diff --git a/packages/vscode-ide-companion/src/webview/App.tsx b/packages/vscode-ide-companion/src/webview/App.tsx
index bb503f3074..7c64ff0ca8 100644
--- a/packages/vscode-ide-companion/src/webview/App.tsx
+++ b/packages/vscode-ide-companion/src/webview/App.tsx
@@ -189,6 +189,7 @@ export const App: React.FC = () => {
             description: cmd.description,
             type: 'command' as const,
             group: 'Slash Commands',
+            value: cmd.name,
           }),
         );
 
@@ -518,9 +519,11 @@ export const App: React.FC = () => {
     setAskUserQuestionRequest(null);
   }, [vscode]);
 
-  // Handle completion selection
+  // Handle completion selection.
+  // When fillOnly is true (Tab), slash commands are inserted into the input
+  // instead of being sent immediately, so users can append arguments.
   const handleCompletionSelect = useCallback(
-    (item: CompletionItem) => {
+    (item: CompletionItem, fillOnly?: boolean) => {
       // Handle completion selection by inserting the value into the input field
       const inputElement = inputFieldRef.current;
       if (!inputElement) {
@@ -593,13 +596,13 @@ export const App: React.FC = () => {
           }
         };
 
-        // Handle special commands by id
         if (itemId === 'login') {
           clearTriggerText();
           vscode.postMessage({ type: 'login', data: {} });
           completion.closeCompletion();
           return;
         }
+
         if (itemId === 'model') {
           clearTriggerText();
           setShowModelSelector(true);
@@ -607,10 +610,11 @@ export const App: React.FC = () => {
           return;
         }
 
