From c2c938f10250a47d78ceac6c50e03f68eaa320ce Mon Sep 17 00:00:00 2001
From: Kirill Dubovitskiy <kirill2003de@gmail.com>
Date: Thu, 9 Oct 2025 20:05:07 -0700
Subject: [PATCH] fix: auto-detect codex version and use correct MCP command
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Fixes compatibility issues with codex versions 0.43.0-alpha.5 and later
which introduced the new 'mcp-server' subcommand.

The code now:
- Detects the installed codex version at runtime
- Uses 'mcp-server' for versions >= 0.43.0-alpha.5
- Falls back to 'mcp' for older versions
- Defaults to 'mcp-server' if version detection fails

This resolves MCP connection errors when using newer codex versions.

Fixes #39

🤖 Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>
---
 src/codex/codexMcpClient.ts | 36 ++++++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/src/codex/codexMcpClient.ts b/src/codex/codexMcpClient.ts
index 68bd7eb7..8a8c334d 100644
--- a/src/codex/codexMcpClient.ts
+++ b/src/codex/codexMcpClient.ts
@@ -9,9 +9,40 @@ import type { CodexSessionConfig, CodexToolResponse } from './types';
 import { z } from 'zod';
 import { ElicitRequestSchema } from '@modelcontextprotocol/sdk/types.js';
 import { CodexPermissionHandler } from './utils/permissionHandler';
+import { execSync } from 'child_process';
 
 const DEFAULT_TIMEOUT = 14 * 24 * 60 * 60 * 1000; // 14 days, which is the half of the maximum possible timeout (~28 days for int32 value in NodeJS)
 
+/**
+ * Get the correct MCP subcommand based on installed codex version
+ * Versions >= 0.43.0-alpha.5 use 'mcp-server', older versions use 'mcp'
+ */
+function getCodexMcpCommand(): string {
+    try {
+        const version = execSync('codex --version', { encoding: 'utf8' }).trim();
+        const match = version.match(/codex-cli\s+(\d+\.\d+\.\d+(?:-alpha\.\d+)?)/);
+        if (!match) return 'mcp-server'; // Default to newer command if we can't parse
+
+        const versionStr = match[1];
+        const [major, minor, patch] = versionStr.split(/[-.]/).map(Number);
+
+        // Version >= 0.43.0-alpha.5 has mcp-server
+        if (major > 0 || minor > 43) return 'mcp-server';
+        if (minor === 43 && patch === 0) {
+            // Check for alpha version
+            if (versionStr.includes('-alpha.')) {
+                const alphaNum = parseInt(versionStr.split('-alpha.')[1]);
+                return alphaNum >= 5 ? 'mcp-server' : 'mcp';
+            }
+            return 'mcp-server'; // 0.43.0 stable has mcp-server
+        }
+        return 'mcp'; // Older versions use mcp
+    } catch (error) {
+        logger.debug('[CodexMCP] Error detecting codex version, defaulting to mcp-server:', error);
+        return 'mcp-server'; // Default to newer command
+    }
+}
+
 export class CodexMcpClient {
     private client: Client;
     private transport: StdioClientTransport | null = null;
@@ -53,11 +84,12 @@ export class CodexMcpClient {
     async connect(): Promise<void> {
         if (this.connected) return;
 
-        logger.debug('[CodexMCP] Connecting to Codex MCP server...');
+        const mcpCommand = getCodexMcpCommand();
+        logger.debug(`[CodexMCP] Connecting to Codex MCP server using command: codex ${mcpCommand}`);
 
         this.transport = new StdioClientTransport({
             command: 'codex',
-            args: ['mcp']
+            args: [mcpCommand]
         });
 
         // Register request handlers for Codex permission methods