Pure diff functions between item snapshots. No UI types involved.

One minimal mutation to apply to an items collection. Indices refer to the collection state at the moment the change applies.

C#-friendly wrappers around the collection bindings. The overloads that take F# lists upcast each snapshot internally, so model lists bind without a manual conversion. Like the F# extensions, they return the control for chaining and need no disposal.

Keys that appear more than once on one side of a keyed diff.