Add support for search sidebar panel via feature flag

src/sidebar/components/HypothesisApp.tsx

@@ -22,6 +22,7 @@ import SidebarView from './SidebarView';
 import StreamView from './StreamView';
 import ToastMessages from './ToastMessages';
 import TopBar from './TopBar';
+import SearchPanel from './search/SearchPanel';
 
 export type HypothesisAppProps = {
   auth: AuthService;
@@ -69,6 +70,8 @@ function HypothesisApp({
   const showShareButton =
     !isThirdParty || exportAnnotations || importAnnotations;
 
+  const searchPanelEnabled = store.isFeatureEnabled('search_panel');
+
   const login = async () => {
     if (serviceConfig(settings)) {
       // Let the host page handle the login request
@@ -168,6 +171,7 @@ function HypothesisApp({
       <div className="container">
         <ToastMessages />
         <HelpPanel />
+        {searchPanelEnabled && <SearchPanel />}
         {showShareButton && (
           <ShareDialog
             shareTab={!isThirdParty}

src/sidebar/components/SidebarPanel.tsx

+import type { DialogProps } from '@hypothesis/frontend-shared';
 import { Dialog, Slider } from '@hypothesis/frontend-shared';
 import type { IconComponent } from '@hypothesis/frontend-shared/lib/types';
 import type { ComponentChildren } from 'preact';
@@ -22,6 +23,7 @@ export type SidebarPanelProps = {
   onActiveChanged?: (active: boolean) => void;
   /** What Dialog variant to use */
   variant?: 'panel' | 'custom';
+  initialFocus?: DialogProps['initialFocus'];
 };
 
 /**
@@ -35,6 +37,7 @@ export default function SidebarPanel({
   title,
   variant = 'panel',
   onActiveChanged,
+  initialFocus,
 }: SidebarPanelProps) {
   const store = useSidebarStore();
   const panelIsActive = store.isSidebarPanelOpen(panelName);
@@ -61,6 +64,7 @@ export default function SidebarPanel({
     <>
       {panelIsActive && (
         <Dialog
+          initialFocus={initialFocus}
           restoreFocus
           ref={panelElement}
           classes="mb-4"

src/sidebar/components/SidebarView.tsx

@@ -6,13 +6,14 @@ import type { FrameSyncService } from '../services/frame-sync';
 import type { LoadAnnotationsService } from '../services/load-annotations';
 import type { StreamerService } from '../services/streamer';
 import { useSidebarStore } from '../store';
-import FilterStatus from './FilterStatus';
 import LoggedOutMessage from './LoggedOutMessage';
 import LoginPromptPanel from './LoginPromptPanel';
 import SelectionTabs from './SelectionTabs';
 import SidebarContentError from './SidebarContentError';
 import ThreadList from './ThreadList';
 import { useRootThread } from './hooks/use-root-thread';
+import FilterStatus from './old-search/FilterStatus';
+import FilterAnnotationsStatus from './search/FilterAnnotationsStatus';
 
 export type SidebarViewProps = {
   onLogin: () => void;
@@ -66,7 +67,8 @@ function SidebarView({
   const hasContentError =
     hasDirectLinkedAnnotationError || hasDirectLinkedGroupError;
 
-  const showFilterStatus = !hasContentError;
+  const searchPanelEnabled = store.isFeatureEnabled('search_panel');
+  const showFilterStatus = !hasContentError && !searchPanelEnabled;
   const showTabs = !hasContentError && !hasAppliedFilter;
 
   // Show a CTA to log in if successfully viewing a direct-linked annotation
@@ -132,6 +134,7 @@ function SidebarView({
     <div>
       <h2 className="sr-only">Annotations</h2>
       {showFilterStatus && <FilterStatus />}
+      {searchPanelEnabled && <FilterAnnotationsStatus />}
       <LoginPromptPanel onLogin={onLogin} onSignUp={onSignUp} />
       {hasDirectLinkedAnnotationError && (
         <SidebarContentError

src/sidebar/components/TopBar.tsx

@@ -10,10 +10,11 @@ import { useSidebarStore } from '../store';
 import GroupList from './GroupList';
 import PendingUpdatesButton from './PendingUpdatesButton';
 import PressableIconButton from './PressableIconButton';
-import SearchInput from './SearchInput';
 import SortMenu from './SortMenu';
-import StreamSearchInput from './StreamSearchInput';
 import UserMenu from './UserMenu';
+import SearchInput from './old-search/SearchInput';
+import SearchIconButton from './search/SearchIconButton';
+import StreamSearchInput from './search/StreamSearchInput';
 
 export type TopBarProps = {
   showShareButton: boolean;
@@ -54,6 +55,7 @@ function TopBar({
   const filterQuery = store.filterQuery();
   const isLoggedIn = store.isLoggedIn();
   const hasFetchedProfile = store.hasFetchedProfile();
+  const searchPanelEnabled = store.isFeatureEnabled('search_panel');
 
   const toggleSharePanel = () => {
     store.toggleSidebarPanel('shareGroupAnnotations');
@@ -98,10 +100,13 @@ function TopBar({
           {isSidebar && (
             <>
               <PendingUpdatesButton />
+              {!searchPanelEnabled && (
                 <SearchInput
                   query={filterQuery || null}
                   onSearch={store.setFilterQuery}
                 />
+              )}
+              {searchPanelEnabled && <SearchIconButton />}
               <SortMenu />
               {showShareButton && (
                 <PressableIconButton

src/sidebar/components/FilterStatus.tsx → src/sidebar/components/old-search/FilterStatus.tsx

@@ -8,9 +8,9 @@ import {
 import classnames from 'classnames';
 import { useMemo } from 'preact/hooks';
 
-import { countVisible } from '../helpers/thread';
-import { useSidebarStore } from '../store';
-import { useRootThread } from './hooks/use-root-thread';
+import { countVisible } from '../../helpers/thread';
+import { useSidebarStore } from '../../store';
+import { useRootThread } from '../hooks/use-root-thread';
 
 type FilterStatusMessageProps = {
   /**

src/sidebar/components/SearchInput.tsx → src/sidebar/components/old-search/SearchInput.tsx

