diff --git a/app/routes/hyperapi.py b/app/routes/hyperapi.py
index 29dab65..837b66e 100644
--- a/app/routes/hyperapi.py
+++ b/app/routes/hyperapi.py
@@ -1,6 +1,6 @@
 from flask import Blueprint, render_template, request, url_for
 from ..auth import get_active_user, is_logged_in, hard_login_required
-from ..models import BookmarkCollections, BookmarkedPosts, BookmarkedThreads
+from ..models import BookmarkCollections, BookmarkedPosts, BookmarkedThreads, Threads, Posts
 from functools import wraps
 
 bp = Blueprint('hyperapi', __name__, url_prefix='/hyperapi/')
@@ -24,6 +24,14 @@ def get_bookmark_dropdown():
     except ValueError:
         return 'error', 400
     is_thread = concept_kind == 'thread'
+    if is_thread:
+        target_thread = Threads.find({'id': concept_id})
+        if not target_thread:
+            return 'This thread no longer exists. Please refresh the page.', 404
+    else:
+        target_post = Posts.find({'id': concept_id})
+        if not target_post:
+            return 'This post no longer exists. Please refresh the page.', 404
     collections = BookmarkCollections.get_for_user(user.id)
     in_collection = None
     note = ''
@@ -54,6 +62,9 @@ def bookmark_thread():
             bt.delete()
         return '', 204
 
+    if not Threads.find({'id': thread_id}):
+        return 'error', 404
+
     target_collection = BookmarkCollections.find({'id': target_collection_id})
     note = request.form.get('note', '')
     if not target_collection:
@@ -91,6 +102,9 @@ def bookmark_post():
             bp.delete()
         return '', 204
 
+    if not Posts.find({'id': post_id}):
+        return 'error', 404
+
     target_collection = BookmarkCollections.find({'id': target_collection_id})
     note = request.form.get('note', '')
     if not target_collection:
diff --git a/app/routes/users.py b/app/routes/users.py
index e4ef761..9316bd9 100644
--- a/app/routes/users.py
+++ b/app/routes/users.py
@@ -445,8 +445,9 @@ def inbox(username):
 @login_required
 @redirect_to_own
 def bookmarks(username):
-    username = username.lower()
-    return 'stub'
+    user = get_active_user()
+    collections = BookmarkCollections.get_for_user(user.id)
+    return render_template('users/bookmarks.html', collections=collections)
 
 @bp.get('/<username>/bookmarks/collections/')
 @login_required
diff --git a/app/templates/common/macros.html b/app/templates/common/macros.html
index 1993e06..865d7e0 100644
--- a/app/templates/common/macros.html
+++ b/app/templates/common/macros.html
@@ -136,10 +136,16 @@
 </div>
 {%- endmacro %}
 
+{% macro bookmark_button(kind, id, text='Bookmark') -%}
+<button autocomplete='off' data-r="enhance" data-s="showBookmarkMenu" disabled title="This feature requires JavaScript to be enabled." data-concept-kind="{{kind}}" data-concept-id="{{id}}">{{icn_bookmark(24)}}{{text}}&hellip;</button>
+{%- endmacro %}
+
 {% macro full_post(
   post, render_sig=true, is_latest=false,
   show_toolbar=true, is_editing=false, thread=none,
-  show_reactions=true, show_thread=false, allow_reacting=true
+  show_reactions=true, show_thread=false, allow_reacting=true,
+  tb_edit=true, tb_quote=true, tb_delete=true, tb_bookmark=true,
+  bookmark_btn='Bookmark', tb_pretext=''
 ) -%}
 {%- if is_logged_in() -%}
 {%- set can_delete = post.user_id == get_active_user().id or is_mod() -%}
@@ -169,6 +175,9 @@
 <div class="post-content">
   <div class="plank even minimal secondary-bg no-shadow post-info">
     <span>
+      {%- if tb_pretext -%}
+      <span>{{tb_pretext}} &bullet; </span>
+      {%- endif -%}
       <a href="{{get_post_url(post.id, _anchor=true)}}">
         {%- if post.edited_at <= post.created_at -%}
         <i>Posted on {{timestamp(post.created_at)}}</i>
@@ -181,17 +190,19 @@
       {%- endif -%}
     </span>
     {%- if show_toolbar -%}
-    <span class="thread-actions">
-      {%- if owns -%}
+    <span class="subheader-actions">
+      {%- if owns and tb_edit -%}
       <a class="linkbutton" href="{{url_for('posts.edit', post_id=post.id, _anchor='babycode-content')}}">Edit</a>
       {%- endif -%}
-      {%- if can_reply -%}
+      {%- if can_reply and tb_quote -%}
       <button autocomplete='off' data-r="enhance" data-s="babycodeEditorQuote" disabled title="This feature requires JavaScript to be enabled." data-quote="{{post.original_markup}}" data-poster-name="{{ post.display_name if post.display_name else post.username }}">Quote</button>
       {%- endif -%}
-      {%- if can_delete -%}
+      {%- if can_delete and tb_delete -%}
       <a class="linkbutton critical" href="{{url_for('posts.delete', post_id=post.id)}}">Delete</a>
       {%- endif -%}
-      <button autocomplete='off' data-r="enhance" data-s="showBookmarkMenu" disabled title="This feature requires JavaScript to be enabled." data-concept-kind="post" data-concept-id="{{post.id}}">{{icn_bookmark(24)}}Bookmark&hellip;</button>
+      {%- if tb_bookmark -%}
+      {{ bookmark_button('post', post.id, bookmark_btn) }}
+      {%- endif -%}
     </span>
     {%- endif -%}
   </div>
@@ -229,6 +240,18 @@
 </div>
 {%- endmacro %}
 
