feat: add support for Codex agent

Adds Codex to the available agents in the ACP sidebar

Author: mscolnick

frontend/src/components/ai/ai-provider-icon.tsx

@@ -15,14 +15,15 @@ import type { ProviderId } from "@/core/ai/ids/ids";
 import { cn } from "@/utils/cn";
 import marimoIcon from "../../assets/icon-32x32.png?inline";
 
-type Aliases = "claude" | "gemini";
+type Aliases = "claude" | "gemini" | "codex";
 
 const icons: Record<ProviderId | Aliases, string> = {
   openai: OpenAIIcon,
   anthropic: AnthropicIcon,
   claude: AnthropicIcon,
   gemini: GeminiIcon,
   google: GeminiIcon,
+  codex: OpenAIIcon,
   ollama: OllamaIcon,
   azure: AzureIcon,
   bedrock: BedrockIcon,

frontend/src/components/chat/acp/agent-selector.tsx

@@ -42,6 +42,11 @@ const AVAILABLE_AGENTS = [
     displayName: "Gemini",
     iconId: "google",
   },
+  {
+    id: "codex",
+    displayName: "Codex",
+    iconId: "openai",
+  },
 ] as const;
 
 interface AgentMenuItemProps {

frontend/src/components/chat/acp/state.ts

@@ -11,7 +11,7 @@ import type { ExternalAgentSessionId, SessionSupportType } from "./types";
 
 // Types
 export type TabId = TypedString<"TabId">;
-export type ExternalAgentId = "claude" | "gemini";
+export type ExternalAgentId = "claude" | "gemini" | "codex";
 
 // No agents support loading sessions, so we limit to 1, otherwise
 // this is confusing to the user when switching between sessions
@@ -220,7 +220,7 @@ export function getSessionsByAgent(
 }
 
 export function getAllAgentIds(): ExternalAgentId[] {
-  return ["claude", "gemini"];
+  return ["claude", "gemini", "codex"];
 }
 
 export function getAgentDisplayName(agentId: ExternalAgentId): string {
@@ -251,6 +251,12 @@ const AGENT_CONFIG: Record<ExternalAgentId, AgentConfig> = {
     webSocketUrl: "ws://localhost:3019/message",
     sessionSupport: "single",
   },
+  codex: {
+    port: 3021,
+    command: "npx @zed-industries/codex-acp",
+    webSocketUrl: "ws://localhost:3021/message",
+    sessionSupport: "single",
+  },
 };
 
 export function getAgentSessionSupport(