@@ -8,9 +8,9 @@ import classnames from 'classnames';
 import type { RefObject } from 'preact';
 import { useCallback, useRef, useState } from 'preact/hooks';
 
-import { useShortcut } from '../../shared/shortcut';
-import { isMacOS } from '../../shared/user-agent';
-import { useSidebarStore } from '../store';
+import { useShortcut } from '../../../shared/shortcut';
+import { isMacOS } from '../../../shared/user-agent';
+import { useSidebarStore } from '../../store';
 
 /**
  * Respond to keydown events on the document (shortcut keys):

src/sidebar/components/test/FilterStatus-test.js → src/sidebar/components/old-search/test/FilterStatus-test.js

@@ -40,9 +40,9 @@ describe('FilterStatus', () => {
 
     $imports.$mock(mockImportedComponents());
     $imports.$mock({
-      './hooks/use-root-thread': { useRootThread: fakeUseRootThread },
-      '../store': { useSidebarStore: () => fakeStore },
-      '../helpers/thread': fakeThreadUtil,
+      '../hooks/use-root-thread': { useRootThread: fakeUseRootThread },
+      '../../store': { useSidebarStore: () => fakeStore },
+      '../../helpers/thread': fakeThreadUtil,
     });
   });
 

src/sidebar/components/test/SearchInput-test.js → src/sidebar/components/old-search/test/SearchInput-test.js

@@ -34,8 +34,8 @@ describe('SearchInput', () => {
 
     $imports.$mock(mockImportedComponents());
     $imports.$mock({
-      '../store': { useSidebarStore: () => fakeStore },
-      '../../shared/user-agent': {
+      '../../store': { useSidebarStore: () => fakeStore },
+      '../../../shared/user-agent': {
         isMacOS: fakeIsMacOS,
       },
     });

src/sidebar/components/search/FilterAnnotationsStatus.tsx

+import {
+  Button,
+  CancelIcon,
+  Card,
+  CardContent,
+  Spinner,
+} from '@hypothesis/frontend-shared';
+import classnames from 'classnames';
+import { useMemo } from 'preact/hooks';
+
+import { countVisible } from '../../helpers/thread';
+import { useSidebarStore } from '../../store';
+import { useRootThread } from '../hooks/use-root-thread';
+
+type FilterStatusMessageProps = {
+  /**
+   * A count of items that are visible but do not match the filters (i.e. items
+   * that have been "forced visible" by the user)
+   */
+  additionalCount: number;
+
+  /** Singular unit of the items being shown, e.g. "result" or "annotation" */
+  entitySingular: string;
+
+  /** Plural unit of the items being shown */
+  entityPlural: string;
+
+  /** Display name for the user currently focused, if any */
+  focusDisplayName?: string | null;
+
+  /**
+   * The number of items that match the current filter(s). When focusing on a
+   * user, this value includes annotations and replies.
+   * When there are selected annotations, this number includes only top-level
+   * annotations.
+   */
+  resultCount: number;
+};
+
+/**
+ * Render status text describing the currently-applied filters.
+ */
+function FilterStatusMessage({
+  additionalCount,
+  entitySingular,
+  entityPlural,
+  focusDisplayName,
+  resultCount,
+}: FilterStatusMessageProps) {
+  return (
+    <>
+      {resultCount > 0 && <span>Showing </span>}
+      <span className="whitespace-nowrap font-bold">
+        {resultCount > 0 ? resultCount : 'No'}{' '}
+        {resultCount === 1 ? entitySingular : entityPlural}
+      </span>
+      {focusDisplayName && (
+        <span>
+          {' '}
+          by{' '}
+          <span className="whitespace-nowrap font-bold">
+            {focusDisplayName}
+          </span>
+        </span>
+      )}
+      {additionalCount > 0 && (
+        <span className="whitespace-nowrap italic text-color-text-light">
+          {' '}
+          (and {additionalCount} more)
+        </span>
+      )}
+    </>
+  );
+}
+
+/**
+ * Show a description of currently-applied filters and a button to clear the
+ * filter(s).
+ *
+ * There are three filter modes. Exactly one is applicable at any time. In order
+ * of precedence:
+ *
+ * 1. selection
+ *    One or more annotations are "selected", either by direct user input or
+ *    "direct-linked" annotation(s)
+ *
+ *    Message formatting:
+ *      "[Showing] (No|<resultCount>) annotation[s] [\(and <additionalCount> more\)]"
+ *    Button:
+ *      "<cancel icon> Show all [\(<totalCount)\)]" - clears the selection
+ *
+ * 2. focus
+ *    User-focused mode is configured, but may or may not be active/applied.
+ *
+ *    Message formatting:
+ *      "[Showing] (No|<resultCount>) annotation[s] [by <focusDisplayName>]
+ *       [\(and <additionalCount> more\)]"
+ *    Button:
+ *    - If there are no forced-visible threads:
+ *      "Show (all|only <focusDisplayName>)" - Toggles the user filter activation
+ *    - If there are any forced-visible threads:
+ *      "Reset filters" - Clears selection/filters (does not affect user filter activation)
+ *
+ * 3. null
+ *    No filters are applied.
+ *
+ *    Message formatting:
+ *      N/A (but container elements still render)
+ *    Button:
+ *      N/A
+ *
+ * This component must render its container elements if no filters are applied
+ * ("null" filter mode). This is because the element with `role="status"`
+ * needs to be continuously present in the DOM such that dynamic updates to its
+ * text content are available to assistive technology.
+ * See https://www.w3.org/WAI/WCAG21/Techniques/aria/ARIA22
+ */
+export default function FilterAnnotationsStatus() {
+  const store = useSidebarStore();
+  const rootThread = useRootThread();
+
+  const annotationCount = store.annotationCount();
+  const directLinkedId = store.directLinkedAnnotationId();
+  const focusState = store.focusState();
+  const forcedVisibleCount = store.forcedVisibleThreads().length;
+  const selectedCount = store.selectedAnnotations().length;
+
+  const filterMode = useMemo(() => {
+    if (selectedCount > 0) {
+      return 'selection';
+    } else if (focusState.configured) {
+      return 'focus';
+    }
+    return null;
+  }, [selectedCount, focusState]);
+
+  // Number of items that match the current filters
+  const resultCount = useMemo(() => {
+    return filterMode === 'selection'
+      ? selectedCount
+      : countVisible(rootThread) - forcedVisibleCount;
+  }, [filterMode, selectedCount, rootThread, forcedVisibleCount]);
+
+  // Number of additional items that are visible but do not match current
+  // filters. This can happen when, e.g.:
+  //  - A user manually expands a thread that does not match the current
+  //    filtering
+  //  - A user creates a new annotation when there are applied filters
+  const additionalCount = useMemo(() => {
+    if (filterMode === 'selection') {
+      // Selection filtering deals in top-level annotations only.
+      // Compare visible top-level annotations against the count of selected
+      // (top-level) annotatinos.
+      const visibleAnnotationCount = (rootThread.children || []).filter(
+        thread => thread.annotation && thread.visible,
+      ).length;
+      return visibleAnnotationCount - selectedCount;
+    } else {
+      return forcedVisibleCount;
+    }
+  }, [filterMode, forcedVisibleCount, rootThread.children, selectedCount]);
+
+  const buttonText = useMemo(() => {
+    if (filterMode === 'selection') {
+      // Because of the confusion between counts of entities between selected
+      // annotations and filtered annotations, don't display the total number
+      // when in user-focus mode because the numbers won't appear to make sense.
+      // Don't display total count, either, when viewing a direct-linked annotation.
+      const showCount = !focusState.configured && !directLinkedId;
+      return showCount ? `Show all (${annotationCount})` : 'Show all';
+    } else if (filterMode === 'focus') {
+      if (forcedVisibleCount > 0) {
+        return 'Reset filters';
+      }
+      return focusState.active
+        ? 'Show all'
+        : `Show only ${focusState.displayName}`;
+    }
+    return 'Clear search';
+  }, [
+    annotationCount,
+    directLinkedId,
+    focusState,
+    filterMode,
+    forcedVisibleCount,
+  ]);
+
+  return (
+    <div
+      // This container element needs to be present at all times but
+      // should only be visible when there are applied filters
+      className={classnames('mb-3', { 'sr-only': !filterMode })}
+      data-testid="filter-status-container"
+    >
+      <Card>
+        <CardContent>
+          {store.isLoading() ? (
+            <Spinner size="md" />
+          ) : (
+            <div className="flex items-center justify-center space-x-1">
+              <div
+                className={classnames(
+                  // Setting `min-width: 0` here allows wrapping to work as
+                  // expected for long strings.
+                  // See https://css-tricks.com/flexbox-truncated-text/
+                  'grow min-w-[0]',
+                )}
+                role="status"
+              >
+                {filterMode && (
+                  <FilterStatusMessage
+                    additionalCount={additionalCount}
+                    entitySingular="annotation"
+                    entityPlural="annotations"
+                    focusDisplayName={
+                      filterMode !== 'selection' && focusState.active
+                        ? focusState.displayName
+                        : ''
+                    }
+                    resultCount={resultCount}
+                  />
+                )}
+              </div>
+              {filterMode && (
+                <Button
+                  onClick={
+                    filterMode === 'focus' && !forcedVisibleCount
+                      ? () => store.toggleFocusMode()
+                      : () => store.clearSelection()
+                  }
+                  size="sm"
+                  title={buttonText}
+                  variant="primary"
+                  data-testid="clear-button"
+                >
+                  {/** @TODO: Set `icon` prop in `Button` instead when https://github.com/hypothesis/frontend-shared/issues/675 is fixed*/}
+                  {filterMode !== 'focus' && <CancelIcon />}
+                  {buttonText}
+                </Button>
+              )}
+            </div>
+          )}
+        </CardContent>
+      </Card>
+    </div>
+  );
+}

