去掉 Action.js 里对 ActionXxx 的引入，这样还是会造成循环引入的。

Action.js

@@ -1,6 +1,5 @@
 const Ling = require('so.ling')
 const ticCrypto = require('tic.crypto')
-const wo = require('./index.js') // 许多地方需要 wo[type]
 
 /** ****************** Public of instance ********************/
 
@@ -84,7 +83,7 @@ DAD.verifyHash = function (actionData) {
 
 DAD.build = async function (action, keypair) { // Applicable on client. 客户端调用 Action.build，即可新建、并打包成一个完整的子事务，不需要亲自调用 constructor, packMe 等方法。 
   if (action && action.type && keypair && keypair.seckey && keypair.pubkey) {
-    let typedAction = new wo[action.type](action)
+    let typedAction = new require(`./${action.type}`)(action)
     if (typedAction.validateMe()) {
       await typedAction.packMe(keypair)
       return typedAction

index.js

@@ -3,7 +3,7 @@ const ActionTransfer = require('./ActionTransfer.js')
 const ActionStore = require('./ActionStore.js')
 const ActionMultisig = require('./ActionMultisig.js')
 const ActionLockProof = require('./ActionLockProof.js')
-const ActionTac = require('./ActionTac.js')
+// const ActionTac = require('./ActionTac.js')
 
 module.exports = {
 //	Action,