diff --git a/.changeset/blue-lizards-type.md b/.changeset/blue-lizards-type.md
new file mode 100644
index 000000000000..814fc1ebc397
--- /dev/null
+++ b/.changeset/blue-lizards-type.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+[fix] prevent data types from becoming type `never`, notice moved/deleted files
diff --git a/packages/kit/src/core/sync/write_types/index.js b/packages/kit/src/core/sync/write_types/index.js
index fc18f0c0eca2..1e4b29aea395 100644
--- a/packages/kit/src/core/sync/write_types/index.js
+++ b/packages/kit/src/core/sync/write_types/index.js
@@ -46,11 +46,82 @@ export async function write_all_types(config, manifest_data) {
 		}
 	}
 
+	// Read/write meta data on each invocation, not once per node process,
+	// it could be invoked by another process in the meantime.
+	const meta_data_file = `${types_dir}/route_meta_data.json`;
+	const has_meta_data = fs.existsSync(meta_data_file);
+	let meta_data = has_meta_data
+		? /** @type {Record<string, string[]>} */ (JSON.parse(fs.readFileSync(meta_data_file, 'utf-8')))
+		: {};
 	const routes_map = create_routes_map(manifest_data);
 	// For each directory, write $types.d.ts
 	for (const route of manifest_data.routes) {
-		update_types(config, routes_map, route);
+		if (!route.leaf && !route.layout && !route.endpoint) continue; // nothing to do
+
+		const outdir = path.join(config.kit.outDir, 'types', routes_dir, route.id);
+
+		// check if the types are out of date
+		/** @type {string[]} */
+		const input_files = [];
+
+		/** @type {import('types').PageNode | null} */
+		let node = route.leaf;
+		while (node) {
+			if (node.shared) input_files.push(node.shared);
+			if (node.server) input_files.push(node.server);
+			node = node.parent ?? null;
+		}
+
+		/** @type {import('types').PageNode | null} */
+		node = route.layout;
+		while (node) {
+			if (node.shared) input_files.push(node.shared);
+			if (node.server) input_files.push(node.server);
+			node = node.parent ?? null;
+		}
+
+		if (route.endpoint) {
+			input_files.push(route.endpoint.file);
+		}
+
+		try {
+			fs.mkdirSync(outdir, { recursive: true });
+		} catch {}
+
+		const output_files = compact(
+			fs.readdirSync(outdir).map((name) => {
+				const stats = fs.statSync(path.join(outdir, name));
+				if (stats.isDirectory()) return;
+				return {
+					name,
+					updated: stats.mtimeMs
+				};
+			})
+		);
+
+		const source_last_updated = Math.max(
+			// ctimeMs includes move operations whereas mtimeMs does not
+			...input_files.map((file) => fs.statSync(file).ctimeMs)
+		);
+		const types_last_updated = Math.max(...output_files.map((file) => file.updated));
+
+		const should_generate =
+			// source files were generated more recently than the types
+			source_last_updated > types_last_updated ||
+			// no meta data file exists yet
+			!has_meta_data ||
+			// some file was deleted
+			!meta_data[route.id]?.every((file) => input_files.includes(file));
+
+		if (should_generate) {
+			// track which old files end up being surplus to requirements
+			const to_delete = new Set(output_files.map((file) => file.name));
+			update_types(config, routes_map, route, to_delete);
+			meta_data[route.id] = input_files;
+		}
 	}
+
+	fs.writeFileSync(meta_data_file, JSON.stringify(meta_data, null, '\t'));
 }
 
