Merge pull request #6658 from matrix-org/gsouquet/threaded-messaging-2349

src/MatrixClientPeg.ts

@@ -213,6 +213,7 @@ class MatrixClientPegClass implements IMatrixClientPeg {
         opts.pendingEventOrdering = PendingEventOrdering.Detached;
         opts.lazyLoadMembers = true;
         opts.clientWellKnownPollPeriod = 2 * 60 * 60; // 2 hours
+        opts.experimentalThreadSupport = SettingsStore.getValue("feature_thread");
 
         // Connect the matrix client to the dispatcher and setting handlers
         MatrixActionCreators.start(this.matrixClient);

src/components/structures/MessagePanel.tsx

@@ -173,6 +173,8 @@ interface IProps {
     onUnfillRequest?(backwards: boolean, scrollToken: string): void;
 
     getRelationsForEvent?(eventId: string, relationType: string, eventType: string): Relations;
+
+    hideThreadedMessages?: boolean;
 }
 
 interface IState {
@@ -265,6 +267,9 @@ export default class MessagePanel extends React.Component<IProps, IState> {
     componentDidMount() {
         this.calculateRoomMembersCount();
         this.props.room?.on("RoomState.members", this.calculateRoomMembersCount);
+        if (SettingsStore.getValue("feature_thread")) {
+            this.props.room?.getThreads().forEach(thread => thread.fetchReplyChain());
+        }
         this.isMounted = true;
     }
 
@@ -443,6 +448,12 @@ export default class MessagePanel extends React.Component<IProps, IState> {
         // Always show highlighted event
         if (this.props.highlightedEventId === mxEv.getId()) return true;
 
+        if (mxEv.replyEventId
+                && this.props.hideThreadedMessages
+                && SettingsStore.getValue("feature_thread")) {
+            return false;
+        }
+
         return !shouldHideEvent(mxEv, this.context);
     }
 

src/components/structures/RightPanel.tsx

@@ -45,17 +45,21 @@ import GroupRoomInfo from "../views/groups/GroupRoomInfo";
 import UserInfo from "../views/right_panel/UserInfo";
 import ThirdPartyMemberInfo from "../views/rooms/ThirdPartyMemberInfo";
 import FilePanel from "./FilePanel";
+import ThreadView from "./ThreadView";
+import ThreadPanel from "./ThreadPanel";
 import NotificationPanel from "./NotificationPanel";
 import ResizeNotifier from "../../utils/ResizeNotifier";
 import PinnedMessagesCard from "../views/right_panel/PinnedMessagesCard";
 import { throttle } from 'lodash';
 import SpaceStore from "../../stores/SpaceStore";
+import { RoomPermalinkCreator } from '../../utils/permalinks/Permalinks';
 
 interface IProps {
     room?: Room; // if showing panels for a given room, this is set
     groupId?: string; // if showing panels for a given group, this is set
     user?: User; // used if we know the user ahead of opening the panel
     resizeNotifier: ResizeNotifier;
+    permalinkCreator?: RoomPermalinkCreator;
 }
 
 interface IState {
@@ -309,6 +313,22 @@ export default class RightPanel extends React.Component<IProps, IState> {
                 panel = <FilePanel roomId={roomId} resizeNotifier={this.props.resizeNotifier} onClose={this.onClose} />;
                 break;
 
+            case RightPanelPhases.ThreadView:
+                panel = <ThreadView
+                    room={this.props.room}
+                    resizeNotifier={this.props.resizeNotifier}
+                    onClose={this.onClose}
+                    mxEvent={this.state.event}
+                    permalinkCreator={this.props.permalinkCreator} />;
+                break;
+
+            case RightPanelPhases.ThreadPanel:
+                panel = <ThreadPanel
+                    roomId={roomId}
+                    resizeNotifier={this.props.resizeNotifier}
+                    onClose={this.onClose} />;
+                break;
+
             case RightPanelPhases.RoomSummary:
                 panel = <RoomSummaryCard room={this.props.room} onClose={this.onClose} />;
                 break;

src/components/structures/RoomView.tsx

@@ -2052,7 +2052,10 @@ export default class RoomView extends React.Component<IProps, IState> {
 
         const showRightPanel = this.state.room && this.state.showRightPanel;
         const rightPanel = showRightPanel
-            ? <RightPanel room={this.state.room} resizeNotifier={this.props.resizeNotifier} />
+            ? <RightPanel
+                room={this.state.room}
+                resizeNotifier={this.props.resizeNotifier}
+                permalinkCreator={this.getPermalinkCreatorForRoom(this.state.room)} />
             : null;
 
