diff --git a/.changeset/lemon-numbers-look.md b/.changeset/lemon-numbers-look.md
new file mode 100644
index 0000000000..d8c46a623f
--- /dev/null
+++ b/.changeset/lemon-numbers-look.md
@@ -0,0 +1,21 @@
+---
+"@platejs/combobox": patch
+---
+
+Add `getUserId` option to `TriggerComboboxPluginOptions` to fix combobox popover opening for all users in Yjs collaboration mode
+
+When a user types a trigger character (e.g. `/` or `@`), the combobox input now stores the creator's `userId`. Only the creator will see the auto-focused combobox popover.
+
+```tsx
+SlashPlugin.configure({
+  options: {
+    getUserId: (editor) => editor.getOption(YjsPlugin, 'userId'),
+  },
+})
+
+MentionPlugin.configure({
+  options: {
+    getUserId: (editor) => editor.getOption(YjsPlugin, 'userId'),
+  },
+})
+```
diff --git a/.changeset/yjs-user-id.md b/.changeset/yjs-user-id.md
new file mode 100644
index 0000000000..e9925fc219
--- /dev/null
+++ b/.changeset/yjs-user-id.md
@@ -0,0 +1,13 @@
+---
+"@platejs/yjs": patch
+---
+
+Add `userId` option to **YjsPlugin** for combobox collaboration support
+
+```tsx
+YjsPlugin.configure({
+  options: {
+    userId: user?.id,
+  },
+})
+```
diff --git a/apps/www/src/registry/ui/inline-combobox.tsx b/apps/www/src/registry/ui/inline-combobox.tsx
index 8567f3c751..f32084fb92 100644
--- a/apps/www/src/registry/ui/inline-combobox.tsx
+++ b/apps/www/src/registry/ui/inline-combobox.tsx
@@ -27,6 +27,7 @@ import { cva } from 'class-variance-authority';
 import { useComposedRef, useEditorRef } from 'platejs/react';
 
 import { cn } from '@/lib/utils';
+import { YjsPlugin } from '@platejs/yjs/react';
 
 type FilterFn = (
   item: { value: string; group?: string; keywords?: string[]; label?: string },
@@ -89,6 +90,17 @@ const InlineCombobox = ({
   const hasValueProp = valueProp !== undefined;
   const value = hasValueProp ? valueProp : valueState;
 
+  // Check if current user is the creator of this element (for Yjs collaboration)
+  const isCreator = React.useMemo(() => {
+    const elementUserId = (element as any).userId;
+    const currentUserId = editor.getOption(YjsPlugin, 'userId');
+
+    // If no userId (backwards compatibility or non-Yjs), allow
+    if (!elementUserId) return true;
+
+    return elementUserId === currentUserId;
+  }, [editor, element]);
+
   const setValue = React.useCallback(
     (newValue: string) => {
       setValueProp?.(newValue);
@@ -126,6 +138,7 @@ const InlineCombobox = ({
   const { props: inputProps, removeInput } = useComboboxInput({
     cancelInputOnBlur: true,
     cursorState,
+    autoFocus: isCreator,
     ref: inputRef,
     onCancelInput: (cause) => {
       if (cause !== 'backspace') {
diff --git a/docs/components/changelog.mdx b/docs/components/changelog.mdx
index 4b24f33965..f5583cf733 100644
--- a/docs/components/changelog.mdx
+++ b/docs/components/changelog.mdx
@@ -8,6 +8,9 @@ Since Plate UI is not a component library, a changelog is maintained here.
 
 Use the [CLI](https://platejs.org/docs/components/cli) to install the latest version of the components.
 
+### November 30 #26.10
+- `inline-combobox`: Added Yjs collaboration support - combobox popover now only shows for the user who triggered it, preventing the popover from opening for all users in collaborative editing
+
 ### October 21 #26.9
 - `suggestion-kit`: Remove `BlockSuggestion`use `SuggestionLineBreak` instead to fixes styles.
 - `use-chat`: Fix AI comment hiding when finished.
diff --git a/packages/combobox/src/lib/types.ts b/packages/combobox/src/lib/types.ts
index 9e4c9bf6d3..9c23c8a5d0 100644
--- a/packages/combobox/src/lib/types.ts
+++ b/packages/combobox/src/lib/types.ts
@@ -18,5 +18,7 @@ export type TriggerComboboxPluginOptions = {
   trigger?: RegExp | string[] | string;
   triggerPreviousCharPattern?: RegExp;
   createComboboxInput?: (trigger: string) => TElement;
+  /** Get current user ID for Yjs collaboration - used to set userId on combobox input */
+  getUserId?: (editor: SlateEditor) => string | undefined;
   triggerQuery?: (editor: SlateEditor) => boolean;
 };
diff --git a/packages/combobox/src/lib/withTriggerCombobox.ts b/packages/combobox/src/lib/withTriggerCombobox.ts
index 7e76c45169..b005ab4e08 100644
--- a/packages/combobox/src/lib/withTriggerCombobox.ts
+++ b/packages/combobox/src/lib/withTriggerCombobox.ts
@@ -28,6 +28,7 @@ export const withTriggerCombobox: OverrideEditor<
       insertText(text, options) {
         const {
           createComboboxInput,
+          getUserId,
           triggerPreviousCharPattern,
           triggerQuery,
         } = getOptions();
@@ -54,6 +55,13 @@ export const withTriggerCombobox: OverrideEditor<
             ? createComboboxInput(text)
             : { children: [{ text: '' }], type };
 
+          // Add userId for Yjs collaboration - only the creator sees the combobox
+          const userId = getUserId?.(editor as SlateEditor);
+
+          if (userId) {
+            (inputNode as any).userId = userId;
+          }
+
           return editor.tf.insertNodes(inputNode, options);
         }
 
diff --git a/packages/yjs/src/lib/BaseYjsPlugin.ts b/packages/yjs/src/lib/BaseYjsPlugin.ts
index 61fdfd5b8b..3edb028c31 100644
--- a/packages/yjs/src/lib/BaseYjsPlugin.ts
+++ b/packages/yjs/src/lib/BaseYjsPlugin.ts
@@ -33,6 +33,7 @@ export const BaseYjsPlugin = createTSlatePlugin<YjsConfig>({
   options: {
     _isConnected: false,
     _isSynced: false,
+    userId: null,
     _providers: [],
     awareness: null!,
     cursors: {},
diff --git a/packages/yjs/src/lib/providers/types.ts b/packages/yjs/src/lib/providers/types.ts
index f28657f699..69bccc11c4 100644
--- a/packages/yjs/src/lib/providers/types.ts
+++ b/packages/yjs/src/lib/providers/types.ts
@@ -101,6 +101,8 @@ export type YjsConfig = PluginConfig<
     _isConnected: boolean;
     /** Whether the plugin is currently synced. */
     _isSynced: boolean;
+    /** The current user ID. */
+    userId: string | null;
     /** Array of all active, instantiated providers. */
     _providers: UnifiedProvider[];
     /** The shared Awareness instance used by the plugin. */