Implement UI for history visibility acknowledgement.

packages/shared-components/src/composer/HistoryVisibleBannerView/HistoryVisibleBannerView.stories.tsx

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2025 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 Meta, type StoryFn } from "@storybook/react-vite";
+import React, { type JSX } from "react";
+import { fn } from "storybook/test";
+
+import { useMockedViewModel } from "../../useMockedViewModel";
+import {
+    HistoryVisibleBannerView,
+    type HistoryVisibleBannerViewActions,
+    type HistoryVisibleBannerViewSnapshot,
+} from "./HistoryVisibleBannerView";
+
+type HistoryVisibleBannerProps = HistoryVisibleBannerViewSnapshot & HistoryVisibleBannerViewActions;
+
+const HistoryVisibleBannerViewWrapper = ({ onClose, ...rest }: HistoryVisibleBannerProps): JSX.Element => {
+    const vm = useMockedViewModel(rest, {
+        onClose,
+    });
+    return <HistoryVisibleBannerView vm={vm} />;
+};
+
+export default {
+    title: "composer/HistoryVisibleBannerView",
+    component: HistoryVisibleBannerViewWrapper,
+    tags: ["autodocs"],
+    argTypes: {},
+    args: {
+        visible: true,
+        onClose: fn(),
+    },
+} as Meta<typeof HistoryVisibleBannerViewWrapper>;
+
+const Template: StoryFn<typeof HistoryVisibleBannerViewWrapper> = (args) => (
+    <HistoryVisibleBannerViewWrapper {...args} />
+);
+
+export const Default = Template.bind({});

packages/shared-components/src/composer/HistoryVisibleBannerView/HistoryVisibleBannerView.test.tsx

@@ -0,0 +1,28 @@
+/*
+ * Copyright (c) 2025 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 React from "react";
+import { render } from "jest-matrix-react";
+import { composeStories } from "@storybook/react-vite";
+
+import * as stories from "./HistoryVisibleBannerView.stories.tsx";
+
+const { Default } = composeStories(stories);
+
+describe("HistoryVisibleBannerView", () => {
+    it("renders a history visible banner", () => {
+        const dismissFn = jest.fn();
+
+        const { container } = render(<Default onClose={dismissFn} />);
+        expect(container).toMatchSnapshot();
+
+        const button = container.querySelector("button");
+        expect(button).not.toBeNull();
+        button?.click();
+        expect(dismissFn).toHaveBeenCalled();
+    });
+});

packages/shared-components/src/composer/HistoryVisibleBannerView/HistoryVisibleBannerView.tsx

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2025 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 { Link } from "@vector-im/compound-web";
+import React, { type JSX } from "react";
+
+import { useViewModel } from "../../useViewModel";
+import { _t } from "../../utils/i18n";
+import { type ViewModel } from "../../viewmodel";
+import { Banner } from "../Banner";
+
+export interface HistoryVisibleBannerViewActions {
+    /**
+     * Called when the user dismisses the banner.
+     */
+    onClose: () => void;
+}
+
+export interface HistoryVisibleBannerViewSnapshot {
+    /**
+     * Whether the banner is currently visible.
+     */
+    visible: boolean;
+}
+
+/**
+ * The view model for the banner.
+ */
+export type HistoryVisibleBannerViewModel = ViewModel<HistoryVisibleBannerViewSnapshot> &
+    HistoryVisibleBannerViewActions;
+
+interface HistoryVisibleBannerViewProps {
+    /**
+     * The view model for the banner.
+     */
+    vm: HistoryVisibleBannerViewModel;
+}
+
+/**
+ * A component to alert that history is shared to new members of the room.
+ *
+ * @example
+ * ```tsx
+ * <HistoryVisibleBannerView vm={historyVisibleBannerViewModel} />
+ * ```
+ */
+export function HistoryVisibleBannerView({ vm }: Readonly<HistoryVisibleBannerViewProps>): JSX.Element {
+    const { visible } = useViewModel(vm);
+
+    const contents = _t(
+        "room|status_bar|history_visible",
+        {},
+        {
+            a: substituteATag,
+        },
+    );
+
+    return (
+        <>
+            {visible && (
+                <Banner type="info" onClose={() => vm.onClose()}>
+                    {contents}
+                </Banner>
+            )}
+        </>
+    );
+}
+
+function substituteATag(sub: string): JSX.Element {
+    return (
+        <Link href="https://element.io/en/help#e2ee-history-sharing" target="_blank">
+            {sub}
+        </Link>
+    );
+}

packages/shared-components/src/composer/HistoryVisibleBannerView/__snapshots__/HistoryVisibleBannerView.test.tsx.snap

