diff --git a/.storybook/preview-head.html b/.storybook/preview-head.html
index 086a0ee571c1..6d16920b164e 100644
--- a/.storybook/preview-head.html
+++ b/.storybook/preview-head.html
@@ -50,5 +50,9 @@
       hasCustomTitleBar: () => false,
     },
   };
+
+  window.ConversationController = window.ConversationController || {};
+  window.ConversationController.isSignalConversation = () => false;
+  window.ConversationController.onConvoMessageMount = noop;
   window.getPreferredSystemLocales = () => ['en'];
 </script>
diff --git a/ts/components/EditHistoryMessagesModal.tsx b/ts/components/EditHistoryMessagesModal.tsx
index 9a57b8b50ea2..42745a550789 100644
--- a/ts/components/EditHistoryMessagesModal.tsx
+++ b/ts/components/EditHistoryMessagesModal.tsx
@@ -19,6 +19,7 @@ export type PropsType = {
   editHistoryMessages: Array<MessagePropsType>;
   getPreferredBadge: PreferredBadgeSelectorType;
   i18n: LocalizerType;
+  platform: string;
   kickOffAttachmentDownload: (options: {
     attachment: AttachmentType;
     messageId: string;
@@ -70,6 +71,7 @@ export function EditHistoryMessagesModal({
   getPreferredBadge,
   editHistoryMessages,
   i18n,
+  platform,
   kickOffAttachmentDownload,
   showLightbox,
 }: PropsType): JSX.Element {
@@ -100,6 +102,7 @@ export function EditHistoryMessagesModal({
             containerElementRef={containerElementRef}
             getPreferredBadge={getPreferredBadge}
             i18n={i18n}
+            platform={platform}
             key={messageAttributes.timestamp}
             kickOffAttachmentDownload={kickOffAttachmentDownload}
             showLightbox={closeAndShowLightbox}
diff --git a/ts/components/GroupV1MigrationDialog.tsx b/ts/components/GroupV1MigrationDialog.tsx
index a30a9aa4ee04..72aafb47d2dd 100644
--- a/ts/components/GroupV1MigrationDialog.tsx
+++ b/ts/components/GroupV1MigrationDialog.tsx
@@ -7,7 +7,7 @@ import type { ConversationType } from '../state/ducks/conversations';
 import type { PreferredBadgeSelectorType } from '../state/selectors/badges';
 import { GroupDialog } from './GroupDialog';
 import { sortByTitle } from '../util/sortByTitle';
-import { missingCaseError } from '../util';
+import { missingCaseError } from '../util/missingCaseError';
 
