@@ -1,7 +1,7 @@
 {
   "name": "qryptchat-web",
   "private": true,
-  "version": "0.15.1",
+  "version": "0.16.0",
   "type": "module",
   "bin": {
     "qc": "./bin/qc.js",
 
@@ -35,7 +35,8 @@ The first run signs you in through your browser, then opens your chats.
 | Enter | send (or open the highlighted chat) |
 | Ctrl+E | the emoji picker: search, recents and every group, drawn with [OpenEmoji](https://github.com/profullstack/openemoji) |
 | `:rocket:` | shortcodes turn into emoji when you send |
-| Tab / Esc | move between the chat list and the composer |
+| `@` `@ali` + Tab | complete a mention, like x.com and IRC: Tab again cycles the matches, Shift+Tab goes back; the line above the composer lists who matches |
+| Tab / Esc | move between the chat list and the composer (Tab completes instead when the cursor is in an `@name`) |
 | Ctrl+N / Ctrl+P | next / previous chat |
 | PgUp / PgDn, wheel | scroll back through the conversation |
 | Ctrl+R | reload |
@@ -49,6 +50,8 @@ The mouse works too: click a chat, scroll the transcript, click an emoji. Unread
 qc chats                        # id and name of every chat
 qc read alice -n 20             # the last 20 messages, decrypted
 qc send alice "on my way"       # encrypted to every participant
+qc send ops "@ri deploy is done" # an @partial matching one person is sent as @riotcoder
+qc mentions ops @al             # who @al completes to: @alice, @alina
 echo "deploy done" | qc send ops -
 qc listen --json                # new messages as NDJSON, until you stop it
 qc whoami
@@ -62,7 +65,7 @@ qc whoami
 qc mcp
 ```
 
-runs an MCP server on stdio with three tools: `list_chats`, `read_chat` and `send_message`. Encryption and decryption happen on this machine; the server only ever sees ciphertext. For Claude Code:
+runs an MCP server on stdio with `list_chats`, `read_chat`, `send_message`, `list_mentions` (who an `@partial` completes to) and `react_to_message`; `send_message` writes out an `@partial` that matches exactly one person. Encryption and decryption happen on this machine; the server only ever sees ciphertext. For Claude Code:
 
 ```sh
 claude mcp add qryptchat -- qc mcp
 
@@ -1,6 +1,6 @@
 {
   "name": "@profullstack/qryptchat",
-  "version": "0.10.0",
+  "version": "0.11.0",
   "description": "qc: qrypt.chat in your terminal. A full-screen end-to-end encrypted chat client (ML-KEM-1024), plus a scriptable CLI and an MCP server.",
   "type": "module",
   "bin": {
 
@@ -12,6 +12,7 @@ import { notify } from './notify.js';
 import { parseVoiceArgs, runPairux, voiceLink, VOICE_HELP } from './voice.js';
 import { voiceMessage } from '../lib/chat/voice.js';
 import { namesLines } from '../lib/chat/irc.js';
+import { expandMentions, matchMentions, mentionCandidates } from '../lib/chat/mentions.js';
 export { exitWhenFlushed } from './exit.js';
 
 /** An error as qc prints it: the error icon and the message. */
@@ -43,10 +44,12 @@ Usage:
   qc call <number>        call a phone (US/Canada free 10 min a day; +country code for others):
                           opens qrypt.chat's dialer with the number filled in
   qc read <chat> [-n 20]  print the last messages of a chat
-  qc send <chat> <text>   send a message (text "-" reads stdin; --reply <message-id> to reply)
+  qc send <chat> <text>   send a message (text "-" reads stdin; --reply <message-id> to reply);
+                          an @partial that matches one person becomes their @username
+  qc mentions <chat> [@partial]   who @ completes to in a chat, best match first (one per line)
   qc react <chat> <message-id> <emoji> [--remove]   react to a message
   qc listen               print new messages as they arrive (NDJSON with --json; --notify alerts with it)
-  qc mcp                  run as an MCP server on stdio (list_chats, read_chat, send_message)
+  qc mcp                  run as an MCP server on stdio (list_chats, read_chat, send_message, list_mentions)
   qc join <link>          join a group chat from its invite link (https://qrypt.chat/join/...)
   qc invite <chat>        print a group's invite link (group admins) [--reset makes a new one, --off turns it off]
 
