Add labs option for history sharing on invite

src/i18n/strings/en_EN.json

@@ -1534,6 +1534,9 @@
         "render_reaction_images_description": "Sometimes referred to as \"custom emojis\".",
         "report_to_moderators": "Report to moderators",
         "report_to_moderators_description": "In rooms that support moderation, the “Report” button will let you report abuse to room moderators.",
+        "share_history_on_invite": "Share encrypted history with new members",
+        "share_history_on_invite_description": "When inviting a user to an encrypted room that has history visibility set to \"shared\", share encrypted history with that user, and accept encrypted history when you re invited to such a room.",
+        "share_history_on_invite_warning": "This feature is EXPERIMENTAL and not all security precautions are implemented. Do not enable on production accounts.",
         "sliding_sync": "Sliding Sync mode",
         "sliding_sync_description": "Under active development, cannot be disabled.",
         "sliding_sync_disabled_notice": "Log out and back in to disable",

src/settings/Settings.tsx

@@ -205,6 +205,7 @@ export interface Settings {
     "feature_mjolnir": IFeature;
     "feature_custom_themes": IFeature;
     "feature_exclude_insecure_devices": IFeature;
+    "feature_share_history_on_invite": IFeature;
     "feature_html_topic": IFeature;
     "feature_bridge_state": IFeature;
     "feature_jump_to_date": IFeature;
@@ -503,6 +504,29 @@ export const SETTINGS: Settings = {
         supportedLevelsAreOrdered: true,
         default: false,
     },
+    "feature_share_history_on_invite": {
+        isFeature: true,
+        labsGroup: LabGroup.Encryption,
+        displayName: _td("labs|share_history_on_invite"),
+        description: () => (
+            <>
+                {_t("labs|share_history_on_invite_description")}
+                <div className="mx_SettingsFlag_microcopy">
+                    {_t(
+                        "settings|warning",
+                        {},
+                        {
+                            w: (sub) => <span className="mx_SettingsTab_microcopy_warning">{sub}</span>,
+                            description: _t("labs|share_history_on_invite_warning"),
+                        },
+                    )}
+                </div>
+            </>
+        ),
+        supportedLevels: LEVELS_DEVICE_ONLY_SETTINGS_WITH_CONFIG_PRIORITISED,
+        supportedLevelsAreOrdered: true,
+        default: false,
+    },
     "useOnlyCurrentProfiles": {
         supportedLevels: LEVELS_ACCOUNT_SETTINGS,
         displayName: _td("settings|disable_historical_profile"),

src/stores/RoomViewStore.tsx

@@ -10,7 +10,7 @@ Please see LICENSE files in the repository root for full details.
 
 import React, { type ReactNode } from "react";
 import * as utils from "matrix-js-sdk/src/utils";
-import { MatrixError, JoinRule, type Room, type MatrixEvent } from "matrix-js-sdk/src/matrix";
+import { MatrixError, JoinRule, type Room, type MatrixEvent, type IJoinRoomOpts } from "matrix-js-sdk/src/matrix";
 import { KnownMembership } from "matrix-js-sdk/src/types";
 import { logger } from "matrix-js-sdk/src/logger";
 import { type ViewRoom as ViewRoomEvent } from "@matrix-org/analytics-events/types/typescript/ViewRoom";
@@ -512,15 +512,19 @@ export class RoomViewStore extends EventEmitter {
         // take a copy of roomAlias & roomId as they may change by the time the join is complete
         const { roomAlias, roomId = payload.roomId } = this.state;
         const address = roomAlias || roomId!;
-        const viaServers = this.state.viaServers || [];
+
+        const joinOpts: IJoinRoomOpts = {
+            viaServers: this.state.viaServers || [],
+            ...(payload.opts ?? {}),
+        };
+        if (SettingsStore.getValue("feature_share_history_on_invite")) {
+            joinOpts.acceptSharedHistory = true;
+        }
+
         try {
             const cli = MatrixClientPeg.safeGet();
             await retry<Room, MatrixError>(
-                () =>
-                    cli.joinRoom(address, {
-                        viaServers,
-                        ...(payload.opts || {}),
-                    }),
+                () => cli.joinRoom(address, joinOpts),
                 NUM_JOIN_RETRY,
                 (err) => {
                     // if we received a Gateway timeout or Cloudflare timeout then retry

src/utils/MultiInviter.ts

@@ -6,7 +6,7 @@ SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Com
 Please see LICENSE files in the repository root for full details.
 */
 
-import { MatrixError, type MatrixClient, EventType, type EmptyObject } from "matrix-js-sdk/src/matrix";
+import { MatrixError, type MatrixClient, EventType, type EmptyObject, type InviteOpts } from "matrix-js-sdk/src/matrix";
 import { KnownMembership } from "matrix-js-sdk/src/types";
 import { logger } from "matrix-js-sdk/src/logger";
 
