Yes it’s actually intended. The contract constraint are specified at design-time and thus not meant to be modified at runtime.
The goal here is to validate that the input are valid from a semantic point of view. Then the task resolution will drive the more complex business logic that can depends from runtime information and/or external systems.
That seems a rather poor design choice. What (for example) if you want to validate that an ordered item is in stock, or an unknown post/zip code has been entered? It would be good to be able to detect and report the issue without moving away from the page at the point “submit” is clicked - giving the user the chance to correct the input rather than spawning a new task. I would have thought that was good “SPA” design.
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