[Protocol] Implement Session Rollovers

[Olshansk]

Objective

Resolve the infamous session rollover issue once and for all

Origin Document

While working on #252, we had to add a temporary hack below due to:

• Very fast block times
• Small number of blocks per session

Overall, this is us hitting the session rollover issue in Shannon

	// TODO_IN_THIS_PR: Either slow down blocks, or increase numBlocksPerSession,
	// or create a ticket related to session rollovers and link to it here.
	// currentBlock := rp.blockClient.LastNBlocks(ctx, 1)[0]
	// session, err := rp.sessionQuerier.GetSession(ctx, appAddress, service.Id, currentBlock.Height())
	// session, err := rp.sessionQuerier.GetSession(ctx, appAddress, service.Id, relayRequest.Meta.SessionHeader.SessionStartBlockHeight)
	currentBlock := rp.blockClient.LastNBlocks(ctx, 1)[0]
	session, err := rp.sessionQuerier.GetSession(ctx, appAddress, service.Id, currentBlock.Height())

Goals

• Design & Implement an on-chain solution for session rollovers in Shannon

Deliverables

• A PR that implements and solves session rollovers
• A governance parameter that modulates how much leeway session rollovers have
• Document how session rollovers are solved in Shannon

Non-goals / Non-deliverables

• Using the same solution for session rollovers as in Morse (i.e. client side)

General deliverables

• Comments: Add/update TODOs and comments alongside the source code so it is easier to follow.
• Testing: Add new tests (unit and/or E2E) to the test suite.
• Makefile: Add new targets to the Makefile to make the new functionality easier to use.
• Documentation: Update architectural or development READMEs; use mermaid diagrams where appropriate.

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Creator: @Olshansk
Co-Owners: @red-0ne

[Olshansk]

tl;dr In pkg/relayer/proxy/relay_verifier.go:

+  session, err := rp.sessionQuerier.GetSession(ctx, appAddress, service.Id, relayRequest.Meta.SessionHeader.SessionStartBlockHeight)
- currentBlock := rp.blockClient.LastNBlocks(ctx, 1)[0]
- session, err := rp.sessionQuerier.GetSession(ctx, appAddress, service.Id, currentBlock.Height())

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While implementing the quickstart guide in #252, the change above was necessary to make things work E2E because the session was ending too quickly.

Until session rollovers are implemented, we can potentially run into bugs / issues in local development as well. The solution is to either:

1. Add the diff above (the easier temp workaround)
2. Locally increase blocks per session (not gov param at the time of writing this)
3. Reducing block time (a rollkit flag)

[red-0ne]

Initial investigation and solution proposal https://www.notion.so/buildwithgrove/Sessions-rollover-f2845bd812c24b9c98934ca510bb70e9

[Olshansk]

Initial investigation and solution proposal notion.so/buildwithgrove/Sessions-rollover-f2845bd812c24b9c98934ca510bb70e9

Reviewed!

Overall, the idea I had in mind was a little different. Only copy-pasting the mermaid diagram here for reference:

CCing @bryanchriswhite since this may be dependant on the work in #141 (comment)

[red-0ne]

Closing as per #326 and #332