This is a draft of https://github.com/filecoin-project/FIPs/discussions/298 rebasing it on top of FIL+ indefinite term limits, which makes all the changes to the verified registry actors.

This replaces Architecture for programmable storage markets.

TODO:

• Decide whether to support multiple notified actors (i.e. markets) per data piece
• Can we design an incremental rollout where old methods keep working initially?

Abstract

This proposal is a refactoring of the APIs and interactions between the storage miner actor, built-in storage market actor, and Filecoin Plus verified registry actor to provide a platform for alternative storage markets, incentive schemes, and other sector-content-related applications to be built on the FVM.

The thrust of the architecture is a decoupling and separation of concerns between the three actors. Notable points include:

• Both clients and miner actors can interact with the verified registry directly to allocate and claim data cap allowances. Market actors are not necessarily involved, but can act as a delegates (this property comes from FIL+ indefinite term limits).
• The built-in market actor is no longer used to calculate the sector data commitment, quality-adjusted power, or other consensus inputs. The miner actor takes all trusted computations.
• Storage provider operators specify deal metadata at proof-of-replication instead of fetching it from the market actor during sector pre-commit. The miner actor forwards it to the market. Deal metadata is really just piece metadata, which could be for a market or any other application.
• The market actor is informed of piece commitments into sectors, but has no power to deny them. Other actors could similarly be informed of changes to sector content.

This proposal requires FIP-0034 simplifying pre-commit deposit as pre-requisite.

This proposal is complemented by to miner←→market registrations: if/when we support updatable sector content we would need such a notification mechanism.

Motivation

High level motivation for why to provide a platform for alternative storage markets and other content-related contracts is given in #241.

We need to change the storage market contract architecture because the current structure does not provide the information and hooks that would be needed by new applications to implement storage-deal-like functionality. It privileges the built-in market actor as the one which the storage miner actor consults. In order to enable the development of useful storage-related applications and features, we need to break the tight coupling between these built-in actors, expose composable on-chain primitives, and make the capabilities of the built-in market actor available to user-programmable contracts.