src/sidebar/components/search/SearchField.tsx

+import {
+  IconButton,
+  Input,
+  InputGroup,
+  SearchIcon,
+  useSyncedRef,
+} from '@hypothesis/frontend-shared';
+import classnames from 'classnames';
+import type { RefObject, JSX } from 'preact';
+import { useState } from 'preact/hooks';
+
+import { useShortcut } from '../../../shared/shortcut';
+import { useSidebarStore } from '../../store';
+
+export type SearchFieldProps = {
+  /** The currently-active filter query */
+  query: string | null;
+
+  /** Callback for when the current filter query changes */
+  onSearch: (value: string) => void;
+
+  /** Callback for when a key is pressed in the input itself */
+  onKeyDown?: JSX.KeyboardEventHandler<HTMLInputElement>;
+
+  /** The input's ref object, in case it needs to be handled by consumers */
+  inputRef?: RefObject<HTMLInputElement | undefined>;
+
+  /** Classes to be added to the outermost element */
+  classes?: string | string[];
+};
+
+/**
+ * An input field for entering a query that filters annotations (in the sidebar)
+ * or searches annotations (in the stream/single annotation view).
+ */
+export default function SearchField({
+  query,
+  onSearch,
+  inputRef,
+  classes,
+  onKeyDown,
+}: SearchFieldProps) {
+  const store = useSidebarStore();
+  const isLoading = store.isLoading();
+  const input = useSyncedRef(inputRef);
+
+  // The active filter query from the previous render.
+  const [prevQuery, setPrevQuery] = useState(query);
+
+  // The query that the user is currently typing, but may not yet have applied.
+  const [pendingQuery, setPendingQuery] = useState(query);
+
+  // As long as this input is mounted, pressing `/` should make it recover focus
+  useShortcut('/', e => {
+    if (document.activeElement !== input.current) {
+      e.preventDefault();
+      input.current?.focus();
+    }
+  });
+
+  const onSubmit = (e: Event) => {
+    e.preventDefault();
+    if (input.current?.value || prevQuery) {
+      // Don't set an initial empty query, but allow a later empty query to
+      // clear `prevQuery`
+      onSearch(input.current?.value ?? '');
+    }
+  };
+  // When the active query changes outside of this component, update the input
+  // field to match. This happens when clearing the current filter for example.
+  if (query !== prevQuery) {
+    setPendingQuery(query);
+    setPrevQuery(query);
+  }
+
+  return (
+    <form
+      name="searchForm"
+      onSubmit={onSubmit}
+      className={classnames('space-y-3', classes)}
+    >
+      <InputGroup>
+        <Input
+          aria-label="Search annotations"
+          classes={classnames(
+            'text-base p-1.5',
+            'transition-[max-width] duration-300 ease-out',
+          )}
+          data-testid="search-input"
+          dir="auto"
+          name="query"
+          placeholder={(isLoading && 'Loading…') || 'Search annotations…'}
+          disabled={isLoading}
+          elementRef={input}
+          value={pendingQuery || ''}
+          onInput={(e: Event) =>
+            setPendingQuery((e.target as HTMLInputElement).value)
+          }
+          onKeyDown={onKeyDown}
+        />
+        <IconButton
+          icon={SearchIcon}
+          title="Search"
+          type="submit"
+          variant="dark"
+        />
+      </InputGroup>
+    </form>
+  );
+}

