v3: the chat stops dropping things and holds up to long messages — a message sent while the socket was down vanished with the draft already cleared, and a rejected one fared no better since the client ignored any error that wasn't about a vote or a like. Sends now carry a nonce and sit dimmed in the list until their echo retires them; the server's refusal, an offline socket or ten seconds of silence turns one into a failed row with retry, edit and discard, and a failed row that turns up in the history after a reconnect is retired as having landed after all. Failed edits and deletes show in a bar above the composer. The live stream only goes to signed-in sockets, matching the history behind auth; sends, edits and deletes share a per-user token bucket (typing and read markers get their own, and are just dropped past it); and moderation re-reads the role from the database on every check rather than trusting the one a week-old socket captured. Unread now lives on the server as users.chat_read_at (migration 0014, existing users start caught up), so the count survives a reload and every tab and device clears together; opening onto unread history lands on a "new" divider rather than the bottom, and marks it read only once you've scrolled down to it. After a reconnect the chat re-reads everything from its oldest loaded message and takes that as the truth, edits and deletions included, or reloads the latest page if too much happened. History pages on (created_at, id) so a shared millisecond can't hide a message at a boundary. In the modal: a run of messages from one author shares a header with the time in the gutter on hover, mentions and replies to you get an accent edge, a pill counts what arrived while you were scrolled up, the draft survives closing and reloading, relative times tick, reply previews are flattened from markdown, owners can delete their own messages, ↑ in an empty composer edits your last one, and there's a proper loading and retry state instead of a flash of "No messages yet". Long messages: the composer and edit box grow only so far and then scroll, instead of squeezing the list away; the counter shows only near the limit and sits above the box, since .comment-reply-textarea's padding shorthand had quietly cancelled the room kept for it inside; TextEditor sizes itself before paint, so opening an edit animates to the right height instead of dipping and snapping; and the list follows the bottom through any change in its content's height while pinned there, so ending an edit returns you to the end. A mention notification opens the chat over the page you're on rather than the home page.

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

src/model.ts

@@ -464,6 +464,8 @@ export interface WSWelcomeMessage {
   myVotes: string[];
   myCommentLikes: string[];
   unreadNotificationCount: number;
+  chatReadAt?: string;
+  unreadChatCount: number;
 }
 export interface WSPresenceUpdateMessage {
   type: "presence_update";
@@ -554,6 +556,10 @@ export interface WSErrorMessage {
   dumpId?: string;
   commentId?: string;
   action?: "cast" | "remove";
+  /** Set when a chat action failed, so it can be surfaced in the chat. */
+  scope?: "chat";
+  /** Echo of the failed chat_send's nonce. */
+  nonce?: string;
 }
 
 export interface WSForceLogoutMessage {
@@ -563,6 +569,7 @@ export interface WSForceLogoutMessage {
 export interface WSChatMessageMessage {
   type: "chat_message";
   message: RawChatMessage;
+  nonce?: string;
 }
 
 export interface WSChatMessageUpdatedMessage {
@@ -580,6 +587,12 @@ export interface WSChatTypingUpdateMessage {
   users: OnlineUser[];
 }
 
+export interface WSChatReadUpdateMessage {
+  type: "chat_read_update";
+  readAt: string;
+  unread: number;
+}
+
 export type IncomingWSMessage =
   | WSPingMessage
   | WSWelcomeMessage
@@ -605,7 +618,8 @@ export type IncomingWSMessage =
   | WSChatMessageMessage
   | WSChatMessageUpdatedMessage
   | WSChatMessageDeletedMessage
-  | WSChatTypingUpdateMessage;
+  | WSChatTypingUpdateMessage
+  | WSChatReadUpdateMessage;
 
 /**
  * WebSocket messages — client → server (outgoing)
@@ -635,6 +649,7 @@ export interface WSChatSendMessage {
   type: "chat_send";
   body: string;
   replyToId?: string;
+  nonce?: string;
 }
 
 export interface WSChatTypingMessage {
@@ -658,6 +673,11 @@ export interface WSChatDeleteMessage {
   id: string;
 }
 
+export interface WSChatReadMessage {
+  type: "chat_read";
+  at: string;
+}
+
 export type OutgoingWSMessage =
   | WSPongMessage
   | WSVoteCastMessage
@@ -668,7 +688,8 @@ export type OutgoingWSMessage =
   | WSChatTypingMessage
   | WSChatFocusMessage
   | WSChatEditMessage
-  | WSChatDeleteMessage;
+  | WSChatDeleteMessage
+  | WSChatReadMessage;
 
 /**
  * Follows