Should passthrough parts allow EVA?

[JonnyOThan]

A user created a craft like: cockpit - passthrough tanks - cargo ramp. They expected the kerbal to be able to EVA into the cargo ramp, but this does not work. https://forum.kerbalspaceprogram.com/topic/210548-112-freeiva/page/23/#findComment-4478400

At first glance this seems like a bug, but it's not easily fixable: the passthrough tanks don't have airlocks, so the game would have no idea where to place the kerbal. Further, consider the case where the cargo ramp isn't even involved: would the user expect to be able to go EVA from the other end of the fuel tank?

There are two scenarios to consider:

1. when a "does not block EVA" part is attached to a passthrough part (the original issue). Perhaps something can be done specifically for these parts to add an artificial airlock?
2. When a passthrough part is attached to a node that is associated with an airlock, with nothing attached to the other side. It's not as obvious that EVA should be allowed from here. It seems intractable to go and add actual airlocks to all of these parts (not to mention they should be conditionally added based on whether the passthrough is active). Moving the airlock from the original part to the end of the passthrough stack MIGHT work, or somehow dynamically creating one as needed.

The intention behind passthrough was mostly a shortcut so that I didn't have to create actual internals for every single part that could conceivably be traversible by crew. It also helps in cases with very thin parts like batteries and probe cores where there's not enough room for hatches anyway. Under that logic, it would still be up to the part author to decide if a part should have an airlock on it - although basically every existing crewed part DOES have one, and therefore passthrough parts should too.

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On the other hand, this is cleanly worked around by adding a docking port: