Refactor EventTile using the MVVM pattern - #5a (#33587)

* Extract EventTile receipt state

* Extract EventTile thread state

* Extract EventTile reaction relation state

* Extract EventTile reply-chain state

* Keep reply chain collapse wiring in EventTile

* Reuse message event eligibility for receipts

apps/web/src/components/structures/MessagePanel.tsx

@@ -34,7 +34,6 @@ import { Layout } from "../../settings/enums/Layout";
 import EventTile, {
     type GetRelationsForEvent,
     type IReadReceiptProps,
-    isEligibleForSpecialReceipt,
     type UnwrappedEventTile,
 } from "../views/rooms/EventTile";
 import IRCTimelineProfileResizer from "../views/elements/IRCTimelineProfileResizer";
@@ -58,6 +57,7 @@ import { CreationGrouper } from "./grouper/CreationGrouper";
 import { _t } from "../../languageHandler";
 import { getLateEventInfo } from "./grouper/LateEventGrouper";
 import { DateSeparatorViewModel } from "../../viewmodels/room/timeline/DateSeparatorViewModel";
+import { isEligibleForSpecialReceipt } from "../../viewmodels/room/timeline/event-tile/EventTileReceiptState";
 
 const CONTINUATION_MAX_INTERVAL = 5 * 60 * 1000; // 5 minutes
 const continuedTypes = [EventType.Sticker, EventType.RoomMessage];

apps/web/src/components/views/rooms/EventTile.tsx

@@ -26,9 +26,7 @@ import {
     EventType,
     type MatrixEvent,
     MatrixEventEvent,
-    type NotificationCountType,
     type Relations,
-    type RelationType,
     type Room,
     RelationsEvent,
     RoomEvent,
@@ -89,7 +87,6 @@ import { MediaEventHelper } from "../../../utils/MediaEventHelper";
 import { copyPlaintext } from "../../../utils/strings";
 import { DecryptionFailureTracker } from "../../../DecryptionFailureTracker";
 import { type ViewRoomPayload } from "../../../dispatcher/payloads/ViewRoomPayload";
-import { shouldDisplayReply } from "../../../utils/Reply";
 import PosthogTrackers from "../../../PosthogTrackers";
 import { haveRendererForEvent, isMessageEvent, renderTile } from "../../../events/EventTileFactory";
 import ThreadSummary, { ThreadMessagePreview } from "./ThreadSummary";
@@ -105,6 +102,16 @@ import { E2eMessageSharedIcon } from "./EventTile/E2eMessageSharedIcon.tsx";
 import SettingsStore from "../../../settings/SettingsStore";
 import { CardContext } from "../right_panel/context";
 import { EventTileViewModel } from "../../../viewmodels/room/timeline/event-tile/EventTileViewModel";
+import {
+    getEventTileReceiptState,
+    type EventTileReceiptState,
+} from "../../../viewmodels/room/timeline/event-tile/EventTileReceiptState";
+import {
+    getEventTileThread,
+    getEventTileThreadState,
+    type EventTileThreadState,
+} from "../../../viewmodels/room/timeline/event-tile/EventTileThreadState";
+import { getEventTileReplyChainState } from "../../../viewmodels/room/timeline/event-tile/EventTileReplyChainState";
 import {
     eventTileActionBarFocusChange,
     eventTileBlurWithin,
@@ -126,6 +133,11 @@ import {
     MAX_ITEMS_WHEN_LIMITED,
     ReactionsRowViewModel,
 } from "../../../viewmodels/room/timeline/event-tile/reactions/ReactionsRowViewModel";
+import {
+    getEventTileReactionRelations,
+    isEventTileReactionRelation,
+    type GetRelationsForEvent,
+} from "../../../viewmodels/room/timeline/event-tile/reactions/EventTileReactionState";
 import { TileErrorViewModel } from "../../../viewmodels/message-body/TileErrorViewModel";
 import { EventTileActionBarViewModel } from "../../../viewmodels/room/EventTileActionBarViewModel";
 import { ThreadListActionBarViewModel } from "../../../viewmodels/room/ThreadListActionBarViewModel";
@@ -133,11 +145,8 @@ import { useMatrixClientContext } from "../../../contexts/MatrixClientContext";
 import { useSettingValue } from "../../../hooks/useSettings";
 import { DecryptionFailureBodyFactory, RedactedBodyFactory } from "../messages/MBodyFactory";
 
-export type GetRelationsForEvent = (
-    eventId: string,
-    relationType: RelationType | string,
-    eventType: EventType | string,
-) => Relations | null | undefined;
+/** Relation lookup type retained for EventTile consumers. */
+export type { GetRelationsForEvent } from "../../../viewmodels/room/timeline/event-tile/reactions/EventTileReactionState";
 
 // Our component structure for EventTiles on the timeline is:
 //
@@ -302,22 +311,6 @@ interface IState {
     isQuoteExpanded?: boolean;
 
     thread: Thread | null;
-    threadNotification?: NotificationCountType;
-}
-
-/**
- * When true, the tile qualifies for some sort of special read receipt.
- * This could be a 'sending' or 'sent' receipt, for example.
- * @returns {boolean}
- */
-export function isEligibleForSpecialReceipt(event: MatrixEvent): boolean {
-    // Determine if the type is relevant to the user.
-    // This notably excludes state events and pretty much anything that can't be sent by the composer as a message.
-    // For those we rely on local echo giving the impression of things changing, and expect them to be quick.
-    if (!isMessageEvent(event) && event.getType() !== EventType.RoomMessageEncrypted) return false;
-
-    // Default case
-    return true;
 }
 
