diff --git a/ui/src/App.tsx b/ui/src/App.tsx
index 4a830f8..ddde90f 100644
--- a/ui/src/App.tsx
+++ b/ui/src/App.tsx
@@ -36,6 +36,9 @@ import { Badge } from '@/components/ui/badge'
 const STORAGE_KEY = 'autocoder-selected-project'
 const VIEW_MODE_KEY = 'autocoder-view-mode'
 
+// Bottom padding for main content when debug panel is collapsed (40px header + 8px margin)
+const COLLAPSED_DEBUG_PANEL_CLEARANCE = 48
+
 function App() {
   // Initialize selected project from localStorage
   const [selectedProject, setSelectedProject] = useState<string | null>(() => {
@@ -331,7 +334,7 @@ function App() {
       {/* Main Content */}
       <main
         className="max-w-7xl mx-auto px-4 py-8"
-        style={{ paddingBottom: debugOpen ? debugPanelHeight + 32 : 48 }}
+        style={{ paddingBottom: debugOpen ? debugPanelHeight + 32 : COLLAPSED_DEBUG_PANEL_CLEARANCE }}
       >
         {!selectedProject ? (
           <div className="text-center mt-12">
diff --git a/ui/src/components/AssistantChat.tsx b/ui/src/components/AssistantChat.tsx
index a2d7ba8..a9d8b5f 100644
--- a/ui/src/components/AssistantChat.tsx
+++ b/ui/src/components/AssistantChat.tsx
@@ -12,6 +12,7 @@ import { useAssistantChat } from '../hooks/useAssistantChat'
 import { ChatMessage as ChatMessageComponent } from './ChatMessage'
 import { ConversationHistory } from './ConversationHistory'
 import type { ChatMessage } from '../lib/types'
+import { isSubmitEnter } from '../lib/keyboard'
 import { Button } from '@/components/ui/button'
 import { Textarea } from '@/components/ui/textarea'
 
@@ -134,8 +135,7 @@ export function AssistantChat({
   }
 
   const handleKeyDown = (e: React.KeyboardEvent<HTMLTextAreaElement>) => {
-    // Skip if composing (e.g., Japanese IME input)
-    if (e.key === 'Enter' && !e.shiftKey && !e.nativeEvent.isComposing) {
+    if (isSubmitEnter(e)) {
       e.preventDefault()
       handleSend()
     }
diff --git a/ui/src/components/ExpandProjectChat.tsx b/ui/src/components/ExpandProjectChat.tsx
index 2eb30b3..d1ccd21 100644
--- a/ui/src/components/ExpandProjectChat.tsx
+++ b/ui/src/components/ExpandProjectChat.tsx
@@ -11,6 +11,7 @@ import { useExpandChat } from '../hooks/useExpandChat'
 import { ChatMessage } from './ChatMessage'
 import { TypingIndicator } from './TypingIndicator'
 import type { ImageAttachment } from '../lib/types'
+import { isSubmitEnter } from '../lib/keyboard'
 import { Button } from '@/components/ui/button'
 import { Input } from '@/components/ui/input'
 import { Card, CardContent } from '@/components/ui/card'
@@ -88,8 +89,7 @@ export function ExpandProjectChat({
   }
 
