v4: a moderator's or an admin's @everyone in the chat notifies every user — there was no way to reach everyone at once. The new chat:everyone permission, held by moderators and admins, lets a chat message saying @everyone notify every user but its author and those reading the chat, through notifyEveryone, after notifyMentions, so a user also named is told once, by name; the notification is a user_mentioned with everyone set, which the notifications page and the digest word as "mentioned everyone in the chat". chat_messages.mentions_everyone, sent as ChatMessage.mentionsEveryone, is set from the author's role each time the body is written, so a user's @everyone reaches no one, a moderator's edit of a user's message can't make it reach everyone, and a demoted author's next edit loses it. Only an edit that adds @everyone notifies, so fixing an announcement's typo reaches no one new. The client highlights and chimes by the flag, never by the text; Markdown shows @everyone as a mention only in a flagged message, and never links it to a profile. The chat composer offers @everyone first to those who may say it. No account may be named everyone, in any case: migration 0023 adds the column, flags the moderators' and admins' past @everyone messages, renames a user named everyone to everyone_N and drops an alias everyone. 265 backend tests and 681 frontend tests pass, and deno check, tsc, eslint, doc:lint and i18n:compile --strict are clean; checked in screenshots of the chat at 1280 and 390px, with a moderator's and a user's @everyone and the suggestions open.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

api/services/notification-service.ts

@@ -379,6 +379,50 @@ export function notifyMentions(
   }
 }
 
+/**
+ * Notifies every user but its author of chat message `messageId`, which says
+ * `@everyone`. The WebSocket route calls it, after {@link notifyMentions} so
+ * that a user also named is told by name, when the message is sent flagged
+ * `mentionsEveryone`, or when an edit flags it. Each user is notified once per
+ * message, however often it is edited. `skipUserId` spares the users who have
+ * the chat open, as for a mention.
+ */
+export function notifyEveryone(
+  mentionerUserId: string,
+  messageId: string,
+  skipUserId?: (userId: string) => boolean,
+): void {
+  const mentionerRow = db.prepare(
+    `SELECT username FROM users WHERE id = ?;`,
+  ).get(mentionerUserId) as { username: string } | undefined;
+  if (!mentionerRow) return;
+
+  const userRows = db.prepare(`SELECT id FROM users WHERE id != ?;`).all(
+    mentionerUserId,
+  ) as { id: string }[];
+
+  // One transaction for the fan-out, as for a dump's followers.
+  transaction(() => {
+    for (const row of userRows) {
+      if (skipUserId?.(row.id)) continue;
+      createNotification(
+        row.id,
+        "user_mentioned",
+        {
+          mentionerId: mentionerUserId,
+          mentionerUsername: mentionerRow.username,
+          contextType: "chat",
+          contextId: messageId,
+          contextTitle: "",
+          everyone: true,
+        },
+        // The key of a mention by name, so a user named too gets one.
+        `mention:chat:${messageId}:${row.id}`,
+      );
+    }
+  });
+}
+
 /**
  * Notifies a dump's poster that `commenterId` commented on it, unless they are
  * the poster. `createComment` calls it for replies too, but not on an edit.