[macOS Desktop] Enabled plugin skill is injected but its stdio MCP tools are absent after full restart

What version of Codex CLI is running?

0.147.0-alpha.6.5

What model / provider were you using?

Default OpenAI GPT model (not a custom provider).

What platform are you using?

macOS, Codex Desktop.

What issue are you seeing?

A Git marketplace plugin is enabled and its skill is injected into a newly created Desktop task, but the stdio MCP server declared by that same plugin is not exposed in the task's tool inventory.

Concrete reproduction: Cowart 0.1.25 from zhongerxin/Cowart.

The skill cowart-open-canvas is available and instructs the agent to call render_cowart_canvas_widget. The plugin manifest correctly declares .mcp.json, which defines a cowart_mcp stdio server. However, the current task has no callable cowart_mcp / render_cowart_canvas_widget tool, so the native canvas cannot open.

This survives fully quitting Codex Desktop, reopening it, and creating a brand-new task twice. The plugin/cache is current, enabled, and points at the latest upstream commit.

Environment / evidence

• Plugin: cowart@cowart-github, enabled = true
• Marketplace: https://github.com/zhongerxin/Cowart.git, ref main
• Cowart version: 0.1.25
• Installed commit: 6a338f016dee21fd97346c5fd8fe1bd81b1a7522; matches origin/main
• Cowart skill is visible in the task environment.
• The expected MCP tool is absent from the task environment/tool discovery.
• The plugin's MCP probe can launch the server and enumerate/reach its core tools outside the Desktop task surface. A later probe assertion that writes a sample download to ~/Downloads fails under this sandboxed diagnostic environment, but that is unrelated to the missing-tool symptom.
• Active provider is OpenAI, ruling out the custom Responses-provider unsupported call issue.

Steps to reproduce

1. Register zhongerxin/Cowart as a Git marketplace and install/enable cowart@cowart-github.
2. Fully quit Codex Desktop.
3. Reopen Codex Desktop and create a new task.
4. Ask: Open the Cowart canvas for this project.
5. Observe that the skill is injected, but the task does not expose mcp__cowart_mcp__render_cowart_canvas_widget (or any Cowart MCP tool).

Expected behavior

When a plugin skill is loaded into a new Desktop task, its declared stdio MCP server should be started/discovered and its tools should be available in that task (or dynamically discoverable).

Actual behavior

Skills and MCP tool exposure are inconsistent: the skill is available, while the associated server tools are missing even after the documented restart/new-task recovery flow.

Related issues

• https://github.com/openai/codex/issues/19425 — custom stdio MCP tools discovered but not exposed to Desktop threads
• https://github.com/openai/codex/issues/32636 — plugin replacement can leave stale skill/tool inventories
• Cowart-specific report: https://github.com/zhongerxin/Cowart/issues/56

Start with the plugin manifest's .mcp.json and the new Desktop task creation flow. Compare how the Cowart skill is injected with how its stdio MCP server is started and added to the task tool inventory, using the provided reproduction steps and related issues as context. Done means the declared server and render_cowart_canvas_widget are available after a full restart and new task.