WIP: Codex MCP investigation - config writing but not working

[mistercrunch]

Status: Work in Progress / Reference Only ⚠️

This PR documents investigation and attempted fixes for Codex MCP support. MCP still does not work with Codex even after these changes. Keeping as reference for future work.

Summary

Attempted to enable MCP server support for Codex by writing MCP configuration to ~/.codex/config.toml. The config is written correctly but Codex still doesn't see or use MCP servers, even in the raw CLI.

What's in This Branch

1. STDIO Bridge Script (Previous Work)

• Created scripts/agor-mcp-stdio-bridge.js for HTTP-to-STDIO translation
• Allows STDIO-only clients (like Codex) to connect to HTTP MCP endpoints
• Not currently used due to other blocking issues

2. Playwright MCP Installation (Previous Work)

• Added @playwright/mcp@latest to Docker container
• Created as global MCP server in database
• Auto-attached to new Codex sessions

3. Config Writing Logic (Latest Commits)

First attempt: Tried writing to both worktree-local and global config

• Reverted: Investigation confirmed Codex does NOT support repo-local .codex/config.toml
• Codex documentation only mentions ~/.codex/config.toml
• No mention of project-local, repo-local, or CWD-relative configs

Current approach: Write only to global ~/.codex/config.toml

• Verified this is the only documented config location
• Added detailed logging to debug config writing
• Config IS being written correctly with proper TOML format

Investigation Findings

Config File Location ✅

• ✅ Codex ONLY supports ~/.codex/config.toml (confirmed from docs)
• ❌ Does NOT support repo-local .codex/config.toml (no documentation)
• ❌ CODEX_HOME environment variable not tested/confirmed

Config Writing ✅

From Docker logs:

📝 [Codex MCP] Writing config to: /home/agor/.codex/config.toml
   Found existing config with 0 Agor-managed server(s)
   📝 [Codex MCP] Configuring server: Playwright Browser Automation -> playwright_browser_automation
      command: npx
      args: ["-y","@playwright/mcp@latest"]
✅ [Codex MCP] Updated global config with 1 managed MCP server(s)
   Config written to: /home/agor/.codex/config.toml
🔄 [Codex] Reinitializing SDK to pick up config changes...
✅ [Codex] SDK reinitialized

Config file contains:

# Codex configuration
# Generated by Agor - 2025-11-12T...

approval_policy = "on-request"

[mcp_servers.playwright_browser_automation]
transport = "stdio"
command = "npx"
args = ["-y", "@playwright/mcp@latest"]

agor_managed_servers = ["playwright_browser_automation"]

Still Not Working ❌

Even with correct config, Codex doesn't see MCP servers:

• Config file is valid TOML and in correct location
• Raw codex CLI also doesn't show MCP resources
• SDK reinitializes but servers not visible
• No errors in logs about config parsing

Possible causes:

1. SDK bug or version incompatibility
2. MCP servers need additional initialization
3. Missing environment variables or setup
4. Codex SDK caches config differently than expected
5. The @playwright/mcp package itself has issues

Thread-Level MCP Locking ✅ (Documented Limitation)

Existing Codex threads lock in MCP config at creation time. This is a known Codex SDK limitation. New sessions correctly get MCP servers attached, but existing sessions can't pick up newly added servers.

Agor handles this correctly with warnings in logs.

What Works

• ✅ MCP server management (CRUD operations)
• ✅ Auto-attaching MCP servers to new Codex sessions
• ✅ Writing TOML config to ~/.codex/config.toml
• ✅ SDK reinitialization on config changes
• ✅ Proper config format (validated manually)
• ✅ Logging and debugging output

What Doesn't Work

• ❌ Codex actually seeing/using MCP servers
• ❌ MCP resources appearing in codex CLI
• ❌ MCP tools available during Codex execution
• ❌ Any evidence that Codex reads the config we write

Files Changed

• packages/core/src/tools/codex/prompt-service.ts - Config writing logic (simplified to global only)
• scripts/agor-mcp-stdio-bridge.js - HTTP-to-STDIO bridge (created earlier, unused)
• Dockerfile.dev - Playwright MCP installation (created earlier)

Next Steps for Investigation

1. Test with different MCP servers - Try simpler servers besides Playwright
2. Verify Codex version - Check if using latest SDK with MCP support
3. Manual config test - Write config manually and test raw codex CLI
4. Check Codex logs - Look for MCP-related errors in Codex's own logs
5. Contact OpenAI - May need to report SDK issue or get clarification
6. Try CODEX_HOME - Test if setting env var per-session helps

Commits

1. 2978620 - Initial fix: write to worktree-local config (incorrect assumption)
2. 64a9dd2 - Revert to global config only (correct approach)

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🤖 Generated with Claude Code