 // MUST be rendered within a RoomContext with a set timelineRenderingType
@@ -344,7 +337,10 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
     public constructor(props: EventTileProps, context: React.ContextType<typeof RoomContext>) {
         super(props, context);
 
-        const thread = this.thread;
+        const thread = getEventTileThread(
+            this.props.mxEvent,
+            MatrixClientPeg.safeGet().getRoom(this.props.mxEvent.getRoomId()),
+        );
 
         this.state = {
             interaction: initialEventTileInteractionState,
@@ -369,62 +365,18 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
         this.isListeningForReceipts = false;
     }
 
-    /**
-     * When true, the tile qualifies for some sort of special read receipt. This could be a 'sending'
-     * or 'sent' receipt, for example.
-     * @returns {boolean}
-     */
-    private get isEligibleForSpecialReceipt(): boolean {
-        // First, if there are other read receipts then just short-circuit this.
-        if (this.props.readReceipts && this.props.readReceipts.length > 0) return false;
-        if (!this.props.mxEvent) return false;
+    private get receiptState(): EventTileReceiptState {
+        const client = MatrixClientPeg.safeGet();
 
-        // Sanity check (should never happen, but we shouldn't explode if it does)
-        const room = MatrixClientPeg.safeGet().getRoom(this.props.mxEvent.getRoomId());
-        if (!room) return false;
-
-        // Quickly check to see if the event was sent by us. If it wasn't, it won't qualify for
-        // special read receipts.
-        const myUserId = MatrixClientPeg.safeGet().getSafeUserId();
-        // Check to see if the event was sent by us. If it wasn't, it won't qualify for special read receipts.
-        if (this.props.mxEvent.getSender() !== myUserId) return false;
-        return isEligibleForSpecialReceipt(this.props.mxEvent);
-    }
-
-    private get shouldShowSentReceipt(): boolean {
-        // If we're not even eligible, don't show the receipt.
-        if (!this.isEligibleForSpecialReceipt) return false;
-
-        // We only show the 'sent' receipt on the last successful event.
-        if (!this.props.lastSuccessful) return false;
-
-        // Don't show this in the thread view as it conflicts with the thread counter.
-        if (this.context.timelineRenderingType === TimelineRenderingType.ThreadsList) return false;
-
-        // Check to make sure the sending state is appropriate. A null/undefined send status means
-        // that the message is 'sent', so we're just double checking that it's explicitly not sent.
-        if (this.props.eventSendStatus && this.props.eventSendStatus !== EventStatus.SENT) return false;
-
-        // If anyone has read the event besides us, we don't want to show a sent receipt.
-        const receipts = this.props.readReceipts || [];
-        const myUserId = MatrixClientPeg.safeGet().getUserId();
-        if (receipts.some((r) => r.userId !== myUserId)) return false;
-
-        // Finally, we should show a receipt.
-        return true;
-    }
-
-    private get shouldShowSendingReceipt(): boolean {
-        // If we're not even eligible, don't show the receipt.
-        if (!this.isEligibleForSpecialReceipt) return false;
-
-        // Check the event send status to see if we are pending. Null/undefined status means the
-        // message was sent, so check for that and 'sent' explicitly.
-        if (!this.props.eventSendStatus || this.props.eventSendStatus === EventStatus.SENT) return false;
-
-        // Default to showing - there's no other event properties/behaviours we care about at
-        // this point.
-        return true;
+        return getEventTileReceiptState({
+            mxEvent: this.props.mxEvent,
+            readReceipts: this.props.readReceipts,
+            hasRoom: !!client.getRoom(this.props.mxEvent.getRoomId()),
+            ownUserId: client.getSafeUserId(),
+            lastSuccessful: this.props.lastSuccessful,
+            eventSendStatus: this.props.eventSendStatus,
+            timelineRenderingType: this.context.timelineRenderingType,
+        });
     }
 
     public componentDidMount(): void {
@@ -440,7 +392,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
                 this.props.mxEvent.on(MatrixEventEvent.RelationsCreated, this.onReactionsCreated);
             }
 
-            if (this.shouldShowSentReceipt || this.shouldShowSendingReceipt) {
+            if (this.receiptState.shouldListenForReceipts) {
                 client.on(RoomEvent.Receipt, this.onRoomReceipt);
                 this.isListeningForReceipts = true;
             }
@@ -498,7 +450,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
         }
 
         // If we're not listening for receipts and expect to be, register a listener.
-        if (!this.isListeningForReceipts && (this.shouldShowSentReceipt || this.shouldShowSendingReceipt)) {
+        if (!this.isListeningForReceipts && this.receiptState.shouldListenForReceipts) {
             MatrixClientPeg.safeGet().on(RoomEvent.Receipt, this.onRoomReceipt);
             this.isListeningForReceipts = true;
         }
@@ -531,52 +483,46 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
         }
     };
 
-    private get thread(): Thread | null {
-        let thread: Thread | undefined = this.props.mxEvent.getThread();
-        /**
-         * Accessing the threads value through the room due to a race condition
-         * that will be solved when there are proper backend support for threads
-         * We currently have no reliable way to discover than an event is a thread
-         * when we are at the sync stage
-         */
-        if (!thread) {
-            const room = MatrixClientPeg.safeGet().getRoom(this.props.mxEvent.getRoomId());
-            thread = room?.findThreadForEvent(this.props.mxEvent) ?? undefined;
-        }
-        return thread ?? null;
+    private get threadState(): EventTileThreadState {
+        return getEventTileThreadState({
+            mxEvent: this.props.mxEvent,
+            thread: this.state.thread,
+            timelineRenderingType: this.context.timelineRenderingType,
+            highlightLink: this.props.highlightLink,
+        });
     }
 
