From e43c6f1d4e9658a35d6568e3b2c23c41aa94bb37 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 14:27:01 -0400
Subject: [PATCH 01/27] WIP

---
 packages/kit/src/cli.js                       |   2 +-
 packages/kit/src/core/env.js                  |  28 ++++-
 packages/kit/src/core/sync/sync.js            |   7 +-
 packages/kit/src/exports/vite/index.js        | 113 +++++------------
 packages/kit/src/exports/vite/module_ids.js   |   3 -
 .../kit/src/exports/vite/plugins/env-vars.js  | 116 ++++++++++++++++++
 packages/kit/src/exports/vite/utils.js        |   5 +-
 7 files changed, 174 insertions(+), 100 deletions(-)
 create mode 100644 packages/kit/src/exports/vite/plugins/env-vars.js

diff --git a/packages/kit/src/cli.js b/packages/kit/src/cli.js
index d5aa39564a92..6a588403aaaf 100755
--- a/packages/kit/src/cli.js
+++ b/packages/kit/src/cli.js
@@ -106,7 +106,7 @@ if (command === 'sync') {
 		sync.all_types(sveltekit_config, vite_config.root);
 
 		const explicit_env_entry = resolve_explicit_env_entry(sveltekit_config);
-		await sync.env(vite, sveltekit_config, explicit_env_entry, vite_config.root, values.mode);
+		await sync.env(sveltekit_config, explicit_env_entry, vite_config.root, values.mode);
 	} catch (error) {
 		handle_error(error);
 	} finally {
diff --git a/packages/kit/src/core/env.js b/packages/kit/src/core/env.js
index 372a1aeb525d..9c42fac73c10 100644
--- a/packages/kit/src/core/env.js
+++ b/packages/kit/src/core/env.js
@@ -10,6 +10,7 @@ import { resolve_entry } from '../utils/filesystem.js';
 import { handle_issues, validate } from '../exports/internal/env.js';
 import { get_config_aliases } from '../exports/vite/utils.js';
 import { get_runner } from '../runner.js';
+import { import_peer } from '../utils/import.js';
 
 /**
  * @typedef {'public' | 'private'} EnvType
@@ -24,15 +25,22 @@ export function resolve_explicit_env_entry(config) {
 }
 
 /**
- * @param {typeof import('vite')} vite
  * @param {ValidatedConfig} kit
  * @param {string | null} file
  * @param {string} root
  * @param {string} mode
- * @returns {Promise<Record<string, EnvVarConfig<any>> | null>}
+ * @returns {Promise<{ variables: Record<string, EnvVarConfig<any>> | null, deps: Set<string> }>}
  */
-export async function load_explicit_env(vite, kit, file, root, mode) {
-	if (!file) return null;
+export async function load_explicit_env(kit, file, root, mode) {
+	/** @type {Set<string>} */
+	const deps = new Set();
+
+	if (!file) {
+		return { variables: null, deps };
+	}
+
+	/** @type {typeof import('vite')} */
+	const vite = await import_peer('vite', root);
 
 	const server = await vite.createServer({
 		configFile: false,
@@ -49,7 +57,15 @@ export async function load_explicit_env(vite, kit, file, root, mode) {
 				{ find: '$app/env', replacement: `${runtime_directory}/app/env` },
 				...get_config_aliases(kit, root)
 			]
-		}
+		},
+		plugins: [
+			{
+				name: 'dependency-scanner',
+				load(id) {
+					deps.add(id);
+				}
+			}
+		]
 	});
 
 	/** @type {Record<string, EnvVarConfig<any>>} */
@@ -92,7 +108,7 @@ export async function load_explicit_env(vite, kit, file, root, mode) {
 		await server.close();
 	}
 
-	return variables;
+	return { variables, deps };
 }
 
 /**
diff --git a/packages/kit/src/core/sync/sync.js b/packages/kit/src/core/sync/sync.js
index 50d3e53a4101..2a089e2a0e76 100644
--- a/packages/kit/src/core/sync/sync.js
+++ b/packages/kit/src/core/sync/sync.js
@@ -102,16 +102,15 @@ export function all_types(config, root) {
 
 /**
  * Generate modules and types for explicit env vars
- * @param {typeof import('vite')} vite
  * @param {import('types').ValidatedConfig} kit
  * @param {string | null} entry
  * @param {string} root The Vite root
  * @param {string} mode The Vite mode
  */
-export async function env(vite, kit, entry, root, mode) {
-	const env_config = await load_explicit_env(vite, kit, entry, root, mode);
+export async function env(kit, entry, root, mode) {
+	const env_config = await load_explicit_env(kit, entry, root, mode);
 
-	write_env(entry, env_config, root);
+	write_env(entry, env_config.variables, root);
 
 	return env_config;
 }
diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index 8cd15c9e170d..5404b14d5c88 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -24,12 +24,9 @@ import { copy, read, resolve_entry } from '../../utils/filesystem.js';
 import { posixify } from '../../utils/os.js';
 import { to_fs } from '../../utils/vite.js';
 import {
-	create_sveltekit_env,
-	create_sveltekit_env_public,
 	resolve_explicit_env_entry,
 	create_sveltekit_env_service_worker,
 	create_sveltekit_env_service_worker_dev,
-	create_sveltekit_env_private,
 	create_exported_declarations
 } from '../../core/env.js';
 import * as sync from '../../core/sync/sync.js';
@@ -66,12 +63,9 @@ import { get_import_aliases, get_hash_import_keys } from '../../utils/imports.js
 import {
 	app_env_private,
 	app_server,
-	sveltekit_env,
-	sveltekit_env_private,
 	sveltekit_env_service_worker,
 	sveltekit_manifest_data,
-	sveltekit_env_public_client,
-	sveltekit_env_public_server
+	sveltekit_env_public_client
 } from './module_ids.js';
 import { import_peer } from '../../utils/import.js';
 import { compact } from '../../utils/array.js';
@@ -79,6 +73,7 @@ import { should_ignore, has_children } from './static_analysis/utils.js';
 import { process_config, split_config, validate_config } from '../../core/config/index.js';
 import { treeshake_prerendered_remotes } from './build/remote.js';
 import { get_runner } from '../../runner.js';
+import { plugin_env_vars } from './plugins/env-vars.js';
 
 /** @type {import('./types.js').EnforcedConfig} */
 const enforced_config = {
@@ -663,38 +658,6 @@ function kit({ svelte_config }) {
 	const plugin_virtual_modules = {
 		name: 'vite-plugin-sveltekit-virtual-modules',
 
-		async configResolved(config) {
-			explicit_env_entry = resolve_explicit_env_entry(kit);
-			explicit_env_config = await sync.env(vite, kit, explicit_env_entry, config.root, config.mode);
-		},
-
-		configureServer(server) {
-			server.watcher.on('all', async (_, file) => {
-				if (!file.includes('env')) {
-					return;
-				}
-
-				const resolved = resolve_explicit_env_entry(kit);
-
-				if (file === explicit_env_entry || file === resolved) {
-					explicit_env_entry = resolved;
-					explicit_env_config = await sync.env(
-						vite,
-						kit,
-						explicit_env_entry,
-						vite_config.root,
-						vite_config.mode
-					);
-
-					for (const id of [sveltekit_env, sveltekit_env_public_client]) {
-						invalidate_module(server, id);
-					}
-
-					server.hot.send({ type: 'full-reload' });
-				}
-			});
-		},
-
 		applyToEnvironment(environment) {
 			return environment.name !== 'serviceWorker';
 		},
@@ -708,6 +671,22 @@ function kit({ svelte_config }) {
 					return `${out_dir}/generated/client-optimized/app.js`;
 				}
 
+				if (id === '__sveltekit/env') {
+					return `${out_dir}/generated/env/config.js`;
+				}
+
+				if (id === '__sveltekit/env/public/client') {
+					return `${out_dir}/generated/env/public/client.js`;
+				}
+
+				if (id === '__sveltekit/env/public/server') {
+					return `${out_dir}/generated/env/public/server.js`;
+				}
+
+				if (id === '__sveltekit/env/private') {
+					return `${out_dir}/generated/env/private/server.js`;
+				}
+
 				if (id === '__sveltekit/remote') {
 					return `${runtime_directory}/client/remote-functions/index.js`;
 				}
@@ -718,40 +697,13 @@ function kit({ svelte_config }) {
 
 		load: {
 			filter: {
-				id: [
-					exactRegex(sveltekit_env),
-					exactRegex(sveltekit_env_private),
-					exactRegex(sveltekit_env_public_client),
-					exactRegex(sveltekit_env_public_server),
-					exactRegex(sveltekit_env_service_worker),
-					exactRegex(sveltekit_manifest_data)
-				]
+				id: [exactRegex(sveltekit_env_service_worker), exactRegex(sveltekit_manifest_data)]
 			},
 			handler(id) {
 				switch (id) {
 					case sveltekit_manifest_data:
 						return create_manifest_data_module(is_build, manifest_data);
 
-					case sveltekit_env:
-						return create_sveltekit_env(explicit_env_config, env, explicit_env_entry, !is_build);
-
-					case sveltekit_env_public_client:
-						return create_sveltekit_env_public(
-							explicit_env_config,
-							env,
-							`import { payload } from ${s(`${runtime_directory}/client/payload.js`)};\nconst env = payload.env;`
-						);
-
-					case sveltekit_env_public_server:
-						return create_sveltekit_env_public(
-							explicit_env_config,
-							env,
-							`import { rendered_env as env } from '__sveltekit/env';`
-						);
-
-					case sveltekit_env_private:
-						return create_sveltekit_env_private(explicit_env_config, env);
-
 					case sveltekit_env_service_worker:
 						return is_build
 							? create_sveltekit_env_service_worker(
@@ -1201,6 +1153,10 @@ function kit({ svelte_config }) {
 				id: prefixRegex('__sveltekit/')
 			},
 			handler(id) {
+				if (id === '__sveltekit/env/public/client') {
+					return `${out_dir}/generated/env/public/service-worker.js`;
+				}
+
 				return `\0virtual:${id}`;
 			}
 		},
@@ -1210,8 +1166,7 @@ function kit({ svelte_config }) {
 				id: [
 					exactRegex('\0virtual:app/manifest'),
 					exactRegex(sveltekit_manifest_data),
-					exactRegex(sveltekit_env_service_worker),
-					exactRegex(sveltekit_env_public_client)
+					exactRegex(sveltekit_env_service_worker)
 				]
 			},
 			handler(id) {
@@ -1264,14 +1219,6 @@ function kit({ svelte_config }) {
 								kit_global
 							);
 				}
-
-				if (id === sveltekit_env_public_client) {
-					return create_sveltekit_env_public(
-						explicit_env_config,
-						env,
-						`const env = ${kit_global}.env;`
-					);
-				}
 			}
 		},
 