src/sidebar/components/search/SearchIconButton.tsx

+import { SearchIcon, Spinner } from '@hypothesis/frontend-shared';
+import { useCallback, useRef } from 'preact/hooks';
+
+import { useShortcut } from '../../../shared/shortcut';
+import { isMacOS } from '../../../shared/user-agent';
+import type { SidebarStore } from '../../store';
+import { useSidebarStore } from '../../store';
+import PressableIconButton from '../PressableIconButton';
+
+/**
+ * Respond to keydown events on the document (shortcut keys):
+ *
+ * - Open the search panel when the user presses '/', unless the user is
+ *   currently typing in or focused on an input field.
+ * - Open the search panel when the user presses CMD-K (MacOS) or CTRL-K
+ *   (everyone else)
+ */
+function useSearchKeyboardShortcuts(store: SidebarStore) {
+  const prevFocusRef = useRef<HTMLOrSVGElement | null>(null);
+
+  const openSearch = useCallback(
+    (event: KeyboardEvent) => {
+      // When user is in an input field, respond to CMD-/CTRL-K keypresses,
+      // but ignore '/' keypresses
+      if (
+        !event.metaKey &&
+        !event.ctrlKey &&
+        event.target instanceof HTMLElement &&
+        ['INPUT', 'TEXTAREA'].includes(event.target.tagName)
+      ) {
+        return;
+      }
+      prevFocusRef.current = document.activeElement as HTMLOrSVGElement | null;
+      if (!store.isSidebarPanelOpen('searchAnnotations')) {
+        store.openSidebarPanel('searchAnnotations');
+        event.preventDefault();
+        event.stopPropagation();
+      }
+    },
+    [store],
+  );
+
+  const modifierKey = isMacOS() ? 'meta' : 'ctrl';
+
+  useShortcut('/', openSearch);
+  useShortcut(`${modifierKey}+k`, openSearch);
+}
+
+export default function SearchIconButton() {
+  const store = useSidebarStore();
+  const isLoading = store.isLoading();
+  const isSearchPanelOpen = store.isSidebarPanelOpen('searchAnnotations');
+
+  const toggleSearchPanel = useCallback(() => {
+    store.toggleSidebarPanel('searchAnnotations');
+  }, [store]);
+
+  useSearchKeyboardShortcuts(store);
+
+  return (
+    <>
+      {isLoading && <Spinner />}
+      {!isLoading && (
+        <PressableIconButton
+          icon={SearchIcon}
+          expanded={isSearchPanelOpen}
+          pressed={isSearchPanelOpen}
+          onClick={toggleSearchPanel}
+          title="Search annotations"
+          // The containing form has a white background. The top bar is only
+          // 40px high. If we allow standard touch-minimum height here (44px),
+          // the visible white background exceeds the height of the top bar in
+          // touch contexts. Disable touch sizing via `size="custom"`, then
+          // add back the width rule and padding to keep horizontal spacing
+          // consistent.
+          size="custom"
+          classes="touch:min-w-touch-minimum p-1"
+        />
+      )}
+    </>
+  );
+}

src/sidebar/components/search/SearchPanel.tsx

+import { Card, CardContent, CloseButton } from '@hypothesis/frontend-shared';
+import { useRef } from 'preact/hooks';
+
+import { useSidebarStore } from '../../store';
+import SidebarPanel from '../SidebarPanel';
+import SearchField from './SearchField';
+import SearchStatus from './SearchStatus';
+
+export default function SearchPanel() {
+  const store = useSidebarStore();
+  const filterQuery = store.filterQuery();
+  const inputRef = useRef<HTMLInputElement | null>(null);
+
+  return (
+    <SidebarPanel
+      panelName="searchAnnotations"
+      variant="custom"
+      title="Search annotations"
+      initialFocus={inputRef}
+      onActiveChanged={active => {
+        if (!active) {
+          store.clearSelection();
+        }
+      }}
+    >
+      <Card>
+        <CardContent>
+          <div className="flex gap-x-3">
+            <SearchField
+              inputRef={inputRef}
+              classes="grow"
+              query={filterQuery || null}
+              onSearch={store.setFilterQuery}
+              onKeyDown={e => {
+                // Close panel on Escape, which will also clear search
+                if (e.key === 'Escape') {
+                  store.closeSidebarPanel('searchAnnotations');
+                }
+              }}
+            />
+            <CloseButton
+              classes="text-[16px] text-grey-6 hover:text-grey-7 hover:bg-grey-3/50"
+              title="Close"
+              variant="custom"
+              size="sm"
+            />
+          </div>
+          {filterQuery && <SearchStatus />}
+        </CardContent>
+      </Card>
+    </SidebarPanel>
+  );
+}

