diff --git a/src/index.ts b/src/index.ts
index 0496b2ca..52fe3e66 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -9,41 +9,56 @@ import {CodexAcpClient} from "./CodexAcpClient";
 import {CodexAppServerClient} from "./CodexAppServerClient";
 import packageJson from "../package.json";
 import {logger} from "./Logger";
+import {runLoginCommand} from "./login";
 
 if (process.argv.includes("--version")) {
     console.log(`${packageJson.name} ${packageJson.version}`);
     process.exit(0);
 }
 
-const codexPath = process.env["CODEX_PATH"] ?? "codex";
-const configString = process.env["CODEX_CONFIG"];
-const authRequestString = process.env["DEFAULT_AUTH_REQUEST"];
-const modelProvider = process.env["MODEL_PROVIDER"];
-const config = configString ? JSON.parse(configString) : undefined;
-const parsedAuthRequest = authRequestString ? JSON.parse(authRequestString) : undefined;
-const defaultAuthRequest = parsedAuthRequest && isCodexAuthRequest(parsedAuthRequest) ? parsedAuthRequest : undefined;
-
-logger.log("Startup", {
-    name: packageJson.name,
-    version: packageJson.version,
-    codexPath: codexPath,
-    modelProvider: modelProvider ?? null,
-    codexConfig: config ?? null,
-    authRequest: authRequestString ?? null,
-    defaultAuthRequest: defaultAuthRequest ?? null,
-});
-
-const codexConnection = startCodexConnection(codexPath);
-process.stdin.on("close", (chunk: Buffer) => {
-    codexConnection.process.stdin.end();
-});
-
-const acpJsonStream = createJsonStream(process.stdin, process.stdout);
-
-function createAgent(connection: acp.AgentSideConnection): CodexAcpServer {
-    const appServerClient = new CodexAppServerClient(codexConnection.connection);
-    const codexClient = new CodexAcpClient(appServerClient, config, modelProvider);
-    return new CodexAcpServer(connection, codexClient, defaultAuthRequest, () => codexConnection.process.exitCode);
+if (process.argv[2] === "login") {
+    const args = process.argv.slice(3);
+    runLoginCommand(args)
+        .then((success) => process.exit(success ? 0 : 1))
+        .catch((error) => {
+            console.error("Login error:", error.message);
+            process.exit(1);
+        });
+} else {
+    startAcpServer();
 }
 
