Graph Horizon: upgrade overview

Protocol timeline

The protocol will undergo three distinct stages during the Horizon upgrade, each one having different functionality at the protocol level:

Stage 0: Current protocol (legacy)
Stage 1: Graph Horizon: Transition period
Stage 2: Graph Horizon

Upgrade timeline

The upgrade itself consists of 4 deployment phases and will take the protocol from Stage 0 to Stage 1. For a detailed itemization on these phases and the overall deployment plan, see Graph Horizon: deployment plan (Template), a tl;dr:

Phase 1: Contracts and Subgraph setup
Phase 2: Proxies acceptance and indexer setup
Phase 3: Contract deployment
Phase 4: Accept Graph Horizon

Why do we need 4 deployment phases?

The Horizon upgrade requires executing a series of steps in order, some of which can only be done by the protocol governance due to the brownfield nature of the upgrade.

Phase	Executed by	Description
1	Deployer account
(E&N Protocol team)	New contract proxies are deployed.
2	Protocol governor
(Graph Council)	The new proxies are registered in the Controller contract.
3	Deployer account
(E&N Protocol team)	New implementations are deployed.
4	Protocol governor
(Graph Council)	Contracts are upgraded to their new implementations.