+{% macro bookmark_menu() -%}
+{%- if is_logged_in() -%}
+<div id="bookmark-popover" data-r="showBookmarkMenu" class="plank even" popover>
+  <div class="bookmark-menu-header">
+    <span>Bookmark collections</span>
+    <a href="{{url_for('users.bookmarks', username=get_active_user().username)}}">View bookmarks</a>
+  </div>
+  <div class="bookmark-menu-inner" data-r="fillBookmarkMenu">Loading&hellip;</div>
+</div>
+{%- endif -%}
+{%- endmacro %}
+
 {% macro infobox(message, kind=InfoboxKind.INFO) -%}
 <div class="infobox plank top contain-svg horizontal {{InfoboxHTMLClass[kind]}}">
   {%- if kind == InfoboxKind.INFO -%}
diff --git a/app/templates/posts/delete.html b/app/templates/posts/delete.html
index b371db2..97b2989 100644
--- a/app/templates/posts/delete.html
+++ b/app/templates/posts/delete.html
@@ -5,7 +5,7 @@
 {%- block content -%}
   {%- call() subheader("Delete post", "Are you sure you want to delete this post? This action can not be undone.") -%}
   <form method="POST">
-    <fieldset class="plank minimal even no-shadow thread-actions">
+    <fieldset class="plank minimal even no-shadow subheader-actions">
         <legend>Please confirm</legend>
         <a href="{{get_post_url(post.id, _anchor=true)}}" class="linkbutton">Cancel</a>
         <input type="submit" value="Delete" class="critical">
diff --git a/app/templates/threads/thread.html b/app/templates/threads/thread.html
index 0f72d71..1f35193 100644
--- a/app/templates/threads/thread.html
+++ b/app/templates/threads/thread.html
@@ -1,6 +1,6 @@
 {%- from 'common/macros.html' import subheader, timestamp, pager, babycode_editor_component -%}
 {%- from 'common/icons.html' import icn_bookmark -%}
-{%- from 'common/macros.html' import full_post with context -%}
+{%- from 'common/macros.html' import full_post, bookmark_menu with context -%}
 {%- extends 'base.html' -%}
 {%- block title -%}{{thread.title}}{%- endblock -%}
 {%- block content -%}
@@ -19,7 +19,7 @@
 </ul>
 {%- endset -%}
 {%- call() subheader(thread.title, td) -%}
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Actions</legend>
   {%- if is_logged_in() -%}
   {%- if thread.user_id == get_active_user().id -%}
@@ -35,7 +35,7 @@
   <a href="{{url_for('threads.feed', thread_id=thread.id)}}" class="linkbutton rss">Subscribe via RSS</a>
 </fieldset>
 {%- if is_mod() -%}
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Moderation actions</legend>
   {%- if thread.user_id != get_active_user().id -%}
   <a class="linkbutton warn" href="{{url_for('threads.edit', thread_id=thread.id)}}">Rename</a>
@@ -56,7 +56,7 @@
     <input type="submit" value="Move" class="warn">
   </form>
 </fieldset>
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Page</legend>
   {{- pager(page, page_count) -}}
 </fieldset>
@@ -70,7 +70,7 @@
   {%- endfor -%}
 </main>
 <div class="plank secondary-bg">
-  <fieldset class="plank even no-shadow minimal thread-actions">
+  <fieldset class="plank even no-shadow minimal subheader-actions">
     <legend>Page</legend>
     {{- pager(page, page_count) -}}
   </fieldset>
@@ -83,15 +83,7 @@
     <button>Stop updates</button>
   </span>
 </div>
-{%- if is_logged_in() -%}
-<div id="bookmark-popover" data-r="showBookmarkMenu" class="plank even" popover>
-  <div class="bookmark-menu-header">
-    <span>Bookmark collections</span>
-    <a href="{{url_for('users.bookmarks', username=get_active_user().username)}}">View bookmarks</a>
-  </div>
-  <div class="bookmark-menu-inner" data-r="fillBookmarkMenu">Loading&hellip;</div>
-</div>
-{%- endif -%}
+{{ bookmark_menu() }}
 {%- if is_logged_in() and get_active_user().can_post_to_thread_or_topic(thread) -%}
 <form action="{{url_for('threads.reply', thread_id=thread.id)}}" method="POST" class="plank post-edit-form" data-listen="submit" data-r="clearThreadDraft" data-s="clearThreadDraft">
   <h2 class="info">Reply to "{{thread.title}}"</h2>
diff --git a/app/templates/topics/topic.html b/app/templates/topics/topic.html
index 99bb559..b7e2427 100644
--- a/app/templates/topics/topic.html
+++ b/app/templates/topics/topic.html
@@ -12,7 +12,7 @@
 </ul>
 {%- endset -%}
 {%- call() subheader(('Threads in "%s"' % topic.name), td) -%}
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Actions</legend>
