diff --git a/frontend/src/desktop/createDesktopSurface.js b/frontend/src/desktop/createDesktopSurface.js
index 0ca4a33..2b1dd9a 100644
--- a/frontend/src/desktop/createDesktopSurface.js
+++ b/frontend/src/desktop/createDesktopSurface.js
@@ -84,12 +84,13 @@ const createDesktopSurface = ({
   const sidebarToggle = renderSidebarToggle ? renderSidebarToggle() : null;
   const detail = detailOpen && detailProps
     ? (() => {
-        const { onClose, onOpenPreview, ...restDetailProps } = detailProps;
+        const { onClose, onOpenPreview, tags: tagOptions, ...restDetailProps } = detailProps;
         return (
           <DocumentViewerPanel
             variant="sidebar"
             onCollapsePanel={onClose}
             onMaximizePanel={onOpenPreview}
+            tagOptions={tagOptions}
             {...restDetailProps}
           />
         );
diff --git a/frontend/src/documents/SelectionAssignmentMenu.jsx b/frontend/src/documents/SelectionAssignmentMenu.jsx
index e5ff17b..6bd0aa6 100644
--- a/frontend/src/documents/SelectionAssignmentMenu.jsx
+++ b/frontend/src/documents/SelectionAssignmentMenu.jsx
@@ -1,10 +1,6 @@
 import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react';
 import useFloatingMenu from '../ui/useFloatingMenu';
-import {
-  PlusIcon,
-  CheckIcon,
-  CircleDashedCheckIcon,
-} from '../ui/icons';
+import { CheckIcon, CircleDashedCheckIcon, PlusIcon } from '../ui/icons';
 
 const STATE_ORDER = {
   all: 0,
@@ -117,7 +113,8 @@ const SelectionAssignmentMenu = ({
   );
 
   const handleCreate = useCallback(
-    async () => {
+    async (event) => {
+      event?.preventDefault?.();
       if (typeof onCreate !== 'function') {
         return;
       }
@@ -144,9 +141,12 @@ const SelectionAssignmentMenu = ({
   );
 
   const canCreate = Boolean(onCreate);
-  const showCreateOption = canCreate
-    && query.trim().length > 0
-    && !existingLabels.has(query.trim().toLowerCase());
+  const trimmedQuery = query.trim();
+  const queryKey = trimmedQuery.toLowerCase();
+  const canSubmitCreate = canCreate
+    && trimmedQuery.length > 0
+    && !existingLabels.has(queryKey)
+    && !pending;
 
   const handleTriggerClick = useCallback(() => {
     if (disabled) {
@@ -184,15 +184,28 @@ const SelectionAssignmentMenu = ({
           data-floating-position
         >
           <div className="selection-assignment__header">
-            <input
-              ref={inputRef}
-              type="text"
-              value={query}
-              onChange={(event) => setQuery(event.target.value)}
-              placeholder={placeholder}
-              aria-label={placeholder}
-              disabled={pending}
-            />
+            <form className="selection-assignment__form" onSubmit={handleCreate}>
+              <input
+                ref={inputRef}
+                type="text"
+                value={query}
+                onChange={(event) => setQuery(event.target.value)}
+                placeholder={placeholder}
+                aria-label={placeholder}
+                disabled={pending}
+              />
+              {canCreate ? (
+                <button
+                  type="submit"
+                  className="icon-button selection-assignment__add"
+                  disabled={!canSubmitCreate}
+                  aria-label={createLabel || 'Add'}
+                  title={createLabel || 'Add'}
+                >
+                  <PlusIcon aria-hidden="true" />
+                </button>
+              ) : null}
+            </form>
           </div>
           <div className="selection-assignment__list" role="presentation">
             {filteredItems.length ? (
@@ -237,19 +250,6 @@ const SelectionAssignmentMenu = ({
               <div className="menu__empty selection-assignment__empty">{emptyMessage}</div>
             )}
           </div>
-          {showCreateOption ? (
-            <button
-              type="button"
-              className="menu__item selection-assignment__create"
-              onClick={handleCreate}
-              disabled={pending}
-            >
-              <PlusIcon className="selection-assignment__icon" aria-hidden="true" />
-              <span className="selection-assignment__label">
-                {createLabel ? `${createLabel} “${query.trim()}”` : `Create “${query.trim()}”`}
-              </span>
-            </button>
-          ) : null}
         </div>
       ) : null}
     </div>
diff --git a/frontend/src/documents/panel/createDocumentsSurface.js b/frontend/src/documents/panel/createDocumentsSurface.js
index 794e2f4..a0ee776 100644
--- a/frontend/src/documents/panel/createDocumentsSurface.js
+++ b/frontend/src/documents/panel/createDocumentsSurface.js
@@ -93,12 +93,13 @@ const createDocumentsSurface = ({
   const sidebarToggle = renderSidebarToggle ? renderSidebarToggle() : null;
   const detail = detailOpen && detailProps
     ? (() => {
-        const { onClose, onOpenPreview, ...restDetailProps } = detailProps;
+        const { onClose, onOpenPreview, tags: tagOptions, ...restDetailProps } = detailProps;
         return (
           <DocumentViewerPanel
             variant="sidebar"
             onCollapsePanel={onClose}
             onMaximizePanel={onOpenPreview}
+            tagOptions={tagOptions}
             {...restDetailProps}
           />
         );
diff --git a/frontend/src/styles/detail/detail-panels.css b/frontend/src/styles/detail/detail-panels.css
index a51f469..f5584c6 100644
--- a/frontend/src/styles/detail/detail-panels.css
+++ b/frontend/src/styles/detail/detail-panels.css
@@ -191,7 +191,14 @@
   border-bottom: 1px solid var(--border-subtle);
 }
 
-.selection-assignment__header input {
+.selection-assignment__form {
+  display: flex;
+  gap: 0.4rem;
+  align-items: stretch;
+}
+
+.selection-assignment__form input {
+  flex: 1 1 auto;
   width: 100%;
   padding: 0.35rem 0.6rem;
   border: 1px solid var(--border-subtle);
@@ -201,12 +208,20 @@
   font-size: 0.95rem;
 }
 
-.selection-assignment__header input:focus-visible {
+.selection-assignment__form input:focus-visible {
   outline: none;
   border-color: color-mix(in oklch, var(--accent) 60%, transparent);
   box-shadow: 0 0 0 1px color-mix(in oklch, var(--accent) 35%, transparent);
 }
 
+.selection-assignment__add {
+  align-self: stretch;
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  min-width: 2rem;
+}
+
 .selection-assignment__list {
   max-height: max(240px, 50vh);
   overflow-y: auto;
diff --git a/frontend/src/styles/sidebar/sidebar.css b/frontend/src/styles/sidebar/sidebar.css
index a1a8479..0b8ae83 100644
--- a/frontend/src/styles/sidebar/sidebar.css
+++ b/frontend/src/styles/sidebar/sidebar.css
@@ -247,6 +247,7 @@
 
 .menu__list {
   overflow-y: auto;
+  max-height: min(20rem, 60vh);
   padding: 0.25rem;
   display: flex;
   flex-direction: column;