fix(chat): header ellipsis, Codex logo on light theme, portal copy menu

- MainContentTitle: truncate the session title with an ellipsis instead
  of horizontal-scrolling it
- MessageComponent: use text-foreground for the provider logo chip so the
  currentColor Codex/OpenAI mark is visible on the light theme
- MessageCopyControl: render the copy-format dropdown in a portal so it
  escapes the chat message's `contain: paint` clip box; anchor it to the
  trigger, flip above near the viewport bottom, close on scroll/resize

src/components/chat/view/subcomponents/MessageComponent.tsx

@@ -166,7 +166,7 @@ const MessageComponent = memo(({ message, prevMessage, createDiff, onFileOpen, a
                   🔧
                 </div>
               ) : (
-                <div className="flex h-8 w-8 flex-shrink-0 items-center justify-center rounded-full p-1 text-sm text-white">
+                <div className="flex h-8 w-8 flex-shrink-0 items-center justify-center rounded-full p-1 text-sm text-foreground">
                   <SessionProviderLogo provider={provider} className="h-full w-full" />
                 </div>
               )}

src/components/chat/view/subcomponents/MessageCopyControl.tsx

@@ -1,4 +1,6 @@
 import { useEffect, useMemo, useRef, useState } from 'react';
+import type { CSSProperties } from 'react';
+import { createPortal } from 'react-dom';
 import { useTranslation } from 'react-i18next';
 import { copyTextToClipboard } from '../../../../utils/clipboard';
 
@@ -49,9 +51,32 @@ const MessageCopyControl = ({
   const [selectedFormat, setSelectedFormat] = useState<CopyFormat>(defaultFormat);
   const [copied, setCopied] = useState(false);
   const [isDropdownOpen, setIsDropdownOpen] = useState(false);
+  const [menuStyle, setMenuStyle] = useState<CSSProperties>({});
   const dropdownRef = useRef<HTMLDivElement | null>(null);
+  const triggerRef = useRef<HTMLButtonElement | null>(null);
+  const menuRef = useRef<HTMLDivElement | null>(null);
   const copyFeedbackTimerRef = useRef<ReturnType<typeof setTimeout> | null>(null);
 
+  // The dropdown is rendered in a portal so it escapes the chat message's
+  // `contain: paint` box (which would otherwise clip it). Anchor it to the
+  // trigger, flipping above when there isn't room below.
+  const openDropdown = () => {
+    const rect = triggerRef.current?.getBoundingClientRect();
+    if (rect) {
+      const ESTIMATED_MENU_HEIGHT = 84;
+      const openUp = rect.bottom + ESTIMATED_MENU_HEIGHT + 8 > window.innerHeight;
+      setMenuStyle({
+        position: 'fixed',
+        right: Math.max(8, window.innerWidth - rect.right),
+        zIndex: 1000,
+        ...(openUp
+          ? { bottom: window.innerHeight - rect.top + 4 }
+          : { top: rect.bottom + 4 }),
+      });
+    }
+    setIsDropdownOpen(true);
+  };
+
   const copyFormatOptions: CopyFormatOption[] = useMemo(
     () => [
       {
@@ -83,18 +108,28 @@ const MessageCopyControl = ({
   }, [defaultFormat]);
 
   useEffect(() => {
-    // Close the dropdown when clicking anywhere outside this control.
+    if (!isDropdownOpen) return;
+
+    // Close when clicking outside both the control and the portaled menu.
     const closeOnOutsideClick = (event: MouseEvent) => {
-      if (!isDropdownOpen) return;
       const target = event.target as Node;
-      if (dropdownRef.current && !dropdownRef.current.contains(target)) {
-        setIsDropdownOpen(false);
+      if (dropdownRef.current?.contains(target) || menuRef.current?.contains(target)) {
+        return;
       }
+      setIsDropdownOpen(false);
     };
 
+    // The menu is fixed-positioned; close it if the page scrolls so it can't
+    // detach from the trigger.
+    const closeOnScroll = () => setIsDropdownOpen(false);
+
     window.addEventListener('mousedown', closeOnOutsideClick);
+    window.addEventListener('scroll', closeOnScroll, true);
+    window.addEventListener('resize', closeOnScroll);
     return () => {
       window.removeEventListener('mousedown', closeOnOutsideClick);
+      window.removeEventListener('scroll', closeOnScroll, true);
+      window.removeEventListener('resize', closeOnScroll);
     };
   }, [isDropdownOpen]);
 
@@ -170,8 +205,9 @@ const MessageCopyControl = ({
       {canSelectCopyFormat && (
         <>
           <button
+            ref={triggerRef}
             type="button"
-            onClick={() => setIsDropdownOpen((prev) => !prev)}
+            onClick={() => (isDropdownOpen ? setIsDropdownOpen(false) : openDropdown())}
             className={`rounded px-1 py-0.5 transition-colors ${toneClass}`}
             aria-label={t('copyMessage.selectFormat', { defaultValue: 'Select copy format' })}
             title={t('copyMessage.selectFormat', { defaultValue: 'Select copy format' })}
@@ -186,8 +222,12 @@ const MessageCopyControl = ({
             </svg>
           </button>
 
-          {isDropdownOpen && (
-            <div className="absolute left-auto top-full z-30 mt-1 min-w-36 rounded-md border border-gray-200 bg-white p-1 shadow-lg dark:border-gray-700 dark:bg-gray-900">
+          {isDropdownOpen && createPortal(
+            <div
+              ref={menuRef}
+              style={menuStyle}
+              className="min-w-36 rounded-md border border-border bg-popover p-1 shadow-lg"
+            >
               {copyFormatOptions.map((option) => {
                 const isSelected = option.format === selectedFormat;
                 return (
@@ -196,15 +236,16 @@ const MessageCopyControl = ({
                     type="button"
                     onClick={() => handleFormatChange(option.format)}
                     className={`block w-full rounded px-2 py-1.5 text-left transition-colors ${isSelected
-                      ? 'bg-gray-100 text-gray-900 dark:bg-gray-800 dark:text-gray-100'
-                      : 'text-gray-700 hover:bg-gray-50 dark:text-gray-300 dark:hover:bg-gray-800/60'
+                      ? 'bg-accent text-foreground'
+                      : 'text-foreground hover:bg-accent'
                       }`}
                   >
                     <span className="block text-xs font-medium">{option.label}</span>
                   </button>
                 );
               })}
-            </div>
+            </div>,
+            document.body,
           )}
         </>
       )}