diff --git a/lib/shared/markdown.js b/lib/shared/markdown.js
index 514c08996..bccc9fe67 100644
--- a/lib/shared/markdown.js
+++ b/lib/shared/markdown.js
@@ -1,320 +1,346 @@
 // @flow
 
 import invariant from 'invariant';
 
-import { markdownMentionRegex } from './mention-utils.js';
-import type { RelativeMemberInfo } from '../types/thread-types.js';
+import {
+  markdownMentionRegex,
+  decodeChatMentionText,
+} from './mention-utils.js';
+import type {
+  RelativeMemberInfo,
+  ResolvedThreadInfo,
+  ChatMentionCandidates,
+} from '../types/thread-types.js';
 
 // simple-markdown types
 export type State = {
   key?: string | number | void,
   inline?: ?boolean,
   [string]: any,
 };
 
 export type Parser = (source: string, state?: ?State) => Array<SingleASTNode>;
 
 export type Capture =
   | (Array<string> & { +index: number, ... })
   | (Array<string> & { +index?: number, ... });
 
 export type SingleASTNode = {
   type: string,
   [string]: any,
 };
 
 export type ASTNode = SingleASTNode | Array<SingleASTNode>;
 
 type UnTypedASTNode = {
   [string]: any,
   ...
 };
 
 type MatchFunction = { regex?: RegExp, ... } & ((
   source: string,
   state: State,
   prevCapture: string,
 ) => ?Capture);
 
 export type ReactElement = React$Element<any>;
 type ReactElements = React$Node;
 
 export type Output<Result> = (node: ASTNode, state?: ?State) => Result;
 
 type ArrayNodeOutput<Result> = (
   node: Array<SingleASTNode>,
   nestedOutput: Output<Result>,
   state: State,
 ) => Result;
 
 type ArrayRule = {
   +react?: ArrayNodeOutput<ReactElements>,
   +html?: ArrayNodeOutput<string>,
   +[string]: ArrayNodeOutput<any>,
 };
 
 type ParseFunction = (
   capture: Capture,
   nestedParse: Parser,
   state: State,
 ) => UnTypedASTNode | ASTNode;
 
 type ParserRule = {
   +order: number,
   +match: MatchFunction,
   +quality?: (capture: Capture, state: State, prevCapture: string) => number,
   +parse: ParseFunction,
   ...
 };
 
 export type ParserRules = {
   +Array?: ArrayRule,
   +[type: string]: ParserRule,
   ...
 };
 
 const paragraphRegex: RegExp = /^((?:[^\n]*)(?:\n|$))/;
 const paragraphStripTrailingNewlineRegex: RegExp = /^([^\n]*)(?:\n|$)/;
 
 const headingRegex: RegExp = /^ *(#{1,6}) ([^\n]+?)#* *(?![^\n])/;
 const headingStripFollowingNewlineRegex: RegExp =
   /^ *(#{1,6}) ([^\n]+?)#* *(?:\n|$)/;
 
 const fenceRegex: RegExp = /^(`{3,}|~{3,})[^\n]*\n([\s\S]*?\n)\1(?:\n|$)/;
 const fenceStripTrailingNewlineRegex: RegExp =
   /^(`{3,}|~{3,})[^\n]*\n([\s\S]*?)\n\1(?:\n|$)/;
 
 const codeBlockRegex: RegExp = /^(?: {4}[^\n]*\n*?)+(?!\n* {4}[^\n])(?:\n|$)/;
 const codeBlockStripTrailingNewlineRegex: RegExp =
   /^((?: {4}[^\n]*\n*?)+)(?!\n* {4}[^\n])(?:\n|$)/;
 
 const urlRegex: RegExp = /^(https?:\/\/[^\s<]+[^<.,:;"')\]\s])/i;
 
 export type JSONCapture = Array<string> & {
   +json: Object,
   +index?: void,
   ...
 };
 function jsonMatch(source: string): ?JSONCapture {
   if (!source.startsWith('{')) {
     return null;
   }
 
