This proposal aims to fix the problem that occurred whilst opening the bi-directional HRMP channel between Robonomics and Statemine. The [previous attempt](https://kusama.polkassembly.io/referendum/207) successfully passed through the voting stage, but failed on the last stage due to insufficient weight provided for the XCM Transact operation to open channels. This proposal describes the fix for the problem and is based on [the solution](https://hackmd.io/f3NITCDrRJel0ewxzLGMqQ?view) provided by the Polkadot team.

### Technical Details

The proposal is to send an XCM message (`xcmPallet.send`) to Statemine to execute a transaction with superuser (root) permission. This time it is not needed to transfer KSM from Kusama Treasury, so the transaction consists only of executing XCM Transact. 

Preimage design can be reviewed [here](https://drive.google.com/file/d/1UX-LJnv3sxBkCJZ5WM5x8KgbvxcJQ4SO).

Encoded call hash:

`0x946b6aee1b23b04bc3a8d1e60642ca567ed6c2e968876eaa981fcf0588c08a39`

Encoded call data of this transaction, which can be decoded on Kusama:

```
0x630001000100a10f020406020208af2fb5011f0001010002141804000000000760f0f8d1e8000013000000000760f0f8d1e800060003009435775c1802083c01000800003c0000080000e803000000900100140d01010000000004000101006d6f646c70792f74727372790000000000000000000000000000000000000000
```

### XCM message

The XCM message that is sent to Statemine looks like:

```
0x1f0001010002141804000000000760f0f8d1e8000013000000000760f0f8d1e800060003009435775c1802083c01000800003c0000080000e803000000900100140d01010000000004000101006d6f646c70792f74727372790000000000000000000000000000000000000000
```

The message can be decoded on Statemine. It consists of `polkadotXcm.send`, which sends a XCM message back to Kusama to perform `Transact` of this call:

`0x1802083c01000800003c0000080000e803000000900100`

which can be decoded on Kusama. This call is a batch transaction with two calls: the first one accepts the open channel request (`hrmp.hrmpAcceptOpenChannel`) from Robonomics (ParaId: 2048), and the second one to make a reciprocal open channel request (`hrmp.hrmpInitOpenChannel`) to Robonomics.

Following the guidelines for calculating weight, this time `requreWeightAtMost` is set to 2,000,000,000.

The message also includes a `ClaimAsset` instruction to claim trapped fee assets (about 0.999955 KSM) from the previous proposal. After `Transact`, it follows up with `RefundSurplus`, which refunds any unused weight from execution, and then `DepositAsset`, which instructs the executor to deposit any KSM that wasn't used on transaction fees back into Kusama Treasury.

Preimage design of the XCM message can be reviewed [here](https://drive.google.com/file/d/1loEQuRS-_QwRg2EMH1XVbCLhtsw617Ji).

Preimage design of the a batch transaction for accepting/requesting can be reviewed [here](https://drive.google.com/file/d/127jr8HDlHsTxRbx7d4WdRJbwrTO-hDdb).


- This proposal is about fixing a problem with opening a channel between two systems.
- The proposal suggests sending a message to execute a transaction with special permission.
- The message includes instructions to accept and request the channel.
- The proposal also includes instructions to claim trapped fee assets and refund unused weight.
- The details of the proposal can be found in the provided links.

#224 Fix Opening HRMP Channel Between Robonomics and Statemine