The Unbrick Collective

text/0117-unbrick-collective.md

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+# RFC-0117: The Unbrick Collective
+
+|                 |                                                                                          |
+| --------------- | ---------------------------------------------------------------------------------------- |
+| **Start Date**  | 22 August 2024                                                                           |
+| **Description** | The Unbrick Collective aims to help teams rescuing a para once it stops producing blocks |
+| **Authors**     | Bryan Chen, Pablo Dorado                                                                 |
+
+## Summary
+
+A followup of the [RFC-0014]. This RFC proposes adding a new collective to the Polkadot Collectives
+Chain: The Unbrick Collective, as well as improvements in the mechanisms that will allow teams
+operating paras that had stopped producing blocks to be assisted, in order to restore the production
+of blocks of these paras.
+
+## Motivation
+
+Since the initial launch of Polkadot parachains, there has been many incidients causing parachains
+to stop producing new blocks (therefore, being _bricked_) and many occurrences that required
+Polkadot governance to update the parachain head state/wasm. This can be due to many reasons range
+from incorrectly registering the initial head state, inability to use sudo key, bad runtime
+migration, bad weight configuration, and bugs in the development of the Polkadot SDK.
+
+Currently, when the para is not unlocked in the _paras registrar_[^1], the `Root` origin is required to
+perform such actions, involving the governance process to invoke this origin, which can be very
+resource expensive for the teams. The long voting and enactment times also could result significant
+damage to the parachain and users.
+
+Finally, other instances of governance that might enact a call using the `Root` origin (like the
+Polkadot Fellowship), due to the nature of their mission, are not fit to carry these kind of tasks.
+
+In consequence, the idea of a Unbrick Collective that can provide assistance to para teams when
+they brick and further protection against future halts is reasonable enough.
+
+## Stakeholders
+
+- Parachain teams
+- Parachain users
+- OpenGov users
+- Polkadot Fellowship
+
+## Explanation
+
+### The Collective
+
+The Unbrick Collective is defined as an unranked collective of members, not paid by the Polkadot
+Treasury. Its main goal is to serve as a point of contact and assistance for enacting the actions
+needed to unbrick a para. Such actions are:
+
+- Updating the Parachain Verification Function (a.k.a. a new WASM) of a para.
+- Updating the head state of a para.
+- A combination of the above.
+
+In order to ensure these changes are safe enough for the network, actions enacted by the Unbrick
+Collective must be whitelisted via similar mechanisms followed by collectives like the Polkadot
+Fellowship. This will prevent unintended, not overseen changes on other paras to occur.
+
+Also, teams might opt-in to delegate handling their para in the registry to the Collective. This
+allows to perform similar actions using the _paras registrar_, allowing for a shorter path to unbrick a
+para.
+
+Initially, the unbrick collective has powers similar to a parachains own sudo, but permits more
+decentralized control. In the future, Polkadot shall provide functionality like SPREE or JAM that
+exceeds sudo permissions, so the unbrick collective cannot modify those state roots or code.  
+
+### The Unbrick Process
+
+```mermaid
+flowchart TD
+    A[Start] 
+
+    A -- Bricked --> C[Request para unlock via Root]
+    C -- Approved --> Y
+    C -- Rejected --> A
+
+    D[unbrick call proposal on WhitelistedUnbrickCaller]
+    E[whitelist call proposal on the Unbrick governance]
+    E -- call whitelisted --> F[unbrick call enacted]
+    D -- unbrick called --> F
+    F --> Y
+
+    A -- Not bricked --> O[Opt-in to the Collective]
+    O -- Bricked --> D
+    O -- Bricked --> E
+
+    Y[update PVF / head state] -- Unbricked --> Z[End]
+```
+
+Initially, a para team has two paths to handle a potential unbrick of their para in the case it
+stops producing blocks.
+
+1. **Opt-in to the Unbrick Collective**: This is done by delegating the handling of the para
+  in the _paras registrar_ to an origin related to the Collective. This doesn't require unlocking
+  the para. This way, the collective is enabled to perform changes in the _paras_ module, after
+  the **Unbrick Process** proceeds.
+2. **Request a Para Unlock**: In case the para hasn't delegated its handling in the _paras
+  registrar_, it'll be still possible for the para team to submit a proposal to unlock the para,
+  which can be assisted by the Collective. However, this involves submitting a proposal to the `Root`
+  governance origin.
+
+### Belonging to the Collective
+
+The collective will be initially created without members (no seeding). There will be additional
+governance proposals to setup the seed members.
+
+The origins able to modify the members of the collective are:
+
+- The `Fellows` track in the Polkadot Fellowship.
+- `Root` track in the Relay.
+- More than two thirds of the existing Unbrick Collective.
+
+The members are responsible to verify the technical details of the unbrick requests (i.e. the hash
+of the new PVF being set). Therefore, they must have the technical capacity to perform such tasks.
+
+Suggested requirements to become a member are the following:
+
+- Rank 3 or above in the Polkadot Fellowship.
+- Being a CTO or Technical Lead in a para team that has opted-in to delegate the Unbrick Collective
+  to manage the PVF/head state of the para.
+
+## Drawbacks
+
+The ability to modify the Head State and/or the PVF of a para means a possibility to perform
+arbitrary modifications of it (i.e. take control the native parachain token or any bridged assets
+in the para).
+
+This could introduce a new attack vector, and therefore, such great power needs to be handled
+carefully.
+
+## Testing, Security, and Privacy
+
+The implementation of this RFC will be tested on testnets (Rococo and Westend) first.
+
+An audit will be required to ensure the implementation doesn't introduce unwanted side effects.
+
+There are no privacy related concerns.
+
+## Performance, Ergonomics, and Compatibility
+
+### Performance
+
+This RFC should not introduce any performance impact.
+
+### Ergonomics
+
+This RFC should improve the experience for new and existing parachain teams, lowering the barrier
+to unbrick a stalled para.
+
+### Compatibility
+
+This RFC is fully compatible with existing interfaces.
+
+## Prior Art and References
+
+- [RFC-0014: Improve Locking Mechanisms for Parachains][RFC-0014]
+- [How to Recover a Parachain, Polkadot Forum][forum:673]
+- [Unbrick Collective, Polkadot Forum][forum:6931]
+
+## Unresolved Questions
+
+- What are the parameters for the `WhitelistedUnbrickCaller` track?
+- Any other methods that shall be updated to accept `Unbrick` origin?
+- Any other requirements to become a member?
+- We would like to keep this simple, so no funding support from the Polkadot treasury. But do we
+  want to compensate the members somehow? i.e. Allow parachain teams to donate to the collective.
+- We hope SPREE/JAM would be carefully audited for miss-use risks before being  
+  provided to parachain teams, but could the unbrick collective have an elections  
+  that warranted trust beyond sudo powers?
+- An auditing framework/collective makes sense parachain code upgrades, but  
+   could also strengthen the unbrick collective.  
+- Do we want to have this collective offer additional technical support to help bricked parachains?
+  i.e. help debug the code, create the rescue plan, create postmortem report, provide resources on
+  how to avoid getting bricked
+
+<!-- Footnotes -->
+
+[^1]: The _paras registrar_ refers to a pallet in the Relay, responsible to gather registration info
+of the paras, the locked/unlocked state, and the manager info.
+
+<!-- Links -->
+
+[RFC-0014]: ./0014-improve-locking-mechanism-for-parachains
+[forum:673]: https://forum.polkadot.network/t/how-to-recover-a-parachain/673
+[forum:6931]: https://forum.polkadot.network/t/unbrick-collective/6931