src/sidebar/components/search/SearchStatus.tsx

+import { Button, CancelIcon } from '@hypothesis/frontend-shared';
+import classnames from 'classnames';
+import { useMemo } from 'preact/hooks';
+
+import { countVisible } from '../../helpers/thread';
+import { useSidebarStore } from '../../store';
+import { useRootThread } from '../hooks/use-root-thread';
+
+export default function SearchStatus() {
+  const store = useSidebarStore();
+  const rootThread = useRootThread();
+
+  const filterQuery = store.filterQuery();
+  const forcedVisibleCount = store.forcedVisibleThreads().length;
+
+  // Number of items that match current search query
+  const resultCount = useMemo(
+    () => countVisible(rootThread) - forcedVisibleCount,
+    [rootThread, forcedVisibleCount],
+  );
+
+  const buttonText = 'Clear search';
+
+  return (
+    <div
+      // This container element needs to be present at all times but
+      // should only be visible when there are applied filters
+      className={classnames('mb-3 flex items-center justify-center space-x-1', {
+        'sr-only': !filterQuery,
+      })}
+      data-testid="search-status-container"
+    >
+      <div
+        className={classnames(
+          // Setting `min-width: 0` here allows wrapping to work as
+          // expected for long `filterQuery` strings. See
+          // https://css-tricks.com/flexbox-truncated-text/
+          'grow min-w-[0]',
+        )}
+        role="status"
+      >
+        {filterQuery && (
+          <>
+            {resultCount > 0 && <span>Showing </span>}
+            <span className="whitespace-nowrap font-bold">
+              {resultCount > 0 ? resultCount : 'No'}{' '}
+              {resultCount === 1 ? 'result' : 'results'}
+            </span>
+            <span>
+              {' '}
+              for <span className="break-words">{`'${filterQuery}'`}</span>
+            </span>
+          </>
+        )}
+      </div>
+      {filterQuery && (
+        <Button
+          onClick={() => store.clearSelection()}
+          size="sm"
+          title={buttonText}
+          variant="primary"
+          data-testid="clear-button"
+        >
+          {/** @TODO: Set `icon` prop in `Button` instead when https://github.com/hypothesis/frontend-shared/issues/675 is fixed */}
+          {filterQuery && <CancelIcon />}
+          {buttonText}
+        </Button>
+      )}
+    </div>
+  );
+}

src/sidebar/components/StreamSearchInput.tsx → src/sidebar/components/search/StreamSearchInput.tsx

-import { withServices } from '../service-context';
-import type { RouterService } from '../services/router';
-import { useSidebarStore } from '../store';
-import SearchInput from './SearchInput';
+import { withServices } from '../../service-context';
+import type { RouterService } from '../../services/router';
+import { useSidebarStore } from '../../store';
+import SearchInput from '../old-search/SearchInput';
+import SearchField from './SearchField';
 
 export type StreamSearchInputProps = {
   router: RouterService;
@@ -14,6 +15,7 @@ export type StreamSearchInputProps = {
  */
 function StreamSearchInput({ router }: StreamSearchInputProps) {
   const store = useSidebarStore();
+  const searchPanelEnabled = store.isFeatureEnabled('search_panel');
   const { q } = store.routeParams();
   const setQuery = (query: string) => {
     // Re-route the user to `/stream` if they are on `/a/:id` and then set
@@ -21,8 +23,10 @@ function StreamSearchInput({ router }: StreamSearchInputProps) {
     router.navigate('stream', { q: query });
   };
 
-  return (
-    <SearchInput query={q ?? ''} onSearch={setQuery} alwaysExpanded={true} />
+  return searchPanelEnabled ? (
+    <SearchField query={q ?? ''} onSearch={setQuery} />
+  ) : (
+    <SearchInput query={q ?? ''} onSearch={setQuery} alwaysExpanded />
   );
 }
 

src/sidebar/components/search/test/SearchField-test.js

+import {
+  checkAccessibility,
+  mockImportedComponents,
+} from '@hypothesis/frontend-testing';
+import { mount } from 'enzyme';
+
+import SearchField, { $imports } from '../SearchField';
+
+describe('SearchField', () => {
+  let fakeStore;
+  let container;
+  let wrappers;
+
+  const createSearchField = (props = {}) => {
+    const wrapper = mount(<SearchField {...props} />, { attachTo: container });
+    wrappers.push(wrapper);
+    return wrapper;
+  };
+
+  function typeQuery(wrapper, query) {
+    const input = wrapper.find('input');
+    input.getDOMNode().value = query;
+    input.simulate('input');
+  }
+
+  beforeEach(() => {
+    wrappers = [];
+    container = document.createElement('div');
+    document.body.appendChild(container);
+    fakeStore = { isLoading: sinon.stub().returns(false) };
+
+    $imports.$mock(mockImportedComponents());
+    $imports.$mock({
+      '../../store': { useSidebarStore: () => fakeStore },
+    });
+  });
+
+  afterEach(() => {
+    wrappers.forEach(wrapper => wrapper.unmount());
+    container.remove();
+    $imports.$restore();
+  });
+
+  it('displays the active query', () => {
+    const wrapper = createSearchField({ query: 'foo' });
+    assert.equal(wrapper.find('input').prop('value'), 'foo');
+  });
+
+  it('resets input field value to active query when active query changes', () => {
+    const wrapper = createSearchField({ query: 'foo' });
+
+    // Simulate user editing the pending query, but not committing it.
+    typeQuery(wrapper, 'pending-query');
+
+    // Check that the pending query is displayed.
+    assert.equal(wrapper.find('input').prop('value'), 'pending-query');
+
+    // Simulate active query being reset.
+    wrapper.setProps({ query: '' });
+
+    assert.equal(wrapper.find('input').prop('value'), '');
+  });
+
+  it('invokes `onSearch` with pending query when form is submitted', () => {
+    const onSearch = sinon.stub();
+    const wrapper = createSearchField({ query: 'foo', onSearch });
+    typeQuery(wrapper, 'new-query');
+    wrapper.find('form').simulate('submit');
+    assert.calledWith(onSearch, 'new-query');
+  });
+
+  it('does not set an initial empty query when form is submitted', () => {
+    // If the first query entered is empty, it will be ignored
+    const onSearch = sinon.stub();
+    const wrapper = createSearchField({ onSearch });
+    typeQuery(wrapper, '');
+    wrapper.find('form').simulate('submit');
+    assert.notCalled(onSearch);
+  });
+
+  it('sets subsequent empty queries if entered', () => {
+    // If there has already been at least one query set, subsequent
+    // empty queries will be honored
+    const onSearch = sinon.stub();
+    const wrapper = createSearchField({ query: 'foo', onSearch });
+    typeQuery(wrapper, '');
+    wrapper.find('form').simulate('submit');
+    assert.calledWith(onSearch, '');
+  });
+
+  it('disables input when app is in a "loading" state', () => {
+    fakeStore.isLoading.returns(true);
+
+    const wrapper = createSearchField();
+    const { placeholder, disabled } = wrapper.find('Input').props();
+
+    assert.equal(placeholder, 'Loading…');
+    assert.isTrue(disabled);
+  });
+
+  it('doesn\'t disable input when app is not in "loading" state', () => {
+    fakeStore.isLoading.returns(false);
+
+    const wrapper = createSearchField();
+    const { placeholder, disabled } = wrapper.find('Input').props();
+
+    assert.equal(placeholder, 'Search annotations…');
+    assert.isFalse(disabled);
+  });
+
+  it('focuses search input when "/" is pressed outside of the component element', () => {
+    const wrapper = createSearchField();
+    const searchInputEl = wrapper.find('input').getDOMNode();
+
+    document.body.dispatchEvent(
+      new KeyboardEvent('keydown', {
+        bubbles: true,
+        cancelable: true,
+        key: '/',
+      }),
+    );
+
+    assert.equal(document.activeElement, searchInputEl);
+  });
+
+  it(
+    'should pass a11y checks',
+    checkAccessibility([
+      {
+        content: () => createSearchField(),
+      },
+      {
+        name: 'loading state',
+        content: () => {
+          fakeStore.isLoading.returns(true);
+          return createSearchField();
+        },
+      },
+    ]),
+  );
+});

