RoyalVNCKit prioritizes .diffieHellman (ARD) over .vnc during handshake when
both are offered. My delegate adapter was passing an empty username to
VNCUsernamePasswordCredential, so any Mac with user-account screen sharing
enabled rejected the credential before .vnc fallback could happen.
Fix: persist a username on SavedConnection and pipe it through to the
credential callback. Leave blank to use the VNC-only password path.
AddConnection footer now explains the two Mac paths:
• User account (ARD) — macOS short name + full account password
• VNC-only password — blank username + ≤8 char password
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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