@@ -99,6 +102,12 @@ export function findChat(chats, query) {
 	throw new Error(`No chat matches "${query}". Try qc chats.`);
 }
 
+/** Who @ can complete to in a chat (everyone with a username but you), best match first. */
+export const mentionMatches = (chat, me, partial = '') => matchMentions(mentionCandidates(chat.participants, me?.id), String(partial).replace(/^@/, ''));
+
+/** Text about to be sent with each @partial that matches one person written out in full. */
+export const withMentions = (chat, me, text) => expandMentions(text, mentionCandidates(chat.participants, me?.id));
+
 async function client(flags, { interactive = false } = {}) {
 	if (flags.url) process.env.QC_URL = flags.url;
 	// The session on disk is sealed: unlocking may ask for the passphrase (or read QC_PASSPHRASE / the keychain).
@@ -266,6 +275,15 @@ export async function main(argv, { version = '0.0.0' } = {}) {
 			for (const line of namesLines(chat, chat.title)) out(line);
 			return;
 		}
+		case 'mentions': {
+			if (!rest[0]) throw new Error('Usage: qc mentions <chat> [@partial]');
+			const c = await client(flags);
+			const chat = findChat(await c.conversations(), rest[0]);
+			const matches = mentionMatches(chat, c.me, rest[1] ?? '');
+			if (flags.json) return json(matches);
+			for (const p of matches) out(`@${p.username}${p.agent ? ' 🤖' : ''}${p.name ? `  ${p.name}` : ''}`);
+			return;
+		}
 		case 'read': {
 			if (!rest[0]) throw new Error('Usage: qc read <chat> [-n 20]');
 			const c = await client(flags);
@@ -317,9 +335,11 @@ export async function main(argv, { version = '0.0.0' } = {}) {
 			if (!text) throw new Error('Nothing to send.');
 			const c = await client(flags);
 			const chat = findChat(await c.conversations(), rest[0]);
-			const { message, skipped } = await c.send(chat.id, text, { replyTo: flags.reply || undefined });
-			if (flags.json) return json({ id: message?.id, conversation: chat.id, skipped });
+			const m = withMentions(chat, c.me, text);
+			const { message, skipped } = await c.send(chat.id, m.text, { replyTo: flags.reply || undefined });
+			if (flags.json) return json({ id: message?.id, conversation: chat.id, skipped, mentions: m.mentions, ambiguous: m.ambiguous });
 			if (skipped) out(warn(`${skipped} participant(s) have no key yet and will not see it.`));
+			for (const a of m.ambiguous) out(warn(`@${a.query} could be ${a.matches.join(', ')}: sent as typed.`));
 			return out(`${mark('send')}Sent to ${chat.title}.`);
 		}
 		case 'listen': {
 
@@ -4,7 +4,7 @@
  * the keys; the server only ever sees ciphertext.
  */
 import { createInterface } from 'node:readline';
-import { findChat } from './commands.js';
+import { findChat, mentionMatches, withMentions } from './commands.js';
 
