V1 upgradeability path for tBTC

[pdyraga]

Figure out how upgrades are going to work in tBTC for the first version and externalize it into some document (RFC?)

[mhluongo]

Related to #22 and #119.

Basic idea for upgrades is that Deposits don't change based on dev team actions- once a depositor enters into a deposit it's immutable. The ERC-20 contract is also immutable, and any bugs there will require a social upgrade to a new ERC-20 ("TBTCv2" or similar).

Try to sync this work with RFC-9 from keep-core

[gakonst]

I am generally a fan of upgrading via migration, by a one-way peg (burn 1 tbtcV1, get 1 tbtcV2), but you might have issues coordinating with exchanges.

[mhluongo]

I'm in the same boat re: social migrations, just trying to draw the fully nuanced line here. I think we get close with

• No Deposits should change via any sort of upgrade scheme. A new DepositFactory can be enabled via governance. Users can decide which factory they use for new deposits.
• Old DepositFactorys should have a big red button in case of an exploit, shutting them down.

So new signature schemes can be opted into by individual depositors, as can larger or smaller lot-sizes. System-wide economic concerns need global opt-in (social upgrade). I don't think we can assume 1-way pegs between tokens, since there will be BTC locked up in the "old" token in some situations and we need to maintain the supply peg. Instead, folks can redeem their BTC and move it to the new token via a deposit.

What do you think @gakonst? It feels like a practical middle ground while leaning heavily toward social upgrades

[gakonst]

OK I agree with this. Basically just add a killswitch to prevent new deposits from being created - no further interference with the system. Also fine with redeeming the TBTCv1, getting back your BTC and redepositing to get TBTCv2 vs burning-TBTCv1-mint-TBTCv2.

[mhluongo]

We've opted for an even more extreme version, removing all "kill switches". Caveat emptor folks

[mhluongo]

Details on the slim governance surface area that has been included can be found here