   {%- if is_logged_in() and get_active_user().can_post_to_thread_or_topic(topic) -%}
   <a href="{{url_for('threads.new', topic_id=topic.id)}}" class="linkbutton">New thread</a>
@@ -27,7 +27,7 @@
   </form>
 </fieldset>
 {%- if is_mod() -%}
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Moderation actions</legend>
   <a href="{{url_for('mod.edit_topic', topic_id=topic.id)}}" class="linkbutton">Edit</a>
   <form action="{{url_for('mod.lock_topic', topic_id=topic.id)}}" method="POST">
@@ -37,7 +37,7 @@
 </fieldset>
 {%- endif -%}
 {%- if threads | length > 0 -%}
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Page</legend>
   {{- pager(page, page_count, args=request.args) -}}
 </fieldset>
@@ -77,7 +77,7 @@
 {%- endfor -%}
 {%- if threads | length > 0 -%}
 <div class="plank secondary-bg">
-  <fieldset class="plank even no-shadow minimal thread-actions">
+  <fieldset class="plank even no-shadow minimal subheader-actions">
     <legend>Page</legend>
     {{- pager(page, page_count, args=request.args) -}}
   </fieldset>
diff --git a/app/templates/topics/topics.html b/app/templates/topics/topics.html
index 71acc80..b00baef 100644
--- a/app/templates/topics/topics.html
+++ b/app/templates/topics/topics.html
@@ -4,7 +4,7 @@
 {%- block content -%}
 {%- call() subheader('All topics') -%}
 {%- if is_mod() -%}
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Moderation actions</legend>
   <a href="{{url_for('mod.new_topic')}}" class="linkbutton">New topic</a>
   <a href="{{url_for('mod.index', _anchor='sort-topics')}}" class="linkbutton">Sort topics</a>
diff --git a/app/templates/users/bookmarks.html b/app/templates/users/bookmarks.html
new file mode 100644
index 0000000..5564e21
--- /dev/null
+++ b/app/templates/users/bookmarks.html
@@ -0,0 +1,56 @@
+{%- from 'common/macros.html' import full_post, bookmark_menu with context -%}
+{%- from 'common/macros.html' import subheader, bookmark_button -%}
+{%- extends 'base.html' -%}
+{%- block title -%}bookmarks"{%- endblock -%}
+{%- block content -%}
+<bitty-8 data-connect="/static/js/bits/bookmark-menu.js"></bitty-8>
+<bitty-8 data-connect="/static/js/bits/bookmarks.js"></bitty-8>
+{%- call() subheader('Your bookmarks') -%}
+<fieldset class="plank even no-shadow minimal subheader-actions js-only" data-r="enhance">
+  <legend>Actions</legend>
+  <a href="{{url_for('users.bookmark_collections', username=get_active_user().username)}}" class="linkbutton">Manage collections</a>
+</fieldset>
+{%- endcall -%}
+<div class="plank">
+  {%- for collection in collections -%}
+  {%- set thread_count = collection.get_threads_count() -%}
+  {%- set post_count = collection.get_posts_count() -%}
+    <details class="separated" data-id="{{collection.id}}" data-r="restoreCollectionDetails setCollectionDetails" data-s="setCollectionDetails">
+      <summary class="plank secondary-bg no-shadow even">{{collection.name}} ({{thread_count}} {{'thread' | pluralize(num=thread_count)}}, {{post_count}} {{'post' | pluralize(num=post_count)}})</summary>
+      {%- if thread_count > 0 -%}
+        <details class="inner" data-id="{{collection.id}}" data-r="restoreThreadDetails setThreadDetails" data-s="setThreadDetails">
+          <summary class="plank no-shadow even">Threads</summary>
+          <table class="three-cols">
+            <thead>
+              <tr>
+                <th class="plank even no-shadow contrast-bg">Title</th>
+                <th class="plank even no-shadow contrast-bg">Memo</th>
+                <th class="plank even no-shadow contrast-bg">Manage</th>
+              </tr>
+            </thead>
+            <tbody>
+              {%- for bt in collection.get_threads() -%}
+              {%- set thread = bt.get_thread() -%}
+              <tr>
+                <td class="plank even no-shadow minimal secondary-bg"><a href="{{url_for('threads.thread_by_id', thread_id=thread.id)}}">{{thread.title}}</a></td>
+                <td class="plank even no-shadow minimal secondary-bg">{{bt.note}}</td>
+                <td class="plank even no-shadow minimal secondary-bg">{{bookmark_button('thread', id=thread.id, text='Manage')}}</td>
+              </tr>
+              {%- endfor -%}
+            </tbody>
+          </table>