 /**
@@ -72,6 +143,7 @@ export async function write_types(config, manifest_data, file) {
 
 	const route = manifest_data.routes.find((route) => route.id === id);
 	if (!route) return; // this shouldn't ever happen
+	if (!route.leaf && !route.layout && !route.endpoint) return; // nothing to do
 
 	update_types(config, create_routes_map(manifest_data), route);
 }
@@ -96,60 +168,12 @@ function create_routes_map(manifest_data) {
  * @param {import('types').ValidatedConfig} config
  * @param {Map<import('types').PageNode, import('types').RouteData>} routes
  * @param {import('types').RouteData} route
+ * @param {Set<string>} [to_delete]
  */
-function update_types(config, routes, route) {
-	if (!route.leaf && !route.layout && !route.endpoint) return; // nothing to do
-
+function update_types(config, routes, route, to_delete = new Set()) {
 	const routes_dir = posixify(path.relative('.', config.kit.files.routes));
 	const outdir = path.join(config.kit.outDir, 'types', routes_dir, route.id);
 
-	// first, check if the types are out of date
-	const input_files = [];
-
-	/** @type {import('types').PageNode | null} */
-	let node = route.leaf;
-	while (node) {
-		if (node.shared) input_files.push(node.shared);
-		if (node.server) input_files.push(node.server);
-		node = node.parent ?? null;
-	}
-
-	/** @type {import('types').PageNode | null} */
-	node = route.layout;
-	while (node) {
-		if (node.shared) input_files.push(node.shared);
-		if (node.server) input_files.push(node.server);
-		node = node.parent ?? null;
-	}
-
-	if (route.endpoint) {
-		input_files.push(route.endpoint.file);
-	}
-
-	try {
-		fs.mkdirSync(outdir, { recursive: true });
-	} catch {}
-
-	const output_files = compact(
-		fs.readdirSync(outdir).map((name) => {
-			const stats = fs.statSync(path.join(outdir, name));
-			if (stats.isDirectory()) return;
-			return {
-				name,
-				updated: stats.mtimeMs
-			};
-		})
-	);
-
-	const source_last_updated = Math.max(...input_files.map((file) => fs.statSync(file).mtimeMs));
-	const types_last_updated = Math.max(...output_files.map((file) => file?.updated));
-
-	// types were generated more recently than the source files, so don't regenerate
-	if (types_last_updated > source_last_updated) return;
-
-	// track which old files end up being surplus to requirements
-	const to_delete = new Set(output_files.map((file) => file.name));
-
 	// now generate new types
 	const imports = [`import type * as Kit from '@sveltejs/kit';`];
 
@@ -180,7 +204,7 @@ function update_types(config, routes, route) {
 			`type OutputDataShape<T> = MaybeWithVoid<Omit<App.PageData, RequiredKeys<T>> & Partial<Pick<App.PageData, keyof T & keyof App.PageData>> & Record<string, any>>`
 		);
 		// null & {} == null, we need to prevent that in some situations
-		declarations.push(`type EnsureParentData<T> = T extends null | undefined ? {} : T;`);
+		declarations.push(`type EnsureDefined<T> = T extends null | undefined ? {} : T;`);
 	}
 
 	if (route.leaf) {
@@ -329,9 +353,13 @@ function process_node(node, outdir, is_page, all_pages_have_load = true) {
 			written_proxies.push(`proxy${path.basename(node.shared)}`);
 		}
 
-		const type = get_data_type(node.shared, `${parent_type} & ${prefix}ServerData`, proxy);
+		const type = get_data_type(
+			node.shared,
+			`${parent_type} & EnsureDefined<${prefix}ServerData>`,
+			proxy
+		);
 
-		data = `Expand<Omit<${parent_type}, keyof ${type}> & ${type}>`;
+		data = `Expand<Omit<${parent_type}, keyof ${type}> & EnsureDefined<${type}>>`;
 
 		const output_data_shape =
 			!is_page && all_pages_have_load
@@ -345,7 +373,7 @@ function process_node(node, outdir, is_page, all_pages_have_load = true) {
 	} else if (server_data === 'null') {
 		data = `Expand<${parent_type}>`;
 	} else {
-		data = `Expand<Omit<${parent_type}, keyof ${prefix}ServerData> & ${prefix}ServerData>`;
+		data = `Expand<Omit<${parent_type}, keyof ${prefix}ServerData> & EnsureDefined<${prefix}ServerData>>`;
 	}
 
 	exports.push(`export type ${prefix}Data = ${data};`);
@@ -396,14 +424,14 @@ function get_parent_type(node, type) {
 		parent = parent.parent;
 	}
 
