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/chat-service.ts

@@ -14,6 +14,9 @@ import { chatMessageRowToApi, isChatMessageRow } from "../model/chat.ts";
 import { db } from "../db/connection.ts";
 import { linkAttachments } from "./attachment-service.ts";
 import { VALIDATION } from "../../shared/validation.ts";
+import { mentionsEveryone } from "../../shared/mention.ts";
+import { hasPermission } from "../../shared/permissions.ts";
+import { isRole } from "../../shared/user.ts";
 
 const DEFAULT_LIMIT = 50;
 const MAX_LIMIT = 100;
@@ -28,7 +31,7 @@ const REPLY_SNIPPET_LEN = 300;
 /** The columns of a `ChatMessageRow`, to select over {@link FROM_JOINS}. */
 const SELECT_COLS =
   `m.id, m.user_id, m.body, m.created_at, m.updated_at, m.reply_to_id,
-  u.username as author_username, u.avatar_mime as author_avatar_mime,
+  m.mentions_everyone, u.username as author_username, u.avatar_mime as author_avatar_mime,
   ru.username as reply_to_author, substr(rm.body, 1, ${REPLY_SNIPPET_LEN}) as reply_to_body`;
 
 /**
@@ -51,10 +54,27 @@ function fetchMessage(id: string): ChatMessage {
   return chatMessageRowToApi(row);
 }
 
+/**
+ * Returns 1 when `body`, written by `authorId`, reaches everyone: it says
+ * `@everyone` and the author's role, read now, has `chat:everyone`. Else 0,
+ * for `chat_messages.mentions_everyone`.
+ */
+function everyoneFlag(authorId: string, body: string): number {
+  if (!mentionsEveryone(body)) return 0;
+  const row = db.prepare(`SELECT role FROM users WHERE id = ?;`).get(
+    authorId,
+  ) as { role: unknown } | undefined;
+  return row && isRole(row.role) && hasPermission(row.role, "chat:everyone")
+    ? 1
+    : 0;
+}
+
 /**
  * Stores a message from `userId` on a `chat_send`, and claims the pasted images
  * it links to. A `replyToId` naming no message is dropped, and the message is
- * posted as no reply. The caller broadcasts the result.
+ * posted as no reply. The message `mentionsEveryone` when it says `@everyone`
+ * and `userId` may. The caller broadcasts the result, and notifies everyone
+ * when it is flagged.
  *
  * @throws {APIException} 400 when the body is blank or longer than
  * `VALIDATION.CHAT_MESSAGE_MAX`.
@@ -84,8 +104,9 @@ export function createChatMessage(
   const id = crypto.randomUUID();
   const createdAt = new Date().toISOString();
   db.prepare(
-    `INSERT INTO chat_messages (id, user_id, body, created_at, reply_to_id) VALUES (?, ?, ?, ?, ?);`,
-  ).run(id, userId, trimmed, createdAt, replyTo);
+    `INSERT INTO chat_messages (id, user_id, body, created_at, reply_to_id, mentions_everyone)
+     VALUES (?, ?, ?, ?, ?, ?);`,
+  ).run(id, userId, trimmed, createdAt, replyTo, everyoneFlag(userId, trimmed));
   // Unclaimed attachments are deleted as orphans at startup.
   linkAttachments(trimmed, "chat", id);
   return fetchMessage(id);
@@ -102,10 +123,24 @@ function getMessageOwner(id: string): string {
   return row.user_id;
 }
 
+/**
+ * Checks whether message `id` is flagged `mentionsEveryone`, false when there
+ * is no such message. The WebSocket route reads it before an edit, to notify
+ * everyone only when the edit adds `@everyone`.
+ */
+export function chatMessageMentionsEveryone(id: string): boolean {
+  const row = db.prepare(
+    `SELECT mentions_everyone FROM chat_messages WHERE id = ?;`,
+  ).get(id) as { mentions_everyone: number } | undefined;
+  return row?.mentions_everyone === 1;
+}
+
 /**
  * Replaces a message's body on a `chat_edit`, and claims any image the new body
- * links to. `canModerate` lets a moderator edit anyone's message. The caller
- * broadcasts the result.
+ * links to. `canModerate` lets a moderator edit anyone's message. The flag
+ * `mentionsEveryone` is set again from the new body and the author's role, not
+ * the editor's: a moderator's edit can't make a user's message reach everyone.
+ * The caller broadcasts the result.
  *
  * @throws {APIException} 404 when there is no such message, 403 when the user
  * is neither its author nor a moderator, 400 when the body is blank or too
@@ -131,8 +166,10 @@ export function updateChatMessage(
       `Message exceeds ${VALIDATION.CHAT_MESSAGE_MAX} characters`,
     );
   }
-  db.prepare(`UPDATE chat_messages SET body = ?, updated_at = ? WHERE id = ?;`)
-    .run(trimmed, new Date().toISOString(), id);
+  db.prepare(
+    `UPDATE chat_messages SET body = ?, updated_at = ?, mentions_everyone = ?
+      WHERE id = ?;`,
+  ).run(trimmed, new Date().toISOString(), everyoneFlag(ownerId, trimmed), id);
   linkAttachments(trimmed, "chat", id);
   return fetchMessage(id);
 }