@@ -0,0 +1,62 @@
+// Jest Snapshot v1, https://jestjs.io/docs/snapshot-testing
+
+exports[`HistoryVisibleBannerView renders a history visible banner 1`] = `
+<div>
+  <div
+    class="banner"
+    data-type="info"
+  >
+    <div
+      class="icon"
+    >
+      <svg
+        fill="currentColor"
+        font-size="24"
+        height="1em"
+        viewBox="0 0 24 24"
+        width="1em"
+        xmlns="http://www.w3.org/2000/svg"
+      >
+        <path
+          d="M11.288 7.288A.97.97 0 0 1 12 7q.424 0 .713.287Q13 7.576 13 8t-.287.713A.97.97 0 0 1 12 9a.97.97 0 0 1-.713-.287A.97.97 0 0 1 11 8q0-.424.287-.713m.001 4.001A.97.97 0 0 1 12 11q.424 0 .713.287.287.288.287.713v4q0 .424-.287.712A.97.97 0 0 1 12 17a.97.97 0 0 1-.713-.288A.97.97 0 0 1 11 16v-4q0-.424.287-.713"
+        />
+        <path
+          clip-rule="evenodd"
+          d="M22 12c0 5.523-4.477 10-10 10S2 17.523 2 12 6.477 2 12 2s10 4.477 10 10m-2 0a8 8 0 1 1-16 0 8 8 0 0 1 16 0"
+          fill-rule="evenodd"
+        />
+      </svg>
+    </div>
+    <span
+      class="content"
+    >
+      <span>
+        Messages you send will be shared with new members invited to this room. 
+        <a
+          class="_link_1v5rz_8"
+          data-kind="primary"
+          data-size="medium"
+          href="https://element.io/en/help#e2ee-history-sharing"
+          rel="noreferrer noopener"
+          target="_blank"
+        >
+          Learn more
+        </a>
+      </span>
+    </span>
+    <div
+      class="actions"
+    >
+      <button
+        class="_button_187yx_8"
+        data-kind="secondary"
+        data-size="sm"
+        role="button"
+        tabindex="0"
+      >
+        Dismiss
+      </button>
+    </div>
+  </div>
+</div>
+`;

packages/shared-components/src/composer/HistoryVisibleBannerView/index.ts

@@ -0,0 +1,8 @@
+/*
+ * Copyright (c) 2025 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.
+ */
+
+export * from "./HistoryVisibleBannerView";

packages/shared-components/src/index.ts

@@ -12,6 +12,7 @@ export * from "./audio/PlayPauseButton";
 export * from "./audio/SeekBar";
 export * from "./avatar/AvatarWithDetails";
 export * from "./composer/Banner";
+export * from "./composer/HistoryVisibleBannerView";
 export * from "./event-tiles/TextualEventView";
 export * from "./message-body/MediaBody";
 export * from "./pill-input/Pill";

src/components/views/rooms/MessageComposer.tsx

@@ -20,6 +20,7 @@ import { type Optional } from "matrix-events-sdk";
 import { Tooltip } from "@vector-im/compound-web";
 import { logger } from "matrix-js-sdk/src/logger";
 import { LockOffIcon } from "@vector-im/compound-design-tokens/assets/web/icons";
+import { HistoryVisibleBannerView } from "@element-hq/web-shared-components";
 
 import { _t } from "../../../languageHandler";
 import { MatrixClientPeg } from "../../../MatrixClientPeg";
@@ -55,6 +56,7 @@ import { type MatrixClientProps, withMatrixClientHOC } from "../../../contexts/M
 import { UIFeature } from "../../../settings/UIFeature";
 import { formatTimeLeft } from "../../../DateUtils";
 import RoomReplacedSvg from "../../../../res/img/room_replaced.svg";
+import { HistoryVisibleBannerViewModel } from "../../../viewmodels/composer/HistoryVisibleBannerViewModel";
 
 // The prefix used when persisting editor drafts to localstorage.
 export const WYSIWYG_EDITOR_STATE_STORAGE_PREFIX = "mx_wysiwyg_state_";
@@ -666,6 +668,7 @@ export class MessageComposer extends React.Component<IProps, IState> {
         return (
             <Tooltip open={isTooltipOpen} description={formatTimeLeft(secondsLeft)} placement="bottom">
                 <div className={classes} ref={this.ref} role="region" aria-label={_t("a11y|message_composer")}>
+                    <HistoryVisibleBannerView vm={new HistoryVisibleBannerViewModel({ room: this.props.room })} />
                     <div className="mx_MessageComposer_wrapper">
                         <UserIdentityWarning room={this.props.room} key={this.props.room.roomId} />
                         <ReplyPreview

src/i18n/strings/en_EN.json

@@ -2112,6 +2112,7 @@
         "status_bar": {
             "delete_all": "Delete all",
             "exceeded_resource_limit": "Your message wasn't sent because this homeserver has exceeded a resource limit. Please <a>contact your service administrator</a> to continue using the service.",
+            "history_visible": "Messages you send will be shared with new members invited to this room. <a>Learn more</a>",
             "homeserver_blocked": "Your message wasn't sent because this homeserver has been blocked by its administrator. Please <a>contact your service administrator</a> to continue using the service.",
             "monthly_user_limit_reached": "Your message wasn't sent because this homeserver has hit its Monthly Active User Limit. Please <a>contact your service administrator</a> to continue using the service.",
             "requires_consent_agreement": "You can't send any messages until you review and agree to <consentLink>our terms and conditions</consentLink>.",

