Make shared-components tiles render identically outside Element Web - # 1 (#33418)

* Apply event presentation attributes to timeline previews and errors

* Make TextualEventView render the same in web and storybook

* Make TileErrorView render the same in app/web and storybook

* Updated snapshots

* Make it possible to view shared components with default app/web base styling.

* Adjust styling and add underline to pass tests

* Fix Sonar issue

* Rename base css to root css

* Handle font styling correctly

apps/web/res/css/views/messages/_TextualEvent.pcss

@@ -7,12 +7,8 @@ Please see LICENSE files in the repository root for full details.
 */
 
 .mx_TextualEvent {
-    overflow-y: hidden;
-    line-height: normal;
-
     a {
         color: $accent;
-        cursor: pointer;
     }
 
     .mx_RoomView_searchResultsPanel & {

apps/web/src/events/EventTileFactory.tsx

@@ -84,7 +84,7 @@ const LegacyCallEventFactory: Factory<FactoryProps & { callEventGrouper: LegacyC
 const CallEventFactory: Factory = (ref, props) => <CallEvent ref={ref} {...props} />;
 export const TextualEventFactory: Factory = (ref, props) => {
     const vm = new TextualEventViewModel(props);
-    return <TextualEventView vm={vm} />;
+    return <TextualEventView vm={vm} className="mx_TextualEvent" />;
 };
 function EncryptionEventWrappedView({ mxEvent, ref }: IBodyProps): JSX.Element {
     const cli = useMatrixClientContext();

packages/shared-components/.storybook/app-web-root.css

@@ -0,0 +1,71 @@
+/*
+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.
+*/
+
+/*
+ * Match the app/web shell baseline without importing app/web component styles.
+ * Shared component stories should inherit the same root typography and font
+ * feature settings as the real app, while still owning their component styling.
+ */
+@layer app-web {
+    :root[data-storybook-root-css="app-web"] {
+        [class^="cpd-theme"][class^="cpd-theme"] {
+            --cpd-font-family-sans:
+                "Inter", "Twemoji", "Apple Color Emoji", "Segoe UI Emoji", "Arial", "Helvetica", sans-serif,
+                "Noto Color Emoji";
+        }
+
+        body {
+            font: var(--cpd-font-body-md-regular) !important;
+            letter-spacing: var(--cpd-font-letter-spacing-body-md) !important;
+            font-feature-settings:
+                "kern" 1,
+                "liga" 1,
+                "calt" 1 !important;
+
+            background-color: var(--cpd-color-bg-canvas-default);
+            color: var(--cpd-color-text-primary);
+            border: 0;
+            margin: 0;
+
+            -webkit-font-smoothing: antialiased;
+            -moz-osx-font-smoothing: grayscale;
+        }
+
+        pre,
+        code {
+            font-family:
+                "Fira Code", "Twemoji", "Apple Color Emoji", "Segoe UI Emoji", "Courier", monospace, "Noto Color Emoji";
+            font-size: 100% !important;
+        }
+    }
+
+    /* Username color classes - these are defined in the main app's _common.pcss
+   but need to be available in Storybook for components that use colorClass */
+    .mx_Username_color1 {
+        color: var(--cpd-color-text-decorative-1);
+    }
+
+    .mx_Username_color2 {
+        color: var(--cpd-color-text-decorative-2);
+    }
+
+    .mx_Username_color3 {
+        color: var(--cpd-color-text-decorative-3);
+    }
+
+    .mx_Username_color4 {
+        color: var(--cpd-color-text-decorative-4);
+    }
+
+    .mx_Username_color5 {
+        color: var(--cpd-color-text-decorative-5);
+    }
+
+    .mx_Username_color6 {
+        color: var(--cpd-color-text-decorative-6);
+    }
+}