@@ -183,7 +183,11 @@ export default class MultiInviter {
                 }
             }
 
-            return this.matrixClient.invite(roomId, addr, this.reason);
+            const opts: InviteOpts = {};
+            if (this.reason !== undefined) opts.reason = this.reason;
+            if (SettingsStore.getValue("feature_share_history_on_invite")) opts.shareEncryptedHistory = true;
+
+            return this.matrixClient.invite(roomId, addr, opts);
         } else {
             throw new Error("Unsupported address");
         }

test/unit-tests/stores/RoomViewStore-test.ts

@@ -440,6 +440,17 @@ describe("RoomViewStore", function () {
             });
             expect(mocked(dis.dispatch).mock.calls[2][0]).toEqual({ action: "prompt_ask_to_join" });
         });
+
+        it("sets 'acceptSharedHistory' if that option is enabled", async () => {
+            jest.spyOn(SettingsStore, "getValue").mockImplementation((settingName, roomId, value) => {
+                return settingName === "feature_share_history_on_invite"; // this is enabled, everything else is disabled.
+            });
+
+            dis.dispatch({ action: Action.ViewRoom, room_id: roomId });
+            dis.dispatch({ action: Action.JoinRoom });
+            await untilDispatch(Action.JoinRoomReady, dis);
+            expect(mockClient.joinRoom).toHaveBeenCalledWith(roomId, { acceptSharedHistory: true, viaServers: [] });
+        });
     });
 
     describe("Action.JoinRoomError", () => {

test/unit-tests/utils/MultiInviter-test.ts

@@ -96,9 +96,9 @@ describe("MultiInviter", () => {
                 const result = await inviter.invite([MXID1, MXID2, MXID3]);
 
                 expect(client.invite).toHaveBeenCalledTimes(3);
-                expect(client.invite).toHaveBeenNthCalledWith(1, ROOMID, MXID1, undefined);
-                expect(client.invite).toHaveBeenNthCalledWith(2, ROOMID, MXID2, undefined);
-                expect(client.invite).toHaveBeenNthCalledWith(3, ROOMID, MXID3, undefined);
+                expect(client.invite).toHaveBeenNthCalledWith(1, ROOMID, MXID1, {});
+                expect(client.invite).toHaveBeenNthCalledWith(2, ROOMID, MXID2, {});
+                expect(client.invite).toHaveBeenNthCalledWith(3, ROOMID, MXID3, {});
 
                 expectAllInvitedResult(result);
             });
@@ -114,9 +114,9 @@ describe("MultiInviter", () => {
                     const result = await inviter.invite([MXID1, MXID2, MXID3]);
 
                     expect(client.invite).toHaveBeenCalledTimes(3);
-                    expect(client.invite).toHaveBeenNthCalledWith(1, ROOMID, MXID1, undefined);
-                    expect(client.invite).toHaveBeenNthCalledWith(2, ROOMID, MXID2, undefined);
-                    expect(client.invite).toHaveBeenNthCalledWith(3, ROOMID, MXID3, undefined);
+                    expect(client.invite).toHaveBeenNthCalledWith(1, ROOMID, MXID1, {});
+                    expect(client.invite).toHaveBeenNthCalledWith(2, ROOMID, MXID2, {});
+                    expect(client.invite).toHaveBeenNthCalledWith(3, ROOMID, MXID3, {});
 
                     expectAllInvitedResult(result);
                 });
@@ -129,7 +129,7 @@ describe("MultiInviter", () => {
                     const result = await inviter.invite([MXID1, MXID2, MXID3]);
 
                     expect(client.invite).toHaveBeenCalledTimes(1);
-                    expect(client.invite).toHaveBeenNthCalledWith(1, ROOMID, MXID1, undefined);
+                    expect(client.invite).toHaveBeenNthCalledWith(1, ROOMID, MXID1, {});
 
                     // The resolved state is 'invited' for all users.
                     // With the above client expectations, the test ensures that only the first user is invited.
@@ -231,5 +231,15 @@ describe("MultiInviter", () => {
                 `"This space is unfederated. You cannot invite people from external servers."`,
             );
         });
+
+        it("should set shareEncryptedHistory if that setting is enabled", async () => {
+            mocked(SettingsStore.getValue).mockImplementation((settingName, roomId, value) => {
+                return settingName === "feature_share_history_on_invite"; // this is enabled, everything else is disabled.
+            });
+            await inviter.invite([MXID1]);
+
+            expect(client.invite).toHaveBeenCalledTimes(1);
+            expect(client.invite).toHaveBeenNthCalledWith(1, ROOMID, MXID1, { shareEncryptedHistory: true });
+        });
     });
 });