feat: improve rolldown compatibility (#13519)

* feat: improve rolldown compatibility

* chore: remove moduleType

* feat: use object shape

* chore: changeset

21 files changed, 175 insertions, 140 deletions

diff --git a/.changeset/brave-pandas-make.md b/.changeset/brave-pandas-make.md
new file mode 100644
index 000000000..ae34a2033
--- /dev/null
+++ b/.changeset/brave-pandas-make.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Refactors some internals to improve Rolldown compatibility
diff --git a/packages/astro/src/actions/plugins.ts b/packages/astro/src/actions/plugins.ts
index b1a071f1c..6c91dd473 100644
--- a/packages/astro/src/actions/plugins.ts
+++ b/packages/astro/src/actions/plugins.ts
@@ -126,7 +126,7 @@ export function vitePluginActions({
 					shouldAppendForwardSlash(settings.config.trailingSlash, settings.config.build.format),
 				),
 			);
-			return code;
+			return { code };
 		},
 	};
 }
diff --git a/packages/astro/src/assets/vite-plugin-assets.ts b/packages/astro/src/assets/vite-plugin-assets.ts
index f9dffa2fa..9421ece46 100644
--- a/packages/astro/src/assets/vite-plugin-assets.ts
+++ b/packages/astro/src/assets/vite-plugin-assets.ts
@@ -117,32 +117,34 @@ export default function assets({ settings }: { settings: AstroSettings }): vite.
 			},
 			load(id) {
 				if (id === resolvedVirtualModuleId) {
-					return /* ts */ `
-					export { getConfiguredImageService, isLocalService } from "astro/assets";
-					import { getImage as getImageInternal } from "astro/assets";
-					export { default as Image } from "astro/components/${imageComponentPrefix}Image.astro";
-					export { default as Picture } from "astro/components/${imageComponentPrefix}Picture.astro";
-					export { inferRemoteSize } from "astro/assets/utils/inferRemoteSize.js";
-
-					export const imageConfig = ${JSON.stringify({ ...settings.config.image, experimentalResponsiveImages: settings.config.experimental.responsiveImages })};
-					// This is used by the @astrojs/node integration to locate images.
-					// It's unused on other platforms, but on some platforms like Netlify (and presumably also Vercel)
-					// new URL("dist/...") is interpreted by the bundler as a signal to include that directory
-					// in the Lambda bundle, which would bloat the bundle with images.
-					// To prevent this, we mark the URL construction as pure,
-					// so that it's tree-shaken away for all platforms that don't need it.
-					export const outDir = /* #__PURE__ */ new URL(${JSON.stringify(
-						new URL(
-							settings.buildOutput === 'server'
-								? settings.config.build.client
-								: settings.config.outDir,
-						),
-					)});
-					export const assetsDir = /* #__PURE__ */ new URL(${JSON.stringify(
-						settings.config.build.assets,
-					)}, outDir);
-					export const getImage = async (options) => await getImageInternal(options, imageConfig);
-				`;
+					return {
+						code: `
+							export { getConfiguredImageService, isLocalService } from "astro/assets";
+							import { getImage as getImageInternal } from "astro/assets";
+							export { default as Image } from "astro/components/${imageComponentPrefix}Image.astro";
+							export { default as Picture } from "astro/components/${imageComponentPrefix}Picture.astro";
+							export { inferRemoteSize } from "astro/assets/utils/inferRemoteSize.js";
+
+							export const imageConfig = ${JSON.stringify({ ...settings.config.image, experimentalResponsiveImages: settings.config.experimental.responsiveImages })};
+							// This is used by the @astrojs/node integration to locate images.
+							// It's unused on other platforms, but on some platforms like Netlify (and presumably also Vercel)
+							// new URL("dist/...") is interpreted by the bundler as a signal to include that directory
+							// in the Lambda bundle, which would bloat the bundle with images.
+							// To prevent this, we mark the URL construction as pure,
+							// so that it's tree-shaken away for all platforms that don't need it.
+							export const outDir = /* #__PURE__ */ new URL(${JSON.stringify(
+								new URL(
+									settings.buildOutput === 'server'
+										? settings.config.build.client
+										: settings.config.outDir,
+								),
+							)});
+							export const assetsDir = /* #__PURE__ */ new URL(${JSON.stringify(
+								settings.config.build.assets,
+							)}, outDir);
+							export const getImage = async (options) => await getImageInternal(options, imageConfig);
+						`,
+					};
 				}
 			},
 			buildStart() {
@@ -151,7 +153,7 @@ export default function assets({ settings }: { settings: AstroSettings }): vite.
 			},
 			// In build, rewrite paths to ESM imported images in code to their final location
 			async renderChunk(code) {
-				const assetUrlRE = /__ASTRO_ASSET_IMAGE__([\w$]{8})__(?:_(.*?)__)?/g;
+				const assetUrlRE = /__ASTRO_ASSET_IMAGE__([\w$]+)__(?:_(.*?)__)?/g;
 