         const timelineClasses = classNames("mx_RoomView_timeline", {

src/components/structures/ThreadPanel.tsx

@@ -0,0 +1,93 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from 'react';
+import { MatrixEvent, Room } from 'matrix-js-sdk/src';
+import { Thread } from 'matrix-js-sdk/src/models/thread';
+
+import BaseCard from "../views/right_panel/BaseCard";
+import { RightPanelPhases } from "../../stores/RightPanelStorePhases";
+import { replaceableComponent } from "../../utils/replaceableComponent";
+import { MatrixClientPeg } from '../../MatrixClientPeg';
+
+import ResizeNotifier from '../../utils/ResizeNotifier';
+import EventTile from '../views/rooms/EventTile';
+
+interface IProps {
+    roomId: string;
+    onClose: () => void;
+    resizeNotifier: ResizeNotifier;
+}
+
+interface IState {
+    threads?: Thread[];
+}
+
+@replaceableComponent("structures.ThreadView")
+export default class ThreadPanel extends React.Component<IProps, IState> {
+    private room: Room;
+
+    constructor(props: IProps) {
+        super(props);
+        this.room = MatrixClientPeg.get().getRoom(this.props.roomId);
+    }
+
+    public componentDidMount(): void {
+        this.room.on("Thread.update", this.onThreadEventReceived);
+        this.room.on("Thread.ready", this.onThreadEventReceived);
+    }
+
+    public componentWillUnmount(): void {
+        this.room.removeListener("Thread.update", this.onThreadEventReceived);
+        this.room.removeListener("Thread.ready", this.onThreadEventReceived);
+    }
+
+    private onThreadEventReceived = () => this.updateThreads();
+
+    private updateThreads = (callback?: () => void): void => {
+        this.setState({
+            threads: this.room.getThreads(),
+        }, callback);
+    };
+
+    private renderEventTile(event: MatrixEvent): JSX.Element {
+        return <EventTile
+            key={event.getId()}
+            mxEvent={event}
+            enableFlair={false}
+            showReadReceipts={false}
+            as="div"
+        />;
+    }
+
+    public render(): JSX.Element {
+        return (
+            <BaseCard
+                className="mx_ThreadPanel"
+                onClose={this.props.onClose}
+                previousPhase={RightPanelPhases.RoomSummary}
+            >
+                {
+                    this.state?.threads.map((thread: Thread) => {
+                        if (thread.ready) {
+                            return this.renderEventTile(thread.rootEvent);
+                        }
+                    })
+                }
+            </BaseCard>
+        );
+    }
+}