   let jsonString = '';
   let counter = 0;
   for (let i = 0; i < source.length; i++) {
     const char = source[i];
     jsonString += char;
     if (char === '{') {
       counter++;
     } else if (char === '}') {
       counter--;
     }
     if (counter === 0) {
       break;
     }
   }
   if (counter !== 0) {
     return null;
   }
 
   let json;
   try {
     json = JSON.parse(jsonString);
   } catch {
     return null;
   }
   if (!json || typeof json !== 'object') {
     return null;
   }
 
   return { ...([jsonString]: any), json };
 }
 
 function jsonPrint(capture: JSONCapture): string {
   return JSON.stringify(capture.json, null, '  ');
 }
 
 const listRegex = /^( *)([*+-]|\d+\.) ([\s\S]+?)(?:\n{2}|\s*\n*$)/;
 const listItemRegex =
   /^( *)([*+-]|\d+\.) [^\n]*(?:\n(?!\1(?:[*+-]|\d+\.) )[^\n]*)*(\n|$)/gm;
 const listItemPrefixRegex = /^( *)([*+-]|\d+\.) /;
 const listLookBehindRegex = /(?:^|\n)( *)$/;
 
 function matchList(source: string, state: State): RegExp$matchResult | null {
   if (state.inline) {
     return null;
   }
   const prevCaptureStr = state.prevCapture ? state.prevCapture[0] : '';
   const isStartOfLineCapture = listLookBehindRegex.exec(prevCaptureStr);
   if (!isStartOfLineCapture) {
     return null;
   }
   const fullSource = isStartOfLineCapture[1] + source;
   return listRegex.exec(fullSource);
 }
 
 // We've defined our own parse function for lists because simple-markdown
 // handles newlines differently. Outside of that our implementation is fairly
 // similar. For more details about list parsing works, take a look at the
 // comments in the simple-markdown package
 function parseList(
   capture: Capture,
   parse: Parser,
   state: State,
 ): UnTypedASTNode {
   const bullet = capture[2];
   const ordered = bullet.length > 1;
   const start = ordered ? Number(bullet) : undefined;
   const items = capture[0].match(listItemRegex);
 
   let itemContent = null;
   if (items) {
     itemContent = items.map((item: string) => {
       const prefixCapture = listItemPrefixRegex.exec(item);
       const space = prefixCapture ? prefixCapture[0].length : 0;
       const spaceRegex = new RegExp('^ {1,' + space + '}', 'gm');
       const content: string = item
         .replace(spaceRegex, '')
         .replace(listItemPrefixRegex, '');
       // We're handling this different than simple-markdown -
       // each item is a paragraph
       return parse(content, state);
     });
   }
 
   return {
     ordered: ordered,
     start: start,
     items: itemContent,
   };
 }
 
 function matchMentions(
   members: $ReadOnlyArray<RelativeMemberInfo>,
 ): MatchFunction {
   const memberSet = new Set(
     members
       .filter(({ role }) => role)
       .map(({ username }) => username?.toLowerCase())
       .filter(Boolean),
   );
   const match = (source: string, state: State) => {
     if (!state.inline) {
       return null;
     }
     const result = markdownMentionRegex.exec(source);
     if (!result) {
       return null;
     }
     const username = result[2];
     invariant(username, 'markdownMentionRegex should match two capture groups');
     if (!memberSet.has(username.toLowerCase())) {
       return null;
     }
     return result;
   };
   match.regex = markdownMentionRegex;
   return match;
 }
 
+function parseChatMention(
+  chatMentionCandidates: ChatMentionCandidates,
+  capture: Capture,
+): {
+  threadInfo: ?ResolvedThreadInfo,
+  content: string,
+  hasAccessToChat: boolean,
+} {
+  const threadInfo = chatMentionCandidates[capture[2]];
+  const threadName = threadInfo?.uiName ?? decodeChatMentionText(capture[3]);
+  const content = `@${threadName}`;
+  return {
+    threadInfo,
+    content,
+    hasAccessToChat: !!threadInfo,
+  };
+}
+
 const blockQuoteRegex: RegExp = /^( *>[^\n]+(?:\n[^\n]+)*)(?:\n|$)/;
 const blockQuoteStripFollowingNewlineRegex: RegExp =
   /^( *>[^\n]+(?:\n[^\n]+)*)(?:\n|$){2}/;
 const maxNestedQuotations = 5;
 
