Vessel identifiers can become unassigned between generation and acceptance

[jrossignol]

It's possible for a vessel identifier that was valid when a contract was generated to become unassigned by the time the contract is accepted. Because of the way stuff in data nodes and requirements get checked, it's not currently possible to write a contract that will properly check stuff like this after generation.

My current thoughts on a solution would involve targeting this specific case, and adding a ValidVessel requirement that takes a vessel identifier, replacing the expression entirely.

Raised based on the RP-0 Crew Rotation Contract and this discussion.

[jrossignol]

@inigmatus and @severedsolo should probably also check this one out as it may come in useful for their contract packs.

[NathanKell]

ValidVessel seems a reasonable solution, yeah.

[severedsolo]

That would be very useful as long as I can still use expressions to check I've got a vessel that makes sense

[jrossignol]

Of course!

[inigmatus]

interesting. my contracts typically center around following one from launch to landing. i'll keep the feature in mind though!

[severedsolo]

This worries me:
If at any point the vessel is no // longer valid, this will return false and fail the contract.
When you say "fails" does that mean penalties get applied (even if it isn't the players fault) or will the contract just go away.

[jrossignol]

Penalties will get applied.

Long term I'd like to do a revamp to improve contract requirements to allow more flexibility (allow flags to specify whether checks are done for active contracts, whether failure penalties apply and messages in #464). If you have specific stuff that you want (or specific details for the ones mentioned before), then raise an issue to track it.