src/components/structures/ThreadView.tsx

@@ -0,0 +1,147 @@
+/*
+Copyright 2021 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import React from 'react';
+import { MatrixEvent, Room } from 'matrix-js-sdk/src';
+import { Thread } from 'matrix-js-sdk/src/models/thread';
+
+import BaseCard from "../views/right_panel/BaseCard";
+import { RightPanelPhases } from "../../stores/RightPanelStorePhases";
+import { replaceableComponent } from "../../utils/replaceableComponent";
+
+import ResizeNotifier from '../../utils/ResizeNotifier';
+import { TileShape } from '../views/rooms/EventTile';
+import MessageComposer from '../views/rooms/MessageComposer';
+import { RoomPermalinkCreator } from '../../utils/permalinks/Permalinks';
+import { Layout } from '../../settings/Layout';
+import TimelinePanel from './TimelinePanel';
+import dis from "../../dispatcher/dispatcher";
+import { ActionPayload } from '../../dispatcher/payloads';
+import { SetRightPanelPhasePayload } from '../../dispatcher/payloads/SetRightPanelPhasePayload';
+import { Action } from '../../dispatcher/actions';
+
+interface IProps {
+    room: Room;
+    onClose: () => void;
+    resizeNotifier: ResizeNotifier;
+    mxEvent: MatrixEvent;
+    permalinkCreator?: RoomPermalinkCreator;
+}
+
+interface IState {
+    replyToEvent?: MatrixEvent;
+    thread?: Thread;
+}
+
+@replaceableComponent("structures.ThreadView")
+export default class ThreadView extends React.Component<IProps, IState> {
+    private dispatcherRef: string;
+
+    constructor(props: IProps) {
+        super(props);
+        this.state = {};
+    }
+
+    public componentDidMount(): void {
+        this.setupThread(this.props.mxEvent);
+        this.dispatcherRef = dis.register(this.onAction);
+    }
+
+    public componentWillUnmount(): void {
+        this.teardownThread();
+        dis.unregister(this.dispatcherRef);
+    }
+
+    public componentDidUpdate(prevProps) {
+        if (prevProps.mxEvent !== this.props.mxEvent) {
+            this.teardownThread();
+            this.setupThread(this.props.mxEvent);
+        }
+
+        if (prevProps.room !== this.props.room) {
+            dis.dispatch<SetRightPanelPhasePayload>({
+                action: Action.SetRightPanelPhase,
+                phase: RightPanelPhases.RoomSummary,
+            });
+        }
+    }
+
+    private onAction = (payload: ActionPayload): void => {
+        if (payload.phase == RightPanelPhases.ThreadView && payload.event) {
+            if (payload.event !== this.props.mxEvent) {
+                this.teardownThread();
+                this.setupThread(payload.event);
+            }
+        }
+    };
+
+    private setupThread = (mxEv: MatrixEvent) => {
+        const thread = mxEv.getThread();
+        if (thread) {
+            thread.on("Thread.update", this.updateThread);
+            thread.once("Thread.ready", this.updateThread);
+            this.updateThread(thread);
+        }
+    };
+
+    private teardownThread = () => {
+        if (this.state.thread) {
+            this.state.thread.removeListener("Thread.update", this.updateThread);
+            this.state.thread.removeListener("Thread.ready", this.updateThread);
+        }
+    };
+
+    private updateThread = (thread?: Thread) => {
+        if (thread) {
+            this.setState({ thread });
+        } else {
+            this.forceUpdate();
+        }
+    };
+
+    public render(): JSX.Element {
+        return (
+            <BaseCard
+                className="mx_ThreadView"
+                onClose={this.props.onClose}
+                previousPhase={RightPanelPhases.RoomSummary}
+                withoutScrollContainer={true}
+            >
+                { this.state.thread && (
+                    <TimelinePanel
+                        manageReadReceipts={false}
+                        manageReadMarkers={false}
+                        timelineSet={this.state?.thread?.timelineSet}
+                        showUrlPreview={false}
+                        tileShape={TileShape.Notif}
+                        empty={<div>empty</div>}
+                        alwaysShowTimestamps={true}
+                        layout={Layout.Group}
+                        hideThreadedMessages={false}
+                    />
+                ) }
+                <MessageComposer
+                    room={this.props.room}
+                    resizeNotifier={this.props.resizeNotifier}
+                    replyToEvent={this.state?.thread?.replyToEvent}
+                    showReplyPreview={false}
+                    permalinkCreator={this.props.permalinkCreator}
+                    compact={true}
+                />
+            </BaseCard>
+        );
+    }
+}

src/components/structures/TimelinePanel.tsx

@@ -126,6 +126,8 @@ interface IProps {
 
     // callback which is called when we wish to paginate the timeline window.
     onPaginationRequest?(timelineWindow: TimelineWindow, direction: string, size: number): Promise<boolean>;
+
+    hideThreadedMessages?: boolean;
 }
 
 interface IState {
@@ -214,6 +216,7 @@ class TimelinePanel extends React.Component<IProps, IState> {
         timelineCap: Number.MAX_VALUE,
         className: 'mx_RoomView_messagePanel',
         sendReadReceiptOnLoad: true,
+        hideThreadedMessages: true,
     };
 
     private lastRRSentEventId: string = undefined;
@@ -1511,6 +1514,7 @@ class TimelinePanel extends React.Component<IProps, IState> {
                 showReactions={this.props.showReactions}
                 layout={this.props.layout}
                 enableFlair={SettingsStore.getValue(UIFeature.Flair)}
+                hideThreadedMessages={this.props.hideThreadedMessages}
             />
         );
     }

