fix: add "use server" directive at the start of built files

Next.js needs the `"use server"` directive at the start of index files when creating server
component functions.

fix-use-server.js

@@ -0,0 +1,22 @@
+// This is needed because Next.js files with server functions must have
+// the "use server" directive at the start of file.
+
+const { readFileSync, writeFileSync } = require("fs");
+const { join } = require("path");
+
+const pathDir = join(__dirname, "dist");
+
+const main = () => {
+	const fixFile = (path) => {
+		let rows = readFileSync(path).toString().split("\n");
+		rows.unshift('"use server";');
+		writeFileSync(path, rows.join("\n"));
+
+		console.log("Fixed", path);
+	};
+
+	fixFile(join(pathDir, "index.js"));
+	fixFile(join(pathDir, "index.mjs"));
+};
+
+main();

package.json

@@ -13,7 +13,7 @@
 	"scripts": {
 		"prepare": "is-ci || husky install",
 		"lint": "tsc && eslint --ext ts .",
-		"build": "tsup ./src/index.ts --format cjs,esm --dts",
+		"build": "tsup ./src/index.ts --format cjs,esm --dts; node fix-use-server.js",
 		"semantic-release": "semantic-release --branches main"
 	},
 	"keywords": [

src/index.ts

@@ -1,5 +1,3 @@
-"use server";
-
 import { z } from "zod";
 
 type UndefinedKeys<T extends object> = {