+        </details>
+      {%- endif -%}
+      {%- if post_count > 0 -%}
+        <details class="inner" data-id="{{collection.id}}" data-r="restorePostDetails setPostDetails" data-s="setPostDetails">
+          <summary class="plank no-shadow even">Posts</summary>
+          {%- for bp in collection.get_posts() -%}
+            <div class="post plank no-shadow even">{{ full_post(bp.get_post().get_full_post_view(), render_sig=false, show_thread=true, show_reactions=false, tb_edit=false, tb_quote=false, tb_delete=false, bookmark_btn='Manage', tb_pretext=('memo: ' + bp.note) if bp.note else '') }}</div>
+          {%- endfor -%}
+        </details>
+      {%- endif -%}
+    </details>
+  {%- endfor -%}
+</div>
+{{ bookmark_menu() }}
+{%- endblock -%}
diff --git a/app/templates/users/manage_collections.html b/app/templates/users/manage_collections.html
index 7cd36a1..5a38e0b 100644
--- a/app/templates/users/manage_collections.html
+++ b/app/templates/users/manage_collections.html
@@ -2,7 +2,7 @@
 {%- macro collection_item(name='', can_delete=true, id=-1, thread_count=0, post_count=0) -%}
 <input name="name[]" type="text" autocomplete="off" value="{{name}}" required maxlength=60 placeholder="Collection name">
 <input type="hidden" name="id[]" value="{{ 'new' if id == -1 else id}}" autocomplete="off">
-<span>{{thread_count}} {{'thread' | pluralize(num=thread_count)}}, {{post_count}} {{'post' | pluralize(num=post_count)}} </span>
+<span>{{thread_count}} {{'thread' | pluralize(num=thread_count)}}, {{post_count}} {{'post' | pluralize(num=post_count)}}</span>
 {%- if not can_delete -%}
 <i>Default collection</i>
 {%- else -%}
@@ -20,7 +20,7 @@ Drag collections to reoder them. You cannot move or remove the default collectio
 <div data-r="enhanceHide">This page requires JS enabled to work correctly.</div>
 {%- endset -%}
 {%- call() subheader('Manage bookmark collections', sh) -%}
-<fieldset class="plank even no-shadow minimal thread-actions js-only" data-r="enhance">
+<fieldset class="plank even no-shadow minimal subheader-actions js-only" data-r="enhance">
   <legend>Actions</legend>
   <button data-s="addCollection">Add new collection</button>
   <input type="submit" class="alt" value="Save collections" form="collections-form">
diff --git a/app/templates/users/posts.html b/app/templates/users/posts.html
index 5fa0733..3e7e735 100644
--- a/app/templates/users/posts.html
+++ b/app/templates/users/posts.html
@@ -8,7 +8,7 @@
 {%- endset -%}
 {%- call() subheader("%s's posts" % target_user.get_readable_name(), td) -%}
   {%- if posts -%}
-  <fieldset class="plank even no-shadow minimal thread-actions">
+  <fieldset class="plank even no-shadow minimal subheader-actions">
     <legend>Page</legend>
     {{- pager(page, page_count) -}}
   </fieldset>
@@ -19,7 +19,7 @@
   <div class="post plank">{{full_post(post, show_toolbar=false, show_thread=true, allow_reacting=false)}}</div>
 {%- endfor -%}
 <div class="plank">
-  <fieldset class="plank even no-shadow minimal thread-actions">
+  <fieldset class="plank even no-shadow minimal subheader-actions">
     <legend>Page</legend>
     {{- pager(page, page_count) -}}
   </fieldset>
diff --git a/app/templates/users/threads.html b/app/templates/users/threads.html
index e0ea0ec..fb83b05 100644
--- a/app/templates/users/threads.html
+++ b/app/templates/users/threads.html
@@ -8,7 +8,7 @@
 {%- endset -%}
 {%- call() subheader("%s's started threads" % target_user.get_readable_name(), td) -%}
   {%- if threads -%}
-  <fieldset class="plank even no-shadow minimal thread-actions">
+  <fieldset class="plank even no-shadow minimal subheader-actions">
     <legend>Page</legend>
     {{- pager(page, page_count) -}}
   </fieldset>
@@ -22,7 +22,7 @@
   </div>
   {%- endfor -%}
   <div class="plank">
-    <fieldset class="plank even no-shadow minimal thread-actions">
+    <fieldset class="plank even no-shadow minimal subheader-actions">
       <legend>Page</legend>
       {{- pager(page, page_count) -}}
     </fieldset>
diff --git a/app/templates/users/user_page.html b/app/templates/users/user_page.html
index a396fb6..fd984e1 100644
--- a/app/templates/users/user_page.html
+++ b/app/templates/users/user_page.html
@@ -7,7 +7,7 @@
 {%- if is_logged_in() -%}
 
