Windows Dots: CUA MXC launcher fails with HRESULT 0x80070003 after direct shell recovery

Finding: In an external report on openai/codex issue 52407, a Windows 25H2 (build 26200.9457) Codex Desktop 26.1002.7124.0 install with bundled core 0.162.0-alpha.2 fails its first Computer Use call, cua.getState(), with an MXC launcher error (HRESULT 0x80070003) even though a direct shell command succeeded in the same turn. This is an external report only; KFA did not reproduce it. Source: https://github.com/openai/codex/issues/52407 Reported conditions: the session had windows.sandbox set to elevated, and adding features.prefer_mxc = true was the only change that restored shell execution, with elevated kept as fallback. The first CUA call then ended with the node_repl kernel exiting (exit code 1) and the message that the MXC launcher cannot locate a required Windows platform directory. The reporter says the direct command returned exit code 0 shortly before, verified by reading the chat via the official API. Earlier failures in the same environment, per the report: commands failed before PowerShell with an exec-server helper_unknown_error (setup refresh had errors), with diagnostics showing Windows OS error 32 while opening node_repl.exe for an ACL update. Restarting the app, rebuilding the generated runtime from the installed package and a successful elevated sandbox setup did not restore the executor. The reporter did not attempt manual registry, ACL, manifest or binary changes. Diagnosis status: the reporter points to public source at tag rust-v0.162.0-alpha.2 (codex-rs/mxc-sandbox/src/windows.rs) that queries known folders for Program Files, Program Files (x86) and ProgramData before native launch. The folders exist and queries succeed in the coordinator context, but the launcher's own token/environment was not captured and the error does not name the failing folder. The cause is therefore UNKNOWN; this is a hypothesis direction, not a confirmed cause. Status: the issue is open with labels including windows-os, sandbox and computer-use. No maintainer-confirmed cause, fix commit or released fix appears in the supplied data, and the 17 comments could not be retrieved, so maintainer activity is unseen. The reporter says the official updater found no eligible update. A separate session reportedly exposed only browser surfaces with native computer APIs disabled; whether that shares the cause is not established. A related turn/start AbsolutePathBuf error is explicitly not claimed to share this cause. Limitations: single-session report, not independently reproduced, no verified workaround for CUA. Treat the prefer_mxc setting as shell-only recovery evidence from one user, not as a fix.