[overwrite00]

Summary

On macOS a locked Keychain can wait forever for a graphical confirmation, which hung the first use of the encrypted local key (seen as a stuck macOS job in the beta build).

• The system keyring is probed with a 3 s limit before it is used; if it does not answer, the key file is used instead. Later keyring calls also have a time limit.
• NULLIFYPDF_DISABLE_KEYRING=1 disables the keyring; the test suite sets it so tests never reach a real Keychain.
• Tests with a keyring that never answers and with the environment switch.

Testing

• pytest tests/: 338 passed locally
• Full workflow on Windows, macOS and Linux (including package builds and installation tests): all green