 export type DataPropsType = {
   conversationId: string;
diff --git a/ts/components/StoryViewer.stories.tsx b/ts/components/StoryViewer.stories.tsx
index aeecb86f6f41..254d3dad947a 100644
--- a/ts/components/StoryViewer.stories.tsx
+++ b/ts/components/StoryViewer.stories.tsx
@@ -39,6 +39,9 @@ export default {
     i18n: {
       defaultValue: i18n,
     },
+    platform: {
+      defaultValue: 'darwin',
+    },
     loadStoryReplies: { action: true },
     markStoryRead: { action: true },
     numStories: {
diff --git a/ts/components/StoryViewer.tsx b/ts/components/StoryViewer.tsx
index c569ff379c53..7f909b919d3d 100644
--- a/ts/components/StoryViewer.tsx
+++ b/ts/components/StoryViewer.tsx
@@ -101,6 +101,7 @@ export type PropsType = {
   ) => unknown;
   onUseEmoji: (_: EmojiPickDataType) => unknown;
   onMediaPlaybackStart: () => void;
+  platform: string;
   preferredReactionEmoji: ReadonlyArray<string>;
   queueStoryDownload: (storyId: string) => unknown;
   recentEmojis?: ReadonlyArray<string>;
@@ -155,6 +156,7 @@ export function StoryViewer({
   onTextTooLong,
   onUseEmoji,
   onMediaPlaybackStart,
+  platform,
   preferredReactionEmoji,
   queueStoryDownload,
   recentEmojis,
@@ -914,6 +916,7 @@ export function StoryViewer({
             hasViewReceiptSetting={hasViewReceiptSetting}
             hasViewsCapability={isSent}
             i18n={i18n}
+            platform={platform}
             isInternalUser={isInternalUser}
             group={group}
             onClose={() => setCurrentViewTarget(null)}
diff --git a/ts/components/StoryViewsNRepliesModal.stories.tsx b/ts/components/StoryViewsNRepliesModal.stories.tsx
index c6c20db36810..88e495398481 100644
--- a/ts/components/StoryViewsNRepliesModal.stories.tsx
+++ b/ts/components/StoryViewsNRepliesModal.stories.tsx
@@ -39,6 +39,9 @@ export default {
     i18n: {
       defaultValue: i18n,
     },
+    platform: {
+      defaultValue: 'darwin',
+    },
     onClose: { action: true },
     onSetSkinTone: { action: true },
     onReact: { action: true },
diff --git a/ts/components/StoryViewsNRepliesModal.tsx b/ts/components/StoryViewsNRepliesModal.tsx
index 9d34b4b713fc..8c427407c700 100644
--- a/ts/components/StoryViewsNRepliesModal.tsx
+++ b/ts/components/StoryViewsNRepliesModal.tsx
@@ -87,6 +87,7 @@ export type PropsType = {
   hasViewReceiptSetting: boolean;
   hasViewsCapability: boolean;
   i18n: LocalizerType;
+  platform: string;
   isInternalUser?: boolean;
   onChangeViewTarget: (target: StoryViewTargetType) => unknown;
   onClose: () => unknown;
@@ -120,6 +121,7 @@ export function StoryViewsNRepliesModal({
   hasViewReceiptSetting,
   hasViewsCapability,
   i18n,
+  platform,
   isInternalUser,
   onChangeViewTarget,
   onClose,
@@ -286,6 +288,7 @@ export function StoryViewsNRepliesModal({
               }
               getPreferredBadge={getPreferredBadge}
               i18n={i18n}
+              platform={platform}
               id={reply.id}
               isInternalUser={isInternalUser}
               reply={reply}
@@ -463,6 +466,7 @@ type ReplyOrReactionMessageProps = {
   deleteGroupStoryReplyForEveryone: (replyId: string) => void;
   getPreferredBadge: PreferredBadgeSelectorType;
   i18n: LocalizerType;
+  platform: string;
   id: string;
   isInternalUser?: boolean;
   onContextMenu?: (ev: React.MouseEvent) => void;
@@ -481,6 +485,7 @@ function ReplyOrReactionMessage({
   deleteGroupStoryReplyForEveryone,
   containerElementRef,
   getPreferredBadge,
+  platform,
   shouldCollapseAbove,
   shouldCollapseBelow,
   showContactModal,
@@ -549,6 +554,7 @@ function ReplyOrReactionMessage({
           onContextMenu={onContextMenu}
           getPreferredBadge={getPreferredBadge}
           i18n={i18n}
+          platform={platform}
           id={reply.id}
           interactionMode="mouse"
           readStatus={reply.readStatus}
diff --git a/ts/components/conversation/Message.tsx b/ts/components/conversation/Message.tsx
index 0c7133ada2ec..c508c9b679f9 100644
--- a/ts/components/conversation/Message.tsx
+++ b/ts/components/conversation/Message.tsx
@@ -98,7 +98,6 @@ import { Emojify } from './Emojify';
 import { getPaymentEventDescription } from '../../messages/helpers';
 import { PanelType } from '../../types/Panels';
 import { openLinkInWebBrowser } from '../../util/openLinkInWebBrowser';
-import { isMacOS } from '../../OS';
 