-	let parent_str = `EnsureParentData<${parent_imports[0] || '{}'}>`;
+	let parent_str = `EnsureDefined<${parent_imports[0] || '{}'}>`;
 	for (let i = 1; i < parent_imports.length; i++) {
 		// Omit is necessary because a parent could have a property with the same key which would
 		// cause a type conflict. At runtime the child overwrites the parent property in this case,
 		// so reflect that in the type definition.
-		// EnsureParentData is necessary because {something: string} & null becomes null.
+		// EnsureDefined is necessary because {something: string} & null becomes null.
 		// Output types of server loads can be null but when passed in through the `parent` parameter they are the empty object instead.
-		parent_str = `Omit<${parent_str}, keyof ${parent_imports[i]}> & EnsureParentData<${parent_imports[i]}>`;
+		parent_str = `Omit<${parent_str}, keyof ${parent_imports[i]}> & EnsureDefined<${parent_imports[i]}>`;
 	}
 	return parent_str;
 }
diff --git a/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/$types.d.ts b/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/$types.d.ts
index 437ad8dcb6a7..bf57263b30d8 100644
--- a/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/$types.d.ts
@@ -11,9 +11,9 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
 type LayoutParams = RouteParams & {};
-type LayoutParentData = EnsureParentData<{}>;
+type LayoutParentData = EnsureDefined<{}>;
 
 export type LayoutServerData = null;
 export type LayoutLoad<
@@ -29,7 +29,9 @@ export type LayoutData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
+			>
 		>
 >;
diff --git a/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/(main)/$types.d.ts b/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/(main)/$types.d.ts
index cafaca1162b8..8dce3050a2c8 100644
--- a/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/(main)/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/(main)/$types.d.ts
@@ -11,11 +11,11 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
-type PageParentData = EnsureParentData<import('../$types.js').LayoutData>;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
+type PageParentData = EnsureDefined<import('../$types.js').LayoutData>;
 type LayoutParams = RouteParams & {};
-type LayoutServerParentData = EnsureParentData<import('../$types.js').LayoutServerData>;
-type LayoutParentData = EnsureParentData<import('../$types.js').LayoutData>;
+type LayoutServerParentData = EnsureDefined<import('../$types.js').LayoutServerData>;
+type LayoutParentData = EnsureDefined<import('../$types.js').LayoutData>;
 
 export type PageServerData = null;
 export type PageLoad<
@@ -29,8 +29,10 @@ export type PageData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../../(main)/+page.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../../(main)/+page.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../../(main)/+page.js').load>>
+			>
 		>
 >;
 export type LayoutServerLoad<
@@ -44,4 +46,6 @@ export type LayoutServerData = Expand<
 		Awaited<ReturnType<typeof import('../../../../../../../../../(main)/+layout.server.js').load>>
 	>
 >;
-export type LayoutData = Expand<Omit<LayoutParentData, keyof LayoutServerData> & LayoutServerData>;
+export type LayoutData = Expand<
+	Omit<LayoutParentData, keyof LayoutServerData> & EnsureDefined<LayoutServerData>
+>;
diff --git a/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/(main)/sub/$types.d.ts b/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/(main)/sub/$types.d.ts
index 2a6dcc75e223..6d3a147d3033 100644
--- a/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/(main)/sub/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/layout-advanced/_expected/(main)/sub/$types.d.ts
@@ -11,12 +11,12 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
 type PageParentData = Omit<
-	EnsureParentData<import('../../$types.js').LayoutData>,
+	EnsureDefined<import('../../$types.js').LayoutData>,
 	keyof import('../$types.js').LayoutData
 > &
-	EnsureParentData<import('../$types.js').LayoutData>;
+	EnsureDefined<import('../$types.js').LayoutData>;
 