@@ -2174,13 +2121,10 @@ function kit({ svelte_config }) {
 				fs.mkdirSync(out, { recursive: true });
 
 				explicit_env_entry = resolve_explicit_env_entry(kit);
-				explicit_env_config = await sync.env(
-					vite,
-					kit,
-					explicit_env_entry,
-					vite_config.root,
-					vite_config.mode
-				);
+
+				const synced = await sync.env(kit, explicit_env_entry, vite_config.root, vite_config.mode);
+
+				explicit_env_config = synced.variables;
 
 				await load_and_validate_params({
 					routes: manifest_data.routes,
@@ -2244,6 +2188,7 @@ function kit({ svelte_config }) {
 			plugin_setup,
 			plugin_remote_guard,
 			plugin_remote,
+			plugin_env_vars(svelte_config),
 			plugin_virtual_modules,
 			process.env.TEST !== 'true' ? plugin_guard : undefined,
 			plugin_service_worker,
diff --git a/packages/kit/src/exports/vite/module_ids.js b/packages/kit/src/exports/vite/module_ids.js
index 065df4df902e..cff661849d97 100644
--- a/packages/kit/src/exports/vite/module_ids.js
+++ b/packages/kit/src/exports/vite/module_ids.js
@@ -1,10 +1,7 @@
 import { fileURLToPath } from 'node:url';
 import { posixify } from '../../utils/os.js';
 
-export const sveltekit_env = '\0virtual:__sveltekit/env';
 export const sveltekit_env_public_client = '\0virtual:__sveltekit/env/public/client';
-export const sveltekit_env_public_server = '\0virtual:__sveltekit/env/public/server';
-export const sveltekit_env_private = '\0virtual:__sveltekit/env/private';
 export const sveltekit_env_service_worker = '\0virtual:__sveltekit/env/service-worker';
 export const sveltekit_server = '\0virtual:__sveltekit/server';
 export const service_worker = '\0virtual:service-worker';
diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
new file mode 100644
index 000000000000..2f7a7fe145d6
--- /dev/null
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -0,0 +1,116 @@
+/** @import { Plugin, ResolvedConfig } from 'vite' */
+/** @import { ValidatedConfig } from 'types' */
+import path from 'node:path';
+import * as sync from '../../../core/sync/sync.js';
+import { resolve_entry } from '../../../utils/filesystem.js';
+import {
+	create_sveltekit_env,
+	create_sveltekit_env_private,
+	create_sveltekit_env_public
+} from '../../../core/env.js';
+import { import_peer } from '../../../utils/import.js';
+import { runtime_directory } from '../../../core/utils.js';
+import { s } from '../../../utils/misc.js';
+import { write_if_changed } from '../../../core/sync/utils.js';
+import { hash } from '../../../utils/hash.js';
+
+/**
+ * Generate (and, in dev, maintain) a `${outDir}/generated/env/config.js` module
+ * derived from `src/env.ts`
+ *
+ * @param {ValidatedConfig} config
+ * @returns {Plugin}
+ */
+export function plugin_env_vars(config) {
+	// grab these values eagerly because they get mutated (TODO stop mutating them)
+	const entry = path.join(config.files.src, 'env');
+	const dir = config.env.dir;
+	const out = config.outDir;
+
+	/** @type {Record<string, any>} */
+	let env;
+
+	/** @type {ResolvedConfig} */
+	let resolved_config;
+
+	/** @type {string | null} */
+	let resolved_entry = null;
+
+	let is_build = false;
+
+	/** @type {Set<string>} */
+	let deps;
+
+	/** @type {string} */
+	let kit_global;
+
+	async function generate() {
+		const synced = await sync.env(
+			config,
+			resolved_entry,
+			resolved_config.root,
+			resolved_config.mode
+		);
+
+		deps = synced.deps;
+
+		write_if_changed(
+			`${out}/generated/env/config.js`,
+			create_sveltekit_env(synced.variables, env, resolved_entry, !is_build)
+		);
+
+		write_if_changed(
+			`${out}/generated/env/public/client.js`,
+			create_sveltekit_env_public(
+				synced.variables,
+				env,
+				`import { payload } from ${s(`${runtime_directory}/client/payload.js`)};\nconst env = payload.env;`
+			)
+		);
+
+		write_if_changed(
+			`${out}/generated/env/public/server.js`,
+			create_sveltekit_env_public(
+				synced.variables,
+				env,
+				`import { rendered_env as env } from '../config.js';`
+			)
+		);
+
+		write_if_changed(
+			`${out}/generated/env/public/service-worker.js`,
+			create_sveltekit_env_public(synced.variables, env, `const env = ${kit_global}.env;`)
+		);
+
+		write_if_changed(
+			`${out}/generated/env/private/server.js`,
+			create_sveltekit_env_private(synced.variables, env)
+		);
+	}
+
+	return {
+		name: 'vite-plugin-sveltekit-env-vars',
+		async configResolved(c) {
+			resolved_config = c;
+
+			const vite = await import_peer('vite', c.root);
+			env = vite.loadEnv(c.mode, dir, '');
+
+			is_build = c.command === 'build';
+
+			const version_hash = hash(config.version.name);
+
+			kit_global = is_build
+				? `globalThis.__sveltekit_${version_hash}`
+				: 'globalThis.__sveltekit_dev';
+		},
+		async buildStart() {
+			resolved_entry = resolve_entry(path.join(resolved_config.root, entry)) ?? null;
+			await generate();
+		},
+		async handleHotUpdate(update) {
+			if (!deps.has(update.file)) return;
+			await generate();
+		}
+	};
+}
diff --git a/packages/kit/src/exports/vite/utils.js b/packages/kit/src/exports/vite/utils.js
index a9ddf2279206..06cdc8b18bea 100644
--- a/packages/kit/src/exports/vite/utils.js
+++ b/packages/kit/src/exports/vite/utils.js
@@ -6,7 +6,7 @@ import { escape_html } from '../../utils/escape.js';
 import { escape_for_regexp } from '../../utils/regex.js';
 import { stackless } from '../../utils/error.js';
 import { dedent } from '../../core/sync/utils.js';
-import { app_server, app_env_private, sveltekit_env_private } from './module_ids.js';
+import { app_server, app_env_private } from './module_ids.js';
 
 /**
  * Transforms alias to a valid vite.resolve.alias array.
@@ -119,7 +119,8 @@ export function normalize_id(id, aliases, cwd) {
 		return '$app/server';
 	}
 
-	if (id === app_env_private || id === sveltekit_env_private) {
+	// TODO is this right?
+	if (id === app_env_private || id === '__sveltekit/env/private') {
 		return '$app/env/private';
 	}
 

From 97bfc18bfcf8960245540e58633598bb4ace0615 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 14:49:27 -0400
Subject: [PATCH 02/27] WIP

---
 packages/kit/src/exports/vite/index.js        | 64 +++++--------------
 packages/kit/src/exports/vite/module_ids.js   |  1 -
 .../kit/src/exports/vite/plugins/env-vars.js  | 54 ++++++++++++----
 3 files changed, 58 insertions(+), 61 deletions(-)

diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index 5404b14d5c88..7857131ef622 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -23,12 +23,7 @@ import MagicString from 'magic-string';
 import { copy, read, resolve_entry } from '../../utils/filesystem.js';
 import { posixify } from '../../utils/os.js';
 import { to_fs } from '../../utils/vite.js';
-import {
-	resolve_explicit_env_entry,
-	create_sveltekit_env_service_worker,
-	create_sveltekit_env_service_worker_dev,
-	create_exported_declarations
-} from '../../core/env.js';
+import { resolve_explicit_env_entry, create_exported_declarations } from '../../core/env.js';
 import * as sync from '../../core/sync/sync.js';
 import { load_and_validate_params } from '../../utils/params.js';
 import { runtime_directory, logger } from '../../core/utils.js';
@@ -63,7 +58,6 @@ import { get_import_aliases, get_hash_import_keys } from '../../utils/imports.js
 import {
 	app_env_private,
 	app_server,
-	sveltekit_env_service_worker,
 	sveltekit_manifest_data,
 	sveltekit_env_public_client
 } from './module_ids.js';
@@ -687,6 +681,12 @@ function kit({ svelte_config }) {
 					return `${out_dir}/generated/env/private/server.js`;
 				}
 
+				if (id === '__sveltekit/env/service-worker') {
+					return is_build
+						? `${out_dir}/generated/env/service-worker-prod.js`
+						: `${out_dir}/generated/env/service-worker-dev.js`;
+				}
+
 				if (id === '__sveltekit/remote') {
 					return `${runtime_directory}/client/remote-functions/index.js`;
 				}
@@ -697,29 +697,12 @@ function kit({ svelte_config }) {
 
 		load: {
 			filter: {
-				id: [exactRegex(sveltekit_env_service_worker), exactRegex(sveltekit_manifest_data)]
+				id: [exactRegex(sveltekit_manifest_data)]
 			},
 			handler(id) {
 				switch (id) {
 					case sveltekit_manifest_data:
 						return create_manifest_data_module(is_build, manifest_data);
-
-					case sveltekit_env_service_worker:
-						return is_build
-							? create_sveltekit_env_service_worker(
-									explicit_env_config,
-									env,
-									kit.version.name,
-									kit_global,
-									kit.paths.base,
-									kit.appDir
-								)
-							: create_sveltekit_env_service_worker_dev(
-									explicit_env_config,
-									env,
-									kit.version.name,
-									kit_global
-								);
 				}
 			}
 		}
@@ -1157,17 +1140,19 @@ function kit({ svelte_config }) {
 					return `${out_dir}/generated/env/public/service-worker.js`;
 				}
 