-    private renderThreadPanelSummary(): JSX.Element | null {
-        if (!this.state.thread) {
+    private renderThreadPanelSummary(threadState: EventTileThreadState): JSX.Element | null {
+        if (!threadState.shouldShowThreadPanelSummary || !threadState.thread) {
             return null;
         }
 
         return (
             <div className="mx_ThreadPanel_replies">
                 <ThreadsIcon />
-                <span className="mx_ThreadPanel_replies_amount">{this.state.thread.length}</span>
-                <ThreadMessagePreview thread={this.state.thread} />
+                <span className="mx_ThreadPanel_replies_amount">{threadState.thread.length}</span>
+                <ThreadMessagePreview thread={threadState.thread} />
             </div>
         );
     }
 
-    private renderThreadInfo(): React.ReactNode {
-        if (this.state.thread && this.state.thread.id === this.props.mxEvent.getId()) {
+    private renderThreadInfo(threadState: EventTileThreadState): React.ReactNode {
+        if (threadState.shouldShowThreadSummary && threadState.thread) {
             return (
-                <ThreadSummary mxEvent={this.props.mxEvent} thread={this.state.thread} data-testid="thread-summary" />
+                <ThreadSummary mxEvent={this.props.mxEvent} thread={threadState.thread} data-testid="thread-summary" />
             );
         }
 
-        if (this.context.timelineRenderingType === TimelineRenderingType.Search && this.props.mxEvent.threadRootId) {
-            if (this.props.highlightLink) {
-                return (
-                    <a className="mx_ThreadSummary_icon" href={this.props.highlightLink}>
-                        <ThreadsIcon />
-                        {_t("timeline|thread_info_basic")}
-                    </a>
-                );
-            }
+        if (threadState.searchThreadInfo.kind === "link") {
+            return (
+                <a className="mx_ThreadSummary_icon" href={threadState.searchThreadInfo.href}>
+                    <ThreadsIcon />
+                    {_t("timeline|thread_info_basic")}
+                </a>
+            );
+        }
 
+        if (threadState.searchThreadInfo.kind === "text") {
             return (
                 <p className="mx_ThreadSummary_icon">
                     <ThreadsIcon />
@@ -608,7 +554,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
         const tileRoom = MatrixClientPeg.safeGet().getRoom(this.props.mxEvent.getRoomId());
         if (room !== tileRoom) return;
 
-        if (!this.shouldShowSentReceipt && !this.shouldShowSendingReceipt && !this.isListeningForReceipts) {
+        if (!this.receiptState.shouldListenForReceipts && !this.isListeningForReceipts) {
             return;
         }
 
@@ -616,7 +562,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
         // the getters we use here to determine what needs rendering.
         this.forceUpdate(() => {
             // Per elsewhere in this file, we can remove the listener once we will have no further purpose for it.
-            if (!this.shouldShowSentReceipt && !this.shouldShowSendingReceipt) {
+            if (!this.receiptState.shouldListenForReceipts) {
                 MatrixClientPeg.safeGet().removeListener(RoomEvent.Receipt, this.onRoomReceipt);
                 this.isListeningForReceipts = false;
             }
@@ -965,15 +911,15 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
     private readonly getReplyChain = (): ReplyChain | null => this.replyChain.current;
 
     private readonly getReactions = (): Relations | null => {
-        if (!this.props.showReactions || !this.props.getRelationsForEvent) {
-            return null;
-        }
-        const eventId = this.props.mxEvent.getId()!;
-        return this.props.getRelationsForEvent(eventId, "m.annotation", "m.reaction") ?? null;
+        return getEventTileReactionRelations({
+            mxEvent: this.props.mxEvent,
+            showReactions: this.props.showReactions,
+            getRelationsForEvent: this.props.getRelationsForEvent,
+        });
     };
 
     private readonly onReactionsCreated = (relationType: string, eventType: string): void => {
-        if (relationType !== "m.annotation" || eventType !== "m.reaction") {
+        if (!isEventTileReactionRelation(relationType, eventType)) {
             return;
         }
         this.setState({
@@ -1106,6 +1052,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
         const isEditing = !!this.props.editState;
         const hasPinnedMessageBadge = PinningUtils.isPinned(MatrixClientPeg.safeGet(), this.props.mxEvent);
         const hasReactionsRow = !isRedacted;
+        const threadState = this.threadState;
         // Use `getSender()` because searched events might not have a proper `sender`.
         const isOwnEvent = this.props.mxEvent?.getSender() === MatrixClientPeg.safeGet().getUserId();
 
@@ -1148,7 +1095,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
             timestamp: {
                 alwaysShowTimestamps: this.props.alwaysShowTimestamps,
                 hideTimestamp: this.props.hideTimestamp,
-                threadReplyEventTs: this.state.thread?.replyToEvent?.getTs(),
+                threadReplyEventTs: threadState.threadReplyEventTs,
             },
             footer: {
                 isOwnEvent,
@@ -1258,8 +1205,9 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
         const groupPadlock = !useIRCLayout && !isBubbleMessage && this.renderE2EPadlock();
         const ircPadlock = useIRCLayout && !isBubbleMessage && this.renderE2EPadlock();
 
