Should we be descriptive or prescriptive about how room upgrades work?

[turt2live]

Currently the spec leaves pretty much everything as an implementation detail. Servers appear to all implement the same set of behaviours though, and there are proposals to make the spec more prescriptive:

• MSC4168: Update m.space.* state on room upgrade matrix-spec-proposals#4168
• MSC4167: Copy bans on room upgrade matrix-spec-proposals#4167

This leaves an open question: do we think the spec should be more prescriptive generally for room upgrades, or do we prefer to leave this as an implementation detail? This issue tracks that conversation as no specific MSC fits well imo.