packages/shared-components/.storybook/preview.css

@@ -8,29 +8,3 @@ Please see LICENSE files in the repository root for full details.
 .docs-story {
     background: var(--cpd-color-bg-canvas-default);
 }
-
-/* Username color classes - these are defined in the main app's _common.pcss
-   but need to be available in Storybook for components that use colorClass */
-.mx_Username_color1 {
-    color: var(--cpd-color-text-decorative-1);
-}
-
-.mx_Username_color2 {
-    color: var(--cpd-color-text-decorative-2);
-}
-
-.mx_Username_color3 {
-    color: var(--cpd-color-text-decorative-3);
-}
-
-.mx_Username_color4 {
-    color: var(--cpd-color-text-decorative-4);
-}
-
-.mx_Username_color5 {
-    color: var(--cpd-color-text-decorative-5);
-}
-
-.mx_Username_color6 {
-    color: var(--cpd-color-text-decorative-6);
-}

packages/shared-components/.storybook/preview.tsx

@@ -12,6 +12,7 @@ import "@fontsource/inter/600.css";
 import "@fontsource/inter/700.css";
 
 import "./compound.css";
+import "./app-web-root.css";
 import "./preview.css";
 import React, { useLayoutEffect } from "react";
 import { TooltipProvider } from "@vector-im/compound-web";
@@ -47,7 +48,7 @@ export const globalTypes = {
             icon: "component",
             title: "Event layout",
             items: [
-                { title: "Group", value: "group" },
+                { title: "Modern", value: "group" },
                 { title: "Bubble", value: "bubble" },
                 { title: "IRC", value: "irc" },
             ],
@@ -65,16 +66,47 @@ export const globalTypes = {
             ],
         },
     },
+    rootCss: {
+        name: "Root CSS",
+        description: "Global root CSS for component previews",
+        toolbar: {
+            icon: "paintbrush",
+            title: "Root CSS",
+            items: [
+                { title: "Default", value: "storybook" },
+                { title: "Element Web", value: "app-web" },
+            ],
+        },
+    },
     initialGlobals: {
-        theme: "system",
+        theme: "light",
         language: "en",
         eventLayout: "group",
         eventDensity: "default",
+        rootCss: "storybook",
     },
 } satisfies ArgTypes;
 
 const allThemesClasses = globalTypes.theme.toolbar.items.map(({ value }) => `cpd-theme-${value}`);
 
+const RootCssSwitcher: React.FC<{
+    rootCss: string;
+}> = ({ rootCss }) => {
+    useLayoutEffect(() => {
+        if (rootCss === "app-web") {
+            document.documentElement.dataset.storybookRootCss = rootCss;
+        } else {
+            delete document.documentElement.dataset.storybookRootCss;
+        }
+
+        return () => {
+            delete document.documentElement.dataset.storybookRootCss;
+        };
+    }, [rootCss]);
+
+    return null;
+};
+
 const ThemeSwitcher: React.FC<{
     theme: string;
 }> = ({ theme }) => {
@@ -89,6 +121,15 @@ const ThemeSwitcher: React.FC<{
     return null;
 };
 
+const withRootCss: Decorator = (Story, context) => {
+    return (
+        <>
+            <RootCssSwitcher rootCss={context.globals.rootCss} />
+            <Story />
+        </>
+    );
+};
+
 const withThemeProvider: Decorator = (Story, context) => {
     return (
         <>
@@ -134,12 +175,13 @@ const withEventPresentationProvider: Decorator = (Story, context) => {
 const preview = {
     tags: ["autodocs", "snapshot"],
     initialGlobals: {
-        theme: "system",
+        rootCss: "storybook",
+        theme: "light",
         language: "en",
         eventLayout: "group",
         eventDensity: "default",
     },
-    decorators: [withThemeProvider, withEventPresentationProvider, withTooltipProvider, withI18nProvider],
+    decorators: [withRootCss, withThemeProvider, withEventPresentationProvider, withTooltipProvider, withI18nProvider],
     parameters: {
         options: {
             storySort: {

packages/shared-components/src/room/timeline/EventPresentation/EventPresentationContext.tsx

@@ -37,3 +37,20 @@ export const EventPresentationProvider = EventPresentationContext.Provider;
 export function useEventPresentation(): EventPresentation {
     return useContext(EventPresentationContext);
 }
+
+/** Returns the current event presentation settings attributes.
+ *
+ *  "data-event-layout": "group" | "bubble" | "irc"
+ *  "data-event-density": "default" | "compact"
+ */
+export function useEventPresentationAttributes(): {
+    "data-event-layout": EventLayout;
+    "data-event-density": EventDensity;
+} {
+    const { layout, density } = useEventPresentation();
+
+    return {
+        "data-event-layout": layout,
+        "data-event-density": density,
+    };
+}

packages/shared-components/src/room/timeline/event-tile/EventTileView/TextualEventView/TextualEventView.module.css