+				if (id === '__sveltekit/env/service-worker') {
+					return is_build
+						? `${out_dir}/generated/env/service-worker-prod.js`
+						: `${out_dir}/generated/env/service-worker-dev.js`;
+				}
+
 				return `\0virtual:${id}`;
 			}
 		},
 
 		load: {
 			filter: {
-				id: [
-					exactRegex('\0virtual:app/manifest'),
-					exactRegex(sveltekit_manifest_data),
-					exactRegex(sveltekit_env_service_worker)
-				]
+				id: [exactRegex('\0virtual:app/manifest'), exactRegex(sveltekit_manifest_data)]
 			},
 			handler(id) {
 				if (!manifest_data_code) {
@@ -1201,24 +1186,6 @@ function kit({ svelte_config }) {
 				if (id === sveltekit_manifest_data) {
 					return manifest_data_code;
 				}
-
-				if (id === sveltekit_env_service_worker) {
-					return is_build
-						? create_sveltekit_env_service_worker(
-								explicit_env_config,
-								env,
-								kit.version.name,
-								kit_global,
-								kit.paths.base,
-								kit.appDir
-							)
-						: create_sveltekit_env_service_worker_dev(
-								explicit_env_config,
-								env,
-								kit.version.name,
-								kit_global
-							);
-				}
 			}
 		},
 
@@ -1836,6 +1803,7 @@ function kit({ svelte_config }) {
 					const uses_env_dynamic_public =
 						has_explicit_dynamic_public_env &&
 						client_chunks.some(
+							// TODO need to update this
 							(chunk) => chunk.type === 'chunk' && chunk.modules[sveltekit_env_public_client]
 						);
 
diff --git a/packages/kit/src/exports/vite/module_ids.js b/packages/kit/src/exports/vite/module_ids.js
index cff661849d97..8810be4deaaf 100644
--- a/packages/kit/src/exports/vite/module_ids.js
+++ b/packages/kit/src/exports/vite/module_ids.js
@@ -2,7 +2,6 @@ import { fileURLToPath } from 'node:url';
 import { posixify } from '../../utils/os.js';
 
 export const sveltekit_env_public_client = '\0virtual:__sveltekit/env/public/client';
-export const sveltekit_env_service_worker = '\0virtual:__sveltekit/env/service-worker';
 export const sveltekit_server = '\0virtual:__sveltekit/server';
 export const service_worker = '\0virtual:service-worker';
 
diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 2f7a7fe145d6..a0a71c809b47 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -6,7 +6,9 @@ import { resolve_entry } from '../../../utils/filesystem.js';
 import {
 	create_sveltekit_env,
 	create_sveltekit_env_private,
-	create_sveltekit_env_public
+	create_sveltekit_env_public,
+	create_sveltekit_env_service_worker,
+	create_sveltekit_env_service_worker_dev
 } from '../../../core/env.js';
 import { import_peer } from '../../../utils/import.js';
 import { runtime_directory } from '../../../core/utils.js';
@@ -27,6 +29,8 @@ export function plugin_env_vars(config) {
 	const dir = config.env.dir;
 	const out = config.outDir;
 
+	const version_hash = hash(config.version.name);
+
 	/** @type {Record<string, any>} */
 	let env;
 
@@ -41,9 +45,6 @@ export function plugin_env_vars(config) {
 	/** @type {Set<string>} */
 	let deps;
 
-	/** @type {string} */
-	let kit_global;
-
 	async function generate() {
 		const synced = await sync.env(
 			config,
@@ -78,14 +79,49 @@ export function plugin_env_vars(config) {
 		);
 
 		write_if_changed(
-			`${out}/generated/env/public/service-worker.js`,
-			create_sveltekit_env_public(synced.variables, env, `const env = ${kit_global}.env;`)
+			`${out}/generated/env/public/service-worker-prod.js`,
+			create_sveltekit_env_public(
+				synced.variables,
+				env,
+				`const env = globalThis.__sveltekit_${version_hash}.env;`
+			)
+		);
+
+		write_if_changed(
+			`${out}/generated/env/public/service-worker-dev.js`,
+			create_sveltekit_env_public(
+				synced.variables,
+				env,
+				`const env = globalThis.__sveltekit_dev.env;`
+			)
 		);
 
 		write_if_changed(
 			`${out}/generated/env/private/server.js`,
 			create_sveltekit_env_private(synced.variables, env)
 		);
+
+		write_if_changed(
+			`${out}/generated/env/service-worker-prod.js`,
+			create_sveltekit_env_service_worker(
+				synced.variables,
+				env,
+				config.version.name,
+				`globalThis.__sveltekit_${version_hash}`,
+				config.paths.base,
+				config.appDir
+			)
+		);
+
+		write_if_changed(
+			`${out}/generated/env/service-worker-dev.js`,
+			create_sveltekit_env_service_worker_dev(
+				synced.variables,
+				env,
+				config.version.name,
+				'globalThis.__sveltekit_dev'
+			)
+		);
 	}
 
 	return {
@@ -97,12 +133,6 @@ export function plugin_env_vars(config) {
 			env = vite.loadEnv(c.mode, dir, '');
 
 			is_build = c.command === 'build';
-
-			const version_hash = hash(config.version.name);
-
-			kit_global = is_build
-				? `globalThis.__sveltekit_${version_hash}`
-				: 'globalThis.__sveltekit_dev';
 		},
 		async buildStart() {
 			resolved_entry = resolve_entry(path.join(resolved_config.root, entry)) ?? null;

From b2e68c8594870f7dd1ea4ce92789cdde8d386a0b Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 14:58:19 -0400
Subject: [PATCH 03/27] fix

---
 packages/kit/src/exports/vite/index.js            |  4 +++-
 packages/kit/src/exports/vite/plugins/env-vars.js |  2 +-
 playgrounds/basic/src/env.ts                      | 11 +++++++++++
 3 files changed, 15 insertions(+), 2 deletions(-)
 create mode 100644 playgrounds/basic/src/env.ts

diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index 7857131ef622..4eb059da5cf1 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -1137,7 +1137,9 @@ function kit({ svelte_config }) {
 			},
 			handler(id) {
 				if (id === '__sveltekit/env/public/client') {
-					return `${out_dir}/generated/env/public/service-worker.js`;
+					return is_build
+						? `${out_dir}/generated/env/public/service-worker-prod.js`
+						: `${out_dir}/generated/env/public/service-worker-dev.js`;
 				}
 
 				if (id === '__sveltekit/env/service-worker') {
diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index a0a71c809b47..486c2d80685c 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -130,7 +130,7 @@ export function plugin_env_vars(config) {
 			resolved_config = c;
 
 			const vite = await import_peer('vite', c.root);
-			env = vite.loadEnv(c.mode, dir, '');
+			env = vite.loadEnv(c.mode, path.resolve(c.root, dir), '');
 
 			is_build = c.command === 'build';
 		},
diff --git a/playgrounds/basic/src/env.ts b/playgrounds/basic/src/env.ts
new file mode 100644
index 000000000000..33dc10c2ddfa
--- /dev/null
+++ b/playgrounds/basic/src/env.ts
@@ -0,0 +1,11 @@
+import { defineEnvVars } from '@sveltejs/kit/env';
+
+export const variables = defineEnvVars({
+	MESSAGE: {
+		public: true
+	},
+	SECRET: {},
+	STATIC: {
+		static: true
+	}
+});

From 6bc54ad57830656bd18feeaf1657549d2f5ab8f3 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 15:11:09 -0400
Subject: [PATCH 04/27] move resolveId logic

---
 packages/kit/src/exports/vite/index.js        | 35 +-----------
 .../kit/src/exports/vite/plugins/env-vars.js  | 56 ++++++++++++++++---
 2 files changed, 49 insertions(+), 42 deletions(-)

diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index 4eb059da5cf1..cdd35e9c8cec 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -665,28 +665,6 @@ function kit({ svelte_config }) {
 					return `${out_dir}/generated/client-optimized/app.js`;
 				}
 
-				if (id === '__sveltekit/env') {
-					return `${out_dir}/generated/env/config.js`;
-				}
-
-				if (id === '__sveltekit/env/public/client') {
-					return `${out_dir}/generated/env/public/client.js`;
-				}
-
-				if (id === '__sveltekit/env/public/server') {
-					return `${out_dir}/generated/env/public/server.js`;
-				}
-
-				if (id === '__sveltekit/env/private') {
-					return `${out_dir}/generated/env/private/server.js`;
-				}
-
-				if (id === '__sveltekit/env/service-worker') {
-					return is_build
-						? `${out_dir}/generated/env/service-worker-prod.js`
-						: `${out_dir}/generated/env/service-worker-dev.js`;
-				}
-
 				if (id === '__sveltekit/remote') {
 					return `${runtime_directory}/client/remote-functions/index.js`;
 				}
@@ -1136,18 +1114,7 @@ function kit({ svelte_config }) {
 				id: prefixRegex('__sveltekit/')
 			},
 			handler(id) {
-				if (id === '__sveltekit/env/public/client') {
-					return is_build
-						? `${out_dir}/generated/env/public/service-worker-prod.js`
-						: `${out_dir}/generated/env/public/service-worker-dev.js`;
-				}
-
-				if (id === '__sveltekit/env/service-worker') {
-					return is_build
-						? `${out_dir}/generated/env/service-worker-prod.js`
-						: `${out_dir}/generated/env/service-worker-dev.js`;
-				}
-
+				// TODO do we still need this?
 				return `\0virtual:${id}`;
 			}
 		},
diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 486c2d80685c..fc7ca8cbdac0 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -15,6 +15,7 @@ import { runtime_directory } from '../../../core/utils.js';
 import { s } from '../../../utils/misc.js';
 import { write_if_changed } from '../../../core/sync/utils.js';
 import { hash } from '../../../utils/hash.js';
+import { prefixRegex } from '@rolldown/pluginutils';
 