 				let match;
 				let s;
@@ -205,7 +207,7 @@ export default function assets({ settings }: { settings: AstroSettings }): vite.
 						return;
 					}
 
-					const emitFile = shouldEmitFile ? this.emitFile : undefined;
+					const emitFile = shouldEmitFile ? this.emitFile.bind(this) : undefined;
 					const imageMetadata = await emitESMImage(
 						id,
 						this.meta.watchMode,
@@ -223,20 +225,24 @@ export default function assets({ settings }: { settings: AstroSettings }): vite.
 					if (settings.config.experimental.svg && /\.svg$/.test(id)) {
 						const { contents, ...metadata } = imageMetadata;
 						// We know that the contents are present, as we only emit this property for SVG files
-						return makeSvgComponent(metadata, contents!);
+						return { code: makeSvgComponent(metadata, contents!) };
 					}
 
 					// We can only reliably determine if an image is used on the server, as we need to track its usage throughout the entire build.
 					// Since you cannot use image optimization on the client anyway, it's safe to assume that if the user imported
 					// an image on the client, it should be present in the final build.
 					if (options?.ssr) {
-						return `export default ${getProxyCode(
-							imageMetadata,
-							settings.buildOutput === 'server',
-						)}`;
+						return {
+							code: `export default ${getProxyCode(
+								imageMetadata,
+								settings.buildOutput === 'server',
+							)}`,
+						};
 					} else {
 						globalThis.astroAsset.referencedImages.add(imageMetadata.fsPath);
-						return `export default ${JSON.stringify(imageMetadata)}`;
+						return {
+							code: `export default ${JSON.stringify(imageMetadata)}`,
+						};
 					}
 				}
 			},
diff --git a/packages/astro/src/content/vite-plugin-content-virtual-mod.ts b/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
index 7a9295ba5..df84eed5c 100644
--- a/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
+++ b/packages/astro/src/content/vite-plugin-content-virtual-mod.ts
@@ -141,7 +141,7 @@ export function astroContentVirtualModPlugin({
 			}
 			if (id === RESOLVED_DATA_STORE_VIRTUAL_ID) {
 				if (!fs.existsSync(dataStoreFile)) {
-					return 'export default new Map()';
+					return { code: 'export default new Map()' };
 				}
 				const jsonData = await fs.promises.readFile(dataStoreFile, 'utf-8');
 
@@ -161,18 +161,20 @@ export function astroContentVirtualModPlugin({
 
 			if (id === ASSET_IMPORTS_RESOLVED_STUB_ID) {
 				const assetImportsFile = new URL(ASSET_IMPORTS_FILE, settings.dotAstroDir);
-				if (!fs.existsSync(assetImportsFile)) {
-					return 'export default new Map()';
-				}
-				return fs.readFileSync(assetImportsFile, 'utf-8');
+				return {
+					code: fs.existsSync(assetImportsFile)
+						? fs.readFileSync(assetImportsFile, 'utf-8')
+						: 'export default new Map()',
+				};
 			}
 
 			if (id === MODULES_MJS_VIRTUAL_ID) {
 				const modules = new URL(MODULES_IMPORTS_FILE, settings.dotAstroDir);
-				if (!fs.existsSync(modules)) {
-					return 'export default new Map()';
-				}
-				return fs.readFileSync(modules, 'utf-8');
+				return {
+					code: fs.existsSync(modules)
+						? fs.readFileSync(modules, 'utf-8')
+						: 'export default new Map()',
+				};
 			}
 		},
 
