Worked on the tailscale/tailscale repository to enhance the stability of user authentication by addressing a critical issue in the auto-login flow. Focused on backend development using Go, the work involved fixing a bug that previously caused loss of login flags and session-specific properties during auto-login. The solution merged login flags at key call sites and ensured properties like LoginEphemeral persisted by storing them at construction in LocalBackend. Comprehensive regression tests were added to validate the new behavior and safeguard against future regressions. This approach aligned auto-login with interactive login semantics, resulting in a more reliable authentication experience for users.