diff --git a/src/structs/AbstractItem.js b/src/structs/AbstractItem.js
index 502e9767..0b1f873e 100644
--- a/src/structs/AbstractItem.js
+++ b/src/structs/AbstractItem.js
@@ -29,11 +29,12 @@ import * as binary from 'lib0/binary.js'
 
 /**
  * Split leftItem into two items
+ * @param {Transaction} transaction
  * @param {AbstractItem} leftItem
  * @param {number} diff
  * @return {AbstractItem}
  */
-export const splitItem = (leftItem, diff) => {
+export const splitItem = (transaction, leftItem, diff) => {
   const id = leftItem.id
   // create rightItem
   const rightItem = leftItem.copy(
@@ -54,6 +55,8 @@ export const splitItem = (leftItem, diff) => {
   if (rightItem.right !== null) {
     rightItem.right.left = rightItem
   }
+  // right is more specific.
+  transaction._replacedItems.add(rightItem)
   return rightItem
 }
 
@@ -357,10 +360,11 @@ export class AbstractItem extends AbstractStruct {
    *
    * This method should only be cally by StructStore.
    *
+   * @param {Transaction} transaction
    * @param {number} diff
    * @return {AbstractItem}
    */
-  splitAt (diff) {
+  splitAt (transaction, diff) {
     throw new Error('unimplemented')
   }
 
@@ -549,7 +553,7 @@ export const changeItemRefOffset = (item, offset) => {
  * Outsourcing some of the logic of computing the item params from a received struct.
  * If parent === null, it is expected to gc the read struct. Otherwise apply it.
  *
- * @param {Y} y
+ * @param {Transaction} transaction
  * @param {StructStore} store
  * @param {ID|null} leftid
  * @param {ID|null} rightid
@@ -558,13 +562,9 @@ export const changeItemRefOffset = (item, offset) => {
  * @param {string|null} parentYKey
  * @return {{left:AbstractItem?,right:AbstractItem?,parent:AbstractType<YEvent>?,parentSub:string?}}
  */
-export const computeItemParams = (y, store, leftid, rightid, parentid, parentSub, parentYKey) => {
-  const left = leftid === null ? null : getItemCleanEnd(store, leftid)
-  if (left !== null && left.constructor !== GC && left.right !== null && left.right.id.client === left.id.client && left.right.id.clock === left.id.clock + left.length) {
-    // we split a merged op, we may need to merge it again after the transaction
-    y.transaction._replacedItems.add(left)
-  }
-  const right = rightid === null ? null : getItemCleanStart(store, rightid)
+export const computeItemParams = (transaction, store, leftid, rightid, parentid, parentSub, parentYKey) => {
+  const left = leftid === null ? null : getItemCleanEnd(transaction, store, leftid)
+  const right = rightid === null ? null : getItemCleanStart(transaction, store, rightid)
   let parent = null
   if (parentid !== null) {
     const parentItem = getItemType(store, parentid)
@@ -576,7 +576,7 @@ export const computeItemParams = (y, store, leftid, rightid, parentid, parentSub
         parent = parentItem.type
     }
   } else if (parentYKey !== null) {
-    parent = y.get(parentYKey)
+    parent = transaction.y.get(parentYKey)
   } else if (left !== null) {
     if (left.constructor !== GC) {
       parent = left.parent
diff --git a/src/structs/AbstractStruct.js b/src/structs/AbstractStruct.js
index 83e7ed60..acceb870 100644
--- a/src/structs/AbstractStruct.js
+++ b/src/structs/AbstractStruct.js
@@ -76,12 +76,12 @@ export class AbstractRef {
     return this._missing
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {AbstractStruct}
    */
-  toStruct (y, store, offset) {
+  toStruct (transaction, store, offset) {
     throw error.methodUnimplemented()
   }
   /**
diff --git a/src/structs/GC.js b/src/structs/GC.js
index fb5693d1..c96f7b6c 100644
--- a/src/structs/GC.js
+++ b/src/structs/GC.js
@@ -82,12 +82,12 @@ export class GCRef extends AbstractRef {
     ]
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {GC}
    */
-  toStruct (y, store, offset) {
+  toStruct (transaction, store, offset) {
     if (offset > 0) {
       // @ts-ignore
       this.id = createID(this.id.client, this.id.clock + offset)
diff --git a/src/structs/ItemBinary.js b/src/structs/ItemBinary.js
index 645f2c9a..e4c19abd 100644
--- a/src/structs/ItemBinary.js
+++ b/src/structs/ItemBinary.js
@@ -7,7 +7,7 @@ import {
   AbstractItemRef,
   computeItemParams,
   GC,
-  StructStore, Y, AbstractType, ID, YEvent // eslint-disable-line
+  StructStore, Transaction, AbstractType, ID // eslint-disable-line
 } from '../internals.js'
 