src/components/views/messages/MessageActionBar.js

@@ -23,6 +23,8 @@ import { EventStatus } from 'matrix-js-sdk/src/models/event';
 import { _t } from '../../../languageHandler';
 import * as sdk from '../../../index';
 import dis from '../../../dispatcher/dispatcher';
+import { Action } from '../../../dispatcher/actions';
+import { RightPanelPhases } from '../../../stores/RightPanelStorePhases';
 import { aboveLeftOf, ContextMenu, ContextMenuTooltipButton, useContextMenu } from '../../structures/ContextMenu';
 import { isContentActionable, canEditContent } from '../../../utils/EventUtils';
 import RoomContext from "../../../contexts/RoomContext";
@@ -34,6 +36,7 @@ import Resend from "../../../Resend";
 import { MatrixClientPeg } from "../../../MatrixClientPeg";
 import { MediaEventHelper } from "../../../utils/MediaEventHelper";
 import DownloadActionButton from "./DownloadActionButton";
+import SettingsStore from '../../../settings/SettingsStore';
 
 const OptionsButton = ({ mxEvent, getTile, getReplyThread, permalinkCreator, onFocusChange }) => {
     const [menuDisplayed, button, openMenu, closeMenu] = useContextMenu();
@@ -170,6 +173,17 @@ export default class MessageActionBar extends React.PureComponent {
         });
     };
 
+    onThreadClick = () => {
+        dis.dispatch({
+            action: Action.SetRightPanelPhase,
+            phase: RightPanelPhases.ThreadView,
+            allowClose: false,
+            refireParams: {
+                event: this.props.mxEvent,
+            },
+        });
+    }
+
     onEditClick = (ev) => {
         dis.dispatch({
             action: 'edit_event',
@@ -254,12 +268,22 @@ export default class MessageActionBar extends React.PureComponent {
                 // The only catch is we do the reply button first so that we can make sure the react
                 // button is the very first button without having to do length checks for `splice()`.
                 if (this.context.canReply) {
-                    toolbarOpts.splice(0, 0, <RovingAccessibleTooltipButton
-                        className="mx_MessageActionBar_maskButton mx_MessageActionBar_replyButton"
-                        title={_t("Reply")}
-                        onClick={this.onReplyClick}
-                        key="reply"
-                    />);
+                    toolbarOpts.splice(0, 0, <>
+                        <RovingAccessibleTooltipButton
+                            className="mx_MessageActionBar_maskButton mx_MessageActionBar_replyButton"
+                            title={_t("Reply")}
+                            onClick={this.onReplyClick}
+                            key="reply"
+                        />
+                        { SettingsStore.getValue("feature_thread") && (
+                            <RovingAccessibleTooltipButton
+                                className="mx_MessageActionBar_maskButton mx_MessageActionBar_threadButton"
+                                title={_t("Thread")}
+                                onClick={this.onThreadClick}
+                                key="thread"
+                            />
+                        ) }
+                    </>);
                 }
                 if (this.context.canReact) {
                     toolbarOpts.splice(0, 0, <ReactButton

src/components/views/right_panel/RoomSummaryCard.tsx

@@ -220,6 +220,13 @@ const onRoomFilesClick = () => {
     });
 };
 
+const onRoomThreadsClick = () => {
+    defaultDispatcher.dispatch<SetRightPanelPhasePayload>({
+        action: Action.SetRightPanelPhase,
+        phase: RightPanelPhases.ThreadPanel,
+    });
+};
+
 const onRoomSettingsClick = () => {
     defaultDispatcher.dispatch({ action: "open_room_settings" });
 };
@@ -273,6 +280,11 @@ const RoomSummaryCard: React.FC<IProps> = ({ room, onClose }) => {
             <Button className="mx_RoomSummaryCard_icon_files" onClick={onRoomFilesClick}>
                 { _t("Show files") }
             </Button>
+            { SettingsStore.getValue("feature_thread") && (
+                <Button className="mx_RoomSummaryCard_icon_threads" onClick={onRoomThreadsClick}>
+                    { _t("Show threads") }
+                </Button>
+            ) }
             <Button className="mx_RoomSummaryCard_icon_share" onClick={onShareRoomClick}>
                 { _t("Share room") }
             </Button>

src/components/views/rooms/EventTile.tsx

@@ -21,6 +21,7 @@ import { EventType } from "matrix-js-sdk/src/@types/event";
 import { EventStatus, MatrixEvent } from "matrix-js-sdk/src/models/event";
 import { Relations } from "matrix-js-sdk/src/models/relations";
 import { RoomMember } from "matrix-js-sdk/src/models/room-member";
+import { Thread } from 'matrix-js-sdk/src/models/thread';
 
 import ReplyThread from "../elements/ReplyThread";
 import { _t } from '../../../languageHandler';
@@ -55,6 +56,8 @@ import ReadReceiptMarker from "./ReadReceiptMarker";
 import MessageActionBar from "../messages/MessageActionBar";
 import ReactionsRow from '../messages/ReactionsRow';
 import { getEventDisplayInfo } from '../../../utils/EventUtils';
+import { RightPanelPhases } from "../../../stores/RightPanelStorePhases";
+import SettingsStore from "../../../settings/SettingsStore";
 
 const eventTileTypes = {
     [EventType.RoomMessage]: 'messages.MessageEvent',
@@ -299,6 +302,9 @@ interface IProps {
 
