Bridging: Add pallet-assets

[mattheworris]

Description

In order to teleport Frequency tokens to AssetHub, we need a way to pay the execution fee on AssetHub otherwise it will reject the request and treat the tokens as trapped assets.

Since AssetHub does not accept Frequency as payment for execution fees, we must also include DOT in the message to cover those fees.

To support this, Frequency must be able to handle DOT as an asset — both to receive DOT from AssetHub and to send DOT back out.

Acceptance Criteria

• Add the ability to send and receive DOT on Frequency
• Store DOT as a Multilocation on Frequency
• Decide who should be allowed to create assets on Frequency
• Generate Weights
• Feature Flag frequency-bridging

Implementation suggestions

• User Pallet Assets
• Config

pallet-assets = { workspace = true, default-features = false }
assets-common = { workspace = true, default-features = false }

parameter_types! {
	pub const AssetDeposit: Balance = 0;
	pub const AssetAccountDeposit: Balance = 0;
	pub const ApprovalDeposit: Balance = 0;
	pub const AssetsStringLimit: u32 = 50;
	pub const MetadataDepositBase: Balance = 0;
	pub const MetadataDepositPerByte: Balance = 0;
}

parameter_types! {
	// we just reuse the same deposits
	pub const ForeignAssetsAssetDeposit: Balance = AssetDeposit::get();
	pub const ForeignAssetsAssetAccountDeposit: Balance = AssetAccountDeposit::get();
	pub const ForeignAssetsApprovalDeposit: Balance = ApprovalDeposit::get();
	pub const ForeignAssetsAssetsStringLimit: u32 = AssetsStringLimit::get();
	pub const ForeignAssetsMetadataDepositBase: Balance = MetadataDepositBase::get();
	pub const ForeignAssetsMetadataDepositPerByte: Balance = MetadataDepositPerByte::get();
}

use xcm_config::{RelayLocation, XcmOriginToTransactDispatchOrigin, ForeignAssetsAssetId};
impl pallet_assets::Config  for Runtime {
	type RuntimeEvent = RuntimeEvent;
	type Balance = Balance;
////
	type AssetId = ForeignAssetsAssetId;
	type AssetIdParameter = ForeignAssetsAssetId;
	type Currency = Balances;
	// This is to allow any other remote location to create foreign assets. Used in tests, not
	// recommended on real chains.
	type **CreateOrigin** =
		**ForeignCreators**<Everything, LocationToAccountId, AccountId, xcm::latest::Location>;
	type ForceOrigin = EnsureRoot<AccountId>;
	type AssetDeposit = ForeignAssetsAssetDeposit;
	type MetadataDepositBase = ForeignAssetsMetadataDepositBase;
	type MetadataDepositPerByte = ForeignAssetsMetadataDepositPerByte;
	type ApprovalDeposit = ForeignAssetsApprovalDeposit;
	type StringLimit = ForeignAssetsAssetsStringLimit;
	type Freezer = ();
	type Extra = ();
	type WeightInfo = pallet_assets::weights::SubstrateWeight<Runtime>;
	type CallbackHandle = ();
	type AssetAccountDeposit = ForeignAssetsAssetAccountDeposit;
	type RemoveItemsLimit = frame_support::traits::ConstU32<1000>;
	#[cfg(feature = "runtime-benchmarks")]
	type BenchmarkHelper = xcm_config::XcmBenchmarkHelper;
	type Holder = ();
}

Checklist

• Updated Pallet Readme?
• Updated js/api-augment for Custom RPC APIs?
• Design doc(s) updated?
• Unit Tests added?
• e2e Tests added?
• Benchmarks added?
• Spec version incremented?

[codecov]

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All modified and coverable lines are covered by tests ✅

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[mattheworris]

Currently allows any signed Frequency account to create. This can be assigned to a Council or a specific address, if we need to limit creation.

[mattheworris]

Some xcm stuff will be brought in when other PRs finish the xcm setup.

[Copilot]

Pull Request Overview

This PR introduces bridging support for Frequency by integrating the pallet-assets module to handle DOT as a foreign asset. Key changes include:

• Adding new type definitions (AssetId and AssetBalance) and parameter_types for the foreign assets feature.
• Configuring pallet-assets for bridging with a new CreateOrigin based on EnsureSigned and integrating it in the runtime.
• Updating Cargo.toml files to include the necessary bridging feature flags and dependencies.

Reviewed Changes

Copilot reviewed 6 out of 9 changed files in this pull request and generated no comments.

File	Description
runtime/frequency/src/lib.rs	Introduces type aliases, parameters, and pallet-assets config for bridging
runtime/frequency/Cargo.toml	Adds pallet-assets as an optional dependency and bridging feature flag
runtime/common/Cargo.toml	Adds the frequency-bridging feature
Cargo.toml	Integrates pallet-assets for bridging in the main Cargo configuration

Files not reviewed (3)

• Makefile: Language not supported
• scripts/init.sh: Language not supported
• scripts/run_benchmarks.sh: Language not supported

Comments suppressed due to low confidence (2)

runtime/frequency/src/lib.rs:526

• The placeholder AssetCreatorAccount is hardcoded; please ensure this account is updated with the proper creator account for production to avoid misconfiguration.

pub const AssetCreatorAccount: AccountId = AccountId::new([0u8; 32]); // TODO: Replace with actual AccountId

runtime/frequency/src/lib.rs:1343

• No unit tests currently cover the new foreign assets (bridging) configuration; please add tests to verify asset creation and fee handling behavior under the bridging feature.

impl pallet_assets::Config for Runtime {

[enddynayn]

👍 great!