feat: add Codex local provider integration for desktop

__mocks__/workos.ts

@@ -5,3 +5,9 @@ export const useAuth = () => ({
   signIn: jest.fn(),
   signOut: jest.fn(),
 });
+
+export const useAccessToken = () => ({
+  getAccessToken: jest.fn().mockResolvedValue("mock-access-token"),
+  accessToken: "mock-access-token",
+  refresh: jest.fn().mockResolvedValue("mock-access-token"),
+});

app/components/ChatInput/ChatInput.tsx

@@ -14,6 +14,7 @@ import {
   type RateLimitWarningData,
 } from "../RateLimitWarning";
 import { isAgentMode } from "@/lib/utils/mode-helpers";
+import { isCodexLocal } from "@/types/chat";
 import { NULL_THREAD_DRAFT_ID } from "@/lib/utils/client-storage";
 import { SandboxSelector } from "../SandboxSelector";
 import { ChatInputTextarea } from "./ChatInputTextarea";
@@ -72,6 +73,7 @@ export const ChatInput = ({
     setQueueBehavior,
     sandboxPreference,
     setSandboxPreference,
+    selectedModel,
     subscription,
     isCheckingProPlan,
     temporaryChatsEnabled,
@@ -149,15 +151,19 @@ export const ChatInput = ({
         )}
 
         {/* Sandbox selector for new chats on mobile: shown above input & file upload.
-            On desktop, it's shown below the input (order-3). */}
-        {isMobile && isNewChat && isAgentMode(chatMode) && (
-          <div className="flex px-1 pb-2 min-h-9">
-            <SandboxSelector
-              value={sandboxPreference}
-              onChange={setSandboxPreference}
-            />
-          </div>
-        )}
+            On desktop, it's shown below the input (order-3).
+            Hidden when Codex is selected (it manages its own sandbox). */}
+        {isMobile &&
+          isNewChat &&
+          isAgentMode(chatMode) &&
+          !isCodexLocal(selectedModel) && (
+            <div className="flex px-1 pb-2 min-h-9">
+              <SandboxSelector
+                value={sandboxPreference}
+                onChange={setSandboxPreference}
+              />
+            </div>
+          )}
 
         {uploadedFiles && uploadedFiles.length > 0 && (
           <FileUploadPreview
@@ -198,28 +204,32 @@ export const ChatInput = ({
             chatMode={chatMode}
             contextUsage={contextUsage}
             showContextIndicator={showContextIndicator}
+            hasMessages={hasMessages}
           />
         </div>
 
         {/* Sandbox selector below input.
             Desktop new chats: absolutely positioned to avoid shifting the centered layout.
             Existing chats (all screens): normal flow.
-            Mobile new chats: hidden (uses above-input placement). */}
-        {isAgentMode(chatMode) && (!isMobile || !isNewChat) && (
-          <div
-            className={`order-3 flex items-center px-1 pt-2 ${isNewChat ? "absolute left-4 right-4 top-full" : ""}`}
-          >
-            <SandboxSelector
-              value={sandboxPreference}
-              onChange={setSandboxPreference}
-            />
-            {showContextIndicator && contextUsage && (
-              <div className="ml-auto">
-                <ContextUsageIndicator {...contextUsage} />
-              </div>
-            )}
-          </div>
-        )}
+            Mobile new chats: hidden (uses above-input placement).
+            Hidden when Codex is selected (it manages its own sandbox). */}
+        {isAgentMode(chatMode) &&
+          (!isMobile || !isNewChat) &&
+          !isCodexLocal(selectedModel) && (
+            <div
+              className={`order-3 flex items-center px-1 pt-2 ${isNewChat ? "absolute left-4 right-4 top-full" : ""}`}
+            >
+              <SandboxSelector
+                value={sandboxPreference}
+                onChange={setSandboxPreference}
+              />
+              {showContextIndicator && contextUsage && (
+                <div className="ml-auto">
+                  <ContextUsageIndicator {...contextUsage} />
+                </div>
+              )}
+            </div>
+          )}
 
