Improved representation of Non-fungibles amounts in ERTP

[Chris-Hibbert]

What is the Problem Being Solved?

Before we can add non-fungible assets to ERTP, we will have to address performance problems. The KREAd dApp used CopyBags to represent NFTs, and the performance of insertion and deletion degraded linearly with the number of items in a purse. #8862 has many details.

Description of the Design

We'll need a Store that can hold non-scalar values. Some notes

• Payments may not need a new representation. Since they're immutable, insertion and deletion costs don't matter.
• Updates currently require rewriting the whole CopyBag.
• when a contract calls getCurrentAllocation() we have to enumerate the contents.
• For KREAd, a lot of the costs appeared while serializing to vStorage.
• KREAd used a zcfMint, so the costs were imposed on the Zoe vat.

This was discussed in the Zoe meeting on 20025-1-29.

Security Considerations

Mostly not a security issue

Scaling Considerations

See discussion above.

Test Plan

TBD when the design is fleshed out.

Upgrade Considerations

Zoe would need to be upgraded. Contracts that don't deal with NFTs would be unaffected.