feat(groups): add fail-closed admission management

packages/minecraft/src/index.ts

@@ -46,6 +46,46 @@ export function formatManagedDiscordNickname(
   return [...firstName.trim()].slice(0, DISCORD_NICKNAME_LIMIT).join("").trimEnd();
 }
 
+export interface DiscordGuildIdentity {
+  id: string;
+  username: string;
+  globalName: string | null;
+  nickname: string | null;
+}
+
+export async function getGuildMemberIdentity(
+  input: { guildId: string; discordUserId: string; botToken: string },
+  request: typeof fetch = fetch,
+): Promise<DiscordGuildIdentity> {
+  const response = await request(
+    `https://discord.com/api/v10/guilds/${input.guildId}/members/${input.discordUserId}`,
+    {
+      headers: {
+        authorization: `Bot ${input.botToken}`,
+        accept: "application/json",
+      },
+      cache: "no-store",
+    },
+  );
+  if (!response.ok) throw new Error(`Discord guild member lookup failed (${response.status})`);
+
+  const payload: unknown = await response.json();
+  if (!payload || typeof payload !== "object") throw new Error("Discord guild member lookup returned invalid data");
+  const member = payload as { nick?: unknown; user?: unknown };
+  if (!member.user || typeof member.user !== "object") throw new Error("Discord guild member lookup omitted user data");
+  const user = member.user as { id?: unknown; username?: unknown; global_name?: unknown };
+  if (typeof user.id !== "string" || typeof user.username !== "string") {
+    throw new Error("Discord guild member lookup returned invalid user data");
+  }
+
+  return {
+    id: user.id,
+    username: user.username,
+    globalName: typeof user.global_name === "string" ? user.global_name : null,
+    nickname: typeof member.nick === "string" ? member.nick : null,
+  };
+}
+
 export async function updateGuildNickname(
   input: {
     guildId: string;