-        // Handle server-provided slash commands by sending them as messages
-        // CLI will detect slash commands in session/prompt and execute them
+        // Handle server-provided slash commands by sending them as messages.
+        // Skip when fillOnly (Tab) — let the generic insertion path fill the
+        // command text so the user can keep typing arguments.
         const serverCmd = availableCommands.find((c) => c.name === itemId);
-        if (serverCmd) {
+        if (serverCmd && !fillOnly) {
           // Clear the trigger text since we're sending the command
           clearTriggerText();
           // Send the slash command as a user message
@@ -1031,6 +1035,7 @@ export const App: React.FC = () => {
           completionIsOpen={completion.isOpen}
           completionItems={completion.items}
           onCompletionSelect={handleCompletionSelect}
+          onCompletionFill={(item) => handleCompletionSelect(item, true)}
           onCompletionClose={completion.closeCompletion}
           showModelSelector={showModelSelector}
           availableModels={availableModels}
diff --git a/packages/vscode-ide-companion/src/webview/components/layout/InputForm.test.tsx b/packages/vscode-ide-companion/src/webview/components/layout/InputForm.test.tsx
new file mode 100644
index 0000000000..8bf5ea26f0
--- /dev/null
+++ b/packages/vscode-ide-companion/src/webview/components/layout/InputForm.test.tsx
@@ -0,0 +1,155 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/** @vitest-environment jsdom */
+
+import type React from 'react';
+import { act, createRef } from 'react';
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest';
+import { createRoot, type Root } from 'react-dom/client';
+import { ApprovalMode } from '../../../types/acpTypes.js';
+import type { CompletionItem } from '../../../types/completionItemTypes.js';
+import { InputForm } from './InputForm.js';
+
+vi.mock('@qwen-code/webui', async () => {
+  const actual = await vi.importActual(
+    '../../../../../webui/src/components/layout/InputForm.tsx',
+  );
+
+  return {
+    InputForm: actual.InputForm,
+    getEditModeIcon: actual.getEditModeIcon,
+  };
+});
+
+const completionItem: CompletionItem = {
+  id: 'create-issue',
+  label: '/create-issue',
+  type: 'command',
+  value: 'create-issue',
+};
+
+function renderInputForm(props?: {
+  onCompletionSelect?: (item: CompletionItem) => void;
+  onCompletionFill?: (item: CompletionItem) => void;
+}) {
+  const container = document.createElement('div');
+  document.body.appendChild(container);
+
+  const root = createRoot(container);
+  const inputFieldRef =
+    createRef<HTMLDivElement>() as unknown as React.RefObject<HTMLDivElement>;
+  const onCompletionSelect = props?.onCompletionSelect ?? vi.fn();
+  const onCompletionFill = props?.onCompletionFill ?? vi.fn();
+
+  act(() => {
+    root.render(
+      <InputForm
+        inputText=""
+        inputFieldRef={inputFieldRef}
+        isStreaming={false}
+        isWaitingForResponse={false}
+        isComposing={false}
+        editMode={ApprovalMode.DEFAULT}
+        thinkingEnabled={false}
+        activeFileName={null}
+        activeSelection={null}
+        skipAutoActiveContext={false}
+        contextUsage={null}
+        onInputChange={vi.fn()}
+        onCompositionStart={vi.fn()}
+        onCompositionEnd={vi.fn()}
+        onKeyDown={vi.fn()}
+        onSubmit={vi.fn()}
+        onCancel={vi.fn()}
+        onToggleEditMode={vi.fn()}
+        onToggleThinking={vi.fn()}
+        onToggleSkipAutoActiveContext={vi.fn()}
+        onShowCommandMenu={vi.fn()}
+        onAttachContext={vi.fn()}
+        completionIsOpen={true}
+        completionItems={[completionItem]}
+        onCompletionSelect={onCompletionSelect}
+        onCompletionFill={onCompletionFill}
+        onCompletionClose={vi.fn()}
+      />,
+    );
+  });
+
+  return {
+    container,
+    root,
+    onCompletionSelect,
+    onCompletionFill,
+  };
+}
+
+describe('InputForm completion keyboard handling', () => {
+  let root: Root | null = null;
+  let container: HTMLDivElement | null = null;
+
+  beforeEach(() => {
+    vi.clearAllMocks();
+    (
+      globalThis as typeof globalThis & { IS_REACT_ACT_ENVIRONMENT?: boolean }
+    ).IS_REACT_ACT_ENVIRONMENT = true;
+    Object.defineProperty(HTMLElement.prototype, 'scrollIntoView', {
+      configurable: true,
+      value: vi.fn(),
+    });
+  });
+
+  afterEach(() => {
+    if (root) {
+      act(() => {
+        root?.unmount();
+      });
+      root = null;
+    }
+    if (container) {
+      container.remove();
+      container = null;
+    }
+  });
+
+  it('uses onCompletionFill for Tab without triggering onCompletionSelect', () => {
+    const rendered = renderInputForm();
+    root = rendered.root;
+    container = rendered.container;
+
+    act(() => {
+      document.dispatchEvent(
+        new KeyboardEvent('keydown', {
+          key: 'Tab',
+          bubbles: true,
+          cancelable: true,
+        }),
+      );
+    });
+
+    expect(rendered.onCompletionFill).toHaveBeenCalledWith(completionItem);
+    expect(rendered.onCompletionSelect).not.toHaveBeenCalled();
+  });
+
+  it('keeps Enter mapped to onCompletionSelect', () => {
+    const rendered = renderInputForm();
+    root = rendered.root;
+    container = rendered.container;
+
+    act(() => {
+      document.dispatchEvent(
+        new KeyboardEvent('keydown', {
+          key: 'Enter',
+          bubbles: true,
+          cancelable: true,
+        }),
+      );
+    });
+
+    expect(rendered.onCompletionSelect).toHaveBeenCalledWith(completionItem);
+    expect(rendered.onCompletionFill).not.toHaveBeenCalled();
+  });
+});
diff --git a/packages/vscode-ide-companion/src/webview/components/layout/InputForm.tsx b/packages/vscode-ide-companion/src/webview/components/layout/InputForm.tsx
index cb747aff3b..809f80dbcc 100644
--- a/packages/vscode-ide-companion/src/webview/components/layout/InputForm.tsx
+++ b/packages/vscode-ide-companion/src/webview/components/layout/InputForm.tsx
@@ -13,6 +13,7 @@ import type {
   InputFormProps as BaseInputFormProps,
   EditModeInfo,
 } from '@qwen-code/webui';
+import type { CompletionItem } from '../../../types/completionItemTypes.js';
 import { getApprovalModeInfoFromString } from '../../../types/acpTypes.js';
 import type { ApprovalModeValue } from '../../../types/approvalModeValueTypes.js';
 import type { ModelInfo } from '@agentclientprotocol/sdk';
@@ -22,9 +23,11 @@ import { ModelSelector } from './ModelSelector.js';
  * Extended props that accept ApprovalModeValue and ModelSelector
  */
 export interface InputFormProps
-  extends Omit<BaseInputFormProps, 'editModeInfo'> {
+  extends Omit<BaseInputFormProps, 'editModeInfo' | 'onCompletionFill'> {
   /** Edit mode value (local type) */
   editMode: ApprovalModeValue;
+  /** Completion fill callback (Tab or equivalent) */
+  onCompletionFill?: (item: CompletionItem) => void;
   /** Whether to show model selector */
   showModelSelector?: boolean;
   /** Available models for selection */
diff --git a/packages/webui/src/components/layout/CompletionMenu.tsx b/packages/webui/src/components/layout/CompletionMenu.tsx
index 06727f7eef..eeefd6da7f 100644
--- a/packages/webui/src/components/layout/CompletionMenu.tsx
+++ b/packages/webui/src/components/layout/CompletionMenu.tsx
@@ -17,8 +17,10 @@ import type { CompletionItem } from '../../types/completion.js';
 export interface CompletionMenuProps {
   /** List of completion items to display */
   items: CompletionItem[];
-  /** Callback when an item is selected */
+  /** Callback when an item is selected (Enter / click) */
   onSelect: (item: CompletionItem) => void;
+  /** Optional callback for Tab selection (fill without executing). Falls back to onSelect. */
+  onFill?: (item: CompletionItem) => void;
   /** Callback when menu should close */
   onClose: () => void;
   /** Optional section title */
@@ -75,6 +77,7 @@ const groupItems = (
 export const CompletionMenu: FC<CompletionMenuProps> = ({
   items,
   onSelect,
+  onFill,
   onClose,
   title,
   selectedIndex = 0,
@@ -123,12 +126,17 @@ export const CompletionMenu: FC<CompletionMenuProps> = ({
           setSelected((prev) => Math.max(prev - 1, 0));
           break;
         case 'Enter':
-        case 'Tab':
           event.preventDefault();
           if (items[selected]) {
             onSelect(items[selected]);
           }
           break;
+        case 'Tab':
+          event.preventDefault();
+          if (items[selected]) {
+            (onFill ?? onSelect)(items[selected]);
+          }
+          break;
         case 'Escape':
           event.preventDefault();
           onClose();
@@ -144,7 +152,7 @@ export const CompletionMenu: FC<CompletionMenuProps> = ({
       document.removeEventListener('mousedown', handleClickOutside);
       document.removeEventListener('keydown', handleKeyDown);
     };
-  }, [items, selected, onSelect, onClose]);
+  }, [items, selected, onSelect, onFill, onClose]);
 