@@ -0,0 +1,25 @@
+/*
+ * 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.
+ */
+
+.textualEvent {
+    font-size: var(--cpd-font-size-body-sm);
+    line-height: normal;
+
+    overflow-y: hidden;
+    color: var(--cpd-color-text-secondary);
+
+    a {
+        cursor: pointer;
+        color: var(--cpd-color-text-action-accent);
+    }
+}
+
+.textualEvent[data-event-layout="irc"] {
+    padding: 1px 0; /* add a 1px padding top and bottom because our larger emoji font otherwise gets cropped by anti-zalgo */
+    display: inline-block;
+    line-height: 1.125rem; /* $font-18px equivalent of the legacy --irc-line-height */
+}

packages/shared-components/src/room/timeline/event-tile/EventTileView/TextualEventView/TextualEventView.stories.tsx

@@ -6,6 +6,7 @@ Please see LICENSE files in the repository root for full details.
 */
 
 import { type Meta, type StoryObj } from "@storybook/react-vite";
+import React from "react";
 
 import { TextualEventView as TextualEventComponent } from "./TextualEventView";
 import { MockViewModel } from "../../../../../core/viewmodel/MockViewModel";
@@ -23,3 +24,16 @@ export default meta;
 type Story = StoryObj<typeof meta>;
 
 export const Default: Story = {};
+
+export const WithLink: Story = {
+    args: {
+        vm: new MockViewModel({
+            content: (
+                <>
+                    <span>Dummy [🤒] textual event text </span>
+                    <a href="~">with link</a>
+                </>
+            ),
+        }),
+    },
+};

packages/shared-components/src/room/timeline/event-tile/EventTileView/TextualEventView/TextualEventView.test.tsx

@@ -12,11 +12,16 @@ import { describe, it, expect } from "vitest";
 
 import * as stories from "./TextualEventView.stories.tsx";
 
-const { Default } = composeStories(stories);
+const { Default, WithLink } = composeStories(stories);
 
 describe("TextualEventView", () => {
     it("renders a textual event", () => {
         const { container } = render(<Default />);
         expect(container).toMatchSnapshot();
     });
+
+    it("renders a textual event with link", () => {
+        const { container } = render(<WithLink />);
+        expect(container).toMatchSnapshot();
+    });
 });

packages/shared-components/src/room/timeline/event-tile/EventTileView/TextualEventView/TextualEventView.tsx

@@ -6,15 +6,22 @@ Please see LICENSE files in the repository root for full details.
 */
 
 import React, { type ReactNode, type JSX } from "react";
+import classNames from "classnames";
 
 import { type ViewModel, useViewModel } from "../../../../../core/viewmodel";
+import styles from "./TextualEventView.module.css";
+import { useEventPresentationAttributes } from "../../../EventPresentation/EventPresentationContext";
 
 export type TextualEventViewSnapshot = {
     content: string | ReactNode;
 };
 
 export interface Props {
+    /** The view model for the tile error fallback. */
     vm: ViewModel<TextualEventViewSnapshot>;
+
+    /** Optional host-level class names. */
+    className?: string;
 }
 
 /**
@@ -23,7 +30,12 @@ export interface Props {
  * This view is used for simple informational timeline entries where the
  * content is already prepared by the view model.
  */
-export function TextualEventView({ vm }: Props): JSX.Element {
+export function TextualEventView({ vm, className }: Readonly<Props>): JSX.Element {
+    const eventPresentationAttributes = useEventPresentationAttributes();
     const snapshot = useViewModel(vm);
-    return <div className="mx_TextualEvent">{snapshot.content}</div>;
+    return (
+        <div className={classNames(styles.textualEvent, className)} {...eventPresentationAttributes}>
+            {snapshot.content}
+        </div>
+    );
 }

packages/shared-components/src/room/timeline/event-tile/EventTileView/TextualEventView/__snapshots__/TextualEventView.test.tsx.snap

