From 7f51fc019b3ac1e9ebf3a80058ba2e72442db8ac Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Martin=20Ku=C4=8Dera?= <github@mkucera.cz>
Date: Mon, 1 Jun 2026 16:35:27 +0200
Subject: [PATCH] fix: sort discovered locales for deterministic generator
 output

`getAllLocales` returned locale folders in the order `fs.readdir` yielded
them, which is filesystem-dependent and not stable across platforms or
runs. This caused the generated `Locales` type and `locales` array to be
reordered on regeneration even when nothing changed, producing noisy diffs.

Sort the discovered locales so the output is deterministic.
---
 .../generator/test/get-all-locales.test.ts    | 44 +++++++++++++++++++
 packages/shared/src/file.utils.mts            |  5 ++-
 2 files changed, 48 insertions(+), 1 deletion(-)
 create mode 100644 packages/generator/test/get-all-locales.test.ts

diff --git a/packages/generator/test/get-all-locales.test.ts b/packages/generator/test/get-all-locales.test.ts
new file mode 100644
index 00000000..81955134
--- /dev/null
+++ b/packages/generator/test/get-all-locales.test.ts
@@ -0,0 +1,44 @@
+import { suite } from 'uvu'
+import * as assert from 'uvu/assert'
+import { getAllLocales, type FileSystemUtil } from '../../shared/src/file.utils.mjs'
+
+const test = suite('getAllLocales')
+
+type Dirent = { name: string; isDirectory: () => boolean }
+
+const folder = (name: string): Dirent => ({ name, isDirectory: () => true })
+const file = (name: string): Dirent => ({ name, isDirectory: () => false })
+
+const ROOT = './i18n'
+
+// the order in which the filesystem returns directory entries is not guaranteed
+// to be stable across platforms or runs, so `getAllLocales` must sort the result
+// to produce a deterministic output
+const createFileSystem = (rootEntries: Dirent[]): FileSystemUtil => ({
+	readFile: async () => '',
+	readdir: async (path) => (String(path) === ROOT ? rootEntries : [file('index.ts')]),
+})
+
+test('returns the discovered locales sorted alphabetically', async () => {
+	const fs = createFileSystem([folder('sk'), folder('cs'), folder('en')])
+
+	assert.equal(await getAllLocales(fs, ROOT, 'TypeScript'), ['cs', 'en', 'sk'])
+})
+
+test('sorts locales independently of the filesystem order', async () => {
+	const ascending = createFileSystem([folder('cs'), folder('en'), folder('sk')])
+	const descending = createFileSystem([folder('sk'), folder('en'), folder('cs')])
+
+	assert.equal(await getAllLocales(ascending, ROOT, 'TypeScript'), await getAllLocales(descending, ROOT, 'TypeScript'))
+})
+
+test('also sorts when looking for JavaScript locale files', async () => {
+	const fs: FileSystemUtil = {
+		readFile: async () => '',
+		readdir: async (path) => (String(path) === ROOT ? [folder('sk'), folder('cs')] : [file('index.js')]),
+	}
+
+	assert.equal(await getAllLocales(fs, ROOT, 'JavaScript'), ['cs', 'sk'])
+})
+
+test.run()
diff --git a/packages/shared/src/file.utils.mts b/packages/shared/src/file.utils.mts
index 3c5fb803..f018cf22 100644
--- a/packages/shared/src/file.utils.mts
+++ b/packages/shared/src/file.utils.mts
@@ -38,5 +38,8 @@ export const getAllLocales = async (
 	const fileEnding = outputFormat === 'JavaScript' ? '.js' : '.ts'
 	const files = await getFiles(fs, path, 1)
 
-	return files.filter(({ folder, name }) => folder && name === `index${fileEnding}`).map(({ folder }) => folder)
+	return files
+		.filter(({ folder, name }) => folder && name === `index${fileEnding}`)
+		.map(({ folder }) => folder)
+		.sort()
 }