 // Custom match and parse functions implementation for block quotes
 // to allow us to specify quotes parsing depth
 // to avoid too many recursive calls and e.g. app crash
 function matchBlockQuote(quoteRegex: RegExp): MatchFunction {
   return (source: string, state: State) => {
     if (
       state.inline ||
       (state?.quotationsDepth && state.quotationsDepth >= maxNestedQuotations)
     ) {
       return null;
     }
     return quoteRegex.exec(source);
   };
 }
 
 function parseBlockQuote(
   capture: Capture,
   parse: Parser,
   state: State,
 ): UnTypedASTNode {
   const content = capture[1].replace(/^ *> ?/gm, '');
   const currentQuotationsDepth = state?.quotationsDepth ?? 0;
   return {
     content: parse(content, {
       ...state,
       quotationsDepth: currentQuotationsDepth + 1,
     }),
   };
 }
 
 const spoilerRegex: RegExp = /^\|\|([^\n]+?)\|\|/g;
 const replaceSpoilerRegex: RegExp = /\|\|(.+?)\|\|/g;
 const spoilerReplacement: string = '⬛⬛⬛';
 
 const stripSpoilersFromNotifications = (text: string): string =>
   text.replace(replaceSpoilerRegex, spoilerReplacement);
 
 function stripSpoilersFromMarkdownAST(ast: SingleASTNode[]): SingleASTNode[] {
   // Either takes top-level AST, or array of nodes under an items node (list)
   return ast.map(replaceSpoilersFromMarkdownAST);
 }
 
 function replaceSpoilersFromMarkdownAST(node: SingleASTNode): SingleASTNode {
   const { content, items, type } = node;
   if (typeof content === 'string') {
     // Base case (leaf node)
     return node;
   } else if (type === 'spoiler') {
     // The actual point of this function: replacing the spoilers
     return {
       type: 'text',
       content: spoilerReplacement,
     };
   } else if (content) {
     // Common case... most nodes nest children with content
     // If content isn't a string, it should be an array
     return {
       ...node,
       content: stripSpoilersFromMarkdownAST(content),
     };
   } else if (items) {
     // Special case for lists, which has a nested array of arrays within items
     return {
       ...node,
       items: items.map(stripSpoilersFromMarkdownAST),
     };
   }
   throw new Error(
     `unexpected Markdown node of type ${type} with no content or items`,
   );
 }
 
 export {
   paragraphRegex,
   paragraphStripTrailingNewlineRegex,
   urlRegex,
   blockQuoteRegex,
   blockQuoteStripFollowingNewlineRegex,
   headingRegex,
   headingStripFollowingNewlineRegex,
   codeBlockRegex,
   codeBlockStripTrailingNewlineRegex,
   fenceRegex,
   fenceStripTrailingNewlineRegex,
   spoilerRegex,
   matchBlockQuote,
   parseBlockQuote,
   jsonMatch,
   jsonPrint,
   matchList,
   parseList,
   matchMentions,
   stripSpoilersFromNotifications,
   stripSpoilersFromMarkdownAST,
+  parseChatMention,
 };
diff --git a/lib/shared/mention-utils.js b/lib/shared/mention-utils.js
index 51f028489..273c491ff 100644
--- a/lib/shared/mention-utils.js
+++ b/lib/shared/mention-utils.js
@@ -1,120 +1,130 @@
 // @flow
 
 import { oldValidUsernameRegexString } from './account-utils.js';
 import SearchIndex from './search-index.js';
-import { threadOtherMembers } from './thread-utils.js';
+import { threadOtherMembers, chatNameMaxLength } from './thread-utils.js';
 import { stringForUserExplicit } from './user-utils.js';
 import { threadTypes } from '../types/thread-types-enum.js';
 import {
   type ThreadInfo,
   type RelativeMemberInfo,
 } from '../types/thread-types.js';
+import { idSchemaRegex } from '../utils/validation-utils.js';
 
 export type TypeaheadMatchedStrings = {
   +textBeforeAtSymbol: string,
   +usernamePrefix: string,
 };
 
 export type Selection = {
   +start: number,
   +end: number,
 };
 
