feat(platform): add Discord onboarding and Velocity gate

packages/minecraft/package.json

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+{
+  "name": "@minecraft-account-manager/minecraft",
+  "version": "0.1.0",
+  "private": true,
+  "type": "module",
+  "exports": { ".": "./src/index.ts" },
+  "scripts": {
+    "test": "vitest run",
+    "typecheck": "tsc --noEmit"
+  },
+  "devDependencies": {
+    "typescript": "^5.9.3",
+    "vitest": "^4.1.0"
+  }
+}

packages/minecraft/src/index.ts

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+const MINECRAFT_USERNAME = /^[A-Za-z0-9_]{3,16}$/;
+const MINECRAFT_UUID = /^[0-9a-f]{32}$/i;
+const DISCORD_NICKNAME_LIMIT = 32;
+
+export interface JavaProfile {
+  uuid: string;
+  username: string;
+}
+
+export async function lookupJavaProfile(
+  username: string,
+  request: typeof fetch = fetch,
+): Promise<JavaProfile | null> {
+  const candidate = username.trim();
+  if (!MINECRAFT_USERNAME.test(candidate)) return null;
+
+  const response = await request(
+    `https://api.mojang.com/users/profiles/minecraft/${encodeURIComponent(candidate)}`,
+    { headers: { accept: "application/json" }, cache: "no-store" },
+  );
+
+  if (response.status === 204 || response.status === 404) return null;
+  if (!response.ok) throw new Error(`Mojang profile lookup failed (${response.status})`);
+
+  const profile: unknown = await response.json();
+  if (!profile || typeof profile !== "object") return null;
+  const { id, name } = profile as { id?: unknown; name?: unknown };
+  if (typeof id !== "string" || !MINECRAFT_UUID.test(id)) return null;
+  if (typeof name !== "string" || !MINECRAFT_USERNAME.test(name)) return null;
+
+  return { uuid: id.toLowerCase(), username: name };
+}
+
+export function formatDiscordNickname(firstName: string, minecraftUsername: string) {
+  const suffix = ` (${minecraftUsername})`;
+  const availableCharacters = DISCORD_NICKNAME_LIMIT - [...suffix].length;
+  const shortenedName = [...firstName.trim()].slice(0, Math.max(1, availableCharacters)).join("").trimEnd();
+  return `${shortenedName}${suffix}`;
+}
+
+export async function updateGuildNickname(
+  input: {
+    guildId: string;
+    discordUserId: string;
+    nickname: string;
+    botToken: string;
+  },
+  request: typeof fetch = fetch,
+) {
+  const response = await request(
+    `https://discord.com/api/v10/guilds/${input.guildId}/members/${input.discordUserId}`,
+    {
+      method: "PATCH",
+      headers: {
+        authorization: `Bot ${input.botToken}`,
+        "content-type": "application/json",
+      },
+      body: JSON.stringify({ nick: input.nickname }),
+    },
+  );
+
+  if (!response.ok) {
+    throw new Error(`Discord nickname update failed (${response.status})`);
+  }
+}

packages/minecraft/test/discord.test.ts

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+import { describe, expect, it, vi } from "vitest";
+import { updateGuildNickname } from "../src/index";
+
+describe("Discord nickname updates", () => {
+  it("updates a member in the configured guild using bot authentication", async () => {
+    const request = vi.fn<typeof fetch>().mockResolvedValue(new Response(null, { status: 204 }));
+
+    await updateGuildNickname(
+      { guildId: "123456789012345678", discordUserId: "987654321098765432", nickname: "Sam (Notch)", botToken: "secret" },
+      request,
+    );
+
+    expect(request).toHaveBeenCalledWith(
+      "https://discord.com/api/v10/guilds/123456789012345678/members/987654321098765432",
+      expect.objectContaining({ method: "PATCH", body: JSON.stringify({ nick: "Sam (Notch)" }) }),
+    );
+  });
+
+  it("reports Discord permission failures without pretending the nickname changed", async () => {
+    const request = vi.fn<typeof fetch>().mockResolvedValue(new Response("Missing Permissions", { status: 403 }));
+    await expect(
+      updateGuildNickname(
+        { guildId: "123456789012345678", discordUserId: "987654321098765432", nickname: "Sam (Notch)", botToken: "secret" },
+        request,
+      ),
+    ).rejects.toThrow("Discord nickname update failed (403)");
+  });
+});

packages/minecraft/test/minecraft.test.ts

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+import { describe, expect, it, vi } from "vitest";
+import { formatDiscordNickname, lookupJavaProfile } from "../src/index";
+
+describe("Java Edition profiles", () => {
+  it("returns Mojang's canonical UUID and username", async () => {
+    const request = vi.fn<typeof fetch>().mockResolvedValue(
+      new Response(JSON.stringify({ id: "069a79f444e94726a5befca90e38aaf5", name: "Notch" }), {
+        status: 200,
+        headers: { "content-type": "application/json" },
+      }),
+    );
+
+    await expect(lookupJavaProfile("notch", request)).resolves.toEqual({
+      uuid: "069a79f444e94726a5befca90e38aaf5",
+      username: "Notch",
+    });
+  });
+
+  it("returns null when Mojang does not recognize the username", async () => {
+    const request = vi.fn<typeof fetch>().mockResolvedValue(new Response(null, { status: 204 }));
+    await expect(lookupJavaProfile("UnknownPlayer", request)).resolves.toBeNull();
+  });
+
+  it("preserves the Minecraft username while fitting Discord's nickname limit", () => {
+    expect(formatDiscordNickname("Alexandria Catherine", "SixteenCharName1")).toBe(
+      "Alexandria Ca (SixteenCharName1)",
+    );
+    expect(formatDiscordNickname("Sam", "Notch")).toBe("Sam (Notch)");
+  });
+});

packages/minecraft/tsconfig.json

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+{
+  "extends": "../../tsconfig.base.json",
+  "compilerOptions": { "types": ["vitest/globals"] },
+  "include": ["src/**/*.ts", "test/**/*.ts"]
+}