+        const receiptState = this.receiptState;
         let msgOption: JSX.Element | undefined;
-        if (this.shouldShowSentReceipt || this.shouldShowSendingReceipt) {
+        if (receiptState.shouldShowSentReceipt || receiptState.shouldShowSendingReceipt) {
             msgOption = <SentReceipt messageState={this.props.eventSendStatus} />;
         } else if (this.props.showReadReceipts) {
             msgOption = (
@@ -1273,11 +1221,16 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
             );
         }
 
+        const replyChainState = getEventTileReplyChainState({
+            mxEvent: this.props.mxEvent,
+            hasRenderer: haveRendererForEvent(
+                this.props.mxEvent,
+                MatrixClientPeg.safeGet(),
+                this.context.showHiddenEvents,
+            ),
+        });
         let replyChain: JSX.Element | undefined;
-        if (
-            haveRendererForEvent(this.props.mxEvent, MatrixClientPeg.safeGet(), this.context.showHiddenEvents) &&
-            shouldDisplayReply(this.props.mxEvent)
-        ) {
+        if (replyChainState.shouldShowReplyChain) {
             replyChain = (
                 <ReplyChain
                     parentEv={this.props.mxEvent}
@@ -1434,7 +1387,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
                                     <EventPreview mxEvent={this.props.mxEvent} />
                                 )}
                             </div>
-                            {this.renderThreadPanelSummary()}
+                            {this.renderThreadPanelSummary(threadState)}
                         </div>
                         {this.context.timelineRenderingType === TimelineRenderingType.ThreadsList && (
                             <ThreadListActionBarWrapper
@@ -1547,7 +1500,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
                                             {reactionsRow}
                                         </div>
                                     )}
-                                    {this.renderThreadInfo()}
+                                    {this.renderThreadInfo(threadState)}
                                 </>
                             )}
                         </div>
@@ -1560,7 +1513,7 @@ export class UnwrappedEventTile extends React.Component<EventTileProps, IState>
                                         {showBubblePinnedMessageBadge && pinnedMessageBadge}
                                     </div>
                                 )}
-                                {this.renderThreadInfo()}
+                                {this.renderThreadInfo(threadState)}
                             </>
                         )}
                         {msgOption}

apps/web/src/viewmodels/room/timeline/event-tile/EventTileReceiptState.ts

@@ -0,0 +1,80 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { EventStatus, EventType, type MatrixEvent } from "matrix-js-sdk/src/matrix";
+
+import { TimelineRenderingType } from "../../../../contexts/RoomContext";
+import { isMessageEvent } from "../../../../events/EventTileFactory";
+
+interface ReadReceiptLike {
+    userId: string;
+}
+
+/** Inputs for deriving EventTile receipt display state. */
+export interface EventTileReceiptStateInput {
+    /** The Matrix event rendered by the tile. */
+    mxEvent: MatrixEvent;
+    /** Read receipts supplied for the tile. */
+    readReceipts?: ReadReceiptLike[];
+    /** Whether the event room is known locally. */
+    hasRoom: boolean;
+    /** Current user's safe user ID, used for sender eligibility. */
+    ownUserId: string;
+    /** Whether this is the last successful event sent by the current user. */
+    lastSuccessful?: boolean;
+    /** Current event send status. */
+    eventSendStatus?: EventStatus | null;
+    /** The current timeline rendering mode. */
+    timelineRenderingType: TimelineRenderingType;
+}
+
+/** EventTile receipt display state. */
+export interface EventTileReceiptState {
+    /** Whether the event is eligible for a sent/sending receipt. */
+    isEligibleForSpecialReceipt: boolean;
+    /** Whether EventTile should render the sent receipt. */
+    shouldShowSentReceipt: boolean;
+    /** Whether EventTile should render the sending receipt. */
+    shouldShowSendingReceipt: boolean;
+    /** Whether EventTile should listen for receipt updates. */
+    shouldListenForReceipts: boolean;
+}
+
+/**
+ * Whether the event type qualifies for a sent/sending receipt.
+ * This excludes state events and other events that are not sent by the composer.
+ */
+export function isEligibleForSpecialReceipt(mxEvent: MatrixEvent): boolean {
+    return isMessageEvent(mxEvent) || mxEvent.getType() === EventType.RoomMessageEncrypted;
+}
+
+/** Derives receipt display state for EventTile. */
+export function getEventTileReceiptState({
+    mxEvent,
+    readReceipts,
+    hasRoom,
+    ownUserId,
+    lastSuccessful,
+    eventSendStatus,
+    timelineRenderingType,
+}: EventTileReceiptStateInput): EventTileReceiptState {
+    const isEligible =
+        !readReceipts?.length && hasRoom && mxEvent.getSender() === ownUserId && isEligibleForSpecialReceipt(mxEvent);
+    const shouldShowSentReceipt =
+        isEligible &&
+        !!lastSuccessful &&
+        timelineRenderingType !== TimelineRenderingType.ThreadsList &&
+        (!eventSendStatus || eventSendStatus === EventStatus.SENT);
+    const shouldShowSendingReceipt = isEligible && !!eventSendStatus && eventSendStatus !== EventStatus.SENT;
+
+    return {
+        isEligibleForSpecialReceipt: isEligible,
+        shouldShowSentReceipt,
+        shouldShowSendingReceipt,
+        shouldListenForReceipts: shouldShowSentReceipt || shouldShowSendingReceipt,
+    };
+}