   const handleKeyDown = (e: React.KeyboardEvent) => {
-    // Skip if composing (e.g., Japanese IME input)
-    if (e.key === 'Enter' && !e.shiftKey && !e.nativeEvent.isComposing) {
+    if (isSubmitEnter(e)) {
       e.preventDefault()
       handleSendMessage()
     }
diff --git a/ui/src/components/FolderBrowser.tsx b/ui/src/components/FolderBrowser.tsx
index 8641bdd..2e8171a 100644
--- a/ui/src/components/FolderBrowser.tsx
+++ b/ui/src/components/FolderBrowser.tsx
@@ -18,6 +18,7 @@ import {
   ArrowLeft,
 } from 'lucide-react'
 import * as api from '../lib/api'
+import { isSubmitEnter } from '../lib/keyboard'
 import type { DirectoryEntry, DriveInfo } from '../lib/types'
 import { Button } from '@/components/ui/button'
 import { Input } from '@/components/ui/input'
@@ -269,8 +270,7 @@ export function FolderBrowser({ onSelect, onCancel, initialPath }: FolderBrowser
                     className="flex-1"
                     autoFocus
                     onKeyDown={(e) => {
-                      // Skip if composing (e.g., Japanese IME input)
-                      if (e.key === 'Enter' && !e.nativeEvent.isComposing) handleCreateFolder()
+                      if (isSubmitEnter(e, false)) handleCreateFolder()
                       if (e.key === 'Escape') {
                         setIsCreatingFolder(false)
                         setNewFolderName('')
diff --git a/ui/src/components/SpecCreationChat.tsx b/ui/src/components/SpecCreationChat.tsx
index 24d0c09..c96a1f2 100644
--- a/ui/src/components/SpecCreationChat.tsx
+++ b/ui/src/components/SpecCreationChat.tsx
@@ -12,6 +12,7 @@ import { ChatMessage } from './ChatMessage'
 import { QuestionOptions } from './QuestionOptions'
 import { TypingIndicator } from './TypingIndicator'
 import type { ImageAttachment } from '../lib/types'
+import { isSubmitEnter } from '../lib/keyboard'
 import { Button } from '@/components/ui/button'
 import { Textarea } from '@/components/ui/textarea'
 import { Card, CardContent } from '@/components/ui/card'
@@ -127,8 +128,7 @@ export function SpecCreationChat({
   }
 
   const handleKeyDown = (e: React.KeyboardEvent) => {
-    // Skip if composing (e.g., Japanese IME input)
-    if (e.key === 'Enter' && !e.shiftKey && !e.nativeEvent.isComposing) {
+    if (isSubmitEnter(e)) {
       e.preventDefault()
       handleSendMessage()
     }
diff --git a/ui/src/components/TerminalTabs.tsx b/ui/src/components/TerminalTabs.tsx
index 760d69d..c53ff22 100644
--- a/ui/src/components/TerminalTabs.tsx
+++ b/ui/src/components/TerminalTabs.tsx
@@ -8,6 +8,7 @@
 import { useState, useRef, useEffect, useCallback } from 'react'
 import { Plus, X } from 'lucide-react'
 import type { TerminalInfo } from '@/lib/types'
+import { isSubmitEnter } from '@/lib/keyboard'
 import { Button } from '@/components/ui/button'
 import { Input } from '@/components/ui/input'
 
@@ -96,8 +97,7 @@ export function TerminalTabs({
   // Handle key events during editing
   const handleKeyDown = useCallback(
     (e: React.KeyboardEvent) => {
-      // Skip if composing (e.g., Japanese IME input)
-      if (e.key === 'Enter' && !e.nativeEvent.isComposing) {
+      if (isSubmitEnter(e, false)) {
         e.preventDefault()
         submitEdit()
       } else if (e.key === 'Escape') {
diff --git a/ui/src/lib/keyboard.ts b/ui/src/lib/keyboard.ts
new file mode 100644
index 0000000..4e3cf71
--- /dev/null
+++ b/ui/src/lib/keyboard.ts
@@ -0,0 +1,38 @@
+/**
+ * Keyboard event utilities
+ *
+ * Helpers for handling keyboard events, particularly for IME-aware input handling.
+ */
+
+/**
+ * Check if an Enter keypress should trigger form submission.
+ *
+ * Returns false during IME composition (e.g., Japanese, Chinese, Korean input)
+ * to prevent accidental submission while selecting characters.
+ *
+ * @param e - The keyboard event from React
+ * @param allowShiftEnter - If true, Shift+Enter returns false (for multiline input)
+ * @returns true if Enter should submit, false if it should be ignored
+ *
+ * @example
+ * // In a chat input (Shift+Enter for newline)
+ * if (isSubmitEnter(e)) {
+ *   e.preventDefault()
+ *   handleSend()
+ * }
+ *
+ * @example
+ * // In a single-line input (Enter always submits)
+ * if (isSubmitEnter(e, false)) {
+ *   handleSubmit()
+ * }
+ */
+export function isSubmitEnter(
+  e: React.KeyboardEvent,
+  allowShiftEnter: boolean = true
+): boolean {
+  if (e.key !== 'Enter') return false
+  if (allowShiftEnter && e.shiftKey) return false
+  if (e.nativeEvent.isComposing) return false
+  return true
+}