 const GUESS_METADATA_WIDTH_TIMESTAMP_SIZE = 16;
 const GUESS_METADATA_WIDTH_EXPIRE_TIMER_SIZE = 18;
@@ -297,6 +296,7 @@ export type PropsHousekeeping = {
   getPreferredBadge: PreferredBadgeSelectorType;
   i18n: LocalizerType;
   interactionMode: InteractionModeType;
+  platform: string;
   renderAudioAttachment: (props: AudioAttachmentProps) => JSX.Element;
   shouldCollapseAbove: boolean;
   shouldCollapseBelow: boolean;
@@ -2577,6 +2577,7 @@ export class Message extends React.PureComponent<Props, State> {
       isSelected,
       isSelectMode,
       onKeyDown,
+      platform,
       renderMenu,
       shouldCollapseAbove,
       shouldCollapseBelow,
@@ -2584,6 +2585,7 @@ export class Message extends React.PureComponent<Props, State> {
       onToggleSelect,
       onReplyToMessage,
     } = this.props;
+    const isMacOS = platform === 'darwin';
     const { expired, expiring, isTargeted, imageBroken } = this.state;
 
     if (expired) {
@@ -2622,7 +2624,7 @@ export class Message extends React.PureComponent<Props, State> {
         // We use `onClickCapture` here and preven default/stop propagation to
         // prevent other click handlers from firing.
         onClickCapture: event => {
-          if (isMacOS() ? event.metaKey : event.ctrlKey) {
+          if (isMacOS ? event.metaKey : event.ctrlKey) {
             event.preventDefault();
             event.stopPropagation();
             onToggleSelect(true, false);
diff --git a/ts/components/conversation/MessageDetail.stories.tsx b/ts/components/conversation/MessageDetail.stories.tsx
index 5424780de95d..009711dfa9cc 100644
--- a/ts/components/conversation/MessageDetail.stories.tsx
+++ b/ts/components/conversation/MessageDetail.stories.tsx
@@ -68,6 +68,7 @@ const createProps = (overrideProps: Partial<Props> = {}): Props => ({
 
   getPreferredBadge: () => getFakeBadge(),
   i18n,
+  platform: 'darwin',
   interactionMode: 'keyboard',
   theme: ThemeType.light,
 
diff --git a/ts/components/conversation/MessageDetail.tsx b/ts/components/conversation/MessageDetail.tsx
index fa44bf7e5ef9..28a25b98b505 100644
--- a/ts/components/conversation/MessageDetail.tsx
+++ b/ts/components/conversation/MessageDetail.tsx
@@ -67,6 +67,7 @@ export type PropsData = {
   sentAt: number;
 
