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A @MainActor class passes a closure to a protocol method. The closure fires on a task and the closure is called within the Task. Here is how @isolated(any) solves the problem of landing in the closure in a different context instead of the same context which created it!.

Every piece was correct - @StateObject, @Published, PreferenceKey - yet the view body never re-evaluated. Here is how a single utility function buried three layers deep silently killed our SwiftUI lifecycle.