Discussion of TAP 16: Snapshot Merkle trees

This is a thread to discuss snapshot Merkle trees, introduced in #125.

Pull requests relating to TAP 16: #133

Outstanding issues and questions relating to this TAP (from @joshuagl in #125 (comment))

• A reader has to understand Merkle trees to implement this TAP, for example to understand how to compute the root hash from a leaf node. Is that a concern? Should we link to a good overview of Merkle trees? Should we specify how this is expected to work?
  • are the metadata extensions for the Merkle tree truly abstract enough to support arbitrary (non-Merkle) tree algorithms? Should we PoC some other algorithms? perhaps in a different implementation?
• Further PoC development of auditor integrations?
• Recommendations on specifying the algorithms for a POUF
• The Specification section suggests the snapshot Merkle tree replaces the single snapshot metadata file – is there any reason we shouldn't generate both? If we generate a Merkle tree only, should integrations still have a snapshot role with associated key? Should we explore this a bit more?
• In places the TAP seems to suggest an auditor is required, whereas in others it indicates auditors are optional. Let's be sure to clarify.

Read the TAP 16 discussion, the introduction in #125, and the related pull request #133, then review the outstanding questions listed here. This work is done when the specification has agreed guidance for Merkle tree concepts, algorithm recommendations, auditor requirements, and snapshot metadata handling.