src/settings/Settings.tsx

@@ -371,6 +371,7 @@ export interface Settings {
     "inviteRules": IBaseSetting<ComputedInviteConfig>;
     "blockInvites": IBaseSetting<boolean>;
     "Developer.elementCallUrl": IBaseSetting<string>;
+    "acknowledgedHistoryVisibility": IBaseSetting<boolean>;
 }
 
 export type SettingKey = keyof Settings;
@@ -1480,4 +1481,8 @@ export const SETTINGS: Settings = {
         displayName: _td("devtools|settings|elementCallUrl"),
         default: "",
     },
+    "acknowledgedHistoryVisibility": {
+        supportedLevels: [SettingLevel.ROOM_ACCOUNT],
+        default: false,
+    },
 };

src/viewmodels/composer/HistoryVisibleBannerViewModel.tsx

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2025 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 {
+    BaseViewModel,
+    type HistoryVisibleBannerViewModel as HistoryVisibleBannerViewModelInterface,
+    type HistoryVisibleBannerViewSnapshot,
+} from "@element-hq/web-shared-components";
+import { HistoryVisibility, RoomStateEvent, type Room } from "matrix-js-sdk/src/matrix";
+
+import SettingsStore from "../../settings/SettingsStore";
+import { SettingLevel } from "../../settings/SettingLevel";
+
+interface Props {
+    room: Room;
+}
+
+export class HistoryVisibleBannerViewModel
+    extends BaseViewModel<HistoryVisibleBannerViewSnapshot, Props>
+    implements HistoryVisibleBannerViewModelInterface
+{
+    private readonly featureWatcher: string;
+    private readonly acknowledgedWatcher: string;
+
+    private static readonly computeSnapshot = (room: Room): HistoryVisibleBannerViewSnapshot => {
+        const featureEnabled = SettingsStore.getValue("feature_share_history_on_invite");
+        const acknowledged = SettingsStore.getValue("acknowledgedHistoryVisibility", room.roomId);
+
+        return {
+            visible:
+                featureEnabled &&
+                room.hasEncryptionStateEvent() &&
+                room.getHistoryVisibility() !== HistoryVisibility.Joined &&
+                !acknowledged,
+        };
+    };
+
+    public constructor(props: Props) {
+        super(props, HistoryVisibleBannerViewModel.computeSnapshot(props.room));
+
+        this.disposables.trackListener(props.room, RoomStateEvent.Update, () => this.setSnapshot());
+
+        // `SettingsStore` is not an `EventListener`, so we must manage these manually.
+        this.featureWatcher = SettingsStore.watchSetting(
+            "feature_share_history_on_invite",
+            null,
+            (_key, _roomId, _level, value: boolean) => this.setSnapshot(),
+        );
+        this.acknowledgedWatcher = SettingsStore.watchSetting(
+            "acknowledgedHistoryVisibility",
+            props.room.roomId,
+            (_key, _roomId, _level, value: boolean) => this.setSnapshot(),
+        );
+    }
+
+    private setSnapshot(): void {
+        const acknowledged = SettingsStore.getValue("acknowledgedHistoryVisibility", this.props.room.roomId);
+
+        // Reset the acknowleded flag when the history visibility is set back to joined.
+        if (this.props.room.getHistoryVisibility() === HistoryVisibility.Joined && acknowledged) {
+            SettingsStore.setValue(
+                "acknowledgedHistoryVisibility",
+                this.props.room.roomId,
+                SettingLevel.ROOM_ACCOUNT,
+                false,
+            );
+        }
+
+        this.snapshot.set(HistoryVisibleBannerViewModel.computeSnapshot(this.props.room));
+    }
+
+    /**
+     * Revoke the banner's acknoledgement status.
+     */
+    public async revoke(): Promise<void> {
+        await SettingsStore.setValue(
+            "acknowledgedHistoryVisibility",
+            this.props.room.roomId,
+            SettingLevel.ROOM_ACCOUNT,
+            false,
+        );
+    }
+
+    /**
+     * Called when the user dismisses the banner.
+     */
+    public async onClose(): Promise<void> {
+        await SettingsStore.setValue(
+            "acknowledgedHistoryVisibility",
+            this.props.room.roomId,
+            SettingLevel.ROOM_ACCOUNT,
+            true,
+        );
+    }
+
+    public dispose(): void {
+        super.dispose();
+        SettingsStore.unwatchSetting(this.featureWatcher);
+        SettingsStore.unwatchSetting(this.acknowledgedWatcher);
+    }
+}