add behind an experiment flag

packages/astro/client.d.ts

@@ -2,6 +2,8 @@
 /// <reference path="./types/content.d.ts" />
 /// <reference path="./types/actions.d.ts" />
 
+import type { SvgRenderMode } from './dist/assets/utils/svg';
+
 // eslint-disable-next-line  @typescript-eslint/no-namespace
 declare namespace App {
 	// eslint-disable-next-line  @typescript-eslint/no-empty-interface
@@ -123,9 +125,9 @@ declare module '*.svg' {
 		 */
 		size?: number | string;
 		/**
-		 * Bypasses automatic sprite optimization by directly inlinining the SVG
+		 * Override the default rendering mode for SVGs
 		 */
-		inline?: boolean
+		mode?: SvgRenderMode
 	} & astroHTML.JSX.SVGAttributes
 
 	const Component: ((_props: Props) => any) & ImageMetadata;

packages/astro/src/@types/astro.ts

@@ -57,6 +57,7 @@ import type {
 	REDIRECT_STATUS_CODES,
 	SUPPORTED_MARKDOWN_FILE_EXTENSIONS,
 } from './../core/constants.js';
+import type { SvgRenderMode } from '../assets/utils/svg.js';
 
 export type { AstroIntegrationLogger, ToolbarServerHelpers };
 
@@ -2348,6 +2349,22 @@ export interface AstroUserConfig {
 		 * For a complete overview and the full API reference, see [the Content Layer API RFC](https://github.com/withastro/roadmap/blob/content-layer/proposals/0050-content-layer.md) and [share your feedback](https://github.com/withastro/roadmap/pull/982).
 		 */
 		contentLayer?: boolean;
+
+		/**
+		 * @docs
+		 * @name experimental.svg
+		 * @type {object}
+		 * @default `undefined`
+		 */
+		svg?: {
+			/**
+			 * @docs
+			 * @name experimental.svg.mode
+			 * @type {string}
+			 * @default 'inline'
+			 */
+			mode?: SvgRenderMode;
+		};
 	};
 }
 

packages/astro/src/assets/runtime.ts

@@ -21,24 +21,23 @@ export function createSvgComponent({ meta, attributes, children }: SvgComponentP
 	const id = `a:${ids++}`;
 	const rendered = new WeakSet<Response>();
 	const Component = createComponent((result, props) => {
-		const { title: titleProp, viewBox, ...normalizedProps } = normalizeProps(attributes, props);
+		const { title: titleProp, viewBox, mode, ...normalizedProps } = normalizeProps(attributes, props);
 		const title = titleProp ? unescapeHTML(`<title>${titleProp}</title>`) : '';
 
-		// Bypasses automatic sprite optimization and directly inline the SVG
-		if (normalizedProps['inline']) {
-			delete normalizedProps.inline;
-			return render`<svg${spreadAttributes({viewBox, ...normalizedProps})}>${title}${unescapeHTML(children)}</svg>`
-		}
+		if (mode === 'sprite') {
+			// On the first render, include the symbol definition
+			let symbol: any = '';
+			if (!rendered.has(result.response)) {
+				// We only need the viewBox on the symbol definition, we can drop it everywhere else
+				symbol = unescapeHTML(`<symbol${spreadAttributes({ viewBox, id })}>${children}</symbol>`);
+				rendered.add(result.response);
+			}
 
-		// On the first render, include the symbol definition
-		let symbol: any = '';
-		if (!rendered.has(result.response)) {
-			// We only need the viewBox on the symbol definition, we can drop it everywhere else
-			symbol = unescapeHTML(`<symbol${spreadAttributes({ viewBox, id })}>${children}</symbol>`);
-			rendered.add(result.response);
+			return render`<svg${spreadAttributes(normalizedProps)}>${title}${symbol}<use xlink:href="#${id}" /></svg>`;
 		}
 
-		return render`<svg${spreadAttributes(normalizedProps)}>${title}${symbol}<use xlink:href="#${id}" /></svg>`;
+		// Default to inline mode
+		return render`<svg${spreadAttributes({viewBox, ...normalizedProps})}>${title}${unescapeHTML(children)}</svg>`
 	});
 
 	makeNonEnumerable(Component);

packages/astro/src/assets/utils/svg.ts

@@ -4,7 +4,7 @@ import type { SvgComponentProps } from '../runtime.js';
 type SvgAttributes = Record<string, any>;
 
 /**
- * Some attributes required for `image/svg+xml` are irrelevant when inlined ina `text/html` document. We can save a few bytes by dropping them.
+ * Some attributes required for `image/svg+xml` are irrelevant when inlined in a `text/html` document. We can save a few bytes by dropping them.
  */
 const ATTRS_TO_DROP = ['xmlns', 'xmlns:xlink', 'version'];
 const DEFAULT_ATTRS: SvgAttributes = { role: 'img' };
@@ -40,12 +40,14 @@ function parseSvg(contents: string) {
 	return { attributes, body };
 }
 
-export function makeSvgComponent(meta: ImageMetadata, contents: Buffer | string) {
+export type SvgRenderMode = 'inline' | 'sprite';
+
+export function makeSvgComponent(meta: ImageMetadata, contents: Buffer | string, options?: { mode?: SvgRenderMode }) {
 	const file = typeof contents === 'string' ? contents : contents.toString('utf-8');
 	const { attributes, body: children } = parseSvg(file);
 	const props: SvgComponentProps = {
 		meta,
-		attributes: dropAttributes(attributes),
+		attributes: dropAttributes({ mode: options?.mode, ...attributes }),
 		children,
 	};
 

packages/astro/src/assets/vite-plugin-assets.ts

@@ -230,9 +230,10 @@ export default function assets({
 						});
 					}
 
-					if (/\.svg$/.test(id)) {
+					if (settings.config.experimental.svg && /\.svg$/.test(id)) {
 						const { contents, ...metadata } = imageMetadata;
-						return makeSvgComponent(metadata, contents!);
+						// We know that the contents are present, as we only emit this property for SVG files
+						return makeSvgComponent(metadata, contents!, { mode: settings.config.experimental.svg.mode });
 					}
 
 					// We can only reliably determine if an image is used on the server, as we need to track its usage throughout the entire build.

packages/astro/src/core/config/schema.ts

@@ -93,6 +93,9 @@ export const ASTRO_CONFIG_DEFAULTS = {
 			validateSecrets: false,
 		},
 		contentLayer: false,
+		svg: {
+			mode: 'inline',
+		},
 	},
 } satisfies AstroUserConfig & { server: { open: boolean } };
 
@@ -544,6 +547,14 @@ export const AstroConfigSchema = z.object({
 				.optional()
 				.default(ASTRO_CONFIG_DEFAULTS.experimental.contentIntellisense),
 			contentLayer: z.boolean().optional().default(ASTRO_CONFIG_DEFAULTS.experimental.contentLayer),
+			svg: z
+				.object({
+					mode: z
+						.union([z.literal('inline'), z.literal('sprite')])
+						.optional()
+						.default(ASTRO_CONFIG_DEFAULTS.experimental.svg.mode),
+				})
+				.optional(),
 		})
 		.strict(
 			`Invalid or outdated experimental feature.\nCheck for incorrect spelling or outdated Astro version.\nSee https://docs.astro.build/en/reference/configuration-reference/#experimental-flags for a list of all current experiments.`,