Similar to previous Xcode issue (https://bugreports.qt.io/projects/QBS/issues/QBS-1786), Apple has changed the file again on macOS Tahoe / Xcode 26 so current code errors:

/Applications/Xcode.app/Contents/Developer/../SharedFrameworks/XCBuild.framework/PlugIns/XCBBuildService.bundle/Contents/PlugIns/XCBSpecifications.ideplugin/Contents/Resources/MacOSX Architectures.xcspec: No such file or directory

This time they renamed "MacOSX Architectures.xcspec" to "macOSArchitectures.xcspec".

See https://github.com/swiftlang/swift-build/commit/921cbbc5886e3f3ec14ace1fb91cff6bfbc1ec43 (part of Swift 6.2 release included in Xcode 26)

Locally modifying code for above issue, I hit another error:

BundleModule.qbs:234:15 Bundle product type com.apple.product-type.application is not supported. You may need to upgrade Xcode.