 /**
  * Generate (and, in dev, maintain) a `${outDir}/generated/env/config.js` module
@@ -31,6 +32,9 @@ export function plugin_env_vars(config) {
 
 	const version_hash = hash(config.version.name);
 
+	/** @type {string} */
+	let out_dir;
+
 	/** @type {Record<string, any>} */
 	let env;
 
@@ -56,12 +60,12 @@ export function plugin_env_vars(config) {
 		deps = synced.deps;
 
 		write_if_changed(
-			`${out}/generated/env/config.js`,
+			`${out_dir}/generated/env/config.js`,
 			create_sveltekit_env(synced.variables, env, resolved_entry, !is_build)
 		);
 
 		write_if_changed(
-			`${out}/generated/env/public/client.js`,
+			`${out_dir}/generated/env/public/client.js`,
 			create_sveltekit_env_public(
 				synced.variables,
 				env,
@@ -70,7 +74,7 @@ export function plugin_env_vars(config) {
 		);
 
 		write_if_changed(
-			`${out}/generated/env/public/server.js`,
+			`${out_dir}/generated/env/public/server.js`,
 			create_sveltekit_env_public(
 				synced.variables,
 				env,
@@ -79,7 +83,7 @@ export function plugin_env_vars(config) {
 		);
 
 		write_if_changed(
-			`${out}/generated/env/public/service-worker-prod.js`,
+			`${out_dir}/generated/env/public/service-worker-prod.js`,
 			create_sveltekit_env_public(
 				synced.variables,
 				env,
@@ -88,7 +92,7 @@ export function plugin_env_vars(config) {
 		);
 
 		write_if_changed(
-			`${out}/generated/env/public/service-worker-dev.js`,
+			`${out_dir}/generated/env/public/service-worker-dev.js`,
 			create_sveltekit_env_public(
 				synced.variables,
 				env,
@@ -97,12 +101,12 @@ export function plugin_env_vars(config) {
 		);
 
 		write_if_changed(
-			`${out}/generated/env/private/server.js`,
+			`${out_dir}/generated/env/private/server.js`,
 			create_sveltekit_env_private(synced.variables, env)
 		);
 
 		write_if_changed(
-			`${out}/generated/env/service-worker-prod.js`,
+			`${out_dir}/generated/env/service-worker-prod.js`,
 			create_sveltekit_env_service_worker(
 				synced.variables,
 				env,
@@ -114,7 +118,7 @@ export function plugin_env_vars(config) {
 		);
 
 		write_if_changed(
-			`${out}/generated/env/service-worker-dev.js`,
+			`${out_dir}/generated/env/service-worker-dev.js`,
 			create_sveltekit_env_service_worker_dev(
 				synced.variables,
 				env,
@@ -126,21 +130,57 @@ export function plugin_env_vars(config) {
 
 	return {
 		name: 'vite-plugin-sveltekit-env-vars',
+
 		async configResolved(c) {
 			resolved_config = c;
 
 			const vite = await import_peer('vite', c.root);
 			env = vite.loadEnv(c.mode, path.resolve(c.root, dir), '');
 
+			out_dir = path.resolve(c.root, out);
+
 			is_build = c.command === 'build';
 		},
+
 		async buildStart() {
 			resolved_entry = resolve_entry(path.join(resolved_config.root, entry)) ?? null;
 			await generate();
 		},
+
 		async handleHotUpdate(update) {
 			if (!deps.has(update.file)) return;
 			await generate();
+		},
+
+		resolveId: {
+			filter: {
+				id: prefixRegex('__sveltekit/env')
+			},
+			handler(id) {
+				if (id === '__sveltekit/env') {
+					return `${out_dir}/generated/env/config.js`;
+				}
+
+				if (id === '__sveltekit/env/private') {
+					return `${out_dir}/generated/env/private/server.js`;
+				}
+
+				if (id === '__sveltekit/env/public/server') {
+					return `${out_dir}/generated/env/public/server.js`;
+				}
+
+				if (id === '__sveltekit/env/public/client') {
+					return this.environment.name === 'serviceWorker'
+						? `${out_dir}/generated/env/public/service-worker-prod.js`
+						: `${out_dir}/generated/env/public/client.js`;
+				}
+
+				if (id === '__sveltekit/env/service-worker') {
+					return is_build
+						? `${out_dir}/generated/env/service-worker-prod.js`
+						: `${out_dir}/generated/env/service-worker-dev.js`;
+				}
+			}
 		}
 	};
 }

From af831ded280742f4add10ee8ab930cb6b851eb00 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 15:24:18 -0400
Subject: [PATCH 05/27] fix

---
 .changeset/warm-boats-taste.md                |  6 ++
 packages/kit/src/core/env.js                  | 34 ++++++----
 .../kit/src/exports/vite/plugins/env-vars.js  | 65 +++++++++----------
 3 files changed, 57 insertions(+), 48 deletions(-)
 create mode 100644 .changeset/warm-boats-taste.md

diff --git a/.changeset/warm-boats-taste.md b/.changeset/warm-boats-taste.md
new file mode 100644
index 000000000000..b381aecec82d
--- /dev/null
+++ b/.changeset/warm-boats-taste.md
@@ -0,0 +1,6 @@
+---
+"@sveltejs/kit": patch
+---
+
+chore: emit env modules to disk
+  
\ No newline at end of file
diff --git a/packages/kit/src/core/env.js b/packages/kit/src/core/env.js
index 9c42fac73c10..c6725e119fed 100644
--- a/packages/kit/src/core/env.js
+++ b/packages/kit/src/core/env.js
@@ -116,9 +116,8 @@ export async function load_explicit_env(kit, file, root, mode) {
  * @param {Record<string, EnvVarConfig<any> | undefined> | null} variables
  * @param {Record<string, string>} env
  * @param {string | null} entry
- * @param {boolean} is_dev
  */
-export function create_sveltekit_env(variables, env, entry, is_dev) {
+export function create_sveltekit_env(variables, env, entry) {
 	const imports = entry
 		? [
 				`import { variables } from ${JSON.stringify(entry)};`,
@@ -172,22 +171,31 @@ export function create_sveltekit_env(variables, env, entry, is_dev) {
 			}`
 	];
 
+	const module = blocks.join('\n\n');
+
+	return module;
+}
+
+/**
+ * @param {Record<string, EnvVarConfig<any> | undefined> | null} variables
+ * @param {Record<string, string>} env
+ */
+export function create_sveltekit_env_dev(variables, env) {
 	// In dev, initialise the env immediately. Tools like `vite-node` load modules
 	// through the Vite config but don't run the SvelteKit dev server, which is what
 	// normally calls `set_env`. Without this, dynamic env vars imported from
 	// `$app/env/public` and `$app/env/private` would be `undefined` in such contexts.
-	if (is_dev) {
-		/** @type {Record<string, string>} */
-		const dev_env = {};
-		for (const name of Object.keys(variables ?? {})) {
-			if (name in env) dev_env[name] = env[name];
-		}
-		blocks.push(`set_env(${devalue.uneval(dev_env)});`);
+	/** @type {Record<string, string>} */
+	const dev_env = {};
+	for (const name of Object.keys(variables ?? {})) {
+		if (name in env) dev_env[name] = env[name];
 	}
 
-	const module = blocks.join('\n\n');
-
-	return module;
+	return [
+		`import { set_env } from './config.js';`,
+		`set_env(${devalue.uneval(dev_env)});`,
+		`export * from './config.js';`
+	].join('\n\n');
 }
 
 /**
@@ -218,7 +226,7 @@ export function create_sveltekit_env_private(variables, env) {
 
 	handle_issues(issues);
 
-	return `import { dynamic_private_env as env } from '__sveltekit/env';\n\n${exports.join('')}`;
+	return `import { dynamic_private_env as env } from '../config.js';\n\n${exports.join('')}`;
 }
 
 /**
diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index fc7ca8cbdac0..e8d267fa0366 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -5,6 +5,7 @@ import * as sync from '../../../core/sync/sync.js';
 import { resolve_entry } from '../../../utils/filesystem.js';
 import {
 	create_sveltekit_env,
+	create_sveltekit_env_dev,
 	create_sveltekit_env_private,
 	create_sveltekit_env_public,
 	create_sveltekit_env_service_worker,
@@ -59,56 +60,50 @@ export function plugin_env_vars(config) {
 
 		deps = synced.deps;
 
+		const vars = synced.variables;
+		const dir = `${out_dir}/generated/env`;
+
 		write_if_changed(
-			`${out_dir}/generated/env/config.js`,
-			create_sveltekit_env(synced.variables, env, resolved_entry, !is_build)
+			`${dir}/config.js`,
+			create_sveltekit_env(vars, env, resolved_entry && path.relative(dir, resolved_entry))
 		);
 
+		write_if_changed(`${dir}/config-dev.js`, create_sveltekit_env_dev(vars, env));
+
 		write_if_changed(
-			`${out_dir}/generated/env/public/client.js`,
+			`${dir}/public/client.js`,
 			create_sveltekit_env_public(
-				synced.variables,
+				vars,
 				env,
-				`import { payload } from ${s(`${runtime_directory}/client/payload.js`)};\nconst env = payload.env;`
+				`import { payload } from ${s(path.relative(`${dir}/client`, `${runtime_directory}/client/payload.js`))};\nconst env = payload.env;`
 			)
 		);
 
 		write_if_changed(
-			`${out_dir}/generated/env/public/server.js`,
-			create_sveltekit_env_public(
-				synced.variables,
-				env,
-				`import { rendered_env as env } from '../config.js';`
-			)
+			`${dir}/public/server.js`,
+			create_sveltekit_env_public(vars, env, `import { rendered_env as env } from '../config.js';`)
 		);
 
 		write_if_changed(
-			`${out_dir}/generated/env/public/service-worker-prod.js`,
+			`${dir}/public/service-worker-prod.js`,
 			create_sveltekit_env_public(
-				synced.variables,
+				vars,
 				env,
 				`const env = globalThis.__sveltekit_${version_hash}.env;`
 			)
 		);
 
 		write_if_changed(
-			`${out_dir}/generated/env/public/service-worker-dev.js`,
-			create_sveltekit_env_public(
-				synced.variables,
-				env,
-				`const env = globalThis.__sveltekit_dev.env;`
-			)
+			`${dir}/public/service-worker-dev.js`,
+			create_sveltekit_env_public(vars, env, `const env = globalThis.__sveltekit_dev.env;`)
 		);
 