src/sidebar/components/search/test/SearchIconButton-test.js

+import { checkAccessibility } from '@hypothesis/frontend-testing';
+import { mount } from 'enzyme';
+
+import SearchIconButton, { $imports } from '../SearchIconButton';
+
+describe('SearchIconButton', () => {
+  let fakeIsMacOS;
+  let fakeStore;
+  let container;
+  let wrappers;
+
+  const createSearchIconButton = () => {
+    const wrapper = mount(<SearchIconButton />, { attachTo: container });
+    wrappers.push(wrapper);
+    return wrapper;
+  };
+
+  beforeEach(() => {
+    wrappers = [];
+    container = document.createElement('div');
+    document.body.appendChild(container);
+    fakeIsMacOS = sinon.stub().returns(false);
+    fakeStore = {
+      isLoading: sinon.stub().returns(false),
+      isSidebarPanelOpen: sinon.stub().returns(false),
+      openSidebarPanel: sinon.stub(),
+      toggleSidebarPanel: sinon.stub(),
+    };
+
+    $imports.$mock({
+      '../../store': { useSidebarStore: () => fakeStore },
+      '../../../shared/user-agent': {
+        isMacOS: fakeIsMacOS,
+      },
+    });
+  });
+
+  afterEach(() => {
+    wrappers.forEach(wrapper => wrapper.unmount());
+    container.remove();
+    $imports.$restore();
+  });
+
+  it('renders loading indicator when app is in a "loading" state', () => {
+    fakeStore.isLoading.returns(true);
+    const wrapper = createSearchIconButton();
+
+    assert.isTrue(wrapper.exists('Spinner'));
+    assert.isFalse(wrapper.exists('PressableIconButton'));
+  });
+
+  it('renders search button when app is not in "loading" state', () => {
+    fakeStore.isLoading.returns(false);
+    const wrapper = createSearchIconButton();
+
+    assert.isFalse(wrapper.exists('Spinner'));
+    assert.isTrue(wrapper.exists('PressableIconButton'));
+  });
+
+  it('toggles search panel when button is clicked', () => {
+    const wrapper = createSearchIconButton();
+    wrapper.find('PressableIconButton').find('button').simulate('click');
+    assert.calledWith(fakeStore.toggleSidebarPanel, 'searchAnnotations');
+  });
+
+  [true, false].forEach(isSearchPanelOpen => {
+    it('sets button state based on panel state', () => {
+      fakeStore.isSidebarPanelOpen.returns(isSearchPanelOpen);
+
+      const wrapper = createSearchIconButton();
+      const { expanded, pressed } = wrapper.find('PressableIconButton').props();
+
+      assert.equal(expanded, isSearchPanelOpen);
+      assert.equal(pressed, isSearchPanelOpen);
+    });
+  });
+
+  describe('shortcut key handling', () => {
+    context('when "/" is pressed outside of the component element', () => {
+      const pressForwardSlashKey = () =>
+        document.body.dispatchEvent(
+          new KeyboardEvent('keydown', {
+            bubbles: true,
+            cancelable: true,
+            key: '/',
+          }),
+        );
+
+      it('opens search panel if it is closed', () => {
+        createSearchIconButton();
+        pressForwardSlashKey();
+
+        assert.calledWith(fakeStore.openSidebarPanel, 'searchAnnotations');
+      });
+
+      it('does nothing if search panel is already open', () => {
+        fakeStore.isSidebarPanelOpen.returns(true);
+
+        createSearchIconButton();
+        pressForwardSlashKey();
+
+        assert.notCalled(fakeStore.openSidebarPanel);
+      });
+    });
+
+    it('opens search panel on non-macOS systems when "ctrl-K" is pressed outside of the component element', () => {
+      fakeIsMacOS.returns(false);
+      createSearchIconButton();
+
+      document.body.dispatchEvent(
+        new KeyboardEvent('keydown', {
+          bubbles: true,
+          cancelable: true,
+          key: 'k',
+          ctrlKey: true,
+        }),
+      );
+
+      assert.calledWith(fakeStore.openSidebarPanel, 'searchAnnotations');
+    });
+
+    it('opens search panel for macOS when "Cmd-K" is pressed outside of the component element', () => {
+      fakeIsMacOS.returns(true);
+      createSearchIconButton();
+
+      document.body.dispatchEvent(
+        new KeyboardEvent('keydown', {
+          bubbles: true,
+          cancelable: true,
+          key: 'k',
+          metaKey: true,
+        }),
+      );
+
+      assert.calledWith(fakeStore.openSidebarPanel, 'searchAnnotations');
+    });
+
+    ['textarea', 'input'].forEach(elementName => {
+      it('does not steal focus when "/" pressed if user is in an input field', () => {
+        const input = document.createElement(elementName);
+        input.id = 'an-input';
+        container.append(input);
+
+        createSearchIconButton();
+        input.focus();
+
+        assert.equal(document.activeElement, input);
+
+        input.dispatchEvent(
+          new KeyboardEvent('keydown', {
+            bubbles: true,
+            cancelable: true,
+            key: '/',
+          }),
+        );
+
+        assert.notCalled(fakeStore.openSidebarPanel);
+      });
+    });
+
+    it('opens search panel if user is in an input field and presses "Ctrl-k"', () => {
+      fakeIsMacOS.returns(false);
+      const input = document.createElement('input');
+      input.id = 'an-input';
+      container.append(input);
+
+      createSearchIconButton();
+      input.focus();
+
+      assert.equal(document.activeElement, input);
+
+      input.dispatchEvent(
+        new KeyboardEvent('keydown', {
+          bubbles: true,
+          cancelable: true,
+          key: 'k',
+          ctrlKey: true,
+        }),
+      );
+
+      assert.calledWith(fakeStore.openSidebarPanel, 'searchAnnotations');
+    });
+  });
+
+  it(
+    'should pass a11y checks',
+    checkAccessibility([
+      {
+        content: () => createSearchIconButton(),
+      },
+      {
+        name: 'loading state',
+        content: () => {
+          fakeStore.isLoading.returns(true);
+          return createSearchIconButton();
+        },
+      },
+    ]),
+  );
+});