apps/web/src/viewmodels/room/timeline/event-tile/EventTileReplyChainState.ts

@@ -0,0 +1,34 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { type MatrixEvent } from "matrix-js-sdk/src/matrix";
+
+import { shouldDisplayReply } from "../../../../utils/Reply";
+
+/** Inputs for deriving EventTile reply-chain display state. */
+export interface EventTileReplyChainStateInput {
+    /** Matrix event rendered by the tile. */
+    mxEvent: MatrixEvent;
+    /** Whether the event has a renderer in the current timeline context. */
+    hasRenderer: boolean;
+}
+
+/** EventTile reply-chain display state. */
+export interface EventTileReplyChainState {
+    /** Whether EventTile should render ReplyChain. */
+    shouldShowReplyChain: boolean;
+}
+
+/** Derives reply-chain display state for EventTile. */
+export function getEventTileReplyChainState({
+    mxEvent,
+    hasRenderer,
+}: EventTileReplyChainStateInput): EventTileReplyChainState {
+    return {
+        shouldShowReplyChain: hasRenderer && shouldDisplayReply(mxEvent),
+    };
+}

apps/web/src/viewmodels/room/timeline/event-tile/EventTileThreadState.ts

@@ -0,0 +1,96 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { type MatrixEvent, type Thread } from "matrix-js-sdk/src/matrix";
+
+import { TimelineRenderingType } from "../../../../contexts/RoomContext";
+
+/** Minimal room surface used to look up a thread for an event. */
+export interface EventTileThreadLookup {
+    /** Finds the thread associated with an event. */
+    findThreadForEvent(mxEvent: MatrixEvent): Thread | null | undefined;
+}
+
+/** Search thread-info rendering kind. */
+export type SearchThreadInfoKind = "none" | "text" | "link";
+
+/** Search timeline thread-info display state. */
+export interface EventTileSearchThreadInfo {
+    /** Kind of search thread info to render. */
+    kind: SearchThreadInfoKind;
+    /** Link target when rendering linked thread info. */
+    href?: string;
+}
+
+/** Inputs for deriving EventTile thread display state. */
+export interface EventTileThreadStateInput {
+    /** Matrix event rendered by the tile. */
+    mxEvent: MatrixEvent;
+    /** Thread associated with the event, when available. */
+    thread: Thread | null;
+    /** Current timeline rendering mode. */
+    timelineRenderingType: TimelineRenderingType;
+    /** Optional search-result link for thread info. */
+    highlightLink?: string;
+}
+
+/** EventTile thread display state. */
+export interface EventTileThreadState {
+    /** Thread associated with the event, when available. */
+    thread: Thread | null;
+    /** Whether EventTile should render the main thread summary. */
+    shouldShowThreadSummary: boolean;
+    /** Whether EventTile should render the thread panel reply summary. */
+    shouldShowThreadPanelSummary: boolean;
+    /** Timestamp of the latest thread reply, when available. */
+    threadReplyEventTs?: number;
+    /** Search timeline thread-info display state. */
+    searchThreadInfo: EventTileSearchThreadInfo;
+}
+
+/**
+ * Finds the thread associated with an event.
+ *
+ * Accessing the thread through the room covers a race where the event has not
+ * discovered its thread yet during sync.
+ */
+export function getEventTileThread(mxEvent: MatrixEvent, room?: EventTileThreadLookup | null): Thread | null {
+    return mxEvent.getThread() ?? room?.findThreadForEvent(mxEvent) ?? null;
+}
+
+function getSearchThreadInfo(shouldShowSearchThreadInfo: boolean, highlightLink?: string): EventTileSearchThreadInfo {
+    if (!shouldShowSearchThreadInfo) {
+        return { kind: "none" };
+    }
+
+    if (highlightLink) {
+        return { kind: "link", href: highlightLink };
+    }
+
+    return { kind: "text" };
+}
+
+/** Derives thread display state for EventTile. */
+export function getEventTileThreadState({
+    mxEvent,
+    thread,
+    timelineRenderingType,
+    highlightLink,
+}: EventTileThreadStateInput): EventTileThreadState {
+    const shouldShowThreadSummary = !!thread && thread.id === mxEvent.getId();
+    const shouldShowSearchThreadInfo =
+        !shouldShowThreadSummary && timelineRenderingType === TimelineRenderingType.Search && !!mxEvent.threadRootId;
+    const searchThreadInfo = getSearchThreadInfo(shouldShowSearchThreadInfo, highlightLink);
+
+    return {
+        thread,
+        shouldShowThreadSummary,
+        shouldShowThreadPanelSummary: !!thread,
+        threadReplyEventTs: thread?.replyToEvent?.getTs(),
+        searchThreadInfo,
+    };
+}

apps/web/src/viewmodels/room/timeline/event-tile/reactions/EventTileReactionState.ts

@@ -0,0 +1,52 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { EventType, type MatrixEvent, type Relations, type RelationType } from "matrix-js-sdk/src/matrix";
+
+/** Looks up relations for an event by relation and event type. */
+export type GetRelationsForEvent = (
+    eventId: string,
+    relationType: RelationType | string,
+    eventType: EventType | string,
+) => Relations | null | undefined;
+
+/** Inputs for fetching EventTile reaction relations. */
+export interface EventTileReactionRelationsInput {
+    /** Matrix event rendered by the tile. */
+    mxEvent: MatrixEvent;
+    /** Whether reactions are enabled for the tile. */
+    showReactions?: boolean;
+    /** Relation lookup function supplied by the timeline. */
+    getRelationsForEvent?: GetRelationsForEvent;
+}
+
+/** Relation type used for EventTile reaction annotations. */
+export const EVENT_TILE_REACTION_RELATION_TYPE = "m.annotation";
+
+/** Event type used for EventTile reaction annotations. */
+export const EVENT_TILE_REACTION_EVENT_TYPE = EventType.Reaction;
+
+/** Whether a created relation event should refresh EventTile reactions. */
+export function isEventTileReactionRelation(relationType: string, eventType: string): boolean {
+    return relationType === EVENT_TILE_REACTION_RELATION_TYPE && eventType === EVENT_TILE_REACTION_EVENT_TYPE;
+}
+
+/** Fetches reaction relations for EventTile when reactions are enabled. */
+export function getEventTileReactionRelations({
+    mxEvent,
+    showReactions,
+    getRelationsForEvent,
+}: EventTileReactionRelationsInput): Relations | null {
+    if (!showReactions || !getRelationsForEvent) {
+        return null;
+    }
+
+    return (
+        getRelationsForEvent(mxEvent.getId()!, EVENT_TILE_REACTION_RELATION_TYPE, EVENT_TILE_REACTION_EVENT_TYPE) ??
+        null
+    );
+}