diff --git a/packages/astro/src/core/build/plugins/plugin-component-entry.ts b/packages/astro/src/core/build/plugins/plugin-component-entry.ts
index bfa2ce58c..d7fc8aa5e 100644
--- a/packages/astro/src/core/build/plugins/plugin-component-entry.ts
+++ b/packages/astro/src/core/build/plugins/plugin-component-entry.ts
@@ -64,7 +64,9 @@ export function vitePluginComponentEntry(internals: BuildInternals): VitePlugin
 				const componentId = id.slice(astroEntryPrefix.length);
 				const exportNames = componentToExportNames.get(componentId);
 				if (exportNames) {
-					return `export { ${exportNames.join(', ')} } from ${JSON.stringify(componentId)}`;
+					return {
+						code: `export { ${exportNames.join(', ')} } from ${JSON.stringify(componentId)}`,
+					};
 				}
 			}
 		},
diff --git a/packages/astro/src/core/build/plugins/plugin-manifest.ts b/packages/astro/src/core/build/plugins/plugin-manifest.ts
index 5c3fa6f4f..cd7f62a82 100644
--- a/packages/astro/src/core/build/plugins/plugin-manifest.ts
+++ b/packages/astro/src/core/build/plugins/plugin-manifest.ts
@@ -63,7 +63,7 @@ function vitePluginManifest(options: StaticBuildOptions, internals: BuildInterna
 				];
 				const exports = [`export { manifest }`];
 
-				return [...imports, ...contents, ...exports].join('\n');
+				return { code: [...imports, ...contents, ...exports].join('\n') };
 			}
 		},
 
diff --git a/packages/astro/src/core/build/plugins/plugin-pages.ts b/packages/astro/src/core/build/plugins/plugin-pages.ts
index 75cbde220..df3966e9e 100644
--- a/packages/astro/src/core/build/plugins/plugin-pages.ts
+++ b/packages/astro/src/core/build/plugins/plugin-pages.ts
@@ -50,7 +50,7 @@ function vitePluginPages(opts: StaticBuildOptions, internals: BuildInternals): V
 						imports.push(`import { renderers } from "${RENDERERS_MODULE_ID}";`);
 						exports.push(`export { renderers };`);
 
-						return `${imports.join('\n')}${exports.join('\n')}`;
+						return { code: `${imports.join('\n')}${exports.join('\n')}` };
 					}
 				}
 			}
diff --git a/packages/astro/src/core/build/plugins/plugin-prerender.ts b/packages/astro/src/core/build/plugins/plugin-prerender.ts
index f915c9270..219c07675 100644
--- a/packages/astro/src/core/build/plugins/plugin-prerender.ts
+++ b/packages/astro/src/core/build/plugins/plugin-prerender.ts
@@ -57,6 +57,9 @@ function getNonPrerenderOnlyChunks(bundle: Rollup.OutputBundle, internals: Build
 
 			nonPrerenderOnlyEntryChunks.add(chunk);
 		}
+		if (chunk.type === 'chunk' && chunk.isDynamicEntry) {
+			nonPrerenderOnlyEntryChunks.add(chunk);
+		}
 	}
 
 	// From the `nonPrerenderedEntryChunks`, we crawl all the imports/dynamicImports to find all
diff --git a/packages/astro/src/core/build/plugins/plugin-renderers.ts b/packages/astro/src/core/build/plugins/plugin-renderers.ts
index 99fb4e4ce..1b4b8105a 100644
--- a/packages/astro/src/core/build/plugins/plugin-renderers.ts
+++ b/packages/astro/src/core/build/plugins/plugin-renderers.ts
@@ -37,9 +37,9 @@ export function vitePluginRenderers(opts: StaticBuildOptions): VitePlugin {
 
 					exports.push(`export const renderers = [${rendererItems}];`);
 
