fix(i18n): complete command center texts and merge client fallbacks

src/i18n/commandocentrum-messages.test.ts

@@ -0,0 +1,53 @@
+import { readFileSync } from "node:fs";
+import { createTranslator } from "next-intl";
+import { describe, expect, it } from "vitest";
+import en from "@/messages/en.json";
+import itMessages from "@/messages/it.json";
+import nl from "@/messages/nl.json";
+import { mergeMessages } from "./merge-messages";
+
+const namespace = "pages.admin.commandocentrum";
+const keys = new Set(
+	["page.tsx", "commandocentrum-controls.tsx"].flatMap((file) =>
+		Array.from(
+			readFileSync(`src/app/admin/commandocentrum/${file}`, "utf8").matchAll(
+				/\bt\("([^"]+)"/g,
+			),
+			(match) => match[1],
+		),
+	),
+);
+for (const group of ["hotel", "players", "rewards", "advanced"])
+	keys.add(`groups.${group}`);
+
+describe("command center translations", () => {
+	it.each([
+		["en", en],
+		["it", itMessages],
+	] as const)("provides every rendered message in %s", (locale, messages) => {
+		const errors: unknown[] = [];
+		const t = createTranslator({
+			locale,
+			messages: messages as typeof en,
+			namespace,
+			onError: (error) => errors.push(error),
+		});
+		for (const key of keys) {
+			expect(t.has(key as Parameters<typeof t>[0]), key).toBe(true);
+			expect(
+				t(key as Parameters<typeof t>[0], { count: 42, time: "12:34" }),
+				key,
+			).not.toBe("");
+		}
+		expect(errors).toEqual([]);
+	});
+	it("supplies nested fallback messages to a client translator and formats values", () => {
+		const messages = mergeMessages(en, nl) as typeof en;
+		const t = createTranslator({ locale: "nl", messages, namespace });
+		expect(t("title")).toBe(nl.pages.admin.commandocentrum.title);
+		expect(t("totalAccounts", { count: 42 })).toBe("42 total accounts");
+		expect(t("groups.players")).toBe("Players");
+		expect(t("checkedAt", { time: "12:34" })).toBe("Checked at 12:34");
+		expect(nl.pages.admin.commandocentrum).not.toHaveProperty("totalAccounts");
+	});
+});

src/i18n/merge-messages.ts

@@ -0,0 +1,17 @@
+export type MessageTree = { [key: string]: string | MessageTree };
+
+/** Fill missing translations before sending messages to server and client consumers. */
+export function mergeMessages(
+	fallback: MessageTree,
+	localized: MessageTree,
+): MessageTree {
+	const result: MessageTree = { ...fallback };
+	for (const [key, value] of Object.entries(localized)) {
+		const base = fallback[key];
+		result[key] =
+			typeof value === "object" && typeof base === "object"
+				? mergeMessages(base, value)
+				: value;
+	}
+	return result;
+}

src/i18n/request.ts

@@ -1,5 +1,6 @@
 import { cookies, headers } from "next/headers";
 import { getRequestConfig } from "next-intl/server";
+import { mergeMessages } from "./merge-messages";
 
 // i18n WITHOUT routing: the locale is chosen by a `NEXT_LOCALE` cookie, then
 // the Accept-Language header, and finally English as fallback.
@@ -83,11 +84,19 @@ export default getRequestConfig(async () => {
 
 	return {
 		locale,
-		messages,
+		messages: mergeMessages(fallback, messages),
 		// Never throw on a missing message — use the English value, or a humanised
 		// key as a last resort.
-		getMessageFallback({ key }: { key: string }) {
-			const fromEnglish = key
+		getMessageFallback({
+			namespace,
+			key,
+		}: {
+			namespace?: string;
+			key: string;
+		}) {
+			const fromEnglish = [namespace, key]
+				.filter(Boolean)
+				.join(".")
 				.split(".")
 				.reduce<unknown>(
 					(o, k) =>