@@ -3,9 +3,30 @@
 exports[`TextualEventView > renders a textual event 1`] = `
 <div>
   <div
-    class="mx_TextualEvent"
+    class="TextualEventView-module_textualEvent"
+    data-event-density="default"
+    data-event-layout="group"
   >
     Dummy textual event text
   </div>
 </div>
 `;
+
+exports[`TextualEventView > renders a textual event with link 1`] = `
+<div>
+  <div
+    class="TextualEventView-module_textualEvent"
+    data-event-density="default"
+    data-event-layout="group"
+  >
+    <span>
+      Dummy [🤒] textual event text 
+    </span>
+    <a
+      href="~"
+    >
+      with link
+    </a>
+  </div>
+</div>
+`;

packages/shared-components/src/room/timeline/event-tile/EventTileView/TileErrorView/TileErrorView.module.css

@@ -1,38 +1,42 @@
 .tileErrorView {
-    color: var(--cpd-color-text-critical-primary);
+    font-size: var(--cpd-font-size-body-sm);
+
+    color: var(--cpd-color-text-secondary);
     list-style: none;
     text-align: center;
+
+    .line {
+        display: flex;
+        flex-wrap: wrap;
+        align-items: center;
+        justify-content: center;
+        gap: var(--cpd-space-2x);
+    }
+
+    .message {
+        padding: var(--cpd-space-1x) var(--cpd-space-4x);
+    }
+
+    .viewSourceButton {
+        appearance: none;
+        padding: 0;
+        border: 0;
+        background: none;
+        color: var(--cpd-color-text-action-primary);
+        cursor: pointer;
+        font: inherit;
+        text-decoration: underline;
+    }
+
+    .viewSourceButton:focus-visible {
+        outline: 2px solid var(--cpd-color-border-focused);
+        outline-offset: 2px;
+        border-radius: var(--cpd-space-1x);
+    }
 }
 
-.line {
+.tileErrorView[data-event-layout="bubble"] {
-    display: flex;
+    .line {
-    flex-wrap: wrap;
+        flex-direction: column;
-    align-items: center;
+    }
-    justify-content: center;
-    gap: var(--cpd-space-2x);
-}
-
-.bubble .line {
-    flex-direction: column;
-}
-
-.message {
-    padding: var(--cpd-space-1x) var(--cpd-space-4x);
-}
-
-.viewSourceButton {
-    appearance: none;
-    padding: 0;
-    border: 0;
-    background: none;
-    color: var(--cpd-color-text-action-primary);
-    cursor: pointer;
-    font: inherit;
-    text-decoration: underline;
-}
-
-.viewSourceButton:focus-visible {
-    outline: 2px solid var(--cpd-color-border-focused);
-    outline-offset: 2px;
-    border-radius: var(--cpd-space-1x);
 }

packages/shared-components/src/room/timeline/event-tile/EventTileView/TileErrorView/TileErrorView.stories.tsx

@@ -11,7 +11,6 @@ import { fn } from "storybook/test";
 import type { Meta, StoryObj } from "@storybook/react-vite";
 import { withViewDocs } from "../../../../../../.storybook/withViewDocs";
 import { useMockedViewModel } from "../../../../../core/viewmodel";
-import { EventPresentationProvider } from "../../../EventPresentation";
 import { TileErrorView, type TileErrorViewActions, type TileErrorViewSnapshot } from "./TileErrorView";
 
 type WrapperProps = TileErrorViewSnapshot &
@@ -59,13 +58,9 @@ type Story = StoryObj<typeof meta>;
 export const Default: Story = {};
 
 export const BubbleLayout: Story = {
-    decorators: [
+    globals: {
-        (Story): JSX.Element => (
+        eventLayout: "bubble",
-            <EventPresentationProvider value={{ layout: "bubble", density: "default" }}>
+    },
-                <Story />
-            </EventPresentationProvider>
-        ),
-    ],
 };
 
 export const WithoutActions: Story = {

packages/shared-components/src/room/timeline/event-tile/EventTileView/TileErrorView/TileErrorView.tsx