-					return `${imports.join('\n')}\n${exports.join('\n')}`;
+					return { code: `${imports.join('\n')}\n${exports.join('\n')}` };
 				} else {
-					return `export const renderers = [];`;
+					return { code: `export const renderers = [];` };
 				}
 			}
 		},
diff --git a/packages/astro/src/core/build/plugins/plugin-ssr.ts b/packages/astro/src/core/build/plugins/plugin-ssr.ts
index 7dac35194..fdc05026f 100644
--- a/packages/astro/src/core/build/plugins/plugin-ssr.ts
+++ b/packages/astro/src/core/build/plugins/plugin-ssr.ts
@@ -30,7 +30,7 @@ function vitePluginAdapter(adapter: AstroAdapter): VitePlugin {
 		},
 		async load(id) {
 			if (id === RESOLVED_ADAPTER_VIRTUAL_MODULE_ID) {
-				return `export * from ${JSON.stringify(adapter.serverEntrypoint)};`;
+				return { code: `export * from ${JSON.stringify(adapter.serverEntrypoint)};` };
 			}
 		},
 	};
@@ -103,7 +103,7 @@ function vitePluginSSR(
 				const ssrCode = generateSSRCode(adapter, middleware!.id);
 				imports.push(...ssrCode.imports);
 				contents.push(...ssrCode.contents);
-				return [...imports, ...contents, ...exports].join('\n');
+				return { code: [...imports, ...contents, ...exports].join('\n') };
 			}
 		},
 		async generateBundle(_opts, bundle) {
diff --git a/packages/astro/src/core/middleware/vite-plugin.ts b/packages/astro/src/core/middleware/vite-plugin.ts
index 2587c4565..19cb87bc4 100644
--- a/packages/astro/src/core/middleware/vite-plugin.ts
+++ b/packages/astro/src/core/middleware/vite-plugin.ts
@@ -44,7 +44,7 @@ export function vitePluginMiddleware({ settings }: { settings: AstroSettings }):
 				if (!userMiddlewareIsPresent && settings.config.i18n?.routing === 'manual') {
 					throw new AstroError(MissingMiddlewareForInternationalization);
 				}
-				return 'export const onRequest = (_, next) => next()';
+				return { code: 'export const onRequest = (_, next) => next()' };
 			} else if (id === MIDDLEWARE_MODULE_ID) {
 				if (!userMiddlewareIsPresent && settings.config.i18n?.routing === 'manual') {
 					throw new AstroError(MissingMiddlewareForInternationalization);
@@ -53,7 +53,7 @@ export function vitePluginMiddleware({ settings }: { settings: AstroSettings }):
 				const preMiddleware = createMiddlewareImports(settings.middlewares.pre, 'pre');
 				const postMiddleware = createMiddlewareImports(settings.middlewares.post, 'post');
 
-				const source = `
+				const code = `
 				${
 					userMiddlewareIsPresent
 						? `import { onRequest as userOnRequest } from '${resolvedMiddlewareId}';`
@@ -69,7 +69,7 @@ export const onRequest = sequence(
 );
 `.trim();
 