 export type PageServerData = null;
 export type PageLoad<
@@ -30,7 +30,9 @@ export type PageData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../../../(main)/sub/+page.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../../../(main)/sub/+page.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../../../(main)/sub/+page.js').load>>
+			>
 		>
 >;
diff --git a/packages/kit/src/core/sync/write_types/test/layout/_expected/$types.d.ts b/packages/kit/src/core/sync/write_types/test/layout/_expected/$types.d.ts
index c7ace7bcb076..7aa6216adc85 100644
--- a/packages/kit/src/core/sync/write_types/test/layout/_expected/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/layout/_expected/$types.d.ts
@@ -11,12 +11,12 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
-type PageServerParentData = EnsureParentData<LayoutServerData>;
-type PageParentData = EnsureParentData<LayoutData>;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
+type PageServerParentData = EnsureDefined<LayoutServerData>;
+type PageParentData = EnsureDefined<LayoutData>;
 type LayoutParams = RouteParams & {};
-type LayoutServerParentData = EnsureParentData<{}>;
-type LayoutParentData = EnsureParentData<{}>;
+type LayoutServerParentData = EnsureDefined<{}>;
+type LayoutParentData = EnsureDefined<{}>;
 
 export type PageServerLoad<
 	OutputData extends (Partial<App.PageData> & Record<string, any>) | void =
@@ -41,8 +41,10 @@ export type PageData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
+			>
 		>
 >;
 export type Action = Kit.Action<RouteParams>;
@@ -71,8 +73,10 @@ export type LayoutData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
+			>
 		>
 >;
 export type RequestEvent = Kit.RequestEvent<RouteParams>;
diff --git a/packages/kit/src/core/sync/write_types/test/simple-page-server-and-shared/_expected/$types.d.ts b/packages/kit/src/core/sync/write_types/test/simple-page-server-and-shared/_expected/$types.d.ts
index 4c55aeabc56a..e0aa63a0dc77 100644
--- a/packages/kit/src/core/sync/write_types/test/simple-page-server-and-shared/_expected/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/simple-page-server-and-shared/_expected/$types.d.ts
@@ -11,11 +11,11 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
-type PageServerParentData = EnsureParentData<LayoutServerData>;
-type PageParentData = EnsureParentData<LayoutData>;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
+type PageServerParentData = EnsureDefined<LayoutServerData>;
+type PageParentData = EnsureDefined<LayoutData>;
 type LayoutParams = RouteParams & {};
-type LayoutParentData = EnsureParentData<{}>;
+type LayoutParentData = EnsureDefined<{}>;
 
 export type PageServerLoad<
 	OutputData extends (Partial<App.PageData> & Record<string, any>) | void =
@@ -40,8 +40,10 @@ export type PageData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
+			>
 		>
 >;
 export type Action = Kit.Action<RouteParams>;
diff --git a/packages/kit/src/core/sync/write_types/test/simple-page-server-only/_expected/$types.d.ts b/packages/kit/src/core/sync/write_types/test/simple-page-server-only/_expected/$types.d.ts
index 597cd9a16ce6..83443fcf45bc 100644
--- a/packages/kit/src/core/sync/write_types/test/simple-page-server-only/_expected/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/simple-page-server-only/_expected/$types.d.ts
@@ -11,11 +11,11 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
-type PageServerParentData = EnsureParentData<LayoutServerData>;
-type PageParentData = EnsureParentData<LayoutData>;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
+type PageServerParentData = EnsureDefined<LayoutServerData>;
+type PageParentData = EnsureDefined<LayoutData>;
 type LayoutParams = RouteParams & {};
-type LayoutParentData = EnsureParentData<{}>;
+type LayoutParentData = EnsureDefined<{}>;
 