   useEffect(() => {
     // Only scroll into view for keyboard navigation, not mouse hover
diff --git a/packages/webui/src/components/layout/InputForm.tsx b/packages/webui/src/components/layout/InputForm.tsx
index e77f57e248..7edfac03b5 100644
--- a/packages/webui/src/components/layout/InputForm.tsx
+++ b/packages/webui/src/components/layout/InputForm.tsx
@@ -111,8 +111,10 @@ export interface InputFormProps {
   completionIsOpen: boolean;
   /** Completion items */
   completionItems?: CompletionItem[];
-  /** Completion select callback */
+  /** Completion select callback (Enter / click) */
   onCompletionSelect?: (item: CompletionItem) => void;
+  /** Completion fill callback (Tab — fill without executing). Falls back to onCompletionSelect. */
+  onCompletionFill?: (item: CompletionItem) => void;
   /** Completion close callback */
   onCompletionClose?: () => void;
   /** Placeholder text */
@@ -170,6 +172,7 @@ export const InputForm: FC<InputFormProps> = ({
   completionIsOpen,
   completionItems,
   onCompletionSelect,
+  onCompletionFill,
   onCompletionClose,
   placeholder = 'Ask Qwen Code …',
 }) => {
@@ -242,6 +245,7 @@ export const InputForm: FC<InputFormProps> = ({
               <CompletionMenu
                 items={completionItemsResolved}
                 onSelect={onCompletionSelect}
+                onFill={onCompletionFill}
                 onClose={onCompletionClose}
                 title={undefined}
               />