-				return source;
+				return { code };
 			}
 		},
 	};
diff --git a/packages/astro/src/core/server-islands/vite-plugin-server-islands.ts b/packages/astro/src/core/server-islands/vite-plugin-server-islands.ts
index 3673df534..8cfbd6996 100644
--- a/packages/astro/src/core/server-islands/vite-plugin-server-islands.ts
+++ b/packages/astro/src/core/server-islands/vite-plugin-server-islands.ts
@@ -27,7 +27,7 @@ export function vitePluginServerIslands({ settings, logger }: AstroPluginOptions
 		},
 		load(id) {
 			if (id === RESOLVED_VIRTUAL_ISLAND_MAP_ID) {
-				return `export const serverIslandMap = ${serverIslandPlaceholder};`;
+				return { code: `export const serverIslandMap = ${serverIslandPlaceholder};` };
 			}
 		},
 		transform(_code, id) {
diff --git a/packages/astro/src/env/vite-plugin-env.ts b/packages/astro/src/env/vite-plugin-env.ts
index e01d8f3d6..9511827f7 100644
--- a/packages/astro/src/env/vite-plugin-env.ts
+++ b/packages/astro/src/env/vite-plugin-env.ts
@@ -72,12 +72,12 @@ export function astroEnv({ settings, sync, envLoader }: AstroEnvPluginParams): P
 		load(id, options) {
 			if (id === resolveVirtualModuleId(VIRTUAL_MODULES_IDS.client)) {
 				ensureTemplateAreLoaded();
-				return templates!.client;
+				return { code: templates!.client };
 			}
 			if (id === resolveVirtualModuleId(VIRTUAL_MODULES_IDS.server)) {
 				if (options?.ssr) {
 					ensureTemplateAreLoaded();
-					return templates!.server;
+					return { code: templates!.server };
 				}
 				throw new AstroError({
 					...AstroErrorData.ServerOnlyModule,
@@ -86,7 +86,7 @@ export function astroEnv({ settings, sync, envLoader }: AstroEnvPluginParams): P
 			}
 			if (id === resolveVirtualModuleId(VIRTUAL_MODULES_IDS.internal)) {
 				ensureTemplateAreLoaded();
-				return templates!.internal;
+				return { code: templates!.internal };
 			}
 		},
 	};
diff --git a/packages/astro/src/manifest/virtual-module.ts b/packages/astro/src/manifest/virtual-module.ts
index 03b856265..f99d120d1 100644
--- a/packages/astro/src/manifest/virtual-module.ts
+++ b/packages/astro/src/manifest/virtual-module.ts
@@ -42,7 +42,7 @@ export default function virtualModulePlugin({
 					});
 				}
 				// There's nothing wrong about using `/client` on the server
-				return `${serializeClientConfig(manifest)};`;
+				return { code: serializeClientConfig(manifest) };
 			}
 			// server
 			else if (id == RESOLVED_VIRTUAL_SERVER_ID) {
@@ -58,7 +58,7 @@ export default function virtualModulePlugin({
 						message: AstroErrorData.ServerOnlyModule.message(VIRTUAL_SERVER_ID),
 					});
 				}
-				return `${serializeServerConfig(manifest)};`;
+				return { code: serializeServerConfig(manifest) };
 			}
 		},
 	};
diff --git a/packages/astro/src/prefetch/vite-plugin-prefetch.ts b/packages/astro/src/prefetch/vite-plugin-prefetch.ts
index c908e7cc2..8ab23503c 100644
--- a/packages/astro/src/prefetch/vite-plugin-prefetch.ts
+++ b/packages/astro/src/prefetch/vite-plugin-prefetch.ts
@@ -40,7 +40,7 @@ export default function astroPrefetch({ settings }: { settings: AstroSettings })
 		load(id) {
 			if (id === resolvedVirtualModuleId) {
 				if (!prefetch) throwPrefetchNotEnabledError();
-				return `export { prefetch } from "astro/virtual-modules/prefetch.js";`;
+				return { code: `export { prefetch } from "astro/virtual-modules/prefetch.js";` };
 			}
 		},
 		transform(code, id) {
diff --git a/packages/astro/src/toolbar/vite-plugin-dev-toolbar.ts b/packages/astro/src/toolbar/vite-plugin-dev-toolbar.ts
index e26df2c55..66989a4e3 100644
--- a/packages/astro/src/toolbar/vite-plugin-dev-toolbar.ts
+++ b/packages/astro/src/toolbar/vite-plugin-dev-toolbar.ts
@@ -58,61 +58,63 @@ export default function astroDevToolbar({ settings, logger }: AstroPluginOptions
 		},
 		async load(id) {
 			if (id === resolvedPrivateVirtualModuleId) {
-				return `
-					export const loadDevToolbarApps = async () => {
-						return (await Promise.all([${settings.devToolbarApps
-							.map(
-								(plugin) =>
-									`safeLoadPlugin(${JSON.stringify(
-										plugin,
-									)}, async () => (await import(${JSON.stringify(
-										typeof plugin === 'string' ? plugin : plugin.entrypoint.toString(),
-									)})).default, ${JSON.stringify(
-										typeof plugin === 'string' ? plugin : plugin.entrypoint.toString(),
-									)})`,
-							)
-							.join(',')}]));
-					};
+				return {
+					code: `
+						export const loadDevToolbarApps = async () => {
+							return (await Promise.all([${settings.devToolbarApps
+								.map(
+									(plugin) =>
+										`safeLoadPlugin(${JSON.stringify(
+											plugin,
+										)}, async () => (await import(${JSON.stringify(
+											typeof plugin === 'string' ? plugin : plugin.entrypoint.toString(),
+										)})).default, ${JSON.stringify(
+											typeof plugin === 'string' ? plugin : plugin.entrypoint.toString(),
+										)})`,
+								)
+								.join(',')}]));
+						};
 
-					async function safeLoadPlugin(appDefinition, importEntrypoint, entrypoint) {
-						try {
-							let app;
-							if (typeof appDefinition === 'string') {
-								app = await importEntrypoint();
+						async function safeLoadPlugin(appDefinition, importEntrypoint, entrypoint) {
+							try {
+								let app;
+								if (typeof appDefinition === 'string') {
+									app = await importEntrypoint();
 
