Minecraft 1.26.50+ runs only with the mcpelauncher-updates mod, which asks
for the Google Play sign-in when the game starts. The engine looked for a
binary named mcpelauncher-ui-qt, which this app does not have, so the mod got
no credentials and the game crashed during startup.

- Engine patch: MCPELAUNCHER_UI_EXECUTABLE names the credentials helper; the
  launcher sets it to itself when it starts the game.
- The request window now has explicit Allow and Deny buttons, shows which mod
  is asking and for which account, and explains what to do when signed out
  instead of failing on a missing account.
- Play asks for Google sign-in first when not signed in (trial mode aside),
  including for versions installed by another launcher.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>