     // whether or not to display the sender
     hideSender?: boolean;
+
+    // whether or not to display thread info
+    showThreadInfo?: boolean;
 }
 
 interface IState {
@@ -315,6 +321,8 @@ interface IState {
     reactions: Relations;
 
     hover: boolean;
+
+    thread?: Thread;
 }
 
 @replaceableComponent("views.rooms.EventTile")
@@ -351,6 +359,8 @@ export default class EventTile extends React.Component<IProps, IState> {
             reactions: this.getReactions(),
 
             hover: false,
+
+            thread: this.props.mxEvent?.getThread(),
         };
 
         // don't do RR animations until we are mounted
@@ -451,8 +461,20 @@ export default class EventTile extends React.Component<IProps, IState> {
             client.on("Room.receipt", this.onRoomReceipt);
             this.isListeningForReceipts = true;
         }
+
+        if (SettingsStore.getValue("feature_thread")) {
+            this.props.mxEvent.once("Thread.ready", this.updateThread);
+            this.props.mxEvent.on("Thread.update", this.updateThread);
+        }
     }
 
+    private updateThread = (thread) => {
+        this.setState({
+            thread,
+        });
+        this.forceUpdate();
+    };
+
     // TODO: [REACT-WARNING] Replace with appropriate lifecycle event
     // eslint-disable-next-line
     UNSAFE_componentWillReceiveProps(nextProps) {
@@ -463,7 +485,7 @@ export default class EventTile extends React.Component<IProps, IState> {
         }
     }
 
-    shouldComponentUpdate(nextProps, nextState) {
+    shouldComponentUpdate(nextProps, nextState, nextContext) {
         if (objectHasDiff(this.state, nextState)) {
             return true;
         }
@@ -491,6 +513,43 @@ export default class EventTile extends React.Component<IProps, IState> {
         }
     }
 
+    private renderThreadInfo(): React.ReactNode {
+        if (!SettingsStore.getValue("feature_thread")) {
+            return null;
+        }
+
+        const thread = this.state.thread;
+        const room = MatrixClientPeg.get().getRoom(this.props.mxEvent.getRoomId());
+        if (!thread || this.props.showThreadInfo === false) {
+            return null;
+        }
+
+        const avatars = Array.from(thread.participants).map((mxId: string) => {
+            const member = room.getMember(mxId);
+            return <MemberAvatar key={member.userId} member={member} width={14} height={14} />;
+        });
+
+        return (
+            <div
+                className="mx_ThreadInfo"
+                onClick={() => {
+                    dis.dispatch({
+                        action: Action.SetRightPanelPhase,
+                        phase: RightPanelPhases.ThreadView,
+                        refireParams: {
+                            event: this.props.mxEvent,
+                        },
+                    });
+                }}
+            >
+                <span className="mx_EventListSummary_avatars">
+                    { avatars }
+                </span>
+                { thread.length - 1 } { thread.length === 2 ? 'reply' : 'replies' }
+            </div>
+        );
+    }
+
     private onRoomReceipt = (ev, room) => {
         // ignore events for other rooms
         const tileRoom = MatrixClientPeg.get().getRoom(this.props.mxEvent.getRoomId());
@@ -1180,6 +1239,7 @@ export default class EventTile extends React.Component<IProps, IState> {
                             { keyRequestInfo }
                             { actionBar }
                             { this.props.layout === Layout.IRC && (reactionsRow) }
+                            { this.renderThreadInfo() }
                         </div>
                         { this.props.layout !== Layout.IRC && (reactionsRow) }
                         { msgOption }

src/components/views/rooms/MessageComposer.tsx

@@ -183,7 +183,9 @@ interface IProps {
     resizeNotifier: ResizeNotifier;
     permalinkCreator: RoomPermalinkCreator;
     replyToEvent?: MatrixEvent;
+    showReplyPreview?: boolean;
     e2eStatus?: E2EStatus;
+    compact?: boolean;
 }
 
 interface IState {
@@ -201,6 +203,11 @@ export default class MessageComposer extends React.Component<IProps, IState> {
     private messageComposerInput: SendMessageComposer;
     private voiceRecordingButton: VoiceRecordComposerTile;
 
