feat: deduplicate mentee welcome messages

Track welcomed mentees in data/welcomed.txt to prevent sending the onboarding message multiple times if the mentorship role is re-assigned.

src/modules/processMentorshipRole.ts

@@ -6,6 +6,10 @@
 
 import { ids } from "../config/ids.js";
 import { logger } from "../utils/logger.js";
+import {
+  addWelcomedMentee,
+  welcomedMentees,
+} from "../utils/welcomedMentees.js";
 import type { Amari } from "../interfaces/amari.js";
 import type { GuildMember, PartialGuildMember } from "discord.js";
 
@@ -25,6 +29,7 @@ export const processMentorshipRole = async(
   if (
     oldMember.roles.cache.has(ids.roles.mentorship)
     || !updatedMember.roles.cache.has(ids.roles.mentorship)
+    || welcomedMentees.has(updatedMember.id)
   ) {
     return;
   }
@@ -52,6 +57,7 @@ Last name:
 \`\`\`
 Then read our [mentorship wiki](<https://docs.nhcarrigan.com/mentorship/00-faq/>) for the next steps!`,
   });
+  addWelcomedMentee(updatedMember.id);
   await logger.metric("processed_mentorship_role", 1, {
     user: updatedMember.id,
   });

src/utils/welcomedMentees.ts

@@ -0,0 +1,30 @@
+/**
+ * @copyright NHCarrigan
+ * @license Naomi's Public License
+ * @author Naomi Carrigan
+ */
+
+import { appendFileSync, existsSync, readFileSync } from "node:fs";
+
+const filePath = "data/welcomed.txt";
+
+const loadWelcomedMentees = (): Set<string> => {
+  if (!existsSync(filePath)) {
+    return new Set();
+  }
+  const contents = readFileSync(filePath, "utf-8");
+  return new Set(contents.split("\n").filter(Boolean));
+};
+
+const welcomedMentees = loadWelcomedMentees();
+
+/**
+ * Appends a mentee's ID to the welcomed set and persists it to disk.
+ * @param id - The Discord user ID to record.
+ */
+const addWelcomedMentee = (id: string): void => {
+  welcomedMentees.add(id);
+  appendFileSync(filePath, `${id}\n`);
+};
+
+export { addWelcomedMentee, welcomedMentees };