-		write_if_changed(
-			`${out_dir}/generated/env/private/server.js`,
-			create_sveltekit_env_private(synced.variables, env)
-		);
+		write_if_changed(`${dir}/private/server.js`, create_sveltekit_env_private(vars, env));
 
 		write_if_changed(
-			`${out_dir}/generated/env/service-worker-prod.js`,
+			`${dir}/service-worker-prod.js`,
 			create_sveltekit_env_service_worker(
-				synced.variables,
+				vars,
 				env,
 				config.version.name,
 				`globalThis.__sveltekit_${version_hash}`,
@@ -118,9 +113,9 @@ export function plugin_env_vars(config) {
 		);
 
 		write_if_changed(
-			`${out_dir}/generated/env/service-worker-dev.js`,
+			`${dir}/service-worker-dev.js`,
 			create_sveltekit_env_service_worker_dev(
-				synced.variables,
+				vars,
 				env,
 				config.version.name,
 				'globalThis.__sveltekit_dev'
@@ -157,28 +152,28 @@ export function plugin_env_vars(config) {
 				id: prefixRegex('__sveltekit/env')
 			},
 			handler(id) {
+				const dir = `${out_dir}/generated/env`;
+
 				if (id === '__sveltekit/env') {
-					return `${out_dir}/generated/env/config.js`;
+					return is_build ? `${dir}/config.js` : `${dir}/config-dev.js`;
 				}
 
 				if (id === '__sveltekit/env/private') {
-					return `${out_dir}/generated/env/private/server.js`;
+					return `${dir}/private/server.js`;
 				}
 
 				if (id === '__sveltekit/env/public/server') {
-					return `${out_dir}/generated/env/public/server.js`;
+					return `${dir}/public/server.js`;
 				}
 
 				if (id === '__sveltekit/env/public/client') {
 					return this.environment.name === 'serviceWorker'
-						? `${out_dir}/generated/env/public/service-worker-prod.js`
-						: `${out_dir}/generated/env/public/client.js`;
+						? `${dir}/public/service-worker-prod.js`
+						: `${dir}/public/client.js`;
 				}
 
 				if (id === '__sveltekit/env/service-worker') {
-					return is_build
-						? `${out_dir}/generated/env/service-worker-prod.js`
-						: `${out_dir}/generated/env/service-worker-dev.js`;
+					return is_build ? `${dir}/service-worker-prod.js` : `${dir}/service-worker-dev.js`;
 				}
 			}
 		}

From 2ff33094792784eefc6b401ba8747391ac7993de Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 15:27:02 -0400
Subject: [PATCH 06/27] tweak

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index e8d267fa0366..95acbf1a440f 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -45,11 +45,11 @@ export function plugin_env_vars(config) {
 	/** @type {string | null} */
 	let resolved_entry = null;
 
-	let is_build = false;
-
 	/** @type {Set<string>} */
 	let deps;
 
+	let is_build = false;
+
 	async function generate() {
 		const synced = await sync.env(
 			config,

From 3db6f87e7c15d8713448735a18ecdadc20334d12 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 15:27:49 -0400
Subject: [PATCH 07/27] remove

---
 playgrounds/basic/src/env.ts | 11 -----------
 1 file changed, 11 deletions(-)
 delete mode 100644 playgrounds/basic/src/env.ts

diff --git a/playgrounds/basic/src/env.ts b/playgrounds/basic/src/env.ts
deleted file mode 100644
index 33dc10c2ddfa..000000000000
--- a/playgrounds/basic/src/env.ts
+++ /dev/null
@@ -1,11 +0,0 @@
-import { defineEnvVars } from '@sveltejs/kit/env';
-
-export const variables = defineEnvVars({
-	MESSAGE: {
-		public: true
-	},
-	SECRET: {},
-	STATIC: {
-		static: true
-	}
-});

From 22768541234b48f85eb5fcbfd4daef1409c41db3 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 15:52:27 -0400
Subject: [PATCH 08/27] fix

---
 packages/kit/src/exports/vite/index.js        | 24 +++++--------------
 packages/kit/src/exports/vite/module_ids.js   |  1 -
 .../kit/src/exports/vite/plugins/env-vars.js  |  6 ++++-
 3 files changed, 11 insertions(+), 20 deletions(-)

diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index cdd35e9c8cec..7fc15c7f8ba7 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -55,12 +55,7 @@ import {
 	is_page_route
 } from '../../core/sync/create_manifest_data/index.js';
 import { get_import_aliases, get_hash_import_keys } from '../../utils/imports.js';
-import {
-	app_env_private,
-	app_server,
-	sveltekit_manifest_data,
-	sveltekit_env_public_client
-} from './module_ids.js';
+import { app_env_private, app_server, sveltekit_manifest_data } from './module_ids.js';
 import { import_peer } from '../../utils/import.js';
 import { compact } from '../../utils/array.js';
 import { should_ignore, has_children } from './static_analysis/utils.js';
@@ -642,9 +637,6 @@ function kit({ svelte_config }) {
 		}
 	};
 
-	/** @type {string | null} */
-	let explicit_env_entry = null;
-
 	/** @type {Record<string, EnvVarConfig<any>> | null} */
 	let explicit_env_config = null;
 
@@ -1772,8 +1764,8 @@ function kit({ svelte_config }) {
 					const uses_env_dynamic_public =
 						has_explicit_dynamic_public_env &&
 						client_chunks.some(
-							// TODO need to update this
-							(chunk) => chunk.type === 'chunk' && chunk.modules[sveltekit_env_public_client]
+							(chunk) =>
+								chunk.type === 'chunk' && chunk.modules[`${out_dir}/generated/env/public/client.js`]
 						);
 
 					if (kit.output.bundleStrategy === 'split') {
@@ -2057,12 +2049,6 @@ function kit({ svelte_config }) {
 
 				fs.mkdirSync(out, { recursive: true });
 
-				explicit_env_entry = resolve_explicit_env_entry(kit);
-
-				const synced = await sync.env(kit, explicit_env_entry, vite_config.root, vite_config.mode);
-
-				explicit_env_config = synced.variables;
-
 				await load_and_validate_params({
 					routes: manifest_data.routes,
 					params_path: manifest_data.params,
@@ -2125,7 +2111,9 @@ function kit({ svelte_config }) {
 			plugin_setup,
 			plugin_remote_guard,
 			plugin_remote,
-			plugin_env_vars(svelte_config),
+			plugin_env_vars(svelte_config, (vars) => {
+				explicit_env_config = vars;
+			}),
 			plugin_virtual_modules,
 			process.env.TEST !== 'true' ? plugin_guard : undefined,
 			plugin_service_worker,
diff --git a/packages/kit/src/exports/vite/module_ids.js b/packages/kit/src/exports/vite/module_ids.js
index 8810be4deaaf..a1a07875e4c9 100644
--- a/packages/kit/src/exports/vite/module_ids.js
+++ b/packages/kit/src/exports/vite/module_ids.js
@@ -1,7 +1,6 @@
 import { fileURLToPath } from 'node:url';
 import { posixify } from '../../utils/os.js';
 
-export const sveltekit_env_public_client = '\0virtual:__sveltekit/env/public/client';
 export const sveltekit_server = '\0virtual:__sveltekit/server';
 export const service_worker = '\0virtual:service-worker';
 
diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 95acbf1a440f..75a038c99494 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -1,4 +1,5 @@
 /** @import { Plugin, ResolvedConfig } from 'vite' */
+/** @import { EnvVarConfig } from '@sveltejs/kit/env' */
 /** @import { ValidatedConfig } from 'types' */
 import path from 'node:path';
 import * as sync from '../../../core/sync/sync.js';
@@ -23,9 +24,10 @@ import { prefixRegex } from '@rolldown/pluginutils';
  * derived from `src/env.ts`
  *
  * @param {ValidatedConfig} config
+ * @param {(variables: Record<string, EnvVarConfig<any>> | null) => void} callback
  * @returns {Plugin}
  */
-export function plugin_env_vars(config) {
+export function plugin_env_vars(config, callback) {
 	// grab these values eagerly because they get mutated (TODO stop mutating them)
 	const entry = path.join(config.files.src, 'env');
 	const dir = config.env.dir;
@@ -121,6 +123,8 @@ export function plugin_env_vars(config) {
 				'globalThis.__sveltekit_dev'
 			)
 		);
+
+		callback(vars);
 	}
 
 	return {

From 24156fe6fce3a1483fb53dbad1eba14cd2e5f232 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 16:03:48 -0400
Subject: [PATCH 09/27] tweak

---
 packages/kit/src/cli.js                |  7 ++++---
 packages/kit/src/core/env.js           | 14 +-------------
 packages/kit/src/exports/vite/index.js |  2 +-
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/packages/kit/src/cli.js b/packages/kit/src/cli.js
index 6a588403aaaf..e256d09db43b 100755
--- a/packages/kit/src/cli.js
+++ b/packages/kit/src/cli.js
@@ -1,10 +1,11 @@
 import fs from 'node:fs';
+import path from 'node:path';
 import process from 'node:process';
 import { parseArgs, styleText } from 'node:util';
 import { extract_svelte_config, load_vite_config } from './core/config/index.js';
-import { resolve_explicit_env_entry } from './core/env.js';
 import { coalesce_to_error } from './utils/error.js';
 import { import_peer } from './utils/import.js';
+import { resolve_entry } from './utils/filesystem.js';
 