 const TOOLS = [
 	{
@@ -27,7 +27,7 @@ const TOOLS = [
 	},
 	{
 		name: 'send_message',
-		description: 'Send an end-to-end encrypted message (ML-KEM-1024) to a conversation.',
+		description: 'Send an end-to-end encrypted message (ML-KEM-1024) to a conversation. An @partial in the text that matches exactly one participant is written out as their full @username (list_mentions shows who matches).',
 		inputSchema: {
 			type: 'object',
 			properties: {
@@ -39,6 +39,19 @@ const TOOLS = [
 			additionalProperties: false,
 		},
 	},
+	{
+		name: 'list_mentions',
+		description: 'Who an @mention can complete to in a conversation, best match first (like typing @ali then Tab). Without partial: everyone you can mention.',
+		inputSchema: {
+			type: 'object',
+			properties: {
+				chat: { type: 'string', description: 'Conversation id or part of its name' },
+				partial: { type: 'string', description: 'Optional: the start of a name, with or without the @' },
+			},
+			required: ['chat'],
+			additionalProperties: false,
+		},
+	},
 	{
 		name: 'react_to_message',
 		description: 'React to a message with an emoji (Signal-style: one reaction per person; a new one replaces yours). End-to-end encrypted.',
@@ -80,8 +93,14 @@ export async function callTool(client, name, args = {}) {
 	if (name === 'send_message') {
 		if (!args.text || typeof args.text !== 'string') throw new Error('text is required');
 		const chat = findChat(await client.conversations(), args.chat);
-		const { message, skipped } = await client.send(chat.id, args.text, { replyTo: typeof args.reply_to === 'string' ? args.reply_to : undefined });
-		return { sent: true, id: message?.id, chat: chat.title, skipped };
+		const m = withMentions(chat, client.me, args.text);
+		const { message, skipped } = await client.send(chat.id, m.text, { replyTo: typeof args.reply_to === 'string' ? args.reply_to : undefined });
+		return { sent: true, id: message?.id, chat: chat.title, skipped, ...(m.mentions.length ? { mentions: m.mentions } : {}), ...(m.ambiguous.length ? { ambiguous: m.ambiguous } : {}) };
+	}
+	if (name === 'list_mentions') {
+		const chat = findChat(await client.conversations(), args.chat);
+		const matches = mentionMatches(chat, client.me, typeof args.partial === 'string' ? args.partial : '');
+		return { chat: chat.title, mentions: matches.map(({ username, name: display_name, agent }) => ({ mention: `@${username}`, username, ...(display_name ? { display_name } : {}), agent })) };
 	}
 	if (name === 'react_to_message') {
 		if (!args.emoji || typeof args.emoji !== 'string') throw new Error('emoji is required');
 
@@ -17,6 +17,9 @@
  * between your chats and the archived ones (also Ctrl+O; `a` in the list).
  * /names (who is here) and /list (your chats) answer IRC-style in the
  * transcript, shown only to you and never sent.
+ * @mentions complete like x.com and IRC: type @ and optionally the start of a
+ * name, then Tab (again to cycle, Shift+Tab back); the line above the composer
+ * lists the matches as you type. Tab outside an @name still switches panes.
  * The chat list reloads every 15 s as well as on live events, so it never
  * goes stale if the events stream drops.
  *
@@ -32,6 +35,7 @@ import { notify } from './notify.js';
 import { newVoiceRoomLink, parseSlashCommand, PAIRUX_URL, voiceMessage } from '../lib/chat/voice.js';
 import { listLines, namesLines } from '../lib/chat/irc.js';
 import { CHAT_LIST_EVENTS, MEMBERSHIP_EVENTS } from '../lib/chat/membership-events.js';
+import { completeMention, matchMentions, mentionAt, mentionCandidates, mentionHint } from '../lib/chat/mentions.js';
 
 const SIDEBAR = 30;
 
@@ -53,9 +57,31 @@ export function initialState(me) {
 		notice: '',
 		loading: true,
 		showArchived: false,
+		mention: null,
 	};
 }
 
+/** The people @ can complete in the open chat. */
+const mentionPeople = (state) => mentionCandidates(state.conversations.find((c) => c.id === state.activeId)?.participants, state.me?.id);
+
+/** The @name being typed and who it could be, or null: drawn above the composer. */
+export function mentionSuggestions(state) {
+	if (state.focus !== 'compose' || !state.activeId) return null;
+	const cycle = state.mention;
+	if (cycle && cycle.value === state.field.value && cycle.cursor === state.field.cursor) return { query: cycle.query, matches: cycle.matches, index: cycle.index };
+	const at = mentionAt(state.field.value, state.field.cursor);
+	return at ? { query: at.query, matches: matchMentions(mentionPeople(state), at.query), index: -1 } : null;
+}
+
+/** Tab (dir 1) or Shift+Tab (dir -1) in the composer: true when it completed an @name. */
+export function tabComplete(state, dir = 1) {
+	const done = completeMention(state.field.value, state.field.cursor, mentionPeople(state), state.mention, dir);
+	if (!done) return false;
+	state.field = { value: done.value, cursor: done.cursor };
+	state.mention = done.cycle;
+	return true;
+}
+
 /** The chats the sidebar shows: archived ones only in the archived view. */
 export const listed = (state) => state.conversations.filter((c) => !!c.is_archived === !!state.showArchived);
 