   i18n: LocalizerType;
+  platform: string;
   theme: ThemeType;
   getPreferredBadge: PreferredBadgeSelectorType;
 } & Pick<MessagePropsType, 'getPreferredBadge' | 'interactionMode'>;
@@ -303,6 +304,7 @@ export class MessageDetail extends React.Component<Props> {
       kickOffAttachmentDownload,
       markAttachmentAsCorrupted,
       openGiftBadge,
+      platform,
       pushPanelForConversation,
       renderAudioAttachment,
       saveAttachment,
@@ -346,6 +348,7 @@ export class MessageDetail extends React.Component<Props> {
             kickOffAttachmentDownload={kickOffAttachmentDownload}
             markAttachmentAsCorrupted={markAttachmentAsCorrupted}
             messageExpanded={noop}
+            platform={platform}
             showConversation={showConversation}
             openGiftBadge={openGiftBadge}
             pushPanelForConversation={pushPanelForConversation}
diff --git a/ts/components/conversation/Quote.stories.tsx b/ts/components/conversation/Quote.stories.tsx
index 951cc3dfc38b..08735c2953f5 100644
--- a/ts/components/conversation/Quote.stories.tsx
+++ b/ts/components/conversation/Quote.stories.tsx
@@ -44,6 +44,9 @@ export default {
     i18n: {
       defaultValue: i18n,
     },
+    platform: {
+      defautlValue: 'darwin',
+    },
     isFromMe: {
       control: { type: 'checkbox' },
       defaultValue: false,
@@ -103,6 +106,7 @@ const defaultMessageProps: TimelineMessagesProps = {
   ),
   getPreferredBadge: () => undefined,
   i18n,
+  platform: 'darwin',
   id: 'messageId',
   // renderingContext: 'storybook',
   interactionMode: 'keyboard',
diff --git a/ts/components/conversation/Timeline.stories.tsx b/ts/components/conversation/Timeline.stories.tsx
index 7d9c6203411f..1fcd2e4bed9b 100644
--- a/ts/components/conversation/Timeline.stories.tsx
+++ b/ts/components/conversation/Timeline.stories.tsx
@@ -344,6 +344,7 @@ const renderItem = ({
     interactionMode="keyboard"
     isNextItemCallingNotification={false}
     theme={ThemeType.light}
+    platform="darwin"
     containerElementRef={containerElementRef}
     containerWidthBreakpoint={containerWidthBreakpoint}
     conversationId=""
diff --git a/ts/components/conversation/TimelineItem.stories.tsx b/ts/components/conversation/TimelineItem.stories.tsx
index 8e5606927a5c..d1ae525b09f0 100644
--- a/ts/components/conversation/TimelineItem.stories.tsx
+++ b/ts/components/conversation/TimelineItem.stories.tsx
@@ -61,6 +61,7 @@ const getDefaultProps = () => ({
   isTargeted: false,
   interactionMode: 'keyboard' as const,
   theme: ThemeType.light,
+  platform: 'darwin',
   targetMessage: action('targetMessage'),
   toggleSelectMessage: action('toggleSelectMessage'),
   reactToMessage: action('reactToMessage'),
diff --git a/ts/components/conversation/TimelineItem.tsx b/ts/components/conversation/TimelineItem.tsx
index b9f623b4e226..2b7e8ba8eb33 100644
--- a/ts/components/conversation/TimelineItem.tsx
+++ b/ts/components/conversation/TimelineItem.tsx
@@ -151,6 +151,7 @@ type PropsLocalType = {
   isTargeted: boolean;
   targetMessage: (messageId: string, conversationId: string) => unknown;
   shouldRenderDateHeader: boolean;
+  platform: string;
   renderContact: SmartContactRendererType<FullJSXType>;
   renderUniversalTimerNotification: () => JSX.Element;
   i18n: LocalizerType;
@@ -188,6 +189,7 @@ export class TimelineItem extends React.PureComponent<PropsType> {
       isNextItemCallingNotification,
       isTargeted,
       item,
+      platform,
       renderUniversalTimerNotification,
       returnToActiveCall,
       targetMessage,
@@ -223,6 +225,7 @@ export class TimelineItem extends React.PureComponent<PropsType> {
           shouldHideMetadata={shouldHideMetadata}
           containerElementRef={containerElementRef}
           getPreferredBadge={getPreferredBadge}
+          platform={platform}
           i18n={i18n}
           theme={theme}
         />
diff --git a/ts/components/conversation/TimelineMessage.stories.tsx b/ts/components/conversation/TimelineMessage.stories.tsx
index 4af46ce6d713..22f6f5a0cdb6 100644
--- a/ts/components/conversation/TimelineMessage.stories.tsx
+++ b/ts/components/conversation/TimelineMessage.stories.tsx
@@ -281,6 +281,7 @@ const createProps = (overrideProps: Partial<Props> = {}): Props => ({
   getPreferredBadge: overrideProps.getPreferredBadge || (() => undefined),
   giftBadge: overrideProps.giftBadge,
   i18n,
+  platform: 'darwin',
   id: text('id', overrideProps.id || 'random-message-id'),
   // renderingContext: 'storybook',
   interactionMode: overrideProps.interactionMode || 'keyboard',
diff --git a/ts/components/emoji/EmojiPicker.tsx b/ts/components/emoji/EmojiPicker.tsx
index ca74e64c7447..eab15c438af6 100644
--- a/ts/components/emoji/EmojiPicker.tsx
+++ b/ts/components/emoji/EmojiPicker.tsx
@@ -24,7 +24,7 @@ import { Emoji } from './Emoji';
 import { dataByCategory, search } from './lib';
 import type { LocalizerType } from '../../types/Util';
 import { isSingleGrapheme } from '../../util/grapheme';
-import { missingCaseError } from '../../util';
+import { missingCaseError } from '../../util/missingCaseError';
 