 /** @param {unknown} e */
 function handle_error(e) {
@@ -105,8 +106,8 @@ if (command === 'sync') {
 		const sync = await import('./core/sync/sync.js');
 		sync.all_types(sveltekit_config, vite_config.root);
 
-		const explicit_env_entry = resolve_explicit_env_entry(sveltekit_config);
-		await sync.env(sveltekit_config, explicit_env_entry, vite_config.root, values.mode);
+		const entry = resolve_entry(path.join(sveltekit_config.files.src, 'env'));
+		await sync.env(sveltekit_config, entry, vite_config.root, values.mode);
 	} catch (error) {
 		handle_error(error);
 	} finally {
diff --git a/packages/kit/src/core/env.js b/packages/kit/src/core/env.js
index c6725e119fed..2fdfad908c10 100644
--- a/packages/kit/src/core/env.js
+++ b/packages/kit/src/core/env.js
@@ -1,12 +1,10 @@
 /** @import { StandardSchemaV1 } from '@standard-schema/spec' */
 /** @import { EnvVarConfig } from '@sveltejs/kit/env' */
 /** @import { ValidatedConfig } from 'types' */
-import path from 'node:path';
 import * as devalue from 'devalue';
 import { GENERATED_COMMENT } from '../constants.js';
 import { dedent } from './sync/utils.js';
 import { runtime_directory } from './utils.js';
-import { resolve_entry } from '../utils/filesystem.js';
 import { handle_issues, validate } from '../exports/internal/env.js';
 import { get_config_aliases } from '../exports/vite/utils.js';
 import { get_runner } from '../runner.js';
@@ -16,14 +14,6 @@ import { import_peer } from '../utils/import.js';
  * @typedef {'public' | 'private'} EnvType
  */
 
-/**
- * @param {ValidatedConfig} config
- * @returns {string | null}
- */
-export function resolve_explicit_env_entry(config) {
-	return resolve_entry(path.join(config.files.src, 'env')) ?? null;
-}
-
 /**
  * @param {ValidatedConfig} kit
  * @param {string | null} file
@@ -171,9 +161,7 @@ export function create_sveltekit_env(variables, env, entry) {
 			}`
 	];
 
-	const module = blocks.join('\n\n');
-
-	return module;
+	return blocks.join('\n\n');
 }
 
 /**
diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index 7fc15c7f8ba7..3d3312427412 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -23,7 +23,7 @@ import MagicString from 'magic-string';
 import { copy, read, resolve_entry } from '../../utils/filesystem.js';
 import { posixify } from '../../utils/os.js';
 import { to_fs } from '../../utils/vite.js';
-import { resolve_explicit_env_entry, create_exported_declarations } from '../../core/env.js';
+import { create_exported_declarations } from '../../core/env.js';
 import * as sync from '../../core/sync/sync.js';
 import { load_and_validate_params } from '../../utils/params.js';
 import { runtime_directory, logger } from '../../core/utils.js';

From 857c04acd5f467c8430a9e21945a46c9c4e4d8fb Mon Sep 17 00:00:00 2001
From: "vercel[bot]" <35613825+vercel[bot]@users.noreply.github.com>
Date: Fri, 14 Aug 2026 20:12:58 +0000
Subject: [PATCH 10/27] Fix: On Windows, the `env-vars` plugin builds module
 ids from a non-posixified `out_dir` (backslashes), so index.js's posix-keyed
 `chunk.modules` lookup for the dynamic public env module never matches,
 forcing `uses_env_dynamic_public` to always be false.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This commit fixes the issue reported at packages/kit/src/exports/vite/plugins/env-vars.js:139

## Bug

`packages/kit/src/exports/vite/plugins/env-vars.js` computed:

```js
out_dir = path.resolve(c.root, out); // native separators
```

and its `resolveId` handler returns module ids derived from that value, e.g.:

```js
const dir = `
```

On **Windows**, `path.resolve` produces backslash-separated paths (`C:\proj.svelte-kit`), so the base of the returned module id contains backslashes: `C:\proj.svelte-kit/generated/env/public/client.js`. Rollup/rolldown store the module id exactly as returned by `resolveId`, so `chunk.modules` is keyed with that mixed-separator string.

Meanwhile `packages/kit/src/exports/vite/index.js` (~line 1768) looks the module up using a fully posix key:

```js
out_dir = posixify(kit.outDir); // line 386, forward slashes
// ...
const uses_env_dynamic_public =
  has_explicit_dynamic_public_env &&
  client_chunks.some(
    (chunk) =>
      chunk.type === 'chunk' &&
      chunk.modules[`
```

Because the two keys differ in the base separators on Windows (`` vs `/`), the lookup never matches. **Trigger:** a Windows build with `bundleStrategy: 'split'` and a project that imports `$app/env/public` / uses a dynamic (non-static) public env var. `uses_env_dynamic_public` is forced to `false`, so the code that arranges correct preloading/loading of dynamic public env for the split bundle is skipped, breaking runtime public env vars on Windows.

The rest of the codebase consistently uses `posixify(kit.outDir)` for `out_dir` precisely so module ids match — this plugin was the sole divergence.

## Fix

Posixify `out_dir` in the plugin so the generated module ids use forward slashes and match index.js's lookup key:

```js
import { posixify } from '../../../utils/os.js';
// ...
out_dir = posixify(path.resolve(c.root, out));
```

`posixify` (from `packages/kit/src/utils/os.js`) simply replaces `\` with `/`, which is a no-op on POSIX systems and corrects the separators on Windows, restoring the key match.


Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>
Co-authored-by: Rich-Harris <hello@rich-harris.dev>
---
 packages/kit/src/exports/vite/plugins/env-vars.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 75a038c99494..251b3d64dd16 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -17,6 +17,7 @@ import { runtime_directory } from '../../../core/utils.js';
 import { s } from '../../../utils/misc.js';
 import { write_if_changed } from '../../../core/sync/utils.js';
 import { hash } from '../../../utils/hash.js';
+import { posixify } from '../../../utils/os.js';
 import { prefixRegex } from '@rolldown/pluginutils';
 
 /**
@@ -136,7 +137,7 @@ export function plugin_env_vars(config, callback) {
 			const vite = await import_peer('vite', c.root);
 			env = vite.loadEnv(c.mode, path.resolve(c.root, dir), '');
 
-			out_dir = path.resolve(c.root, out);
+			out_dir = posixify(path.resolve(c.root, out));
 
 			is_build = c.command === 'build';
 		},

From fd1e17f354b224ac828f81daad60f1379e463b84 Mon Sep 17 00:00:00 2001
From: "vercel[bot]" <35613825+vercel[bot]@users.noreply.github.com>
Date: Fri, 14 Aug 2026 20:13:03 +0000
Subject: [PATCH 11/27] Fix: Creating or deleting `src/env.(js|ts)` while the
 dev server is running is no longer handled: new env files are ignored until
 restart, and deleting an existing env file throws because `resolved_entry` is
 never re-resolved.
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

This commit fixes the issue reported at packages/kit/src/exports/vite/plugins/env-vars.js:149

## Bug

The `plugin_env_vars` plugin in `packages/kit/src/exports/vite/plugins/env-vars.js` computes `resolved_entry` only once, in `buildStart`, and only regenerates env modules via `handleHotUpdate` when the changed file is already in `deps`:

```js
async buildStart() {
  resolved_entry = resolve_entry(path.join(resolved_config.root, entry)) ?? null;
  await generate();
},
async handleHotUpdate(update) {
  if (!deps.has(update.file)) return;
  await generate();
},
```

This replaced a watcher previously in `plugin_virtual_modules.configureServer` (in `index.js`) that listened to `server.watcher.on('all', ...)`, re-resolved the entry via `resolve_explicit_env_entry`, regenerated, and triggered a full reload on any add/remove/change of the env entry. (`resolve_explicit_env_entry` is now only imported in `index.js`, never called.)

Vite's `handleHotUpdate` only fires for `change` events on files it already tracks — it is **not** called for file `add`/`unlink`. That produces two concrete dev regressions:

1.  **Creating `src/env.ts` after start**: If it didn't exist at startup, `resolved_entry` is `null` and `deps` is empty (`load_explicit_env` returns an empty dep set when `file` is null). The `add` event doesn't reach `handleHotUpdate`, and even if it did the file isn't in `deps`, so the new env vars are never generated until a manual restart.

2.  **Deleting an existing `src/env.ts`**: The entry file is in `deps` (the dependency-scanner `load` hook records it). On delete, `handleHotUpdate` fires with the deleted file in `deps`, calling `generate()` → `sync.env(config, resolved_entry, ...)` with the stale, now-nonexistent `resolved_entry`, so `load_explicit_env` does `runner.import(file)` on a missing module and throws (`ERR_MODULE_NOT_FOUND`). `resolved_entry` is never reset to `null`.


The dev watcher in `dev/index.js` handles app/error templates, service worker and hooks, but not `src/env`, so it doesn't compensate.

## Fix

Added a `configureServer` hook to the env-vars plugin that listens for `add`/`unlink` events, re-resolves the entry, updates `resolved_entry`, regenerates the modules, and sends a `full-reload` — mirroring the removed watcher. `change` events remain handled by `handleHotUpdate` (for the entry and its transitive deps), so there is no double processing.

```js
configureServer(server) {
  const on_entry_add_unlink = async (file) => {
    const resolved = resolve_entry(path.join(resolved_config.root, entry)) ?? null;
    if (file === resolved_entry || file === resolved) {
      resolved_entry = resolved;
      await generate();
      server.hot.send({ type: 'full-reload' });
    }
  };
  server.watcher.on('add', on_entry_add_unlink);
  server.watcher.on('unlink', on_entry_add_unlink);
},
```

This restores dev handling for both creating (case 1) and deleting (case 2, `resolved` becomes `null` so `generate()` runs with a null entry and produces empty env modules instead of throwing) the env entry. The `server.watcher`/`server.hot` usage matches existing patterns in `dev/index.js`.