src/sidebar/components/search/test/SearchPanel-test.js

+import { mockImportedComponents } from '@hypothesis/frontend-testing';
+import { mount } from 'enzyme';
+
+import SearchPanel, { $imports } from '../SearchPanel';
+
+describe('SearchPanel', () => {
+  let fakeStore;
+
+  beforeEach(() => {
+    fakeStore = {
+      clearSelection: sinon.stub(),
+      setFilterQuery: sinon.stub(),
+      filterQuery: sinon.stub().returns(null),
+      closeSidebarPanel: sinon.stub(),
+    };
+
+    $imports.$mock(mockImportedComponents());
+    $imports.$mock({
+      '../../store': {
+        useSidebarStore: () => fakeStore,
+      },
+    });
+  });
+
+  afterEach(() => {
+    $imports.$restore();
+  });
+
+  function createSearchPanel() {
+    return mount(<SearchPanel />);
+  }
+
+  [true, false].forEach(active => {
+    it('clears selection when search panel becomes inactive', () => {
+      const wrapper = createSearchPanel();
+
+      wrapper.find('SidebarPanel').props().onActiveChanged(active);
+
+      assert.equal(fakeStore.clearSelection.called, !active);
+    });
+  });
+
+  it('closes search panel when Escape is pressed in search field', () => {
+    const wrapper = createSearchPanel();
+
+    wrapper
+      .find('SearchField')
+      .props()
+      .onKeyDown(new KeyboardEvent('keydown', { key: 'Escape' }));
+
+    assert.calledWith(fakeStore.closeSidebarPanel, 'searchAnnotations');
+  });
+
+  it('updates query onSearch', () => {
+    const wrapper = createSearchPanel();
+
+    wrapper.find('SearchField').props().onSearch('foo');
+
+    assert.calledWith(fakeStore.setFilterQuery, 'foo');
+  });
+
+  [
+    { query: null, searchStatusIsRendered: false },
+    { query: '', searchStatusIsRendered: false },
+    { query: 'foo', searchStatusIsRendered: true },
+  ].forEach(({ query, searchStatusIsRendered }) => {
+    it("renders SearchStatus only when there's an active query", () => {
+      fakeStore.filterQuery.returns(query);
+      const wrapper = createSearchPanel();
+
+      assert.equal(wrapper.exists('SearchStatus'), searchStatusIsRendered);
+    });
+  });
+});

src/sidebar/components/search/test/SearchStatus-test.js

+import { mockImportedComponents } from '@hypothesis/frontend-testing';
+import { mount } from 'enzyme';
+
+import SearchStatus, { $imports } from '../SearchStatus';
+
+describe('SearchStatus', () => {
+  let fakeStore;
+  let fakeUseRootThread;
+  let fakeThreadUtil;
+
+  const createComponent = () => {
+    return mount(<SearchStatus />);
+  };
+
+  beforeEach(() => {
+    fakeThreadUtil = {
+      countVisible: sinon.stub().returns(0),
+    };
+    fakeStore = {
+      clearSelection: sinon.stub(),
+      filterQuery: sinon.stub().returns(null),
+      forcedVisibleThreads: sinon.stub().returns([]),
+    };
+
+    fakeUseRootThread = sinon.stub().returns({});
+
+    $imports.$mock(mockImportedComponents());
+    $imports.$mock({
+      '../hooks/use-root-thread': { useRootThread: fakeUseRootThread },
+      '../../store': { useSidebarStore: () => fakeStore },
+      '../../helpers/thread': fakeThreadUtil,
+    });
+  });
+
+  function assertFilterText(wrapper, text) {
+    const filterText = wrapper.find('[role="status"]').text();
+    assert.equal(filterText, text);
+  }
+
+  function clickClearButton(wrapper) {
+    const button = wrapper.find('Button[data-testid="clear-button"]');
+    assert.equal(button.text(), 'Clear search');
+    assert.isTrue(button.find('CancelIcon').exists());
+    button.props().onClick();
+    assert.calledOnce(fakeStore.clearSelection);
+  }
+
+  context('when no search filters are active', () => {
+    it('should render hidden but available to screen readers', () => {
+      const wrapper = createComponent();
+      const containerEl = wrapper
+        .find('div[data-testid="search-status-container"]')
+        .getDOMNode();
+
+      assert.include(containerEl.className, 'sr-only');
+      assertFilterText(wrapper, '');
+    });
+  });
+
+  context('when filtered by query', () => {
+    beforeEach(() => {
+      fakeStore.filterQuery.returns('foobar');
+      fakeThreadUtil.countVisible.returns(1);
+    });
+
+    it('should provide a "Clear search" button that clears the selection', () => {
+      clickClearButton(createComponent());
+    });
+
+    it('should show the count of matching results', () => {
+      assertFilterText(createComponent(), "Showing 1 result for 'foobar'");
+    });
+
+    it('should show pluralized count of results when appropriate', () => {
+      fakeThreadUtil.countVisible.returns(5);
+      assertFilterText(createComponent(), "Showing 5 results for 'foobar'");
+    });
+
+    it('should show a no results message when no matches', () => {
+      fakeThreadUtil.countVisible.returns(0);
+      assertFilterText(createComponent(), "No results for 'foobar'");
+    });
+  });
+
+  context('when filtered by query with force-expanded threads', () => {
+    beforeEach(() => {
+      fakeStore.filterQuery.returns('foobar');
+      fakeStore.forcedVisibleThreads.returns([1, 2, 3]);
+      fakeThreadUtil.countVisible.returns(5);
+    });
+
+    it('should show a separate count for results versus forced visible', () => {
+      assertFilterText(createComponent(), "Showing 2 results for 'foobar'");
+    });
+
+    it('should provide a "Clear search" button that clears the selection', () => {
+      clickClearButton(createComponent());
+    });
+  });
+});