+    static defaultProps = {
+        showReplyPreview: true,
+        compact: false,
+    };
+
     constructor(props) {
         super(props);
         VoiceRecordingStore.instance.on(UPDATE_EVENT, this.onVoiceStoreUpdate);
@@ -362,7 +369,7 @@ export default class MessageComposer extends React.Component<IProps, IState> {
 
     render() {
         const controls = [
-            this.state.me ? <ComposerAvatar key="controls_avatar" me={this.state.me} /> : null,
+            this.state.me && !this.props.compact ? <ComposerAvatar key="controls_avatar" me={this.state.me} /> : null,
             this.props.e2eStatus ?
                 <E2EIcon key="e2eIcon" status={this.props.e2eStatus} className="mx_MessageComposer_e2eIcon" /> :
                 null,
@@ -450,11 +457,19 @@ export default class MessageComposer extends React.Component<IProps, IState> {
             />;
         }
 
+        const classes = classNames({
+            "mx_MessageComposer": true,
+            "mx_GroupLayout": true,
+            "mx_MessageComposer--compact": this.props.compact,
+        });
+
         return (
-            <div className="mx_MessageComposer mx_GroupLayout">
+            <div className={classes}>
                 { recordingTooltip }
                 <div className="mx_MessageComposer_wrapper">
-                    <ReplyPreview permalinkCreator={this.props.permalinkCreator} />
+                    { this.props.showReplyPreview && (
+                        <ReplyPreview permalinkCreator={this.props.permalinkCreator} />
+                    ) }
                     <div className="mx_MessageComposer_row">
                         { controls }
                     </div>

src/i18n/strings/en_EN.json

@@ -806,6 +806,7 @@
     "Render LaTeX maths in messages": "Render LaTeX maths in messages",
     "Communities v2 prototypes. Requires compatible homeserver. Highly experimental - use with caution.": "Communities v2 prototypes. Requires compatible homeserver. Highly experimental - use with caution.",
     "Message Pinning": "Message Pinning",
+    "Threaded messaging": "Threaded messaging",
     "Custom user status messages": "Custom user status messages",
     "Group & filter rooms by custom tags (refresh to apply changes)": "Group & filter rooms by custom tags (refresh to apply changes)",
     "Render simple counters in room header": "Render simple counters in room header",
@@ -1803,6 +1804,7 @@
     "%(count)s people|other": "%(count)s people",
     "%(count)s people|one": "%(count)s person",
     "Show files": "Show files",
+    "Show threads": "Show threads",
     "Share room": "Share room",
     "Room settings": "Room settings",
     "Trusted": "Trusted",
@@ -1922,6 +1924,7 @@
     "React": "React",
     "Edit": "Edit",
     "Reply": "Reply",
+    "Thread": "Thread",
     "Message Actions": "Message Actions",
     "Download %(text)s": "Download %(text)s",
     "Error decrypting attachment": "Error decrypting attachment",

src/settings/Settings.tsx

@@ -211,6 +211,15 @@ export const SETTINGS: {[setting: string]: ISetting} = {
         supportedLevels: LEVELS_FEATURE,
         default: false,
     },
+    "feature_thread": {
+        isFeature: true,
+        // Requires a reload as we change an option flag on the `js-sdk`
+        // And the entire sync history needs to be parsed again
+        controller: new ReloadOnChangeController(),
+        displayName: _td("Threaded messaging"),
+        supportedLevels: LEVELS_FEATURE,
+        default: false,
+    },
     "feature_custom_status": {
         isFeature: true,
         displayName: _td("Custom user status messages"),

src/stores/RightPanelStorePhases.ts

@@ -37,6 +37,10 @@ export enum RightPanelPhases {
     SpaceMemberList = "SpaceMemberList",
     SpaceMemberInfo = "SpaceMemberInfo",
     Space3pidMemberInfo = "Space3pidMemberInfo",
+
+    // Thread stuff
+    ThreadView = "ThreadView",
+    ThreadPanel = "ThreadPanel",
 }
 
 // These are the phases that are safe to persist (the ones that don't require additional