-new acp.AgentSideConnection(createAgent, acpJsonStream);
\ No newline at end of file
+function startAcpServer() {
+    const codexPath = process.env["CODEX_PATH"] ?? "codex";
+    const configString = process.env["CODEX_CONFIG"];
+    const authRequestString = process.env["DEFAULT_AUTH_REQUEST"];
+    const modelProvider = process.env["MODEL_PROVIDER"];
+    const config = configString ? JSON.parse(configString) : undefined;
+    const parsedAuthRequest = authRequestString ? JSON.parse(authRequestString) : undefined;
+    const defaultAuthRequest = parsedAuthRequest && isCodexAuthRequest(parsedAuthRequest) ? parsedAuthRequest : undefined;
+
+    logger.log("Startup", {
+        name: packageJson.name,
+        version: packageJson.version,
+        codexPath: codexPath,
+        modelProvider: modelProvider ?? null,
+        codexConfig: config ?? null,
+        authRequest: authRequestString ?? null,
+        defaultAuthRequest: defaultAuthRequest ?? null,
+    });
+
+    const codexConnection = startCodexConnection(codexPath);
+    process.stdin.on("close", (chunk: Buffer) => {
+        codexConnection.process.stdin.end();
+    });
+
+    const acpJsonStream = createJsonStream(process.stdin, process.stdout);
+
+    function createAgent(connection: acp.AgentSideConnection): CodexAcpServer {
+        const appServerClient = new CodexAppServerClient(codexConnection.connection);
+        const codexClient = new CodexAcpClient(appServerClient, config, modelProvider);
+        return new CodexAcpServer(connection, codexClient, defaultAuthRequest, () => codexConnection.process.exitCode);
+    }
+
+    new acp.AgentSideConnection(createAgent, acpJsonStream);
+}
\ No newline at end of file
diff --git a/src/login.ts b/src/login.ts
new file mode 100644
index 00000000..1e9a026d
--- /dev/null
+++ b/src/login.ts
@@ -0,0 +1,132 @@
+import {startCodexConnection} from "./CodexJsonRpcConnection";
+import {CodexAppServerClient} from "./CodexAppServerClient";
+import type {ClientInfo} from "./app-server";
+import open from "open";
+import packageJson from "../package.json";
+import {logger} from "./Logger";
+
+interface LoginOptions {
+    clientName?: string;
+    clientTitle?: string;
+    clientVersion?: string;
+}
+
+function parseArgs(args: string[]): LoginOptions | null {
+    const options: LoginOptions = {};
+
+    for (let i = 0; i < args.length; i++) {
+        const arg = args[i]!;
+
+        if (arg === "--help" || arg === "-h") {
+            printHelp();
+            return null;
+        }
+
+        if (arg === "--client-name" && i + 1 < args.length) {
+            options.clientName = args[++i]!;
+        } else if (arg.startsWith("--client-name=")) {
+            options.clientName = arg.slice("--client-name=".length);
+        }
+
+        if (arg === "--client-title" && i + 1 < args.length) {
+            options.clientTitle = args[++i]!;
+        } else if (arg.startsWith("--client-title=")) {
+            options.clientTitle = arg.slice("--client-title=".length);
+        }
+
+        if (arg === "--client-version" && i + 1 < args.length) {
+            options.clientVersion = args[++i]!;
+        } else if (arg.startsWith("--client-version=")) {
+            options.clientVersion = arg.slice("--client-version=".length);
+        }
+    }
+
+    return options;
+}
+
+function printHelp() {
+    console.log(`
+codex-acp login - Initialize and login to Codex with client context
+
+Usage:
+  codex-acp login [options]
+
+Options:
+  --client-name <name>       Client application name (default: "codex-acp")
+  --client-title <title>     Client application title (default: "Codex ACP")
+  --client-version <version> Client application version (default: "${packageJson.version}")
+  --help, -h                 Show this help message
+
+Example:
+  codex-acp login --client-name="AIA Plugin" --client-title="AI Assistant" --client-version="1.0.0"
+`);
+}
+
+async function login(options: LoginOptions): Promise<boolean> {
+    const codexPath = process.env["CODEX_PATH"] ?? "codex";
+
+    logger.log("Starting Codex connection...");
+    const codexConnection = startCodexConnection(codexPath);
+
+    const appServerClient = new CodexAppServerClient(codexConnection.connection);
+
+    try {
+        const clientInfo: ClientInfo = {
+            name: options.clientName ?? "codex-acp",
+            title: options.clientTitle ?? "Codex ACP",
+            version: options.clientVersion ?? packageJson.version,
+        };
+
+        logger.log("Initializing with client", {name: clientInfo.name, version: clientInfo.version});
+        await appServerClient.initialize({clientInfo});
+
+        const accountStatus = await appServerClient.accountRead({refreshToken: false});
+        if (accountStatus.account) {
+            logger.log("Already logged in", {accountType: accountStatus.account.type});
+            if (accountStatus.account.type === "chatgpt") {
+                return true;
+            }
+        }
+
+        logger.log("Starting ChatGPT login...");
+        const loginResponse = await appServerClient.accountLogin({type: "chatgpt"});
+
+        if (loginResponse.type === "chatgpt") {
+            logger.log("Opening browser for authentication...", {authUrl: loginResponse.authUrl});
+            await open(loginResponse.authUrl);
+        } else {
+            logger.error("Unexpected login response type", new Error(`Expected 'chatgpt', got '${loginResponse.type}'`));
+            return false;
+        }
+
+        logger.log("Waiting for login completion...");
+        const result = await appServerClient.awaitLoginCompleted();
+
+        if (result.success) {
+            logger.log("Login successful!");
+            return true;
+        } else {
+            logger.error("Login failed", new Error("Login was not successful"));
+            return false;
+        }
+    } finally {
+        codexConnection.connection.dispose();
+        codexConnection.process.kill();
+    }
+}
+
+/**
+ * Run the login command with the given CLI arguments.
+ * @param args CLI arguments after "login" command (e.g., ["--client-name", "AIA"])
+ * @returns true if login succeeded, false otherwise
+ */
+export async function runLoginCommand(args: string[]): Promise<boolean> {
+    const options = parseArgs(args);
+
+    // null means help or version was shown, exit successfully
+    if (options === null) {
+        return true;
+    }
+
+    return login(options);
+}