Add Payload fields

types/submessages.go

@@ -55,10 +55,29 @@ func (s *replyOn) UnmarshalJSON(b []byte) error {
 // SubMsg wraps a CosmosMsg with some metadata for handling replies (ID) and optionally
 // limiting the gas usage (GasLimit)
 type SubMsg struct {
-	ID       uint64    `json:"id"`
-	Msg      CosmosMsg `json:"msg"`
-	GasLimit *uint64   `json:"gas_limit,omitempty"`
-	ReplyOn  replyOn   `json:"reply_on"`
+	// An arbitrary ID chosen by the contract.
+	// This is typically used to match `Reply`s in the `reply` entry point to the submessage.
+	ID  uint64    `json:"id"`
+	Msg CosmosMsg `json:"msg"`
+	// Some arbitrary data that the contract can set in an application specific way.
+	// This is just passed into the `reply` entry point and is not stored to state.
+	// Any encoding can be used. If `id` is used to identify a particular action,
+	// the encoding can also be different for each of those actions since you can match `id`
+	// first and then start processing the `payload`.
+	//
+	// The environment restricts the length of this field in order to avoid abuse. The limit
+	// is environment specific and can change over time. The initial default is 128 KiB.
+	//
+	// Unset/nil/null cannot be differentiated from empty data.
+	//
+	// On chains running CosmWasm 1.x this field will be ignored.
+	Payload []byte `json:"payload"`
+	// Gas limit measured in [Cosmos SDK gas](https://github.com/CosmWasm/cosmwasm/blob/main/docs/GAS.md).
+	//
+	// Setting this to `None` means unlimited. Then the submessage execution can consume all gas of
+	// the current execution context.
+	GasLimit *uint64 `json:"gas_limit,omitempty"`
+	ReplyOn  replyOn `json:"reply_on"`
 }
 
 // The result object returned to `reply`. We always get the ID from the submessage back and then must handle success and error cases ourselves.
@@ -68,6 +87,13 @@ type Reply struct {
 	// The ID that the contract set when emitting the `SubMsg`. Use this to identify which submessage triggered the `reply`.
 	ID     uint64       `json:"id"`
 	Result SubMsgResult `json:"result"`
+	// Some arbitrary data that the contract set when emitting the `SubMsg`.
+	// This is just passed into the `reply` entry point and is not stored to state.
+	//
+	// Unset/nil/null cannot be differentiated from empty data.
+	//
+	// On chains running CosmWasm 1.x this field is never filled.
+	Payload []byte `json:"payload"`
 }
 
 // SubMsgResult is the raw response we return from wasmd after executing a SubMsg.