@@ -10,8 +10,8 @@ import classNames from "classnames";
 import { Button } from "@vector-im/compound-web";
 
 import { type ViewModel, useViewModel } from "../../../../../core/viewmodel";
-import { useEventPresentation } from "../../../EventPresentation";
 import styles from "./TileErrorView.module.css";
+import { useEventPresentationAttributes } from "../../../EventPresentation/EventPresentationContext";
 
 /** Snapshot data for rendering an event tile error fallback. */
 export interface TileErrorViewSnapshot {
@@ -55,14 +55,11 @@ interface TileErrorViewProps {
  * actions when their labels are provided.
  */
 export function TileErrorView({ vm, className }: Readonly<TileErrorViewProps>): JSX.Element {
-    const { layout } = useEventPresentation();
+    const eventPresentationAttributes = useEventPresentationAttributes();
     const { message, eventType, bugReportCtaLabel, viewSourceCtaLabel } = useViewModel(vm);
 
     return (
-        <li
+        <li className={classNames(styles.tileErrorView, className)} {...eventPresentationAttributes}>
-            className={classNames(styles.tileErrorView, className, { [styles.bubble]: layout === "bubble" })}
-            data-layout={layout}
-        >
             <div className={styles.line} role="status">
                 <span className={styles.message}>
                     {message}

packages/shared-components/src/room/timeline/event-tile/EventTileView/TileErrorView/__snapshots__/TileErrorView.test.tsx.snap

@@ -4,8 +4,9 @@ exports[`TileErrorView > renders the bubble layout variant 1`] = `
 <div>
   <ul>
     <li
-      class="TileErrorView-module_tileErrorView TileErrorView-module_bubble"
+      class="TileErrorView-module_tileErrorView"
-      data-layout="bubble"
+      data-event-density="default"
+      data-event-layout="group"
     >
       <div
         class="TileErrorView-module_line"
@@ -43,7 +44,8 @@ exports[`TileErrorView > renders the default tile error state 1`] = `
   <ul>
     <li
       class="TileErrorView-module_tileErrorView"
-      data-layout="group"
+      data-event-density="default"
+      data-event-layout="group"
     >
       <div
         class="TileErrorView-module_line"

packages/shared-components/src/room/timeline/event-tile/UrlPreviewGroupView/UrlPreviewGroupView.module.css

@@ -5,29 +5,31 @@
  * Please see LICENSE files in the repository root for full details.
  */
 
-.previewGroup {
-    flex: 1;
-    display: flex;
-    flex-direction: column;
-    gap: var(--cpd-space-4x);
-    margin-bottom: var(--cpd-space-4x);
-
-    &.compactLayout {
-        gap: var(--cpd-space-2x);
-        margin-bottom: var(--cpd-space-2x);
-    }
-
-    .toggleButton[data-kind="tertiary"] {
-        margin-left: auto;
-        margin-right: auto;
-        text-decoration: none;
-        color: var(--cpd-color-icon-accent-primary);
-        font-weight: var(--cpd-font-weight-regular);
-    }
-}
-
 .wrapper {
     margin-top: var(--cpd-space-4x);
     display: flex;
     flex-direction: row;
+
+    .previewGroup {
+        flex: 1;
+        display: flex;
+        flex-direction: column;
+        gap: var(--cpd-space-4x);
+        margin-bottom: var(--cpd-space-4x);
+
+        .toggleButton[data-kind="tertiary"] {
+            margin-left: auto;
+            margin-right: auto;
+            text-decoration: none;
+            color: var(--cpd-color-icon-accent-primary);
+            font-weight: var(--cpd-font-weight-regular);
+        }
+    }
+}
+
+.wrapper[data-event-density="compact"] {
+    .previewGroup {
+        gap: var(--cpd-space-2x);
+        margin-bottom: var(--cpd-space-2x);
+    }
 }

packages/shared-components/src/room/timeline/event-tile/UrlPreviewGroupView/UrlPreviewGroupView.stories.tsx

@@ -19,7 +19,6 @@ import {
 import { useMockedViewModel } from "../../../../core/viewmodel";
 import { LinkedTextContext } from "../../../../core/utils/LinkedText";
 import { withViewDocs } from "../../../../../.storybook/withViewDocs";
-import { EventPresentationProvider } from "../../EventPresentation";
 
 type UrlPreviewGroupViewProps = UrlPreviewGroupViewSnapshot & UrlPreviewGroupViewActions;
 
