fix(discord): de-dupe allowed_mentions roles/users to avoid silent 400

packages/worker/src/adapters/discord/notify.ts

@@ -13,8 +13,9 @@ export const discordNotifier: Notifier = {
     const total = lines.reduce((s, l) => s + l.amount, 0);
     const content = renderTemplate(template, { period, plans, total: total.toLocaleString() });
     // Pin mentions to exactly the plan role ids — so nothing else in the (admin-authored)
-    // template content can be coerced into a ping.
-    const roles = lines.map((l) => l.role_id).filter((r): r is string => !!r);
+    // template content can be coerced into a ping. De-dupe: two plans can share one role
+    // (e.g. Standard + Premium both → @Claude), and Discord 400s on duplicate snowflakes.
+    const roles = [...new Set(lines.map((l) => l.role_id).filter((r): r is string => !!r))];
     await createChannelMessage(env.DISCORD_BOT_TOKEN ?? "", channelId, {
       content,
       components: [payButtonRow()],
@@ -32,7 +33,8 @@ export const discordNotifier: Notifier = {
       .join("\n");
     const content = renderTemplate(template, { period, count: String(people.length), list });
     // Pin mentions to exactly the overdue members' ids — template/display-name text can't ping.
-    const users = people.map((p) => p.discord_id).filter((d): d is string => !!d);
+    // De-dupe defensively (same Discord duplicate-snowflake 400 risk as roles above).
+    const users = [...new Set(people.map((p) => p.discord_id).filter((d): d is string => !!d))];
     await createChannelMessage(env.DISCORD_BOT_TOKEN ?? "", channelId, {
       content,
       allowed_mentions: { parse: [], users },

packages/worker/test/adapters/discord-notify.test.ts

@@ -40,4 +40,31 @@ describe("discordNotifier rendering", () => {
     expect(c).toContain("共 315");
     expect(sent[0].components).toBeTruthy(); // pay button row present
   });
+
+  it("de-dupes allowed_mentions.roles when two plans share a role (Discord rejects duplicate snowflakes)", async () => {
+    const sent = captureFetch();
+    // Standard + Premium both mapped to the same "Claude" role id.
+    const lines: PlanOpenLine[] = [
+      { plan_id: 1, plan_name: "Claude Standard", amount: 251, role_id: "claude" },
+      { plan_id: 2, plan_name: "Claude Premium", amount: 1258, role_id: "claude" },
+    ];
+    await discordNotifier.sendBillingOpened(env, "chan", "2026-06", lines, "{period}\n{plans}");
+    vi.unstubAllGlobals();
+    const roles = sent[0].allowed_mentions.roles as string[];
+    expect(roles).toEqual(["claude"]); // unique — no duplicate that would 400
+    // Both plan lines still render their own mention in the content (display is per-plan).
+    const c = sent[0].content as string;
+    expect(c.match(/<@&claude>/g)?.length).toBe(2);
+  });
+
+  it("de-dupes allowed_mentions.users when a member appears twice in the overdue list", async () => {
+    const sent = captureFetch();
+    const people: OverduePerson[] = [
+      { user_id: 1, discord_id: "d1", user_name: "小明", lines: [{ plan_name: "ChatGPT", amount: 315 }], total: 315 },
+      { user_id: 1, discord_id: "d1", user_name: "小明", lines: [{ plan_name: "Claude", amount: 251 }], total: 251 },
+    ];
+    await discordNotifier.sendOverdue(env, "chan", "2026-06", people, "{period}\n{list}");
+    vi.unstubAllGlobals();
+    expect(sent[0].allowed_mentions.users as string[]).toEqual(["d1"]);
+  });
 });