Muse launcher-only installation reproduction
Surface: real web client, Chromium on Linux, 1280x800 CSS viewport, light theme, device scale factor 2.
Each side used a fresh isolated T3 home with T3CODE_DEV_SEED=0.
Screenshots are matching crops of the Providers status panel; host selector and binary path excluded.
Pixel difference between stability screenshots: 0 on each side (more than 500 ms apart).

Before commit 4e0b52806be83e66f80839e1e372398307346425
Launcher SHA256: c6db294799a190ca380da274beb3b9c0e160e0da9681a3d364ce8b0e5fa3a4bc
MUSE_NO_AUTO_UPDATE=1 muse --version:
{
  "exitCode": 1,
  "stdout": "",
  "stderr": "muse: installed binary is missing; rerun the installer\n"
}
Real server stored Muse status:
{
  "installed": true,
  "version": null,
  "status": "error",
  "auth": {
    "status": "unknown"
  },
  "message": "Muse Code CLI is installed but failed to run."
}

After commit b3a5b788d3f2b26a8812e07c6f2295654fc39da3
Launcher SHA256: c6db294799a190ca380da274beb3b9c0e160e0da9681a3d364ce8b0e5fa3a4bc
MUSE_NO_AUTO_UPDATE=1 muse --version:
{
  "exitCode": 1,
  "stdout": "",
  "stderr": "muse: installed binary is missing; rerun the installer\n"
}
Real server stored Muse status:
{
  "installed": true,
  "version": null,
  "status": "error",
  "auth": {
    "status": "unknown"
  },
  "message": "Muse Code has not finished installing. Run `muse --version` on this T3 server host, then refresh its status."
}

Not exercised: completing the real Muse runtime download or signing in; the fix supplies recovery instructions and leaves bootstrap manual.
The fix still reports unavailable until setup is completed; it does not expose raw stderr or an exit-code field.
AI-assisted; verified with the tests and tools listed above.