Co-authored-by: Vercel <vercel[bot]@users.noreply.github.com>
Co-authored-by: Rich-Harris <hello@rich-harris.dev>
---
 .../kit/src/exports/vite/plugins/env-vars.js  | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 251b3d64dd16..c17273c3341f 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -147,6 +147,25 @@ export function plugin_env_vars(config, callback) {
 			await generate();
 		},
 
+		configureServer(server) {
+			// `handleHotUpdate` only fires for `change` events on files Vite already knows about,
+			// so it doesn't cover the env entry being created or deleted while the dev server is
+			// running. Watch for those events explicitly, re-resolve the entry, regenerate the
+			// modules and trigger a full reload (mirroring the previous behaviour).
+			const on_entry_add_unlink = async (/** @type {string} */ file) => {
+				const resolved = resolve_entry(path.join(resolved_config.root, entry)) ?? null;
+
+				if (file === resolved_entry || file === resolved) {
+					resolved_entry = resolved;
+					await generate();
+					server.hot.send({ type: 'full-reload' });
+				}
+			};
+
+			server.watcher.on('add', on_entry_add_unlink);
+			server.watcher.on('unlink', on_entry_add_unlink);
+		},
+
 		async handleHotUpdate(update) {
 			if (!deps.has(update.file)) return;
 			await generate();

From 47a9eeb3216011066c171cafe697ed8117f005c3 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 16:42:52 -0400
Subject: [PATCH 12/27] use alias to differentiate between config.js and
 config-dev.js

---
 packages/kit/src/core/env.js                      | 2 +-
 packages/kit/src/exports/vite/plugins/env-vars.js | 6 +++++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/packages/kit/src/core/env.js b/packages/kit/src/core/env.js
index 2fdfad908c10..a370252663f2 100644
--- a/packages/kit/src/core/env.js
+++ b/packages/kit/src/core/env.js
@@ -214,7 +214,7 @@ export function create_sveltekit_env_private(variables, env) {
 
 	handle_issues(issues);
 
-	return `import { dynamic_private_env as env } from '../config.js';\n\n${exports.join('')}`;
+	return `import { dynamic_private_env as env } from '__sveltekit/env';\n\n${exports.join('')}`;
 }
 
 /**
diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index c17273c3341f..295517f83f89 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -84,7 +84,11 @@ export function plugin_env_vars(config, callback) {
 
 		write_if_changed(
 			`${dir}/public/server.js`,
-			create_sveltekit_env_public(vars, env, `import { rendered_env as env } from '../config.js';`)
+			create_sveltekit_env_public(
+				vars,
+				env,
+				`import { rendered_env as env } from '__sveltekit/env';`
+			)
 		);
 
 		write_if_changed(

From e26f614840c4c8fdbfbab8036dd45b6908f5784d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 16:43:52 -0400
Subject: [PATCH 13/27] guard against race condition

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 295517f83f89..6ecf2c4fe9a4 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -49,7 +49,7 @@ export function plugin_env_vars(config, callback) {
 	let resolved_entry = null;
 
 	/** @type {Set<string>} */
-	let deps;
+	let deps = new Set();
 
 	let is_build = false;
 

From 598c3e3b837b980f18a476fb8e2222fcbf69efaf Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 16:47:35 -0400
Subject: [PATCH 14/27] reinstate shared helper

---
 packages/kit/src/cli.js                           |  5 ++---
 packages/kit/src/core/env.js                      | 11 +++++++++++
 packages/kit/src/exports/vite/plugins/env-vars.js |  7 ++++---
 3 files changed, 17 insertions(+), 6 deletions(-)

diff --git a/packages/kit/src/cli.js b/packages/kit/src/cli.js
index e256d09db43b..d3eae6b4fd01 100755
--- a/packages/kit/src/cli.js
+++ b/packages/kit/src/cli.js
@@ -1,11 +1,10 @@
 import fs from 'node:fs';
-import path from 'node:path';
 import process from 'node:process';
 import { parseArgs, styleText } from 'node:util';
 import { extract_svelte_config, load_vite_config } from './core/config/index.js';
 import { coalesce_to_error } from './utils/error.js';
 import { import_peer } from './utils/import.js';
-import { resolve_entry } from './utils/filesystem.js';
+import { resolve_env_entry } from './core/env.js';
 
 /** @param {unknown} e */
 function handle_error(e) {
@@ -106,7 +105,7 @@ if (command === 'sync') {
 		const sync = await import('./core/sync/sync.js');
 		sync.all_types(sveltekit_config, vite_config.root);
 
-		const entry = resolve_entry(path.join(sveltekit_config.files.src, 'env'));
+		const entry = resolve_env_entry(sveltekit_config, vite_config.root);
 		await sync.env(sveltekit_config, entry, vite_config.root, values.mode);
 	} catch (error) {
 		handle_error(error);
diff --git a/packages/kit/src/core/env.js b/packages/kit/src/core/env.js
index a370252663f2..f97a08b768cf 100644
--- a/packages/kit/src/core/env.js
+++ b/packages/kit/src/core/env.js
@@ -1,10 +1,12 @@
 /** @import { StandardSchemaV1 } from '@standard-schema/spec' */
 /** @import { EnvVarConfig } from '@sveltejs/kit/env' */
 /** @import { ValidatedConfig } from 'types' */
+import path from 'node:path';
 import * as devalue from 'devalue';
 import { GENERATED_COMMENT } from '../constants.js';
 import { dedent } from './sync/utils.js';
 import { runtime_directory } from './utils.js';
+import { resolve_entry } from '../utils/filesystem.js';
 import { handle_issues, validate } from '../exports/internal/env.js';
 import { get_config_aliases } from '../exports/vite/utils.js';
 import { get_runner } from '../runner.js';
@@ -14,6 +16,15 @@ import { import_peer } from '../utils/import.js';
  * @typedef {'public' | 'private'} EnvType
  */
 
+/**
+ * @param {ValidatedConfig} config
+ * @param {string} root
+ * @returns {string | null}
+ */
+export function resolve_env_entry(config, root) {
+	return resolve_entry(path.resolve(root, config.files.src, 'env'));
+}
+
 /**
  * @param {ValidatedConfig} kit
  * @param {string | null} file
diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 6ecf2c4fe9a4..75e6c358b7cc 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -10,7 +10,8 @@ import {
 	create_sveltekit_env_private,
 	create_sveltekit_env_public,
 	create_sveltekit_env_service_worker,
-	create_sveltekit_env_service_worker_dev
+	create_sveltekit_env_service_worker_dev,
+	resolve_env_entry
 } from '../../../core/env.js';
 import { import_peer } from '../../../utils/import.js';
 import { runtime_directory } from '../../../core/utils.js';
@@ -147,7 +148,7 @@ export function plugin_env_vars(config, callback) {
 		},
 
 		async buildStart() {
-			resolved_entry = resolve_entry(path.join(resolved_config.root, entry)) ?? null;
+			resolved_entry = resolve_env_entry(config, resolved_config.root);
 			await generate();
 		},
 
@@ -157,7 +158,7 @@ export function plugin_env_vars(config, callback) {
 			// running. Watch for those events explicitly, re-resolve the entry, regenerate the
 			// modules and trigger a full reload (mirroring the previous behaviour).
 			const on_entry_add_unlink = async (/** @type {string} */ file) => {
-				const resolved = resolve_entry(path.join(resolved_config.root, entry)) ?? null;
+				const resolved = resolve_env_entry(config, resolved_config.root);
 
 				if (file === resolved_entry || file === resolved) {
 					resolved_entry = resolved;

From a44eb36f0d5ebb7ec82fe36c8b68b920f84ca6cd Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 17:05:29 -0400
Subject: [PATCH 15/27] only run buildStart logic once

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 75e6c358b7cc..2fe2d971d933 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -148,6 +148,9 @@ export function plugin_env_vars(config, callback) {
 		},
 
 		async buildStart() {
+			// we only need to run this once
+			if (this.environment.name !== 'ssr') return;
+
 			resolved_entry = resolve_env_entry(config, resolved_config.root);
 			await generate();
 		},

From ff2b53783ff3686699a5153fc8abcfbe2ef96f1d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 17:14:45 -0400
Subject: [PATCH 16/27] use configResolved

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 2fe2d971d933..bf7d34b3b8fd 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -145,13 +145,8 @@ export function plugin_env_vars(config, callback) {
 			out_dir = posixify(path.resolve(c.root, out));
 
 			is_build = c.command === 'build';
-		},
-
-		async buildStart() {
-			// we only need to run this once
-			if (this.environment.name !== 'ssr') return;
 
-			resolved_entry = resolve_env_entry(config, resolved_config.root);
+			resolved_entry = resolve_env_entry(config, c.root);
 			await generate();
 		},
 

From e15b257ecf24a6cfbf7c68a3621e4cb8266ce0ac Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Fri, 14 Aug 2026 17:15:32 -0400
Subject: [PATCH 17/27] Update packages/kit/src/exports/vite/utils.js

Co-authored-by: Nic Polumeyv <nicolas.polum@outlook.com>
---
 packages/kit/src/exports/vite/utils.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/kit/src/exports/vite/utils.js b/packages/kit/src/exports/vite/utils.js
index 06cdc8b18bea..81a6960a2676 100644
--- a/packages/kit/src/exports/vite/utils.js
+++ b/packages/kit/src/exports/vite/utils.js
@@ -119,8 +119,7 @@ export function normalize_id(id, aliases, cwd) {
 		return '$app/server';
 	}
 
-	// TODO is this right?
-	if (id === app_env_private || id === '__sveltekit/env/private') {
+	if (id === app_env_private) {
 		return '$app/env/private';
 	}
 

From f8133a373f518e4f5379f09711f98de2962622ca Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Fri, 14 Aug 2026 17:17:05 -0400
Subject: [PATCH 18/27] Update
 packages/kit/src/exports/vite/plugins/env-vars.js