 export type PageServerLoad<
 	OutputData extends OutputDataShape<PageServerParentData> = OutputDataShape<PageServerParentData>
@@ -29,7 +29,9 @@ export type PageServerData = Expand<
 		Awaited<ReturnType<typeof import('../../../../../../../../+page.server.js').load>>
 	>
 >;
-export type PageData = Expand<Omit<PageParentData, keyof PageServerData> & PageServerData>;
+export type PageData = Expand<
+	Omit<PageParentData, keyof PageServerData> & EnsureDefined<PageServerData>
+>;
 export type Action = Kit.Action<RouteParams>;
 export type Actions = Kit.Actions<RouteParams>;
 export type LayoutServerData = null;
diff --git a/packages/kit/src/core/sync/write_types/test/simple-page-shared-only/_expected/$types.d.ts b/packages/kit/src/core/sync/write_types/test/simple-page-shared-only/_expected/$types.d.ts
index b633139a3a75..bd9abf03bb14 100644
--- a/packages/kit/src/core/sync/write_types/test/simple-page-shared-only/_expected/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/simple-page-shared-only/_expected/$types.d.ts
@@ -11,10 +11,10 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
-type PageParentData = EnsureParentData<LayoutData>;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
+type PageParentData = EnsureDefined<LayoutData>;
 type LayoutParams = RouteParams & {};
-type LayoutParentData = EnsureParentData<{}>;
+type LayoutParentData = EnsureDefined<{}>;
 
 export type PageServerData = null;
 export type PageLoad<
@@ -28,8 +28,10 @@ export type PageData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../+page.js').load>>
+			>
 		>
 >;
 export type LayoutServerData = null;
diff --git a/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/$types.d.ts b/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/$types.d.ts
index 01c8cf716180..84ca3b827252 100644
--- a/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/$types.d.ts
@@ -11,9 +11,9 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
 type LayoutParams = RouteParams & { rest?: string; slug?: string };
-type LayoutParentData = EnsureParentData<{}>;
+type LayoutParentData = EnsureDefined<{}>;
 
 export type LayoutServerData = null;
 export type LayoutLoad<
@@ -27,7 +27,9 @@ export type LayoutData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
+			>
 		>
 >;
diff --git a/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/$types.d.ts b/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/$types.d.ts
index 0eb3bde85319..ceb75d063513 100644
--- a/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/$types.d.ts
@@ -11,9 +11,9 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
 type LayoutParams = RouteParams & { rest?: string };
-type LayoutParentData = EnsureParentData<import('../$types.js').LayoutData>;
+type LayoutParentData = EnsureDefined<import('../$types.js').LayoutData>;
 
 export type LayoutServerData = null;
 export type LayoutLoad<
@@ -29,7 +29,9 @@ export type LayoutData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../../nested/+layout.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../../nested/+layout.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../../nested/+layout.js').load>>
+			>
 		>
 >;
diff --git a/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/[...rest]/$types.d.ts b/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/[...rest]/$types.d.ts
index 876364ebf239..1f85afeb0254 100644
--- a/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/[...rest]/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/[...rest]/$types.d.ts
@@ -11,12 +11,12 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
 type PageParentData = Omit<
-	EnsureParentData<import('../../$types.js').LayoutData>,
+	EnsureDefined<import('../../$types.js').LayoutData>,
 	keyof import('../$types.js').LayoutData
 > &
-	EnsureParentData<import('../$types.js').LayoutData>;
+	EnsureDefined<import('../$types.js').LayoutData>;
 
