typing-avatars: add avatar URL resolution helper

plugins/typing-avatars/src/lib/avatarUrl.ts

@@ -0,0 +1,34 @@
+import { findByStoreName } from "@vendetta/metro";
+
+const UserStore = findByStoreName("UserStore");
+const GuildMemberStore = findByStoreName("GuildMemberStore");
+
+function avatarExtension(hash: string): string {
+    return hash.startsWith("a_") ? "gif" : "png";
+}
+
+// member.avatar / user.avatar are the property names Discord's client uses for a per-server /
+// global avatar hash respectively - GuildMemberStore.getMember and UserStore.getUser are both
+// confirmed-working lookups elsewhere in this repo (typingWrapper.ts, getTag.ts), but the avatar
+// hash field itself hasn't been live-verified yet. If avatars come back broken, check these two
+// property reads first via devtools eval against a real member/user record.
+export function getTypingAvatarURL(guildId: string | undefined, userId: string, size = 32): string | null {
+    if (!userId) return null;
+
+    const member = guildId ? GuildMemberStore?.getMember?.(guildId, userId) : null;
+    const guildAvatarHash = member?.avatar;
+    if (guildId && guildAvatarHash) {
+        return `https://cdn.discordapp.com/guilds/${guildId}/users/${userId}/avatars/${guildAvatarHash}.${avatarExtension(guildAvatarHash)}?size=${size * 2}`;
+    }
+
+    const user = UserStore?.getUser?.(userId);
+    const globalAvatarHash = user?.avatar;
+    if (globalAvatarHash) {
+        return `https://cdn.discordapp.com/avatars/${userId}/${globalAvatarHash}.${avatarExtension(globalAvatarHash)}?size=${size * 2}`;
+    }
+
+    // Discord's default avatar for users on the modern username system (no discriminator):
+    // index = (snowflake >> 22) % 6. BigInt is required - the shift loses precision as a Number.
+    const defaultIndex = Number((BigInt(userId) >> 22n) % 6n);
+    return `https://cdn.discordapp.com/embed/avatars/${defaultIndex}.png`;
+}