-								if (typeof app !== 'object' || !app.id || !app.name) {
-									throw new Error("Apps must default export an object with an id, and a name.");
-								}
-							} else {
-								app = appDefinition;
+									if (typeof app !== 'object' || !app.id || !app.name) {
+										throw new Error("Apps must default export an object with an id, and a name.");
+									}
+								} else {
+									app = appDefinition;
 
-								if (typeof app !== 'object' || !app.id || !app.name || !app.entrypoint) {
-									throw new Error("Apps must be an object with an id, a name and an entrypoint.");
-								}
+									if (typeof app !== 'object' || !app.id || !app.name || !app.entrypoint) {
+										throw new Error("Apps must be an object with an id, a name and an entrypoint.");
+									}
 
-								const loadedApp = await importEntrypoint();
+									const loadedApp = await importEntrypoint();
 
-								if (typeof loadedApp !== 'object') {
-									throw new Error("App entrypoint must default export an object.");
+									if (typeof loadedApp !== 'object') {
+										throw new Error("App entrypoint must default export an object.");
+									}
+
+									app = { ...app, ...loadedApp };
 								}
 
-								app = { ...app, ...loadedApp };
-							}
+								return app;
+							} catch (err) {
+								console.error(\`Failed to load dev toolbar app from \${entrypoint}: \${err.message}\`);
 
-							return app;
-						} catch (err) {
-							console.error(\`Failed to load dev toolbar app from \${entrypoint}: \${err.message}\`);
+								if (import.meta.hot) {
+								import.meta.hot.send('astro:devtoolbar:error:load', { entrypoint: entrypoint, error: err.message })
+								}
 
-							if (import.meta.hot) {
-  							import.meta.hot.send('astro:devtoolbar:error:load', { entrypoint: entrypoint, error: err.message })
+								return undefined;
 							}
 
 							return undefined;
 						}
-
-						return undefined;
-					}
-				`;
+					`,
+				};
 			}
 		},
 	};
diff --git a/packages/astro/src/transitions/vite-plugin-transitions.ts b/packages/astro/src/transitions/vite-plugin-transitions.ts
index ea0576477..d72eb0dc9 100644
--- a/packages/astro/src/transitions/vite-plugin-transitions.ts
+++ b/packages/astro/src/transitions/vite-plugin-transitions.ts
@@ -27,26 +27,30 @@ export default function astroTransitions({ settings }: { settings: AstroSettings
 		},
 		load(id) {
 			if (id === resolvedVirtualModuleId) {
-				return `
-				export * from "astro/virtual-modules/transitions.js";
-				export {
-					default as ViewTransitions,
-					default as ClientRouter
-				} from "astro/components/ClientRouter.astro";
-			`;
+				return {
+					code: `
+						export * from "astro/virtual-modules/transitions.js";
+						export {
+							default as ViewTransitions,
+							default as ClientRouter
+						} from "astro/components/ClientRouter.astro";
+					`,
+				};
 			}
 			if (id === resolvedVirtualClientModuleId) {
-				return `
-				export { navigate, supportsViewTransitions, transitionEnabledOnThisPage } from "astro/virtual-modules/transitions-router.js";
-				export * from "astro/virtual-modules/transitions-types.js";
-				export {
-					TRANSITION_BEFORE_PREPARATION, isTransitionBeforePreparationEvent, TransitionBeforePreparationEvent,
-					TRANSITION_AFTER_PREPARATION,
-					TRANSITION_BEFORE_SWAP, isTransitionBeforeSwapEvent, TransitionBeforeSwapEvent,
-					TRANSITION_AFTER_SWAP, TRANSITION_PAGE_LOAD
-				} from "astro/virtual-modules/transitions-events.js";
-				export { swapFunctions } from "astro/virtual-modules/transitions-swap-functions.js";
-			`;
+				return {
+					code: `
+						export { navigate, supportsViewTransitions, transitionEnabledOnThisPage } from "astro/virtual-modules/transitions-router.js";
+						export * from "astro/virtual-modules/transitions-types.js";
+						export {
+							TRANSITION_BEFORE_PREPARATION, isTransitionBeforePreparationEvent, TransitionBeforePreparationEvent,
+							TRANSITION_AFTER_PREPARATION,
+							TRANSITION_BEFORE_SWAP, isTransitionBeforeSwapEvent, TransitionBeforeSwapEvent,
+							TRANSITION_AFTER_SWAP, TRANSITION_PAGE_LOAD
+						} from "astro/virtual-modules/transitions-events.js";
+						export { swapFunctions } from "astro/virtual-modules/transitions-swap-functions.js";
+					`,
+				};
 			}
 		},
 		transform(code, id) {
diff --git a/packages/astro/src/vite-plugin-load-fallback/index.ts b/packages/astro/src/vite-plugin-load-fallback/index.ts
index 199f15c43..f7cc9cd1c 100644
--- a/packages/astro/src/vite-plugin-load-fallback/index.ts
+++ b/packages/astro/src/vite-plugin-load-fallback/index.ts
@@ -59,8 +59,10 @@ export default function loadFallbackPlugin({
 				}
 			},
 			async load(id) {
-				const source = await tryLoadModule(id);
-				return source;
+				const code = await tryLoadModule(id);
+				if (code) {
+					return { code };
+				}
 			},
 		},
 		{
diff --git a/packages/astro/src/vite-plugin-scripts/index.ts b/packages/astro/src/vite-plugin-scripts/index.ts
index f87f6a381..f45fd7952 100644
--- a/packages/astro/src/vite-plugin-scripts/index.ts
+++ b/packages/astro/src/vite-plugin-scripts/index.ts
@@ -30,22 +30,28 @@ export default function astroScriptsPlugin({ settings }: { settings: AstroSettin
 