 export type PageServerData = null;
 export type PageLoad<
@@ -32,9 +32,11 @@ export type PageData = Expand<
 			>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<
-				ReturnType<typeof import('../../../../../../../../../../nested/[...rest]/+page.js').load>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<
+					ReturnType<typeof import('../../../../../../../../../../nested/[...rest]/+page.js').load>
+				>
 			>
 		>
 >;
diff --git a/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/[slug]/$types.d.ts b/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/[slug]/$types.d.ts
index 36a66f7a1d77..1fed4661e16e 100644
--- a/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/[slug]/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/slugs-layout-not-all-pages-have-load/_expected/nested/[slug]/$types.d.ts
@@ -11,8 +11,8 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
-type PageParentData = EnsureParentData<import('../../$types.js').LayoutData>;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
+type PageParentData = EnsureDefined<import('../../$types.js').LayoutData>;
 
 export type PageServerData = null;
 export type PageData = Expand<PageParentData>;
diff --git a/packages/kit/src/core/sync/write_types/test/slugs/_expected/$types.d.ts b/packages/kit/src/core/sync/write_types/test/slugs/_expected/$types.d.ts
index 1d0cf89b6f24..131ee971983d 100644
--- a/packages/kit/src/core/sync/write_types/test/slugs/_expected/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/slugs/_expected/$types.d.ts
@@ -11,9 +11,9 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
 type LayoutParams = RouteParams & { rest?: string; slug?: string };
-type LayoutParentData = EnsureParentData<{}>;
+type LayoutParentData = EnsureDefined<{}>;
 
 export type LayoutServerData = null;
 export type LayoutLoad<
@@ -29,7 +29,9 @@ export type LayoutData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../+layout.js').load>>
+			>
 		>
 >;
diff --git a/packages/kit/src/core/sync/write_types/test/slugs/_expected/[...rest]/$types.d.ts b/packages/kit/src/core/sync/write_types/test/slugs/_expected/[...rest]/$types.d.ts
index bc4cc6f74ae8..3e9a9bf730bf 100644
--- a/packages/kit/src/core/sync/write_types/test/slugs/_expected/[...rest]/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/slugs/_expected/[...rest]/$types.d.ts
@@ -11,8 +11,8 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
-type PageParentData = EnsureParentData<import('../$types.js').LayoutData>;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
+type PageParentData = EnsureDefined<import('../$types.js').LayoutData>;
 
 export type PageServerData = null;
 export type PageLoad<
@@ -26,7 +26,9 @@ export type PageData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../../[...rest]/+page.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../../[...rest]/+page.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../../[...rest]/+page.js').load>>
+			>
 		>
 >;
diff --git a/packages/kit/src/core/sync/write_types/test/slugs/_expected/[slug]/$types.d.ts b/packages/kit/src/core/sync/write_types/test/slugs/_expected/[slug]/$types.d.ts
index 86911f5e0043..ec1208796bf6 100644
--- a/packages/kit/src/core/sync/write_types/test/slugs/_expected/[slug]/$types.d.ts
+++ b/packages/kit/src/core/sync/write_types/test/slugs/_expected/[slug]/$types.d.ts
@@ -11,8 +11,8 @@ type OutputDataShape<T> = MaybeWithVoid<
 		Partial<Pick<App.PageData, keyof T & keyof App.PageData>> &
 		Record<string, any>
 >;
-type EnsureParentData<T> = T extends null | undefined ? {} : T;
-type PageParentData = EnsureParentData<import('../$types.js').LayoutData>;
+type EnsureDefined<T> = T extends null | undefined ? {} : T;
+type PageParentData = EnsureDefined<import('../$types.js').LayoutData>;
 
 export type PageServerData = null;
 export type PageLoad<
@@ -26,7 +26,9 @@ export type PageData = Expand<
 			Awaited<ReturnType<typeof import('../../../../../../../../../[slug]/+page.js').load>>
 		>
 	> &
-		Kit.AwaitedProperties<
-			Awaited<ReturnType<typeof import('../../../../../../../../../[slug]/+page.js').load>>
+		EnsureDefined<
+			Kit.AwaitedProperties<
+				Awaited<ReturnType<typeof import('../../../../../../../../../[slug]/+page.js').load>>
+			>
 		>
 >;