Feat: Added support for a last msg in tx marker in baseapp

baseapp/baseapp.go

@@ -111,6 +111,8 @@ type BaseApp struct { //nolint: maligned
 	// abciListeners for hooking into the ABCI message processing of the BaseApp
 	// and exposing the requests and responses to external consumers
 	abciListeners []ABCIListener
+
+	LastTxManager LastMsgMarkerContainer
 }
 
 type appStore struct {
@@ -742,8 +744,12 @@ func (app *BaseApp) runMsgs(ctx sdk.Context, msgs []sdk.Msg, mode runTxMode) (*s
 		Data: make([]*sdk.MsgData, 0, len(msgs)),
 	}
 
+	// Set the marker as false - future messages may toggle this flag
+	app.LastTxManager.SetMarker(false)
+
 	// NOTE: GasWanted is determined by the AnteHandler and GasUsed by the GasMeter.
 	for i, msg := range msgs {
+
 		// skip actual execution for (Re)CheckTx mode
 		if mode == runTxModeCheck || mode == runTxModeReCheck {
 			break
@@ -755,6 +761,10 @@ func (app *BaseApp) runMsgs(ctx sdk.Context, msgs []sdk.Msg, mode runTxMode) (*s
 			err          error
 		)
 
+		if app.LastTxManager.GetMarker() {
+			return nil, sdkerrors.Wrapf(sdkerrors.ErrLastTx, "message was attempted but last message was marked by a contract; message index: %d", i)
+		}
+
 		if handler := app.msgServiceRouter.Handler(msg); handler != nil {
 			// ADR 031 request type routing
 			msgResult, err = handler(ctx, msg)

baseapp/last_message_marker.go

@@ -0,0 +1,13 @@
+package baseapp
+
+type LastMsgMarkerContainer struct {
+	marker bool
+}
+
+func (mng *LastMsgMarkerContainer) SetMarker(value bool) {
+	mng.marker = value
+}
+
+func (mng *LastMsgMarkerContainer) GetMarker() bool {
+	return mng.marker
+}

types/errors/errors.go

@@ -147,6 +147,9 @@ var (
 	// ErrPanic is only set when we recover from a panic, so we know to
 	// redact potentially sensitive system info
 	ErrPanic = Register(UndefinedCodespace, 111222, "panic")
+
+	// ErrLastTx defines an error occurred if we tried to execute another msg after the last one was set
+	ErrLastTx = Register(RootCodespace, 40404, "Cannot send messages after last tx marker was set")
 )
 
 // Register returns an error instance that should be used as the base for