fix: localize special-folder names by JMAP role #404

lib/mailbox-label.ts

@@ -0,0 +1,44 @@
+/**
+ * Localizes the display name of special-use mailboxes.
+ *
+ * Mail servers (e.g. Stalwart) always create system folders with English
+ * names — "Inbox", "Sent", "Junk" — regardless of the account locale. JMAP
+ * exposes the special-use semantics via the mailbox `role`, so we map that
+ * role onto a translated label (mirroring Roundcube's behaviour). Folders
+ * without a recognized role — i.e. user-created folders — keep their server
+ * name untouched.
+ *
+ * The keys live under the `sidebar.mailboxes` namespace; `junk`, `flagged`
+ * and `all` reuse the existing `spam`/`starred`/`all_mail` keys so every
+ * locale already has a translation.
+ */
+const ROLE_TRANSLATION_KEY: Record<string, string> = {
+  inbox: "inbox",
+  sent: "sent",
+  drafts: "drafts",
+  trash: "trash",
+  archive: "archive",
+  junk: "spam",
+  important: "important",
+  flagged: "starred",
+  all: "all_mail",
+};
+
+/**
+ * Returns the localized name for a mailbox, or its raw server name when the
+ * role is unknown/absent.
+ *
+ * @param translate Resolves a `sidebar.mailboxes` leaf key (e.g. `"inbox"`) to
+ *   its localized string. Callers scoped to the `sidebar` namespace pass
+ *   `(k) => t(`mailboxes.${k}`)`; root-scoped callers pass
+ *   `(k) => t(`sidebar.mailboxes.${k}`)`.
+ */
+export function localizeMailboxName(
+  role: string | undefined | null,
+  name: string,
+  translate: (key: string) => string,
+): string {
+  if (!role) return name;
+  const key = ROLE_TRANSLATION_KEY[role];
+  return key ? translate(key) : name;
+}