⚡️(frontend) improve Comments feature

Improve the comments feature to reduce annoyance:
- gives focus on input when opening comment threads
- hide comment button when mobile view
- improve contrast of overline commented text
- remove thread if last comment deleted
- scroll to bottom thread when adding new comment

src/frontend/apps/impress/src/features/docs/doc-editor/components/comments/CommentToolbarButton.tsx

@@ -1,3 +1,8 @@
+/**
+ * This file is adapted from BlockNote's AddCommentButton component
+ * https://github.com/TypeCellOS/BlockNote/blob/main/packages/react/src/components/FormattingToolbar/DefaultButtons/AddCommentButton.tsx
+ */
+
 import {
   useBlockNoteEditor,
   useComponentsContext,
@@ -10,6 +15,7 @@ import { css } from 'styled-components';
 import { Box, Icon } from '@/components';
 import { useCunninghamTheme } from '@/cunningham';
 import { useDocStore } from '@/features/docs/doc-management';
+import { useResponsiveStore } from '@/stores';
 
 import {
   DocsBlockSchema,
@@ -22,6 +28,7 @@ export const CommentToolbarButton = () => {
   const { currentDoc } = useDocStore();
   const { t } = useTranslation();
   const { spacingsTokens, colorsTokens } = useCunninghamTheme();
+  const { isDesktop } = useResponsiveStore();
 
   const editor = useBlockNoteEditor<
     DocsBlockSchema,
@@ -35,7 +42,18 @@ export const CommentToolbarButton = () => {
     return !!selectedBlocks.find((block) => block.content !== undefined);
   }, [selectedBlocks]);
 
+  const focusOnInputThread = () => {
+    // Use setTimeout to ensure the DOM has been updated with the new comment
+    setTimeout(() => {
+      const threadElement = document.querySelector<HTMLElement>(
+        '.bn-thread .bn-editor',
+      );
+      threadElement?.focus();
+    }, 400);
+  };
+
   if (
+    !isDesktop ||
     !show ||
     !editor.isEditable ||
     !Components ||
@@ -51,6 +69,7 @@ export const CommentToolbarButton = () => {
         onClick={() => {
           editor.comments?.startPendingComment();
           editor.formattingToolbar.closeMenu();
+          focusOnInputThread();
         }}
         aria-haspopup="dialog"
         data-test="comment-toolbar-button"

src/frontend/apps/impress/src/features/docs/doc-editor/components/comments/DocsThreadStore.tsx

@@ -117,6 +117,21 @@ export class DocsThreadStore extends ThreadStore {
     });
   }
 
+  /**
+   * Scrolls to the bottom of a thread modal
+   * @param threadId
+   */
+  private scrollToBottomOfThread() {
+    // Use setTimeout to ensure the DOM has been updated with the new comment
+    setTimeout(() => {
+      const threadElement = document.querySelector('.bn-thread');
+      threadElement?.scrollBy({
+        top: threadElement.scrollHeight,
+        behavior: 'smooth',
+      });
+    }, 200);
+  }
+
   /**
    * Notifies all subscribers about the current thread state
    */
@@ -345,6 +360,10 @@ export class DocsThreadStore extends ThreadStore {
       await this.refreshThread(threadId);
     }
     this.ping(threadId);
+
+    // Auto-scroll to bottom of thread after adding comment
+    this.scrollToBottomOfThread();
+
     return serverCommentToClientComment(comment);
   };
 
@@ -405,10 +424,20 @@ export class DocsThreadStore extends ThreadStore {
     // Optimistically remove the comment locally if we have the thread
     const existing = this.threads.get(threadId);
     if (existing) {
+      const updatedComments = existing.comments.filter(
+        (c) => c.id !== commentId,
+      );
+
+      // If this was the last comment, delete the thread
+      if (updatedComments.length === 0) {
+        await this.deleteThread({ threadId });
+        return;
+      }
+
       const updated: ClientThreadData = {
         ...existing,
         updatedAt: new Date(),
-        comments: existing.comments.filter((c) => c.id !== commentId),
+        comments: updatedComments,
       };
       this.upsertClientThreadData(updated);
       this.notifySubscribers();
@@ -419,10 +448,6 @@ export class DocsThreadStore extends ThreadStore {
     this.ping(threadId);
   };
 
-  /**
-   * UI not implemented
-   * @param _options
-   */
   public deleteThread = async (_options: { threadId: string }) => {
     const response = await fetchAPI(
       `documents/${this.docId}/threads/${_options.threadId}/`,

src/frontend/apps/impress/src/features/docs/doc-editor/components/comments/styles.tsx

@@ -13,6 +13,10 @@ export const cssComments = (
         background: ${canSeeComment ? '#EDB40066' : 'transparent'};
         color: var(--c--globals--colors--gray-700);
       }
+
+      [data-show-selection] {
+        color: HighlightText;
+      }
     }
 
     em-emoji-picker {

src/frontend/apps/impress/src/features/docs/doc-management/components/SimpleDocItem.tsx

@@ -4,12 +4,13 @@ import { css } from 'styled-components';
 
 import { Box, Text } from '@/components';
 import { useCunninghamTheme } from '@/cunningham';
-import { Doc, useDocUtils, useTrans } from '@/docs/doc-management';
 import { useResponsiveStore } from '@/stores';
 
 import ChildDocument from '../assets/child-document.svg';
 import PinnedDocumentIcon from '../assets/pinned-document.svg';
 import SimpleFileIcon from '../assets/simple-document.svg';
+import { useDocUtils, useTrans } from '../hooks';
+import { Doc } from '../types';
 
 const ItemTextCss = css`
   overflow: hidden;