 // The simple-markdown package already breaks words out for us, and we are
 // supposed to only match when the first word of the input matches
 const markdownMentionRegex: RegExp = new RegExp(
   `^(@(${oldValidUsernameRegexString}))\\b`,
 );
 
 function isMentioned(username: string, text: string): boolean {
   return new RegExp(`\\B@${username}\\b`, 'i').test(text);
 }
 
 const mentionsExtractionRegex = new RegExp(
   `\\B(@(${oldValidUsernameRegexString}))\\b`,
   'g',
 );
 
+const chatMentionRegexString = `^(?<!\\\\)(@\\[\\[(${idSchemaRegex}):(.{1,${chatNameMaxLength}}?)(?<!\\\\)\\]\\])`;
+const chatMentionRegex: RegExp = new RegExp(chatMentionRegexString);
+
+function decodeChatMentionText(text: string): string {
+  return text.replace(/\\]/g, ']');
+}
+
 function extractMentionsFromText(text: string): string[] {
   const iterator = text.matchAll(mentionsExtractionRegex);
   return [...iterator].map(matches => matches[2]);
 }
 
 function getTypeaheadRegexMatches(
   text: string,
   selection: Selection,
   regex: RegExp,
 ): null | RegExp$matchResult {
   if (
     selection.start === selection.end &&
     (selection.start === text.length || /\s/.test(text[selection.end]))
   ) {
     return text.slice(0, selection.start).match(regex);
   }
   return null;
 }
 
 function getTypeaheadUserSuggestions(
   userSearchIndex: SearchIndex,
   threadMembers: $ReadOnlyArray<RelativeMemberInfo>,
   viewerID: ?string,
   usernamePrefix: string,
 ): $ReadOnlyArray<RelativeMemberInfo> {
   const userIDs = userSearchIndex.getSearchResults(usernamePrefix);
   const usersInThread = threadOtherMembers(threadMembers, viewerID);
 
   return usersInThread
     .filter(user => usernamePrefix.length === 0 || userIDs.includes(user.id))
     .sort((userA, userB) =>
       stringForUserExplicit(userA).localeCompare(stringForUserExplicit(userB)),
     );
 }
 
 function getNewTextAndSelection(
   textBeforeAtSymbol: string,
   entireText: string,
   usernamePrefix: string,
   user: RelativeMemberInfo,
 ): {
   newText: string,
   newSelectionStart: number,
 } {
   const totalMatchLength =
     textBeforeAtSymbol.length + usernamePrefix.length + 1; // 1 for @ char
 
   let newSuffixText = entireText.slice(totalMatchLength);
   newSuffixText = (newSuffixText[0] !== ' ' ? ' ' : '') + newSuffixText;
 
   const newText =
     textBeforeAtSymbol + '@' + stringForUserExplicit(user) + newSuffixText;
 
   const newSelectionStart = newText.length - newSuffixText.length + 1;
 
   return { newText, newSelectionStart };
 }
 
 function getMentionsCandidates(
   threadInfo: ThreadInfo,
   parentThreadInfo: ?ThreadInfo,
 ): $ReadOnlyArray<RelativeMemberInfo> {
   if (threadInfo.type !== threadTypes.SIDEBAR) {
     return threadInfo.members;
   }
   if (parentThreadInfo) {
     return parentThreadInfo.members;
   }
   // This scenario should not occur unless the user logs out while looking at a
   // sidebar. In that scenario, the Redux store may be cleared before ReactNav
   // finishes transitioning away from the previous screen
   return [];
 }
 
 export {
   markdownMentionRegex,
   isMentioned,
   extractMentionsFromText,
   getTypeaheadUserSuggestions,
   getNewTextAndSelection,
   getTypeaheadRegexMatches,
   getMentionsCandidates,
+  chatMentionRegex,
+  decodeChatMentionText,
 };