@@ -142,10 +141,6 @@ export const WithCompactView = Template.bind({});
 WithCompactView.args = {
     ...MultiplePreviewsVisible.args,
 };
-WithCompactView.decorators = [
+WithCompactView.globals = {
-    (Story): JSX.Element => (
+    eventDensity: "compact",
-        <EventPresentationProvider value={{ layout: "group", density: "compact" }}>
+};
-            <Story />
-        </EventPresentationProvider>
-    ),
-];

packages/shared-components/src/room/timeline/event-tile/UrlPreviewGroupView/UrlPreviewGroupView.tsx

@@ -12,10 +12,10 @@ import classNames from "classnames";
 
 import { useViewModel, type ViewModel } from "../../../../core/viewmodel";
 import { useI18n } from "../../../../core/i18n/i18nContext";
-import { useEventPresentation } from "../../EventPresentation";
 import type { UrlPreview } from "./types";
 import { LinkPreview } from "./LinkPreview";
 import styles from "./UrlPreviewGroupView.module.css";
+import { useEventPresentationAttributes } from "../../EventPresentation/EventPresentationContext";
 
 /** Snapshot data for rendering URL previews attached to an event. */
 export interface UrlPreviewGroupViewSnapshot {
@@ -62,7 +62,7 @@ export type UrlPreviewGroupViewModel = ViewModel<UrlPreviewGroupViewSnapshot, Ur
  */
 export function UrlPreviewGroupView({ vm, className }: UrlPreviewGroupViewProps): JSX.Element | null {
     const { translate: _t } = useI18n();
-    const { density } = useEventPresentation();
+    const eventPresentationAttributes = useEventPresentationAttributes();
     const { previews, totalPreviewCount, previewsLimited, overPreviewLimit } = useViewModel(vm);
     if (previews.length === 0) {
         return null;
@@ -80,8 +80,8 @@ export function UrlPreviewGroupView({ vm, className }: UrlPreviewGroupViewProps)
     }
 
     return (
-        <div className={classNames(className, styles.wrapper)}>
+        <div className={classNames(className, styles.wrapper)} {...eventPresentationAttributes}>
-            <div className={classNames(styles.previewGroup, density === "compact" && styles.compactLayout)}>
+            <div className={styles.previewGroup}>
                 {previews.map((preview) => (
                     <LinkPreview key={preview.link} onImageClick={() => vm.onImageClick(preview)} {...preview} />
                 ))}

packages/shared-components/src/room/timeline/event-tile/UrlPreviewGroupView/__snapshots__/UrlPreviewGroupView.test.tsx.snap

@@ -4,6 +4,8 @@ exports[`UrlPreviewGroupView > renders a single preview 1`] = `
 <div>
   <div
     class="UrlPreviewGroupView-module_wrapper"
+    data-event-density="default"
+    data-event-layout="group"
   >
     <div
       class="UrlPreviewGroupView-module_previewGroup"
@@ -82,6 +84,8 @@ exports[`UrlPreviewGroupView > renders multiple previews 1`] = `
 <div>
   <div
     class="UrlPreviewGroupView-module_wrapper"
+    data-event-density="default"
+    data-event-layout="group"
   >
     <div
       class="UrlPreviewGroupView-module_previewGroup"
@@ -249,6 +253,8 @@ exports[`UrlPreviewGroupView > renders multiple previews which are hidden 1`] =
 <div>
   <div
     class="UrlPreviewGroupView-module_wrapper"
+    data-event-density="default"
+    data-event-layout="group"
   >
     <div
       class="UrlPreviewGroupView-module_previewGroup"
@@ -336,9 +342,11 @@ exports[`UrlPreviewGroupView > renders with compact density 1`] = `
 <div>
   <div
     class="UrlPreviewGroupView-module_wrapper"
+    data-event-density="default"
+    data-event-layout="group"
   >
     <div
-      class="UrlPreviewGroupView-module_previewGroup UrlPreviewGroupView-module_compactLayout"
+      class="UrlPreviewGroupView-module_previewGroup"
     >
       <div
         class="LinkPreview-module_container"