Implement MSC 3981

spec/unit/event-timeline-set.spec.ts

@@ -82,6 +82,7 @@ describe("EventTimelineSet", () => {
     beforeEach(() => {
         client = utils.mock(MatrixClient, "MatrixClient");
         client.reEmitter = utils.mock(ReEmitter, "ReEmitter");
+        client.canSupport = new Map();
         room = new Room(roomId, client, userA);
         eventTimelineSet = new EventTimelineSet(room);
         eventTimeline = new EventTimeline(eventTimelineSet);

src/@types/requests.ts

@@ -186,6 +186,7 @@ export interface IRelationsRequestOpts {
     to?: string;
     limit?: number;
     dir?: Direction;
+    recurse?: boolean;
 }
 
 export interface IRelationsResponse {

src/client.ts

@@ -5736,6 +5736,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
             return undefined;
         }
 
+        const recurse = this.canSupport.get(Feature.RelationsRecursion) !== ServerSupport.Unsupported;
         if (Thread.hasServerSideSupport) {
             if (Thread.hasServerSideFwdPaginationSupport) {
                 if (!timelineSet.thread) {
@@ -5748,14 +5749,14 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
                     thread.id,
                     THREAD_RELATION_TYPE.name,
                     null,
-                    { dir: Direction.Backward, from: res.start },
+                    { dir: Direction.Backward, from: res.start, recurse: recurse || undefined },
                 );
                 const resNewer: IRelationsResponse = await this.fetchRelations(
                     timelineSet.room.roomId,
                     thread.id,
                     THREAD_RELATION_TYPE.name,
                     null,
-                    { dir: Direction.Forward, from: res.end },
+                    { dir: Direction.Forward, from: res.end, recurse: recurse || undefined },
                 );
                 const events = [
                     // Order events from most recent to oldest (reverse-chronological).
@@ -5803,7 +5804,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
                     thread.id,
                     THREAD_RELATION_TYPE.name,
                     null,
-                    { dir: Direction.Backward, from: res.start },
+                    { dir: Direction.Backward, from: res.start, recurse: recurse || undefined },
                 );
                 const eventsNewer: IEvent[] = [];
                 let nextBatch: Optional<string> = res.end;
@@ -5813,7 +5814,7 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
                         thread.id,
                         THREAD_RELATION_TYPE.name,
                         null,
-                        { dir: Direction.Forward, from: nextBatch },
+                        { dir: Direction.Forward, from: nextBatch, recurse: recurse || undefined },
                     );
                     nextBatch = resNewer.next_batch ?? null;
                     eventsNewer.push(...resNewer.chunk);
@@ -5884,12 +5885,13 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
             );
             event = res.chunk?.[0];
         } else if (timelineSet.thread && Thread.hasServerSideSupport) {
+            const recurse = this.canSupport.get(Feature.RelationsRecursion) !== ServerSupport.Unsupported;
             const res = await this.fetchRelations(
                 timelineSet.room.roomId,
                 timelineSet.thread.id,
                 THREAD_RELATION_TYPE.name,
                 null,
-                { dir: Direction.Backward, limit: 1 },
+                { dir: Direction.Backward, limit: 1, recurse: recurse || undefined },
             );
             event = res.chunk?.[0];
         } else {
@@ -6164,10 +6166,12 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
                 throw new Error("Unknown room " + eventTimeline.getRoomId());
             }
 
+            const recurse = this.canSupport.get(Feature.RelationsRecursion) !== ServerSupport.Unsupported;
             promise = this.fetchRelations(eventTimeline.getRoomId() ?? "", thread.id, THREAD_RELATION_TYPE.name, null, {
                 dir,
                 limit: opts.limit,
                 from: token ?? undefined,
+                recurse: recurse || undefined,
             })
                 .then(async (res) => {
                     const mapper = this.getEventMapper();
@@ -7956,6 +7960,9 @@ export class MatrixClient extends TypedEventEmitter<EmittedEvents, ClientEventHa
         if (Thread.hasServerSideFwdPaginationSupport === FeatureSupport.Experimental) {
             params = replaceParam("dir", "org.matrix.msc3715.dir", params);
         }
+        if (this.canSupport.get(Feature.RelationsRecursion) === ServerSupport.Unstable) {
+            params = replaceParam("recurse", "org.matrix.msc3981.recurse", params);
+        }
         const queryString = utils.encodeParams(params);
 
         let templatedUrl = "/rooms/$roomId/relations/$eventId";

src/feature.ts

@@ -31,6 +31,7 @@ export enum Feature {
     LoginTokenRequest = "LoginTokenRequest",
     RelationBasedRedactions = "RelationBasedRedactions",
     AccountDataDeletion = "AccountDataDeletion",
+    RelationsRecursion = "RelationsRecursion",
 }
 
 type FeatureSupportCondition = {
@@ -56,6 +57,9 @@ const featureSupportResolver: Record<string, FeatureSupportCondition> = {
     [Feature.AccountDataDeletion]: {
         unstablePrefixes: ["org.matrix.msc3391"],
     },
+    [Feature.RelationsRecursion]: {
+        unstablePrefixes: ["org.matrix.msc3981"],
+    },
 };
 
 export async function buildFeatureSupportMap(versions: IServerVersions): Promise<Map<Feature, ServerSupport>> {

src/models/thread.ts

@@ -28,6 +28,7 @@ import { ServerControlledNamespacedValue } from "../NamespacedValue";
 import { logger } from "../logger";
 import { ReadReceipt } from "./read-receipt";
 import { CachedReceiptStructure, ReceiptType } from "../@types/read_receipts";
+import { Feature } from "../feature";
 
 export enum ThreadEvent {
     New = "Thread.new",
@@ -458,25 +459,27 @@ export class Thread extends ReadReceipt<EmittedEvents, EventHandlerMap> {
 
     // XXX: Workaround for https://github.com/matrix-org/matrix-spec-proposals/pull/2676/files#r827240084
     private async fetchEditsWhereNeeded(...events: MatrixEvent[]): Promise<unknown> {
-        return Promise.all(
-            events
-                .filter((e) => e.isEncrypted())
-                .map((event: MatrixEvent) => {
-                    if (event.isRelation()) return; // skip - relations don't get edits
-                    return this.client
-                        .relations(this.roomId, event.getId()!, RelationType.Replace, event.getType(), {
-                            limit: 1,
-                        })
-                        .then((relations) => {
-                            if (relations.events.length) {
-                                event.makeReplaced(relations.events[0]);
-                            }
-                        })
-                        .catch((e) => {
-                            logger.error("Failed to load edits for encrypted thread event", e);
-                        });
-                }),
-        );
+        if (!this.client.canSupport.get(Feature.RelationsRecursion)) {
+            return Promise.all(
+                events
+                    .filter((e) => e.isEncrypted())
+                    .map((event: MatrixEvent) => {
+                        if (event.isRelation()) return; // skip - relations don't get edits
+                        return this.client
+                            .relations(this.roomId, event.getId()!, RelationType.Replace, event.getType(), {
+                                limit: 1,
+                            })
+                            .then((relations) => {
+                                if (relations.events.length) {
+                                    event.makeReplaced(relations.events[0]);
+                                }
+                            })
+                            .catch((e) => {
+                                logger.error("Failed to load edits for encrypted thread event", e);
+                            });
+                    }),
+            );
+        }
     }
 
     public setEventMetadata(event: Optional<MatrixEvent>): void {