Spacer: Respect disabled custom spacing sizes when resizing

packages/block-library/CHANGELOG.md

@@ -10,6 +10,10 @@
 
 -   Query: List the existing terms in the taxonomy filters, so categories and tags can be browsed and selected instead of recalled and typed. The controls now use `SearchableChipSelectControl` from `@wordpress/ui` ([#82583](https://github.com/WordPress/gutenberg/pull/82583)).
 
+### Bug Fixes
+
+-   Spacer: Hide resize handles when custom spacing sizes are disabled, preserving preset dimensions ([#84518](https://github.com/WordPress/gutenberg/pull/84518)).
+
 ## 11.2.0 (2026-10-07)
 
 ### Enhancements

packages/block-library/src/spacer/edit.jsx

@@ -348,6 +348,7 @@ const SpacerEdit = ( {
 				} ) }
 			>
 				{ blockEditingMode === 'default' &&
+					! disableCustomSpacingSizes &&
 					resizableBoxWithOrientation( inheritedOrientation ) }
 			</div>
 			{ ! isFlexLayout && (

test/e2e/specs/editor/blocks/spacer.spec.js

@@ -52,6 +52,140 @@ test.describe( 'Spacer', () => {
 		).toBeFocused();
 	} );
 
+	for ( const orientation of [ 'vertical', 'horizontal' ] ) {
+		test( `respects custom spacing restrictions for a ${ orientation } spacer`, async ( {
+			editor,
+			page,
+		} ) => {
+			const originalDisableCustomSpacingSizes = await page.evaluate(
+				() =>
+					window.wp.data.select( 'core/block-editor' ).getSettings()
+						.disableCustomSpacingSizes
+			);
+			const isHorizontal = orientation === 'horizontal';
+			const dimension = isHorizontal ? 'width' : 'height';
+			let selectedPreset = 'var:preset|spacing|40';
+			const spacerAttributes = isHorizontal
+				? {
+						width: selectedPreset,
+						style: {
+							layout: {
+								selfStretch: 'fixed',
+								flexSize: 'var(--wp--preset--spacing--40)',
+							},
+						},
+					}
+				: { height: selectedPreset };
+			const spacerBlock = {
+				name: 'core/spacer',
+				attributes: spacerAttributes,
+			};
+			const getSpacerAttributes = async () => {
+				const [ block ] = await editor.getBlocks();
+				return ( isHorizontal ? block.innerBlocks[ 0 ] : block )
+					.attributes;
+			};
+			const setCustomSpacingDisabled = ( disabled ) =>
+				page.evaluate( ( disableCustomSpacingSizes ) => {
+					window.wp.data
+						.dispatch( 'core/block-editor' )
+						.updateSettings( { disableCustomSpacingSizes } );
+				}, disabled );
+
+			try {
+				await setCustomSpacingDisabled( true );
+				await editor.insertBlock(
+					isHorizontal
+						? {
+								name: 'core/group',
+								attributes: {
+									layout: {
+										type: 'flex',
+										orientation: 'horizontal',
+									},
+								},
+								innerBlocks: [ spacerBlock ],
+							}
+						: spacerBlock
+				);
+				const spacer = editor.canvas.getByRole( 'document', {
+					name: 'Block: Spacer',
+					exact: true,
+				} );
+				const resizeHandle = spacer.locator(
+					'.components-resizable-box__handle'
+				);
+				await spacer.click();
+				await expect( resizeHandle ).toHaveCount( 0 );
+				await expect
+					.poll( getSpacerAttributes )
+					.toMatchObject( spacerAttributes );
+
+				if ( ! isHorizontal ) {
+					await editor.openDocumentSettingsSidebar();
+					await page
+						.getByRole( 'slider', { name: 'Height', exact: true } )
+						.press( 'ArrowRight' );
+					selectedPreset = 'var:preset|spacing|50';
+				}
+				await expect.poll( getSpacerAttributes ).toMatchObject( {
+					[ dimension ]: selectedPreset,
+					...( isHorizontal && { style: spacerAttributes.style } ),
+				} );
+
+				await editor.saveDraft();
+				await page.reload();
+				await spacer.waitFor();
+				await setCustomSpacingDisabled( true );
+				await spacer.click();
+				await expect( resizeHandle ).toHaveCount( 0 );
+				await expect.poll( getSpacerAttributes ).toMatchObject( {
+					[ dimension ]: selectedPreset,
+					...( isHorizontal && { style: spacerAttributes.style } ),
+				} );
+
+				await setCustomSpacingDisabled( false );
+				await expect( resizeHandle ).toBeVisible();
+				const spacerBounds = await spacer.boundingBox();
+				const handleBounds = await resizeHandle.boundingBox();
+				const handleX = handleBounds.x + handleBounds.width / 2;
+				const handleY = handleBounds.y + handleBounds.height / 2;
+				await page.mouse.move( handleX, handleY );
+				await page.mouse.down();
+				await page.mouse.move(
+					handleX + ( isHorizontal ? 50 : 0 ),
+					handleY + ( isHorizontal ? 0 : 50 ),
+					{ steps: 5 }
+				);
+				await page.mouse.up();
+				await expect
+					.poll(
+						async () => ( await getSpacerAttributes() )[ dimension ]
+					)
+					.toMatch( /^\d+px$/ );
+				const resizedAttributes = await getSpacerAttributes();
+				expect(
+					parseFloat( resizedAttributes[ dimension ] )
+				).toBeGreaterThan( spacerBounds[ dimension ] );
+				expect( resizedAttributes ).toMatchObject( {
+					[ dimension ]: expect.stringMatching( /^\d+px$/ ),
+					...( isHorizontal && {
+						style: {
+							layout: {
+								selfStretch: 'fixed',
+								flexSize: resizedAttributes.width,
+							},
+						},
+					} ),
+				} );
+			} finally {
+				await setCustomSpacingDisabled(
+					originalDisableCustomSpacingSizes
+				);
+			}
+		} );
+	}
+
 	test( 'should work in theme without spacing units support', async ( {
 		editor,
 		page,