apps/web/test/viewmodels/event-tiles/EventTileReactionState-test.ts

@@ -0,0 +1,97 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { EventType, type MatrixEvent, type Relations, MsgType, RelationType } from "matrix-js-sdk/src/matrix";
+
+import { mkEvent } from "../../test-utils";
+import {
+    EVENT_TILE_REACTION_EVENT_TYPE,
+    EVENT_TILE_REACTION_RELATION_TYPE,
+    getEventTileReactionRelations,
+    isEventTileReactionRelation,
+    type GetRelationsForEvent,
+} from "../../../src/viewmodels/room/timeline/event-tile/reactions/EventTileReactionState";
+
+const roomId = "!room:example.org";
+const userId = "@alice:example.org";
+
+function makeEvent(): MatrixEvent {
+    return mkEvent({
+        event: true,
+        id: "$event",
+        type: EventType.RoomMessage,
+        room: roomId,
+        user: userId,
+        content: {
+            msgtype: MsgType.Text,
+            body: "Hello",
+        },
+    });
+}
+
+describe("EventTileReactionState", () => {
+    it("gets annotation reaction relations when reactions are enabled", () => {
+        const relations = {} as Relations;
+        const getRelationsForEvent: jest.MockedFunction<GetRelationsForEvent> = jest.fn().mockReturnValue(relations);
+
+        expect(
+            getEventTileReactionRelations({
+                mxEvent: makeEvent(),
+                showReactions: true,
+                getRelationsForEvent,
+            }),
+        ).toBe(relations);
+        expect(getRelationsForEvent).toHaveBeenCalledWith(
+            "$event",
+            EVENT_TILE_REACTION_RELATION_TYPE,
+            EVENT_TILE_REACTION_EVENT_TYPE,
+        );
+    });
+
+    it("does not get relations when reactions are disabled", () => {
+        const getRelationsForEvent: jest.MockedFunction<GetRelationsForEvent> = jest.fn();
+
+        expect(
+            getEventTileReactionRelations({
+                mxEvent: makeEvent(),
+                showReactions: false,
+                getRelationsForEvent,
+            }),
+        ).toBeNull();
+        expect(getRelationsForEvent).not.toHaveBeenCalled();
+    });
+
+    it("does not get relations without a relation lookup", () => {
+        expect(
+            getEventTileReactionRelations({
+                mxEvent: makeEvent(),
+                showReactions: true,
+            }),
+        ).toBeNull();
+    });
+
+    it("normalizes missing relations to null", () => {
+        const getRelationsForEvent: jest.MockedFunction<GetRelationsForEvent> = jest.fn().mockReturnValue(undefined);
+
+        expect(
+            getEventTileReactionRelations({
+                mxEvent: makeEvent(),
+                showReactions: true,
+                getRelationsForEvent,
+            }),
+        ).toBeNull();
+    });
+
+    it("matches reaction relation creation events", () => {
+        expect(isEventTileReactionRelation(RelationType.Annotation, EventType.Reaction)).toBe(true);
+    });
+
+    it("does not match unrelated relation creation events", () => {
+        expect(isEventTileReactionRelation(RelationType.Reference, EventType.RoomMessage)).toBe(false);
+        expect(isEventTileReactionRelation(RelationType.Annotation, EventType.RoomMessage)).toBe(false);
+    });
+});

