chore(lib): extract shared allMessages and resolveKey between context and server-translator

Lifts the per-locale message map and the dotted-key resolver out of
`src/lib/i18n/context.tsx` and `src/lib/i18n/server-translator.ts`
into a new `src/lib/i18n/shared-resolve.ts`. The two surfaces had
each carried their own private copy of the same data structure and
the same six-step path resolver; the maps drifted twice when a new
locale was added during v1.4.18 and v1.4.25 polishing passes.
Pinning both call-sites to a shared module keeps client and server
fallback semantics in lockstep and shrinks the surface a future
locale addition has to touch from two files to one.

src/lib/i18n/context.tsx

@@ -11,41 +11,7 @@ import {
 } from "react";
 import { locales, defaultLocale, type Locale } from "./config";
 import { makeFormatters, type Formatters } from "../format-locale";
-
-import deMessages from "../../../messages/de.json";
-import enMessages from "../../../messages/en.json";
-import frMessages from "../../../messages/fr.json";
-import esMessages from "../../../messages/es.json";
-import itMessages from "../../../messages/it.json";
-import plMessages from "../../../messages/pl.json";
-
-const allMessages: Record<Locale, Record<string, unknown>> = {
-  de: deMessages,
-  en: enMessages,
-  fr: frMessages,
-  es: esMessages,
-  it: itMessages,
-  pl: plMessages,
-};
-
-// Resolve nested key like "nav.dashboard" from a message object
-function resolveKey(
-  messages: Record<string, unknown>,
-  key: string,
-): string | undefined {
-  const parts = key.split(".");
-  let current: unknown = messages;
-
-  for (const part of parts) {
-    if (current && typeof current === "object" && part in current) {
-      current = (current as Record<string, unknown>)[part];
-    } else {
-      return undefined;
-    }
-  }
-
-  return typeof current === "string" ? current : undefined;
-}
+import { allMessages, resolveKey } from "./shared-resolve";
 
 interface I18nContextValue {
   locale: Locale;

src/lib/i18n/server-translator.ts

@@ -1,35 +1,5 @@
-import deMessages from "../../../messages/de.json";
-import enMessages from "../../../messages/en.json";
-import frMessages from "../../../messages/fr.json";
-import esMessages from "../../../messages/es.json";
-import itMessages from "../../../messages/it.json";
-import plMessages from "../../../messages/pl.json";
 import { defaultLocale, type Locale } from "./config";
-
-const allMessages: Record<Locale, Record<string, unknown>> = {
-  de: deMessages,
-  en: enMessages,
-  fr: frMessages,
-  es: esMessages,
-  it: itMessages,
-  pl: plMessages,
-};
-
-function resolveKey(
-  messages: Record<string, unknown>,
-  key: string,
-): string | undefined {
-  const parts = key.split(".");
-  let current: unknown = messages;
-  for (const part of parts) {
-    if (current && typeof current === "object" && part in current) {
-      current = (current as Record<string, unknown>)[part];
-    } else {
-      return undefined;
-    }
-  }
-  return typeof current === "string" ? current : undefined;
-}
+import { allMessages, resolveKey } from "./shared-resolve";
 
 export interface ServerTranslator {
   locale: Locale;

src/lib/i18n/shared-resolve.ts

@@ -0,0 +1,59 @@
+/**
+ * Shared message-bundle map and nested-key resolver used by both the
+ * client-side `I18nProvider` in `context.tsx` and the server-side
+ * `getServerTranslator()` in `server-translator.ts`.
+ *
+ * v1.4.27 B7 / BL-P4-11-S10 — the two surfaces previously each carried
+ * their own private copy of `allMessages` plus a near-identical
+ * `resolveKey` helper. The maps drifted twice during v1.4.18 / v1.4.25
+ * polishing passes when a new locale was added; pinning both call-sites
+ * to the same import keeps client and server fallback semantics in
+ * lockstep and shrinks the surface a future locale addition has to
+ * touch from two to one.
+ */
+import deMessages from "../../../messages/de.json";
+import enMessages from "../../../messages/en.json";
+import frMessages from "../../../messages/fr.json";
+import esMessages from "../../../messages/es.json";
+import itMessages from "../../../messages/it.json";
+import plMessages from "../../../messages/pl.json";
+import { type Locale } from "./config";
+
+/**
+ * Single source of truth for the per-locale message bundle.
+ *
+ * Both the client provider and the server translator import this map.
+ * The bundles ship as static JSON imports so they tree-shake into the
+ * client chunk that needs them and into the server chunk that needs
+ * them without duplicating.
+ */
+export const allMessages: Record<Locale, Record<string, unknown>> = {
+  de: deMessages,
+  en: enMessages,
+  fr: frMessages,
+  es: esMessages,
+  it: itMessages,
+  pl: plMessages,
+};
+
+/**
+ * Resolve a dotted key (`nav.dashboard`) inside a flat-or-nested
+ * message object. Returns `undefined` when the key path doesn't land
+ * on a string leaf so the caller can chain a fallback bundle (English,
+ * raw key) without ambiguity.
+ */
+export function resolveKey(
+  messages: Record<string, unknown>,
+  key: string,
+): string | undefined {
+  const parts = key.split(".");
+  let current: unknown = messages;
+  for (const part of parts) {
+    if (current && typeof current === "object" && part in current) {
+      current = (current as Record<string, unknown>)[part];
+    } else {
+      return undefined;
+    }
+  }
+  return typeof current === "string" ? current : undefined;
+}