 export type EmojiPickDataType = {
   skinTone?: number;
diff --git a/ts/state/smart/EditHistoryMessagesModal.tsx b/ts/state/smart/EditHistoryMessagesModal.tsx
index dcfb183ecbc7..163d94da552a 100644
--- a/ts/state/smart/EditHistoryMessagesModal.tsx
+++ b/ts/state/smart/EditHistoryMessagesModal.tsx
@@ -7,7 +7,7 @@ import type { GlobalModalsStateType } from '../ducks/globalModals';
 import type { MessageAttributesType } from '../../model-types.d';
 import type { StateType } from '../reducer';
 import { EditHistoryMessagesModal } from '../../components/EditHistoryMessagesModal';
-import { getIntl } from '../selectors/user';
+import { getIntl, getPlatform } from '../selectors/user';
 import { getMessagePropsSelector } from '../selectors/message';
 import { getPreferredBadgeSelector } from '../selectors/badges';
 import { useConversationsActions } from '../ducks/conversations';
@@ -17,6 +17,7 @@ import { strictAssert } from '../../util/assert';
 
 export function SmartEditHistoryMessagesModal(): JSX.Element {
   const i18n = useSelector(getIntl);
+  const platform = useSelector(getPlatform);
 
   const { closeEditHistoryModal } = useGlobalModalActions();
 
@@ -50,6 +51,7 @@ export function SmartEditHistoryMessagesModal(): JSX.Element {
       editHistoryMessages={editHistoryMessages}
       getPreferredBadge={getPreferredBadge}
       i18n={i18n}
+      platform={platform}
       kickOffAttachmentDownload={kickOffAttachmentDownload}
       showLightbox={showLightbox}
     />
diff --git a/ts/state/smart/MessageDetail.tsx b/ts/state/smart/MessageDetail.tsx
index f1ca063427c2..cca3bb819a52 100644
--- a/ts/state/smart/MessageDetail.tsx
+++ b/ts/state/smart/MessageDetail.tsx
@@ -7,7 +7,12 @@ import { useSelector } from 'react-redux';
 import type { Props as MessageDetailProps } from '../../components/conversation/MessageDetail';
 import { MessageDetail } from '../../components/conversation/MessageDetail';
 import { getContactNameColorSelector } from '../selectors/conversations';
-import { getIntl, getInteractionMode, getTheme } from '../selectors/user';
+import {
+  getIntl,
+  getInteractionMode,
+  getTheme,
+  getPlatform,
+} from '../selectors/user';
 import { getMessageDetails } from '../selectors/message';
 import { getPreferredBadgeSelector } from '../selectors/badges';
 import { renderAudioAttachment } from './renderAudioAttachment';
@@ -27,6 +32,7 @@ export function SmartMessageDetail(): JSX.Element | null {
   const getContactNameColor = useSelector(getContactNameColorSelector);
   const getPreferredBadge = useSelector(getPreferredBadgeSelector);
   const i18n = useSelector(getIntl);
+  const platform = useSelector(getPlatform);
   const interactionMode = useSelector(getInteractionMode);
   const messageDetails = useSelector(getMessageDetails);
   const theme = useSelector(getTheme);
@@ -76,6 +82,7 @@ export function SmartMessageDetail(): JSX.Element | null {
       errors={errors}
       getPreferredBadge={getPreferredBadge}
       i18n={i18n}
+      platform={platform}
       interactionMode={interactionMode}
       kickOffAttachmentDownload={kickOffAttachmentDownload}
       markAttachmentAsCorrupted={markAttachmentAsCorrupted}
diff --git a/ts/state/smart/StoryViewer.tsx b/ts/state/smart/StoryViewer.tsx
index 7b2d1079e5e7..bad08f96989f 100644
--- a/ts/state/smart/StoryViewer.tsx
+++ b/ts/state/smart/StoryViewer.tsx
@@ -18,7 +18,7 @@ import {
   getPreferredReactionEmoji,
   isInternalUser,
 } from '../selectors/items';
-import { getIntl } from '../selectors/user';
+import { getIntl, getPlatform } from '../selectors/user';
 import { getPreferredBadgeSelector } from '../selectors/badges';
 import {
   getSelectedStoryData,
@@ -56,6 +56,7 @@ export function SmartStoryViewer(): JSX.Element | null {
   const isWindowActive = useIsWindowActive();
 
