added prep docs for the stargate work

README.md

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+# Auxo X Chain
+
+<span style="
+    font-weight:bold;
+    color:orange;
+    border:1px solid orange;
+    padding:5px;
+">
+    Warning! This repository is incomplete state and will be changing heavily
+</span>
+
+This repository contains the source code for the Auxo Cross chain hub, it consists of 3 parts:
+
+1. The XChainHub - an interface for interacting with vaults and strategies deployed on multiple chains.
+
+2. The XChainStrategy - an implementation of the same BaseStrategy used in the Auxo Vaults that adds support for using the XChainHub.
+
+3. LayerZeroApp - an implementation of a nonBlockingLayerZero application that allows for cross chain messaging using the LayerZero protocol.
+
+
+## The Hub
+----------
+The hub itself allows users to intiate vault actions from any chain and have them be executed on any other chain with a [LayerZero endpoint](https://layerzero.gitbook.io/docs/technical-reference/mainnet/supported-chain-ids). 
+
+LayerZero applications initiate cross chain requests by calling the `endpoint.send` method, which then invokes `_nonBlockingLzReceive` on the destination chain. 
+
+The hub itself implements a reducer pattern to route inbound messages from the `_nonBlockingLzReceive` function, to a particular internal action. The main actions are:
+
+1. Deposit into a vault.
+2. Request to withdraw from a vault (this begins the batch burn process).
+3. Provided we have a successful batch burn, complete a batch burn request and send underlying funds from a vault to a user.
+4. Report changes in the underlying balance of each strategy on a given chain.
+
+Therefore, each cross chain request will go through the following workflow:
+
+1. Call the Cross Chain function on the source chain (i.e. `depositToChain`)
+2. Cross chain function will call the `_lzSend` method, which in turn calls the `LayerZeroEndpoint.send` method.
+3. The LZ endpoint will call `_nonBlockingLzReceive` on the destination chain.
+4. The reducer at `_nonBlockingLzReceive` will call the corresponding action passed in the payload (i.e. `_depositAction`)
+
+## Swaps
+----------
+Currently, the hub utilises the [Anyswap router](https://github.com/anyswap/CrossChain-Router/wiki/How-to-integrate-AnySwap-Router) to execute cross chain deposits of the underlying token into the auxo vault. We are discussing removing the router and replacing with stargate. 
+
+### Advantages of Stargate:
+- Guaranteed instant finality if the transaction is approved, due to Stargate's cross-chain liquidity pooling.
+- We can pass our payload data to the Stargate router and use `sgReceive` to both handle the swapping, and post-swap logic. This would remove the need for calls to both the LayerZero endpoint and to Anyswap router.
+
+
+### Advantages of Anyswap:
+- Anyswap supports a much larger array of tokens, whereas stargate only implements a few stables and Eth. 
+
+
+## Implementing Stargate To Do List
+--------
+*This is a development reference only*
+
+Our to do list to swap out AnySwap/LayerZero with Stargate is as follows:
+
+- [ ] Add the `IStargateRouter` to the list of interfaces
+- [ ] Replace the AnySwap swaps with `IStargateRouter.swap`
+    - [ ] `_finalizeWithdrawAction`
+    - [ ] `constructor`
+    - [ ] `depositToChain`
+
+- [ ] Replace* the `_lzSend` messages with encoded payloads in `IStargateRouter.swap`
+    - [ ] `depositToChain`
+    - [ ] `reportUnderlying`*
+- [ ] Replace the `_nonBlockingLzReceive` with `IStargateReceiver.sgReceive`
+
+> \*[IStargateRouter](https://stargateprotocol.gitbook.io/stargate/interfaces/evm-solidity-interfaces/istargaterouter.sol) *does not appear to have a way of sending just messages across (without swaps), it may be that we have to implement both LayerZero and stargate to get the cross chain reporting*