```

src/discord/events/boostGreeting.ts

@@ -1,50 +1,19 @@
 import { logger } from "../../logger";
 
-type GuildTextChannel = {
-  send(input: { content: string }): Promise<unknown>;
-};
-
-type GuildMemberLike = {
-  id: string;
-  user?: { id: string };
-  guild: {
-    id: string;
-    channels: {
-      cache: {
-        get(channelId: string): GuildTextChannel | undefined;
-      };
-    };
-  };
-};
-
 /**
- * Sends a welcome message to the configured greeting channel.
- * Call this after confirming the member newly gained the booster eligibility role.
+ * Sends a welcome message via the given channel when a member newly
+ * acquires the booster eligibility role (i.e. just boosted the server).
  */
 export async function sendBoostGreeting(
-  member: GuildMemberLike,
+  channel: { send(input: { content: string }): Promise<unknown> },
+  userId: string,
   greetingChannelId: string,
 ): Promise<void> {
-  const channel = member.guild.channels.cache.get(greetingChannelId);
-
-  if (!channel) {
-    logger.warn("Boost greeting channel not found", {
-      channelId: greetingChannelId,
-      guildId: member.guild.id,
-    });
-    return;
-  }
-
-  const mention = member.user?.id ?? member.id;
   const message =
-    `🎉 Thank you for boosting <@${mention}>! ` +
+    `🎉 Thank you for boosting <@${userId}>! ` +
     `You can now claim a custom role using \`/booster-role claim\` in <#${greetingChannelId}>.`;
 
   await channel.send({ content: message });
 
-  logger.info("Boost greeting sent", {
-    userId: member.id,
-    guildId: member.guild.id,
-    channelId: greetingChannelId,
-  });
+  logger.info("Boost greeting sent", { userId, channelId: greetingChannelId });
 }