src/sidebar/components/test/StreamSearchInput-test.js → src/sidebar/components/search/test/StreamSearchInput-test.js

@@ -14,10 +14,11 @@ describe('StreamSearchInput', () => {
     };
     fakeStore = {
       routeParams: sinon.stub().returns({}),
+      isFeatureEnabled: sinon.stub().returns(false),
     };
     $imports.$mock(mockImportedComponents());
     $imports.$mock({
-      '../store': { useSidebarStore: () => fakeStore },
+      '../../store': { useSidebarStore: () => fakeStore },
     });
   });
 
@@ -42,4 +43,13 @@ describe('StreamSearchInput', () => {
     });
     assert.calledWith(fakeRouter.navigate, 'stream', { q: 'new-query' });
   });
+
+  it('renders new SearchField when search panel feature is enabled', () => {
+    fakeStore.isFeatureEnabled.returns(true);
+
+    const wrapper = createSearchInput();
+
+    assert.isFalse(wrapper.exists('SearchInput'));
+    assert.isTrue(wrapper.exists('SearchField'));
+  });
 });

src/sidebar/components/test/HypothesisApp-test.js

@@ -424,4 +424,16 @@ describe('HypothesisApp', () => {
       assert.isFalse(wrapper.find('TopBar').prop('showShareButton'));
     });
   });
+
+  describe('search panel', () => {
+    [true, false].forEach(searchPanelEnabled => {
+      it('renders SearchPanel when feature is enabled', () => {
+        fakeStore.isFeatureEnabled.returns(searchPanelEnabled);
+
+        const wrapper = createComponent();
+
+        assert.equal(wrapper.exists('SearchPanel'), searchPanelEnabled);
+      });
+    });
+  });
 });

src/sidebar/components/test/SidebarView-test.js

@@ -62,6 +62,7 @@ describe('SidebarView', () => {
       profile: sinon.stub().returns({ userid: null }),
       searchUris: sinon.stub().returns([]),
       toggleFocusMode: sinon.stub(),
+      isFeatureEnabled: sinon.stub().returns(false),
     };
 
     fakeTabsUtil = {
@@ -240,9 +241,20 @@ describe('SidebarView', () => {
   });
 
   context('user-focus mode', () => {
-    it('shows filter status when focus mode configured', () => {
+    it('shows old filter status when focus mode configured', () => {
       const wrapper = createComponent();
+
       assert.isTrue(wrapper.find('FilterStatus').exists());
+      assert.isFalse(wrapper.find('FilterAnnotationsStatus').exists());
+    });
+
+    it('shows filter status when focus mode configured', () => {
+      fakeStore.isFeatureEnabled.returns(true);
+
+      const wrapper = createComponent();
+
+      assert.isFalse(wrapper.find('FilterStatus').exists());
+      assert.isTrue(wrapper.find('FilterAnnotationsStatus').exists());
     });
   });
 
@@ -264,11 +276,6 @@ describe('SidebarView', () => {
     });
   });
 
-  it('renders the filter status', () => {
-    const wrapper = createComponent();
-    assert.isTrue(wrapper.find('FilterStatus').exists());
-  });
-
   describe('selection tabs', () => {
     it('renders tabs', () => {
       const wrapper = createComponent();

src/sidebar/components/test/TopBar-test.js

@@ -21,6 +21,7 @@ describe('TopBar', () => {
       isSidebarPanelOpen: sinon.stub().returns(false),
       setFilterQuery: sinon.stub(),
       toggleSidebarPanel: sinon.stub(),
+      isFeatureEnabled: sinon.stub().returns(false),
     };
 
     fakeFrameSync = {
@@ -213,6 +214,17 @@ describe('TopBar', () => {
     });
   });
 
+  context('when sidebar panel feature is enabled', () => {
+    it('displays search input in the sidebar', () => {
+      fakeStore.isFeatureEnabled.returns(true);
+
+      const wrapper = createTopBar();
+
+      assert.isFalse(wrapper.exists('SearchInput'));
+      assert.isTrue(wrapper.exists('SearchIconButton'));
+    });
+  });
+
   it(
     'should pass a11y checks',
     checkAccessibility([

src/types/sidebar.ts

@@ -5,7 +5,11 @@
 /**
  * Defined panel components available in the sidebar.
  */
-export type PanelName = 'help' | 'loginPrompt' | 'shareGroupAnnotations';
+export type PanelName =
+  | 'help'
+  | 'loginPrompt'
+  | 'shareGroupAnnotations'
+  | 'searchAnnotations';
 
 /**
  * The top-level tabs in the sidebar interface. Used to reference which tab