Windows Computer Use backend works, but computer tool is not exposed to model

What happened?

On Windows Codex Desktop, Computer Use appears enabled and the native backend is alive, but the model never receives a computer tool in the Responses API tool list.

From the user experience, Computer Use is unavailable / not usable. Typing @Computer or asking the model to use the computer does not expose a native Computer Use tool.

Evidence

• Codex Desktop feature flags include ComputerUse in logs.
• codex-computer-use.exe exists under the bundled cua_node runtime.
• The named pipe exists, e.g. \\.\pipe\codex-computer-use-....
• Directly importing and using @oai/sky from the bundled Node REPL succeeds for read-only backend calls:

const { sky } = await import('@oai/sky');
await sky.list_apps();

This successfully returned a list of installed/running apps, so the Windows backend is not completely dead.

However, parsing the actual /responses request payload sent by Codex Desktop shows the model receives tools such as shell_command, apply_patch, codex_app, tool_search, etc., but no computer / Computer Use tool:

tool_count: 14
0: type='function' name='shell_command'
...
11: type='namespace' name='codex_app'
12: type='tool_search'
13: type='web_search'
has_computer_type: False

Additional observation

Trying to work around this by calling @oai/sky through node_repl is not a reliable replacement for the native tool. Some calls work, such as list_apps() / list_windows(), but app launching or manipulation can fail with:

Computer Use requires app approval but elicitations are unavailable

So the native backend can be partially reached, but the normal model-facing Computer Use tool is not available.

Expected behavior

If Computer Use is installed/enabled and the backend is reachable, Codex Desktop should include a model-facing Computer Use tool in the Responses API request so the model can use it normally.

Environment

• OS: Windows 11
• Codex Desktop: 26.609.30741 / Windows package 26.609.3341.0 observed in process path
• Model: gpt-5.5
• Provider: custom Responses-compatible proxy
• Runtime: bundled cua_node runtime with @oai/sky

Related symptoms

This looks similar to other Windows reports where Browser/Chrome/Computer Use features are enabled or the backend becomes ready, but the model-facing tool is not exposed in the current thread.