Co-authored-by: Nic Polumeyv <nicolas.polum@outlook.com>
---
 packages/kit/src/exports/vite/plugins/env-vars.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 2fe2d971d933..f63334d2d940 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -69,7 +69,7 @@ export function plugin_env_vars(config, callback) {
 
 		write_if_changed(
 			`${dir}/config.js`,
-			create_sveltekit_env(vars, env, resolved_entry && path.relative(dir, resolved_entry))
+			create_sveltekit_env(vars, env, resolved_entry && posixify(path.relative(dir, resolved_entry)))
 		);
 
 		write_if_changed(`${dir}/config-dev.js`, create_sveltekit_env_dev(vars, env));

From 4e2609122465b73c536d8bfdcb3204d7d88a9848 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 17:17:35 -0400
Subject: [PATCH 19/27] posixify

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 748fadbc5198..d5ed8cab7d79 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -79,7 +79,7 @@ export function plugin_env_vars(config, callback) {
 			create_sveltekit_env_public(
 				vars,
 				env,
-				`import { payload } from ${s(path.relative(`${dir}/client`, `${runtime_directory}/client/payload.js`))};\nconst env = payload.env;`
+				`import { payload } from ${s(posixify(path.relative(`${dir}/public`, `${runtime_directory}/client/payload.js`)))};\nconst env = payload.env;`
 			)
 		);
 

From 7949863522a7f11194d0ee34c1dbcc1ed9f9e9cd Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Fri, 14 Aug 2026 17:18:13 -0400
Subject: [PATCH 20/27] Update
 packages/kit/src/exports/vite/plugins/env-vars.js

Co-authored-by: Nic Polumeyv <nicolas.polum@outlook.com>
---
 packages/kit/src/exports/vite/plugins/env-vars.js | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index f63334d2d940..b8292deee41f 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -101,11 +101,6 @@ export function plugin_env_vars(config, callback) {
 			)
 		);
 
-		write_if_changed(
-			`${dir}/public/service-worker-dev.js`,
-			create_sveltekit_env_public(vars, env, `const env = globalThis.__sveltekit_dev.env;`)
-		);
-
 		write_if_changed(`${dir}/private/server.js`, create_sveltekit_env_private(vars, env));
 
 		write_if_changed(

From 58eb6b5583cb4772234ac10cb2af298f4245341f Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 17:18:58 -0400
Subject: [PATCH 21/27] rename file, since no dev version exists

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index c8c6e3fd0c71..2f91086d3db0 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -69,7 +69,11 @@ export function plugin_env_vars(config, callback) {
 
 		write_if_changed(
 			`${dir}/config.js`,
-			create_sveltekit_env(vars, env, resolved_entry && posixify(path.relative(dir, resolved_entry)))
+			create_sveltekit_env(
+				vars,
+				env,
+				resolved_entry && posixify(path.relative(dir, resolved_entry))
+			)
 		);
 
 		write_if_changed(`${dir}/config-dev.js`, create_sveltekit_env_dev(vars, env));
@@ -93,7 +97,7 @@ export function plugin_env_vars(config, callback) {
 		);
 
 		write_if_changed(
-			`${dir}/public/service-worker-prod.js`,
+			`${dir}/public/service-worker.js`,
 			create_sveltekit_env_public(
 				vars,
 				env,
@@ -190,7 +194,7 @@ export function plugin_env_vars(config, callback) {
 
 				if (id === '__sveltekit/env/public/client') {
 					return this.environment.name === 'serviceWorker'
-						? `${dir}/public/service-worker-prod.js`
+						? `${dir}/public/service-worker.js`
 						: `${dir}/public/client.js`;
 				}
 

From db6b5349896ad4131d0febfcc3493385c115c585 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 17:19:48 -0400
Subject: [PATCH 22/27] unused

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index 2f91086d3db0..d0ed8d9b6649 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -31,7 +31,6 @@ import { prefixRegex } from '@rolldown/pluginutils';
  */
 export function plugin_env_vars(config, callback) {
 	// grab these values eagerly because they get mutated (TODO stop mutating them)
-	const entry = path.join(config.files.src, 'env');
 	const dir = config.env.dir;
 	const out = config.outDir;
 

From 5a9a991b67ebf30cf528ab863ca0b7b88ab3bc24 Mon Sep 17 00:00:00 2001
From: Rich Harris <richard.a.harris@gmail.com>
Date: Fri, 14 Aug 2026 17:22:26 -0400
Subject: [PATCH 23/27] Update packages/kit/src/exports/vite/index.js

Co-authored-by: Nic Polumeyv <nicolas.polum@outlook.com>
---
 packages/kit/src/exports/vite/index.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/kit/src/exports/vite/index.js b/packages/kit/src/exports/vite/index.js
index 3d3312427412..47a067e51548 100644
--- a/packages/kit/src/exports/vite/index.js
+++ b/packages/kit/src/exports/vite/index.js
@@ -1103,10 +1103,9 @@ function kit({ svelte_config }) {
 
 		resolveId: {
 			filter: {
-				id: prefixRegex('__sveltekit/')
+				id: exactRegex('__sveltekit/manifest-data')
 			},
 			handler(id) {
-				// TODO do we still need this?
 				return `\0virtual:${id}`;
 			}
 		},

From b79d0ec3636915a2612d9532efa96927729aca51 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 17:29:51 -0400
Subject: [PATCH 24/27] unused

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 1 -
 1 file changed, 1 deletion(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index d0ed8d9b6649..c771f438ecdf 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -3,7 +3,6 @@
 /** @import { ValidatedConfig } from 'types' */
 import path from 'node:path';
 import * as sync from '../../../core/sync/sync.js';
-import { resolve_entry } from '../../../utils/filesystem.js';
 import {
 	create_sveltekit_env,
 	create_sveltekit_env_dev,

From 4ab53e900e13a6f11f5fc4497f4f428b96453c87 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Fri, 14 Aug 2026 17:32:32 -0400
Subject: [PATCH 25/27] remove comment

---
 packages/kit/src/core/env.js | 2 --
 1 file changed, 2 deletions(-)

diff --git a/packages/kit/src/core/env.js b/packages/kit/src/core/env.js
index f97a08b768cf..c70f50502bb7 100644
--- a/packages/kit/src/core/env.js
+++ b/packages/kit/src/core/env.js
@@ -3,7 +3,6 @@
 /** @import { ValidatedConfig } from 'types' */
 import path from 'node:path';
 import * as devalue from 'devalue';
-import { GENERATED_COMMENT } from '../constants.js';
 import { dedent } from './sync/utils.js';
 import { runtime_directory } from './utils.js';
 import { resolve_entry } from '../utils/filesystem.js';
@@ -155,7 +154,6 @@ export function create_sveltekit_env(variables, env, entry) {
 	handle_issues(issues);
 
 	const blocks = [
-		GENERATED_COMMENT,
 		imports.join('\n'),
 		`const issues = {};`,
 		'export { variables }',

From 2f8f6f1f5fe3f93118f08dcbe10f7239ff1e35d0 Mon Sep 17 00:00:00 2001
From: Nic Polumeyv <162764842+Nic-Polumeyv@users.noreply.github.com>
Date: Fri, 14 Aug 2026 17:48:58 -0400
Subject: [PATCH 26/27] =?UTF-8?q?generate=20in=20buildStart,=20not=20confi?=
 =?UTF-8?q?gResolved=20=E2=80=94=20postbuild=20forks=20resolve=20the=20con?=
 =?UTF-8?q?fig=20with=20the=20wrong=20mode?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 packages/kit/src/exports/vite/plugins/env-vars.js | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index c771f438ecdf..bebae4a59cb0 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -142,8 +142,14 @@ export function plugin_env_vars(config, callback) {
 			out_dir = posixify(path.resolve(c.root, out));
 
 			is_build = c.command === 'build';
+		},
+
+		async buildStart() {
+			// we only need to run this once, and not in postbuild forks that
+			// resolve the config without building (analyse/prerender)
+			if (this.environment.name !== 'ssr') return;
 
-			resolved_entry = resolve_env_entry(config, c.root);
+			resolved_entry = resolve_env_entry(config, resolved_config.root);
 			await generate();
 		},
 

From ea22879896bb09108bee6035c22288ce6b795c5a Mon Sep 17 00:00:00 2001
From: Nic Polumeyv <162764842+Nic-Polumeyv@users.noreply.github.com>
Date: Fri, 14 Aug 2026 17:54:41 -0400
Subject: [PATCH 27/27] =?UTF-8?q?gate=20generate=20on=20a=20memo,=20not=20?=
 =?UTF-8?q?the=20environment=20name=20=E2=80=94=20adapter=20environments?=
 =?UTF-8?q?=20aren't=20always=20called=20'ssr'?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../kit/src/exports/vite/plugins/env-vars.js     | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/packages/kit/src/exports/vite/plugins/env-vars.js b/packages/kit/src/exports/vite/plugins/env-vars.js
index bebae4a59cb0..45bbd6cfcb77 100644
--- a/packages/kit/src/exports/vite/plugins/env-vars.js
+++ b/packages/kit/src/exports/vite/plugins/env-vars.js
@@ -52,6 +52,9 @@ export function plugin_env_vars(config, callback) {
 
 	let is_build = false;
 
+	/** @type {Promise<void> | undefined} */
+	let generated;
+
 	async function generate() {
 		const synced = await sync.env(
 			config,
@@ -145,12 +148,13 @@ export function plugin_env_vars(config, callback) {
 		},
 
 		async buildStart() {
-			// we only need to run this once, and not in postbuild forks that
-			// resolve the config without building (analyse/prerender)
-			if (this.environment.name !== 'ssr') return;
-
-			resolved_entry = resolve_env_entry(config, resolved_config.root);
-			await generate();
+			// runs once via the memo — per-process, whichever environment starts first
+			// (environment names vary by adapter), and never in the postbuild forks,
+			// which resolve the config without building
+			await (generated ??= (async () => {
+				resolved_entry = resolve_env_entry(config, resolved_config.root);
+				await generate();
+			})());
 		},
 
 		configureServer(server) {