Thanks for the contribution! The core idea — testing the connection on Save — is good. A few things need to be addressed before this can merge:

Bug: Dashboard XAML missing RowDefinition

StatusText is placed at Grid.Row="2" and the buttons moved to Grid.Row="3", but the Grid only defines 3 rows (0-2). WPF won't crash but elements will overlap. Add a 4th RowDefinition Height="Auto" for the new StatusText row.

IsEnabled on ServerConnection — add the UI or remove the property

The IsEnabled property is added to the Dashboard model but there's no checkbox in the XAML to set it. It's dead code that will serialize to JSON but never be consumed. Either add the "Enable data collection" checkbox to the Dashboard dialog (like Lite has) or remove this property from the PR.

Dashboard should support Entra MFA authentication

If the goal is parity, Dashboard is still missing Entra MFA as an auth option. Dashboard can connect to Azure Managed Instance, which supports Entra MFA. Lite already has this — Dashboard should too.

Failure feedback should use MessageBox, not inline StatusText

Failures should be loud and obvious (MessageBox), not rely on inline text that the user might miss. The Dashboard side does this correctly (MessageBox on failure), but the Lite side was changed to use inline StatusText for save failures — keep it as a MessageBox.

Keep SELECT @@VERSION in the connection test

The PR removes the SELECT @@VERSION test query from Lite's test handler. That query confirmed the connection was fully functional and showed the server version — useful feedback. Please keep it.

Connection string should be built the same way

Dashboard uses DatabaseService.BuildConnectionString() while Lite builds a SqlConnectionStringBuilder directly. These should use the same approach for consistency and to avoid drift.

Duplicate review — please disregard. See the other review for feedback.

Solid contribution — all first-round review items addressed. Code quality is good and backward compatibility is handled correctly.

Highlights:

• Clean UseWindowsAuth → AuthenticationType migration shim for old servers.json files
• MFA cancellation handling prevents nagging popup loops during background checks
• Good refactoring: BuildConnectionBuilder(), ValidateInputs(), RunConnectionTestAsync() consolidate duplicated logic
• Smart Save behavior distinction: Dashboard offers "save anyway?" on failure, Lite blocks save when collection is enabled (correct since Lite collects immediately)

Minor notes (not blockers):

• ConnectTimeout is 10s in dialog test vs 15s at runtime in GetConnectionString() — fine but worth knowing
• MFA connection builder logic exists in both AddServerDialog.BuildConnectionBuilder() and ServerConnection.GetConnectionString() — could drift over time, but acceptable for now

Ready to merge. Thanks @ClaudioESSilva!