Packing

Compressed inputs

Symptom: decompress NSZ stops immediately with nsz: error: unrecognized arguments: --keys ….
Cause: nsz 4.6.1 has no --keys argument. It loads keys.txt beside sys.argv[0], or falls back to ~/.switch/prod.keys, while importing its modules, before parsing arguments (4.6.1 key loader). Newer upstream code supports --keys; staging keys.txt also supports 4.6.1.
Fix: scripts/build_ipa_from_nsp.py decompress_nsz links the file selected by -k as keys.txt in the conversion's temporary folder and runs nsz -D there, with sys.argv[0] set to nsz before import. Input and output paths are absolute. The temporary folder and link are removed on success or failure; the user's default keys are untouched.
Found on: Super Mario Odyssey, converting its v0 NSZ. Applies to NSZ and XCZ inputs for every game.

Symptom: clicking Prepare game stops before any build tools start, with PermissionError: [Errno 1] Operation not permitted at build_session.py os.setsid().
Cause: Foundation Process already launches the worker as its own process-group leader on macOS. POSIX rejects setsid() for a group leader. A normal Python subprocess launch did not expose this difference, so the original regression test missed the GUI path.
Fix: reuse the existing group when os.getpgrp() == os.getpid(); call setsid() only for a worker that still shares its parent's group. Cancellation still signals the worker's separate group. Do not suppress unrelated permission failures. Added regression coverage for Foundation Process, an existing group leader, an existing session leader and a normal subprocess launch, including cancellation.
Found on: a user's clean desktop installation, before game detection; reproduced locally with a Swift Foundation launcher. Applies to every Mac/iPhone game preparation, independent of the game, keys or saves. Released in 1.4.2/build 7.