         {onScrollToBottom && (
           <div className="absolute -top-16 left-1/2 -translate-x-1/2 z-40">

app/components/ChatInput/ChatInputToolbar.tsx

@@ -12,37 +12,42 @@ import {
   type ContextUsageData,
 } from "@/app/components/ContextUsageIndicator";
 import { useGlobalState } from "@/app/contexts/GlobalState";
+import { isCodexLocal } from "@/types/chat";
 
 export interface ChatInputToolbarProps extends SubmitStopButtonProps {
   onAttachClick: () => void;
   contextUsage?: ContextUsageData;
   showContextIndicator?: boolean;
+  hasMessages?: boolean;
 }
 
 export function ChatInputToolbar({
   onAttachClick,
   contextUsage,
   showContextIndicator = false,
   chatMode,
+  hasMessages = false,
   ...submitStopProps
 }: ChatInputToolbarProps) {
   const { selectedModel, setSelectedModel } = useGlobalState();
 
+  // Lock switching away from Codex mid-conversation (but allow sub-model changes)
+  const modelLocked = isCodexLocal(selectedModel) && hasMessages;
+
   return (
     <div className="px-3 flex gap-2 items-center min-w-0">
       <div className="shrink-0">
         <AttachmentButton onAttachClick={onAttachClick} />
       </div>
       <ChatModeSelector />
-      {chatMode === "ask" && (
-        <ModelSelector
-          value={selectedModel}
-          onChange={setSelectedModel}
-          mode={chatMode}
-        />
-      )}
+      <ModelSelector
+        value={selectedModel}
+        onChange={setSelectedModel}
+        mode={chatMode}
+        locked={modelLocked}
+      />
       <div className="ml-auto shrink-0 flex items-center gap-2.5">
-        {showContextIndicator && contextUsage && chatMode !== "agent" && (
+        {showContextIndicator && contextUsage && (
           <ContextUsageIndicator {...contextUsage} />
         )}
         <SubmitStopButton

app/components/DiffView.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import React, { useState } from "react";
+import React, { useState, useRef, useEffect } from "react";
 import { DiffEditor } from "@monaco-editor/react";
 import { ComputerCodeBlock } from "./ComputerCodeBlock";
 
@@ -20,6 +20,23 @@ export const DiffView: React.FC<DiffViewProps> = ({
   wrap = true,
 }) => {
   const [viewMode, setViewMode] = useState<ViewMode>("diff");
+  const editorRef = useRef<any>(null);
+
+  // Safely dispose editor on unmount to prevent "TextModel got disposed" errors
+  useEffect(() => {
+    return () => {
+      try {
+        editorRef.current?.dispose();
+      } catch {
+        // Ignore disposal errors
+      }
+      editorRef.current = null;
+    };
+  }, []);
+
+  const handleEditorMount = (editor: any) => {
+    editorRef.current = editor;
+  };
 
   const tabs: Array<{ id: ViewMode; label: string }> = [
     { id: "diff", label: "Diff" },
@@ -99,6 +116,7 @@ export const DiffView: React.FC<DiffViewProps> = ({
               modified={modifiedContent}
               language={getMonacoLanguage(language)}
               theme="vs-dark"
+              onMount={handleEditorMount}
               options={{
                 readOnly: true,
                 renderSideBySide: false,

app/components/MessagePartHandler.tsx

@@ -11,6 +11,7 @@ import { MemoryToolHandler } from "./tools/MemoryToolHandler";
 import { NotesToolHandler } from "./tools/NotesToolHandler";
 import { GetTerminalFilesHandler } from "./tools/GetTerminalFilesHandler";
 import { SummarizationHandler } from "./tools/SummarizationHandler";
+import { CodexToolHandler } from "./tools/CodexToolHandler";
 import type { ChatStatus } from "@/types";
 import type { FileDetails } from "@/types/file";
 import { ReasoningHandler } from "./ReasoningHandler";
@@ -215,6 +216,13 @@ export const MessagePartHandler = memo(function MessagePartHandler({
       );
 
     default:
+      // Generic Codex tool handler — matches any tool-codex_* type
+      if (
+        typeof part.type === "string" &&
+        part.type.startsWith("tool-codex_")
+      ) {
+        return <CodexToolHandler part={part} status={status} />;
+      }
       return null;
   }
 }, arePropsEqual);