 {%- if target_user.id == get_active_user().id -%}
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Actions</legend>
   <form action="{{url_for('users.log_out')}}" method="POST">
     <input type="submit" class="warn" value="Log out">
@@ -16,9 +16,9 @@
 {%- endif -%}
 
 {%- if get_active_user().is_mod() and target_user.id != get_active_user().id and target_user.permission < get_active_user().permission -%}
-<fieldset class="plank even no-shadow minimal thread-actions">
+<fieldset class="plank even no-shadow minimal subheader-actions">
   <legend>Moderation actions</legend>
-  <form class="thread-actions" method="POST">
+  <form class="subheader-actions" method="POST">
     {{csrf_input() | safe}}
     {%- if target_user.is_guest() -%}
     <input class="warn" type="submit" value="Approve user" formaction="{{url_for('mod.make_user_regular', user_id=target_user.id)}}">
diff --git a/data/static/css/style.css b/data/static/css/style.css
index dfbf2bc..7138be0 100644
--- a/data/static/css/style.css
+++ b/data/static/css/style.css
@@ -465,7 +465,7 @@ footer {
   gap: var(--base-padding);
 }
 
-.thread-actions {
+.subheader-actions {
   display: flex;
   flex-wrap: wrap;
   gap: var(--base-padding);
@@ -662,12 +662,12 @@ details {
     }
   }
 
-  &:not([open]) summary::before {
+  &:not([open]) > summary::before {
     content: '▶';
     padding-inline: var(--base-padding);
   }
 
-  &[open] summary::before {
+  &[open] > summary::before {
     content: '▼';
     padding-inline: var(--base-padding);
   }
@@ -677,6 +677,10 @@ details.separated {
   margin: 0.5em 0;
 }
 
+details.inner {
+  margin-inline: var(--base-padding);
+}
+
 .avatar-form {
   display: flex;
   gap: var(--huge-padding);
@@ -724,6 +728,25 @@ details.separated {
   }
 }
 
+table {
+  border-collapse: collapse;
+  width: 100%;
+
+  &.three-cols > thead > tr > th {
+    &:nth-child(1) {
+      width: 70%;
+    }
+
+    &:nth-child(2) {
+      width: 25%;
+    }
+
+    &:nth-child(3) {
+      width: 15%;
+    }
+  }
+
+}
 
