stronger dynamic env types

.changeset/cold-cherries-watch.md

@@ -0,0 +1,5 @@
+---
+"@sveltejs/kit": patch
+---
+
+create stronger types for dynamically generated env modules

packages/kit/src/core/env.js

@@ -1,6 +1,15 @@
 import { GENERATED_COMMENT } from '../constants.js';
 import { runtime_base } from './utils.js';
 
+/**
+ * @typedef {'public' | 'private'} EnvType
+ * @typedef {{
+ * 	public: Record<string, string>;
+ * 	private: Record<string, string>;
+ * 	prefix: string;
+ * }} EnvData
+ */
+
 /**
  * @param {string} id
  * @param {Record<string, string>} env
@@ -25,46 +34,54 @@ export function create_static_module(id, env) {
 }
 
 /**
- * @param {'public' | 'private'} type
+ * @param {EnvType} type
  * @param {Record<string, string> | undefined} dev_values If in a development mode, values to pre-populate the module with.
  */
 export function create_dynamic_module(type, dev_values) {
 	if (dev_values) {
-		const objectKeys = Object.entries(dev_values).map(
+		const keys = Object.entries(dev_values).map(
 			([k, v]) => `${JSON.stringify(k)}: ${JSON.stringify(v)}`
 		);
-		return `const env = {\n${objectKeys.join(',\n')}\n}\n\nexport { env }`;
+		return `export const env = {\n${keys.join(',\n')}\n}`;
 	}
 	return `export { env } from '${runtime_base}/env-${type}.js';`;
 }
 
 /**
- * @param {string} id
- * @param {Record<string, string>} env
+ * @param {EnvType} id
+ * @param {EnvData} env
  * @returns {string}
  */
 export function create_static_types(id, env) {
-	const declarations = Object.keys(env)
+	const declarations = Object.keys(env[id])
 		.filter((k) => valid_identifier.test(k))
 		.map((k) => `\texport const ${k}: string;`)
 		.join('\n');
 
-	return `declare module '${id}' {\n${declarations}\n}`;
+	return `declare module '$env/static/${id}' {\n${declarations}\n}`;
 }
 
 /**
- * @param {string} id
- * @param {Record<string, string>} env
+ * @param {EnvType} id
+ * @param {EnvData} env
  * @returns {string}
  */
 export function create_dynamic_types(id, env) {
-	const properties = Object.keys(env)
+	const properties = Object.keys(env[id])
 		.filter((k) => valid_identifier.test(k))
 		.map((k) => `\t\t${k}: string;`);
 
-	properties.push(`\t\t[key: string]: string | undefined;`);
+	const prefixed = `[key: \`${env.prefix}\${string}\`]`;
+
+	if (id === 'private') {
+		properties.push(`\t\t${prefixed}: undefined;`);
+		properties.push(`\t\t[key: string]: string | undefined;`);
+	} else {
+		properties.push(`\t\t${prefixed}: string | undefined;`);
+	}
 
-	return `declare module '${id}' {\n\texport const env: {\n${properties.join('\n')}\n\t}\n}`;
+	const declaration = `export const env: {\n${properties.join('\n')}\n\t}`;
+	return `declare module '$env/dynamic/${id}' {\n\t${declaration}\n}`;
 }
 
 export const reserved = new Set([

packages/kit/src/core/sync/write_ambient.js

@@ -19,24 +19,24 @@ function read_description(filename) {
 }
 
 /**
- * @param {{ public: Record<string, string>, private: Record<string, string> }} env
+ * @param {import('../env.js').EnvData} env
  */
 const template = (env) => `
 ${GENERATED_COMMENT}
 
 /// <reference types="@sveltejs/kit" />
 
 ${read_description('$env+static+private.md')}
-${create_static_types('$env/static/private', env.private)}
+${create_static_types('private', env)}
 
 ${read_description('$env+static+public.md')}
-${create_static_types('$env/static/public', env.public)}
+${create_static_types('public', env)}
 
 ${read_description('$env+dynamic+private.md')}
-${create_dynamic_types('$env/dynamic/private', env.private)}
+${create_dynamic_types('private', env)}
 
 ${read_description('$env+dynamic+public.md')}
-${create_dynamic_types('$env/dynamic/public', env.public)}
+${create_dynamic_types('public', env)}
 `;
 
 /**
@@ -49,5 +49,8 @@ ${create_dynamic_types('$env/dynamic/public', env.public)}
 export function write_ambient(config, mode) {
 	const env = get_env(config.env, mode);
 
-	write_if_changed(path.join(config.outDir, 'ambient.d.ts'), template(env));
+	write_if_changed(
+		path.join(config.outDir, 'ambient.d.ts'),
+		template({ ...env, prefix: config.env.publicPrefix })
+	);
 }