forceCancellable.swift

func forceCancellable<R>(isolation: isolated (any Actor)? = #isolation, _ body: @escaping () async throws -> R) async throws -> R {    
    let (stream, continuation) = AsyncThrowingStream.makeStream(
        of: R.self, 
        throwing: Error.self, 
        bufferingPolicy: .bufferingOldest(1)
    )

    let task = Task {
        do {
            let result = try await body()
            continuation.yield(result)
        } catch {
            continuation.yield(with: .failure(error))
        }
    }

    return try await withTaskCancellationHandler(operation: {
        for try await value in stream {
            return value
        }
        throw CancellationError()
    }, onCancel: {
        task.cancel()
    }, isolation: isolation)
}