13 @@ export default function PostTitleEdit( {
 					onChange={ setTitle }
 					__experimentalVersion={ 2 }
 					disableLineBreaks
+					// Rich text only sets pre-wrap when white-space is empty,
+					// and it does not update that later. Inherit lets fit
+					// text's nowrap apply; pre-wrap restores it when fit text
+					// is off.
+					style={ {
+						whiteSpace: fitText ? 'inherit' : 'pre-wrap',
+					} }
 				/>
 			</TagName>
 		) : (