   const i18n = useSelector<StateType, LocalizerType>(getIntl);
+  const platform = useSelector(getPlatform);
   const getPreferredBadge = useSelector(getPreferredBadgeSelector);
   const preferredReactionEmoji = useSelector<StateType, ReadonlyArray<string>>(
     getPreferredReactionEmoji
@@ -111,6 +112,7 @@ export function SmartStoryViewer(): JSX.Element | null {
       hasAllStoriesUnmuted={hasAllStoriesUnmuted}
       hasViewReceiptSetting={hasViewReceiptSetting}
       i18n={i18n}
+      platform={platform}
       isInternalUser={internalUser}
       saveAttachment={internalUser ? saveAttachment : asyncShouldNeverBeCalled}
       isSignalConversation={isSignalConversation({
diff --git a/ts/state/smart/TimelineItem.tsx b/ts/state/smart/TimelineItem.tsx
index 262a37de92c2..318b6e6a7037 100644
--- a/ts/state/smart/TimelineItem.tsx
+++ b/ts/state/smart/TimelineItem.tsx
@@ -16,7 +16,12 @@ import { useLightboxActions } from '../ducks/lightbox';
 import { useStoriesActions } from '../ducks/stories';
 import { useCallingActions } from '../ducks/calling';
 import { getPreferredBadgeSelector } from '../selectors/badges';
-import { getIntl, getInteractionMode, getTheme } from '../selectors/user';
+import {
+  getIntl,
+  getInteractionMode,
+  getTheme,
+  getPlatform,
+} from '../selectors/user';
 import { getTargetedMessage } from '../selectors/conversations';
 import { getTimelineItem } from '../selectors/timeline';
 import {
@@ -67,6 +72,7 @@ export function SmartTimelineItem(props: ExternalProps): JSX.Element {
   const getPreferredBadge = useSelector(getPreferredBadgeSelector);
   const interactionMode = useSelector(getInteractionMode);
   const theme = useSelector(getTheme);
+  const platform = useSelector(getPlatform);
   const item = useProxySelector(getTimelineItem, messageId);
   const previousItem = useProxySelector(getTimelineItem, previousMessageId);
   const nextItem = useProxySelector(getTimelineItem, nextMessageId);
@@ -166,6 +172,7 @@ export function SmartTimelineItem(props: ExternalProps): JSX.Element {
       i18n={i18n}
       interactionMode={interactionMode}
       theme={theme}
+      platform={platform}
       blockGroupLinkRequests={blockGroupLinkRequests}
       checkForAccount={checkForAccount}
       clearTargetedMessage={clearSelectedMessage}