 		async load(id) {
 			if (id === BEFORE_HYDRATION_SCRIPT_ID) {
-				return settings.scripts
-					.filter((s) => s.stage === 'before-hydration')
-					.map((s) => s.content)
-					.join('\n');
+				return {
+					code: settings.scripts
+						.filter((s) => s.stage === 'before-hydration')
+						.map((s) => s.content)
+						.join('\n'),
+				};
 			}
 			if (id === PAGE_SCRIPT_ID) {
-				return settings.scripts
-					.filter((s) => s.stage === 'page')
-					.map((s) => s.content)
-					.join('\n');
+				return {
+					code: settings.scripts
+						.filter((s) => s.stage === 'page')
+						.map((s) => s.content)
+						.join('\n'),
+				};
 			}
 			if (id === PAGE_SSR_SCRIPT_ID) {
-				return settings.scripts
-					.filter((s) => s.stage === 'page-ssr')
-					.map((s) => s.content)
-					.join('\n');
+				return {
+					code: settings.scripts
+						.filter((s) => s.stage === 'page-ssr')
+						.map((s) => s.content)
+						.join('\n'),
+				};
 			}
 			return null;
 		},
diff --git a/packages/astro/src/vite-plugin-ssr-manifest/index.ts b/packages/astro/src/vite-plugin-ssr-manifest/index.ts
index 05e1f54be..1828a9594 100644
--- a/packages/astro/src/vite-plugin-ssr-manifest/index.ts
+++ b/packages/astro/src/vite-plugin-ssr-manifest/index.ts
@@ -14,12 +14,13 @@ export function vitePluginSSRManifest(): VitePlugin {
 		},
 		load(id) {
 			if (id === resolvedManifestVirtualModuleId) {
-				return `export let manifest = {};
+				return {
+					code: `export let manifest = {};
 export function _privateSetManifestDontUseThis(ssrManifest) {
   manifest = ssrManifest;
-}`;
+}`,
+				};
 			}
-			return void 0;
 		},
 	};
 }
diff --git a/packages/astro/test/test-adapter.js b/packages/astro/test/test-adapter.js
index c16ec5e11..15134f230 100644
--- a/packages/astro/test/test-adapter.js
+++ b/packages/astro/test/test-adapter.js
@@ -46,7 +46,8 @@ export default function ({
 								},
 								load(id) {
 									if (id === '@my-ssr') {
-										return `
+										return {
+											code: `
 											import { App } from 'astro/app';
 											import fs from 'fs';
 
@@ -92,7 +93,8 @@ export default function ({
 													createApp: (streaming) => new MyApp(manifest, streaming)
 												};
 											}
-										`;
+										`,
+										};
 									}
 								},
 							},