Run Snowbridge halt and resume bridge preimages for verification

[claravanstaden]

Snowbridge requires an easy accessible, automated way of obtaining the preimage to halt the bridge, in case of an emergency. We added a page on our dApp to get the halt and resume bridge preimage: https://app.snowbridge.network/governance Even though the page is open-source, we need a way to:

• quickly verify the preimage still works against the current Polkadot runtime
• that the preimage hasn't been tampered with and adds any malicious calls

This PR adds the halt and resume bridge preimages, to be tested against a fork of Polkadot mainnet (using Chopsticks) every 6 hours. The test verifies storage state and expected events. The Snowbridge app will show a badge that the preimage match what is in this repo, and it can also of course be compared manually too.

[github-actions]

The changes look good and the tests are well-structured. I have one minor suggestion to improve the clarity of the test file by adding comments to explain the magic numbers used for proposalLength.

---

Review Suggestions

packages/polkadot/src/assetHubPolkadot.bridgeHubPolkadot.snowbridgeGovernance.e2e.test.ts:42, 89

The test uses the magic number 201 for proposalLength. It would be beneficial to add a comment explaining how this value is derived. For example, // 199 bytes for the remark + 2 bytes for the call index.

[claravanstaden]

Review comment details are hallucinated by I added a comment about the preimage length nonetheless: 59d3144

[rockbmb]

@claravanstaden alright, noted! I'll take a look at this PR this week.

[rockbmb]

Can you extract these test bodies out of the describe calls? That also allows for documentation to be written that explains the purpose/mechanism behind these tests.

I get that they're trivial to you as a Snowbridge maintainer, but consider someone without your context. Specifically:

• What do the fee keys (FEE_KEY_V1, FEE_KEY_V2) actually control? Why does setting them to MAX_U128 halt the bridge?
• What's the relationship between Asset Hub and Bridge Hub in this halt flow?
• Why are there V1 and V2 versions of everything?
• What does "halt" actually mean operationally - does it stop inbound, outbound, or both?

[claravanstaden]

@rockbmb good point! Added in b8a42e3.

[rockbmb]

@claravanstaden I was unclear in my previous comment. I've updated it with concrete examples of desirable things to comment, which I guess landed just before you pushed your commit! Sorry!

[claravanstaden]

Thanks for the extra info @rockbmb! I added specific points to your questions in #636.

[rockbmb]

@claravanstaden thanks!