allow transactions within event handlers having different origins

src/types/YText.js

@@ -1064,7 +1064,7 @@ export class YText extends AbstractType {
         n = n.right
       }
       packStr()
-    }, splitSnapshotAffectedStructs)
+    }, 'cleanup')
     return ops
   }
 

src/utils/Transaction.js

@@ -251,7 +251,6 @@ const cleanupTransactions = (transactionCleanups, i) => {
     try {
       sortAndMergeDeleteSet(ds)
       transaction.afterState = getStateVector(transaction.doc.store)
-      doc._transaction = null
       doc.emit('beforeObserverCalls', [transaction, doc])
       /**
        * An array of event callbacks.
@@ -398,16 +397,20 @@ export const transact = (doc, f, origin = null, local = true) => {
   try {
     f(doc._transaction)
   } finally {
-    if (initialCall && transactionCleanups[0] === doc._transaction) {
-      // The first transaction ended, now process observer calls.
-      // Observer call may create new transactions for which we need to call the observers and do cleanup.
-      // We don't want to nest these calls, so we execute these calls one after
-      // another.
-      // Also we need to ensure that all cleanups are called, even if the
-      // observes throw errors.
-      // This file is full of hacky try {} finally {} blocks to ensure that an
-      // event can throw errors and also that the cleanup is called.
-      cleanupTransactions(transactionCleanups, 0)
+    if (initialCall) {
+      const finishCleanup = doc._transaction === transactionCleanups[0]
+      doc._transaction = null
+      if (finishCleanup) {
+        // The first transaction ended, now process observer calls.
+        // Observer call may create new transactions for which we need to call the observers and do cleanup.
+        // We don't want to nest these calls, so we execute these calls one after
+        // another.
+        // Also we need to ensure that all cleanups are called, even if the
+        // observes throw errors.
+        // This file is full of hacky try {} finally {} blocks to ensure that an
+        // event can throw errors and also that the cleanup is called.
+        cleanupTransactions(transactionCleanups, 0)
+      }
     }
   }
 }

tests/doc.tests.js

@@ -2,6 +2,31 @@
 import * as Y from '../src/index.js'
 import * as t from 'lib0/testing'
 
+/**
+ * @param {t.TestCase} _tc
+ */
+export const testOriginInTransaction = _tc => {
+  const doc = new Y.Doc()
+  const ytext = doc.getText()
+  /**
+   * @type {Array<string>}
+   */
+  const origins = []
+  doc.on('afterTransaction', (tr) => {
+    origins.push(tr.origin)
+    if (origins.length <= 1) {
+      ytext.toDelta()
+      doc.transact(() => {
+        ytext.insert(0, 'a')
+      }, 'nested')
+    }
+  })
+  doc.transact(() => {
+    ytext.insert(0, '0')
+  }, 'first')
+  t.compareArrays(origins, ['first', 'cleanup', 'nested'])
+}
+
 /**
  * Client id should be changed when an instance receives updates from another client using the same client id.
  *