apps/web/test/viewmodels/event-tiles/EventTileReceiptState-test.ts

@@ -0,0 +1,140 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { EventStatus, EventType, M_POLL_END, M_POLL_START, type MatrixEvent, MsgType } from "matrix-js-sdk/src/matrix";
+
+import { mkEvent } from "../../test-utils";
+import { TimelineRenderingType } from "../../../src/contexts/RoomContext";
+import {
+    getEventTileReceiptState,
+    isEligibleForSpecialReceipt,
+    type EventTileReceiptStateInput,
+} from "../../../src/viewmodels/room/timeline/event-tile/EventTileReceiptState";
+
+const roomId = "!room:example.org";
+const ownUserId = "@alice:example.org";
+const otherUserId = "@bob:example.org";
+
+function makeEvent({
+    type = EventType.RoomMessage,
+    user = ownUserId,
+}: {
+    type?: string;
+    user?: string;
+} = {}): MatrixEvent {
+    return mkEvent({
+        event: true,
+        type,
+        room: roomId,
+        user,
+        content: {
+            msgtype: MsgType.Text,
+            body: "Hello",
+        },
+    });
+}
+
+function makeInput(overrides: Partial<EventTileReceiptStateInput> = {}): EventTileReceiptStateInput {
+    return {
+        mxEvent: makeEvent(),
+        hasRoom: true,
+        ownUserId,
+        lastSuccessful: true,
+        timelineRenderingType: TimelineRenderingType.Room,
+        ...overrides,
+    };
+}
+
+describe("EventTileReceiptState", () => {
+    it.each([
+        EventType.RoomMessage,
+        EventType.RoomMessageEncrypted,
+        EventType.Sticker,
+        M_POLL_START.name,
+        M_POLL_END.name,
+    ])("treats %s as eligible for special receipts", (type) => {
+        expect(isEligibleForSpecialReceipt(makeEvent({ type }))).toBe(true);
+    });
+
+    it("does not treat state events as eligible for special receipts", () => {
+        expect(isEligibleForSpecialReceipt(makeEvent({ type: EventType.RoomName }))).toBe(false);
+    });
+
+    it("shows a sent receipt for the last successful own event", () => {
+        const state = getEventTileReceiptState(makeInput());
+
+        expect(state).toMatchObject({
+            isEligibleForSpecialReceipt: true,
+            shouldShowSentReceipt: true,
+            shouldShowSendingReceipt: false,
+            shouldListenForReceipts: true,
+        });
+    });
+
+    it("shows a sent receipt for an explicitly sent event", () => {
+        const state = getEventTileReceiptState(makeInput({ eventSendStatus: EventStatus.SENT }));
+
+        expect(state.shouldShowSentReceipt).toBe(true);
+        expect(state.shouldListenForReceipts).toBe(true);
+    });
+
+    it("shows a sending receipt for pending send states", () => {
+        for (const eventSendStatus of [EventStatus.QUEUED, EventStatus.SENDING, EventStatus.ENCRYPTING]) {
+            const state = getEventTileReceiptState(makeInput({ eventSendStatus }));
+
+            expect(state.shouldShowSentReceipt).toBe(false);
+            expect(state.shouldShowSendingReceipt).toBe(true);
+            expect(state.shouldListenForReceipts).toBe(true);
+        }
+    });
+
+    it("does not show a sent receipt in the thread list", () => {
+        const state = getEventTileReceiptState(
+            makeInput({
+                timelineRenderingType: TimelineRenderingType.ThreadsList,
+            }),
+        );
+
+        expect(state.shouldShowSentReceipt).toBe(false);
+        expect(state.shouldListenForReceipts).toBe(false);
+    });
+
+    it("does not show special receipts once read receipts are present", () => {
+        const state = getEventTileReceiptState(
+            makeInput({
+                readReceipts: [
+                    {
+                        userId: otherUserId,
+                    },
+                ],
+            }),
+        );
+
+        expect(state.isEligibleForSpecialReceipt).toBe(false);
+        expect(state.shouldShowSentReceipt).toBe(false);
+        expect(state.shouldShowSendingReceipt).toBe(false);
+        expect(state.shouldListenForReceipts).toBe(false);
+    });
+
+    it("does not show special receipts for another sender", () => {
+        const state = getEventTileReceiptState(
+            makeInput({
+                mxEvent: makeEvent({ user: otherUserId }),
+            }),
+        );
+
+        expect(state.isEligibleForSpecialReceipt).toBe(false);
+        expect(state.shouldListenForReceipts).toBe(false);
+    });
+
+    it("does not show special receipts when the room is not available", () => {
+        const state = getEventTileReceiptState(makeInput({ hasRoom: false }));
+
+        expect(state.isEligibleForSpecialReceipt).toBe(false);
+        expect(state.shouldListenForReceipts).toBe(false);
+    });
+});

apps/web/test/viewmodels/event-tiles/EventTileReplyChainState-test.ts

@@ -0,0 +1,79 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { type MatrixEvent } from "matrix-js-sdk/src/matrix";
+
+import { mkMessage } from "../../test-utils";
+import { getEventTileReplyChainState } from "../../../src/viewmodels/room/timeline/event-tile/EventTileReplyChainState";
+
+const roomId = "!room:example.org";
+
+function makeMessage(): MatrixEvent {
+    return mkMessage({
+        room: roomId,
+        user: "@alice:example.org",
+        msg: "Message",
+        event: true,
+    });
+}
+
+function makeReply(): MatrixEvent {
+    const parentEvent = makeMessage();
+
+    return mkMessage({
+        room: roomId,
+        user: "@bob:example.org",
+        msg: "Reply",
+        event: true,
+        relatesTo: {
+            "m.in_reply_to": {
+                event_id: parentEvent.getId(),
+            },
+        },
+    });
+}
+
+describe("EventTileReplyChainState", () => {
+    it("does not show a reply chain when the event has no renderer", () => {
+        const state = getEventTileReplyChainState({
+            mxEvent: makeReply(),
+            hasRenderer: false,
+        });
+
+        expect(state.shouldShowReplyChain).toBe(false);
+    });
+
+    it("does not show a reply chain for non-reply events", () => {
+        const state = getEventTileReplyChainState({
+            mxEvent: makeMessage(),
+            hasRenderer: true,
+        });
+
+        expect(state.shouldShowReplyChain).toBe(false);
+    });
+
+    it("shows a reply chain for reply events with a renderer", () => {
+        const state = getEventTileReplyChainState({
+            mxEvent: makeReply(),
+            hasRenderer: true,
+        });
+
+        expect(state.shouldShowReplyChain).toBe(true);
+    });
+
+    it("does not show a reply chain for redacted reply events", () => {
+        const replyEvent = makeReply();
+        jest.spyOn(replyEvent, "isRedacted").mockReturnValue(true);
+
+        const state = getEventTileReplyChainState({
+            mxEvent: replyEvent,
+            hasRenderer: true,
+        });
+
+        expect(state.shouldShowReplyChain).toBe(false);
+    });
+});