@@ -162,6 +188,7 @@ function drawTranscript(surface, state) {
 export function render({ ui, width, height, theme }, state, on = {}) {
 	const active = state.conversations.find((c) => c.id === state.activeId);
 	const typingNames = Object.values(state.typing[state.activeId] || {}).map((t) => t.name);
+	const mention = mentionSuggestions(state);
 
 	ui.row({ size: 1 }, (bar) => {
 		bar.draw((s) => {
@@ -218,11 +245,18 @@ export function render({ ui, width, height, theme }, state, on = {}) {
 					drawTranscript(s, state);
 					p.ctx.hit({ rect: s.hitRect(), onScroll: (delta) => on.scroll?.(-delta) });
 				}, { size: 'fill' });
-				p.label(typingNames.length ? `${typingNames.join(', ')} ${typingNames.length === 1 ? 'is' : 'are'} typing…` : ' ', { size: 1 });
+				p.label(
+					mention
+						? mentionHint(mention.matches, mention.query, mention.index)
+						: typingNames.length
+							? `${typingNames.join(', ')} ${typingNames.length === 1 ? 'is' : 'are'} typing…`
+							: ' ',
+					{ size: 1 },
+				);
 				p.textInput({
 					value: state.field.value,
 					cursor: state.field.cursor,
-					placeholder: active ? `Message ${active.title}  (Ctrl+E emoji, :rocket: works too)` : 'Pick a chat first',
+					placeholder: active ? `Message ${active.title}  (@name Tab, Ctrl+E emoji, :rocket: works too)` : 'Pick a chat first',
 					focused: state.focus === 'compose' && !state.picker,
 					size: 1,
 				});
@@ -234,7 +268,7 @@ export function render({ ui, width, height, theme }, state, on = {}) {
 		items: [
 			{ key: 'Enter', label: state.focus === 'list' ? 'open' : 'send' },
 			{ key: 'Ctrl+E', label: 'emoji' },
-			{ key: 'Tab', label: state.focus === 'list' ? 'compose' : 'chats' },
+			{ key: 'Tab', label: state.focus === 'list' ? 'compose' : mention?.matches.length ? 'complete @' : 'chats' },
 			{ key: 'PgUp', label: 'scroll' },
 			...(state.focus === 'list' ? [{ key: 'a', label: state.showArchived ? 'unarchive' : 'archive' }] : []),
 			{ key: 'Ctrl+O', label: state.showArchived ? 'chats' : 'archived' },
@@ -489,6 +523,8 @@ export async function runTui(client, { initialChat } = {}) {
 		if (state.picker) return; // the picker's own key handler has it
 		if (event.key === 'ctrl+e') {
 			state.picker = widgets.createEmojiPicker(state.recent);
+		} else if ((event.key === 'tab' || event.key === 'shift+tab') && state.focus === 'compose' && tabComplete(state, event.key === 'tab' ? 1 : -1)) {
+			typed();
 		} else if (event.key === 'tab' || event.key === 'shift+tab' || (event.key === 'escape' && state.focus === 'compose')) {
 			state.focus = state.focus === 'list' ? 'compose' : 'list';
 		} else if (event.key === 'pageup') {
Original file line number	Diff line number	Diff line change
`@@ -1,7 +1,7 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "qryptchat-web",`
`3`	`3`	`"private": true,`
`4`		`- "version": "0.15.1",`
	`4`	`+ "version": "0.16.0",`
`5`	`5`	`"type": "module",`
`6`	`6`	`"bin": {`
`7`	`7`	`"qc": "./bin/qc.js",`
Original file line number	Diff line number	Diff line change
`@@ -1,6 +1,6 @@`
`1`	`1`	`{`
`2`	`2`	`"name": "@profullstack/qryptchat",`
`3`		`- "version": "0.10.0",`
	`3`	`+ "version": "0.11.0",`
`4`	`4`	`"description": "qc: qrypt.chat in your terminal. A full-screen end-to-end encrypted chat client (ML-KEM-1024), plus a scriptable CLI and an MCP server.",`
`5`	`5`	`"type": "module",`
`6`	`6`	`"bin": {`