<!-- Source: https://docs.paxeer.app/interchain/ -->

# Interchain (IBC)

Inspect Paxeer’s IBC implementation and send native-denomination transfers from the CLI or the EVM precompile.

**Source:** `paxeer-network/interchain/`, `precompiles/ibc/`, and the IBC keeper and router wiring in `node/app.go`.

## Protocol and implementation

The in-tree IBC implementation provides clients, connections, channels, packet commitments, and application routing. Relayers submit proofs and carry packets and acknowledgements between chains. A working transfer requires compatible live clients, an open channel, and relayer delivery.

Query the target network for the port, channel, counterparty, and supported denomination before sending funds.

| Source directory | Purpose |
| --- | --- |
| `interchain/modules/core/` | Client, connection, channel, port, and commitment protocol logic. |
| `interchain/modules/apps/transfer/` | ICS-20 fungible-token transfer messages, packets, and keeper. |
| `interchain/modules/apps/27-interchain-accounts/` | Interchain-account implementation. |
| `interchain/modules/light-clients/` | Tendermint and solo-machine light-client code. |
| `precompiles/ibc/` | EVM interface to native ICS-20 transfers. |

## Inspect clients and channels

Configure the CLI's Cosmos RPC endpoint for the Paxeer node being queried, then inspect its state:

```
paxd query ibc client states
paxd query ibc connection connections
paxd query ibc channel channels
```

Verify the channel's port, connection, remote chain, ordering, and open state. Channel identifiers such as `channel-0` are local to a chain; they are not universal destinations.

## Transfer through the CLI

This command template sends `1,000,000 uhpx`, one PAX. Set `IBC_CHANNEL` to a verified channel and `IBC_RECIPIENT` to an address valid on its destination chain.

```
paxd tx ibc-transfer transfer \
  transfer "$IBC_CHANNEL" "$IBC_RECIPIENT" 1000000uhpx \
  --from mykey --chain-id hyperpax_125-1
```

Use the actual bank denomination for other assets. An IBC voucher has its own denomination trace; do not substitute a display ticker for a bank denomination.

## Transfer directly from the EVM

The precompile at `0x0000000000000000000000000000000000001009` exposes two nonpayable transfer methods. Use the full `precompiles/ibc/abi.json` for client bindings.

```
interface IBC {
    function transfer(
        string calldata toAddress,
        string calldata port,
        string calldata channel,
        string calldata denom,
        uint256 amount,
        uint64 revisionNumber,
        uint64 revisionHeight,
        uint64 timeoutTimestamp,
        string calldata memo
    ) external returns (bool success);

    function transferWithDefaultTimeout(
        string calldata toAddress,
        string calldata port,
        string calldata channel,
        string calldata denom,
        uint256 amount,
        string calldata memo
    ) external returns (bool success);
}
```

The immediate EVM caller must have a Paxeer address association and sufficient native-denomination balance. A wrapper uses the wrapper's associated account. `amount` is a bank base-unit integer, not payable EVM value; delegatecall is rejected.

The explicit method takes an absolute remote timeout height and timestamp. IBC timestamps use nanoseconds. The default-timeout method derives a timeout from the channel's connection, client height, consensus timestamp, current block time, and implementation defaults. It can fail when required channel or client state is absent.

The ABI submits transfers; it does not expose channel enumeration or a general incoming-packet callback. Use the native query interfaces to inspect IBC state.

## Track the whole transfer

A successful local transaction means the source-chain transfer was accepted. It does not mean the destination has already received the assets. Retain the source transaction and packet identifiers, then track relay, acknowledgement, or timeout/refund handling on both chains.

Configure your relayer for both networks, check that its clients are current, and monitor packet delivery and acknowledgement processing.

## Implementation references

- `precompiles/ibc/IBC.sol`: exact public selectors.

- `precompiles/ibc/ibc.go`: associated sender, amount conversion, timeout derivation, and keeper invocation.

- `interchain/modules/apps/transfer/`: packet lifecycle and native transfer behavior.

- [Precompile reference](https://docs.paxeer.app/precompiles) and [native query interfaces](https://docs.paxeer.app/rest-grpc).