apps/web/test/viewmodels/event-tiles/EventTileThreadState-test.ts

@@ -0,0 +1,164 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { EventType, type MatrixEvent, MsgType, type Thread } from "matrix-js-sdk/src/matrix";
+
+import { mkEvent } from "../../test-utils";
+import { TimelineRenderingType } from "../../../src/contexts/RoomContext";
+import {
+    getEventTileThread,
+    getEventTileThreadState,
+    type EventTileThreadLookup,
+    type EventTileThreadStateInput,
+} from "../../../src/viewmodels/room/timeline/event-tile/EventTileThreadState";
+
+const roomId = "!room:example.org";
+const userId = "@alice:example.org";
+
+function makeEvent({ id = "$event" }: { id?: string } = {}): MatrixEvent {
+    return mkEvent({
+        event: true,
+        id,
+        type: EventType.RoomMessage,
+        room: roomId,
+        user: userId,
+        content: {
+            msgtype: MsgType.Text,
+            body: "Hello",
+        },
+    });
+}
+
+function makeThread({
+    id = "$event",
+    replyToEvent,
+}: {
+    id?: string;
+    replyToEvent?: MatrixEvent;
+} = {}): Thread {
+    return {
+        id,
+        length: 2,
+        replyToEvent,
+    } as Thread;
+}
+
+function makeInput(overrides: Partial<EventTileThreadStateInput> = {}): EventTileThreadStateInput {
+    return {
+        mxEvent: makeEvent(),
+        thread: null,
+        timelineRenderingType: TimelineRenderingType.Room,
+        ...overrides,
+    };
+}
+
+function setThreadRootId(mxEvent: MatrixEvent, threadRootId: string): void {
+    Object.defineProperty(mxEvent, "threadRootId", {
+        configurable: true,
+        value: threadRootId,
+    });
+}
+
+describe("EventTileThreadState", () => {
+    it("uses the event thread when it is already available", () => {
+        const mxEvent = makeEvent();
+        const thread = makeThread();
+        jest.spyOn(mxEvent, "getThread").mockReturnValue(thread);
+        const room: EventTileThreadLookup = {
+            findThreadForEvent: jest.fn(),
+        };
+
+        expect(getEventTileThread(mxEvent, room)).toBe(thread);
+        expect(room.findThreadForEvent).not.toHaveBeenCalled();
+    });
+
+    it("falls back to the room thread lookup", () => {
+        const mxEvent = makeEvent();
+        const thread = makeThread();
+        jest.spyOn(mxEvent, "getThread").mockReturnValue(undefined);
+        const room: EventTileThreadLookup = {
+            findThreadForEvent: jest.fn().mockReturnValue(thread),
+        };
+
+        expect(getEventTileThread(mxEvent, room)).toBe(thread);
+        expect(room.findThreadForEvent).toHaveBeenCalledWith(mxEvent);
+    });
+
+    it("returns null when no thread can be found", () => {
+        const mxEvent = makeEvent();
+        jest.spyOn(mxEvent, "getThread").mockReturnValue(undefined);
+
+        expect(getEventTileThread(mxEvent, null)).toBeNull();
+    });
+
+    it("shows the thread summary for thread root events", () => {
+        const mxEvent = makeEvent({ id: "$thread-root" });
+        const thread = makeThread({ id: "$thread-root" });
+
+        const state = getEventTileThreadState(makeInput({ mxEvent, thread }));
+
+        expect(state.shouldShowThreadSummary).toBe(true);
+        expect(state.shouldShowThreadPanelSummary).toBe(true);
+        expect(state.searchThreadInfo.kind).toBe("none");
+    });
+
+    it("derives the thread panel timestamp from the latest reply", () => {
+        const replyToEvent = makeEvent({ id: "$reply" });
+        jest.spyOn(replyToEvent, "getTs").mockReturnValue(123);
+
+        const state = getEventTileThreadState(
+            makeInput({
+                thread: makeThread({ replyToEvent }),
+            }),
+        );
+
+        expect(state.threadReplyEventTs).toBe(123);
+    });
+
+    it("shows linked search thread info for thread replies with a highlight link", () => {
+        const mxEvent = makeEvent();
+        setThreadRootId(mxEvent, "$thread-root");
+
+        const state = getEventTileThreadState(
+            makeInput({
+                mxEvent,
+                timelineRenderingType: TimelineRenderingType.Search,
+                highlightLink: "https://example.org/thread",
+            }),
+        );
+
+        expect(state.searchThreadInfo).toEqual({
+            kind: "link",
+            href: "https://example.org/thread",
+        });
+    });
+
+    it("shows text search thread info for thread replies without a highlight link", () => {
+        const mxEvent = makeEvent();
+        setThreadRootId(mxEvent, "$thread-root");
+
+        const state = getEventTileThreadState(
+            makeInput({
+                mxEvent,
+                timelineRenderingType: TimelineRenderingType.Search,
+            }),
+        );
+
+        expect(state.searchThreadInfo).toEqual({
+            kind: "text",
+        });
+    });
+
+    it("does not show search thread info outside search timelines", () => {
+        const mxEvent = makeEvent();
+        setThreadRootId(mxEvent, "$thread-root");
+
+        const state = getEventTileThreadState(makeInput({ mxEvent }));
+
+        expect(state.searchThreadInfo.kind).toBe("none");
+    });
+});