 /* babycode tags */
 .inline-code {
diff --git a/data/static/js/bits/bookmark-menu.js b/data/static/js/bits/bookmark-menu.js
index 9a5e737..56a7216 100644
--- a/data/static/js/bits/bookmark-menu.js
+++ b/data/static/js/bits/bookmark-menu.js
@@ -7,9 +7,9 @@ async function getHTML(endpoint, options = {}) {
 
   const params = new URLSearchParams(query);
   const res = await fetch(`${endpoint}?${params}`, options);
-  if (!res.ok) {
-    console.error(res);
-  }
+  // if (!res.ok) {
+  //   console.error(res);
+  // }
 
   return { body: await res.text(), status: res.status };
 }
@@ -81,7 +81,7 @@ export async function bookmarkMenuSubmit(ev, _, el) {
   const status = (await getHTML(url, options)).status;
 
   if (status !== 204) {
-    b.trigger('bookmarkMenuShowError');
+    b.send({ status: status }, 'bookmarkMenuShowError');
     return;
   }
 
@@ -99,11 +99,17 @@ export function bookmarkMenuResetSavedButton(_, __, el) {
   el.value = 'Save';
 }
 
-export function bookmarkMenuShowError(_, __, el) {
+export function bookmarkMenuShowError(payload, _, el) {
   if (el === undefined) {
     return;
   }
 
+  if (payload.status === 404) {
+    el.innerText = 'This thread or post no longer exists. Please refresh the page.';
+  } else {
+    el.innerText = 'Something went wrong. Try again later.';
+  }
+
   if (el.classList.contains('hidden')) {
     el.classList.remove('hidden');
     setTimeout(() => { b.trigger('bookmarkMenuHideError') }, 4000);
diff --git a/data/static/js/bits/bookmarks.js b/data/static/js/bits/bookmarks.js
new file mode 100644
index 0000000..b56cdc5
--- /dev/null
+++ b/data/static/js/bits/bookmarks.js
@@ -0,0 +1,62 @@
+export const b = {
+  init: 'restoreCollectionDetails restoreThreadDetails restorePostDetails',
+}
+
+const COLLECTION_DETAILS_KEY = 'collectionsOpen';
+const THREAD_DETAILS_KEY = 'threadsOpen';
+const POST_DETAILS_KEY = 'postsOpen';
+
+let collectionDetailsData = {};
+let collectionThreadDetailsData = {};
+let collectionPostDetailsData = {};
+
+async function setDetailsData(obj, key, id, isOpen) {
+  obj[id] = isOpen;
+  await b.savePageData(obj, key);
+}
+
+export async function restoreCollectionDetails(_, __, el) {
+  collectionDetailsData = await b.loadPageData(COLLECTION_DETAILS_KEY, {});
+  el.open = collectionDetailsData[el.dataset.id] === true;
+}
+
+export async function setCollectionDetails(ev, sender, el) {
+  if (el !== sender) {
+    return;
+  }
+  if (ev.target !== el.querySelector('summary')) {
+    return;
+  }
+  console.log(!el.open);
+  await setDetailsData(collectionDetailsData, COLLECTION_DETAILS_KEY, el.dataset.id, !el.open);
+}
+
+export async function restoreThreadDetails(_, __, el) {
+  collectionThreadDetailsData = await b.loadPageData(THREAD_DETAILS_KEY, {});
+  el.open = collectionThreadDetailsData[el.dataset.id] === true;
+}
+
+export async function setThreadDetails(ev, sender, el) {
+  if (el !== sender) {
+    return;
+  }
+  if (ev.target !== el.querySelector('summary')) {
+    return;
+  }
+  await setDetailsData(collectionThreadDetailsData, THREAD_DETAILS_KEY, el.dataset.id, !el.open);
+}
+
+export async function restorePostDetails(_, __, el) {
+  collectionPostDetailsData = await b.loadPageData(POST_DETAILS_KEY, {});
+  el.open = collectionPostDetailsData[el.dataset.id] === true;
+}
+
+export async function setPostDetails(ev, sender, el) {
+  if (el !== sender) {
+    return;
+  }
+  if (ev.target !== el.querySelector('summary')) {
+    return;
+  }
+  await setDetailsData(collectionPostDetailsData, POST_DETAILS_KEY, el.dataset.id, !el.open);
+}