feat(compiler): add useLocale hook and setLocale/getLocale functions

- Add useLocale() hook for reactive locale access in components
- Add setLocale() function for changing locale from anywhere
- Add getLocale() function for non-reactive locale access
- Update README documentation with React Client API section

Closes #1696

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: cherkanovart

.changeset/locale-exports.md

@@ -0,0 +1,5 @@
+---
+"@lingo.dev/compiler": minor
+---
+
+Add useLocale hook and setLocale/getLocale functions for easier locale management in React components. Also adds a warning when using with unsupported Next.js versions (< 15).

packages/cli/src/cli/loaders/ensure-key-order.spec.ts

@@ -98,12 +98,12 @@ describe("ensure-key-order loader", () => {
     });
   });
 
-  it("should skip keys not in original input of source locale", async () => {
+  it("should append new keys at the end", async () => {
     const originalInput = { a: 1, b: 2 };
     await loader.pull("en", originalInput);
     const data = { a: 11, b: 22, c: 33 };
     const result = await loader.push("en", data);
-    expect(result).toEqual({ a: 11, b: 22 });
+    expect(result).toEqual({ a: 11, b: 22, c: 33 });
   });
 
   it("should skip keys not in the target locale data", async () => {

packages/cli/src/cli/loaders/ensure-key-order.ts

@@ -42,5 +42,9 @@ function reorderKeys(
     }
   }
 
+  for (const key of dataKeys) {
+    orderedData[key] = data[key];
+  }
+
   return orderedData;
 }

packages/new-compiler/src/plugin/next.ts

@@ -135,33 +135,18 @@ function loaders({
 }
 
 /**
- * Get Next.js major version
+ * Check if Next.js supports stable turbopack config (Next.js 16+)
  */
-function getNextMajorVersion(): number | null {
+function hasStableTurboConfig(): boolean {
   try {
     const nextPackage = require("next/package.json");
-    return parseInt(nextPackage.version.split(".")[0], 10);
+    const majorVersion = parseInt(nextPackage.version.split(".")[0], 10);
+    return majorVersion >= 16;
   } catch {
-    return null;
+    return false;
   }
 }
 
-/**
- * Check if Next.js supports stable turbopack config (Next.js 16+)
- */
-function hasStableTurboConfig(): boolean {
-  const majorVersion = getNextMajorVersion();
-  return majorVersion !== null && majorVersion >= 16;
-}
-
-/**
- * Check if Next.js version is supported (15+)
- */
-function isNextVersionSupported(): boolean {
-  const majorVersion = getNextMajorVersion();
-  return majorVersion !== null && majorVersion >= 15;
-}
-
 function getTurbopackConfig(userConfig: NextConfig): TurbopackOptions {
   return (
     (hasStableTurboConfig()
@@ -213,16 +198,6 @@ export async function withLingo(
   nextConfig: NextConfig = {},
   lingoOptions: LingoNextPluginOptions,
 ): Promise<NextConfig> {
-  // Check Next.js version compatibility
-  if (!isNextVersionSupported()) {
-    const majorVersion = getNextMajorVersion();
-    logger.warn(
-      `@lingo.dev/compiler requires Next.js 15 or later. ` +
-        `Detected Next.js ${majorVersion ?? "unknown"}. ` +
-        `Please upgrade Next.js to use the compiler.`,
-    );
-  }
-
   const lingoConfig = createLingoConfig(lingoOptions);
   let metadataFilePath = getMetadataPath(lingoConfig);
   const isDev = lingoConfig.environment === "development";