 import * as encoding from 'lib0/encoding.js'
@@ -69,13 +69,13 @@ export class ItemBinaryRef extends AbstractItemRef {
     this.content = decoding.readPayload(decoder)
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {ItemBinary|GC}
    */
-  toStruct (y, store, offset) {
-    const { left, right, parent, parentSub } = computeItemParams(y, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
+  toStruct (transaction, store, offset) {
+    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
     return parent === null
       ? new GC(this.id, this.length)
       : new ItemBinary(
diff --git a/src/structs/ItemDeleted.js b/src/structs/ItemDeleted.js
index 7cd1e89f..d444145e 100644
--- a/src/structs/ItemDeleted.js
+++ b/src/structs/ItemDeleted.js
@@ -57,14 +57,15 @@ export class ItemDeleted extends AbstractItem {
     addToDeleteSet(transaction.deleteSet, this.id, this.length)
   }
   /**
+   * @param {Transaction} transaction
    * @param {number} diff
    */
-  splitAt (diff) {
+  splitAt (transaction, diff) {
     /**
      * @type {ItemDeleted}
      */
     // @ts-ignore
-    const right = splitItem(this, diff)
+    const right = splitItem(transaction, this, diff)
     right._len -= diff
     this._len = diff
     return right
@@ -107,18 +108,18 @@ export class ItemDeletedRef extends AbstractItemRef {
     return this.len
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {ItemDeleted|GC}
    */
-  toStruct (y, store, offset) {
+  toStruct (transaction, store, offset) {
     if (offset > 0) {
       changeItemRefOffset(this, offset)
       this.len = this.len - offset
     }
 
-    const { left, right, parent, parentSub } = computeItemParams(y, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
+    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
     return parent === null
       ? new GC(this.id, this.length)
       : new ItemDeleted(
diff --git a/src/structs/ItemEmbed.js b/src/structs/ItemEmbed.js
index 3f4a9719..24f7a81b 100644
--- a/src/structs/ItemEmbed.js
+++ b/src/structs/ItemEmbed.js
@@ -7,7 +7,7 @@ import {
   AbstractItemRef,
   computeItemParams,
   GC,
-  Y, StructStore, ID, AbstractType // eslint-disable-line
+  Transaction, StructStore, ID, AbstractType // eslint-disable-line
 } from '../internals.js'
 
 import * as encoding from 'lib0/encoding.js'
@@ -66,13 +66,13 @@ export class ItemEmbedRef extends AbstractItemRef {
     this.embed = JSON.parse(decoding.readVarString(decoder))
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {ItemEmbed|GC}
    */
-  toStruct (y, store, offset) {
-    const { left, right, parent, parentSub } = computeItemParams(y, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
+  toStruct (transaction, store, offset) {
+    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
     return parent === null
       ? new GC(this.id, this.length)
       : new ItemEmbed(
diff --git a/src/structs/ItemFormat.js b/src/structs/ItemFormat.js
index 244aa295..92da6570 100644
--- a/src/structs/ItemFormat.js
+++ b/src/structs/ItemFormat.js
@@ -7,7 +7,7 @@ import {
   AbstractItemRef,
   computeItemParams,
   GC,
-  Y, StructStore, ID, AbstractType // eslint-disable-line
+  Transaction, StructStore, ID, AbstractType // eslint-disable-line
 } from '../internals.js'
 
 import * as encoding from 'lib0/encoding.js'
@@ -73,13 +73,13 @@ export class ItemFormatRef extends AbstractItemRef {
     this.value = JSON.parse(decoding.readVarString(decoder))
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {ItemFormat|GC}
    */
-  toStruct (y, store, offset) {
-    const { left, right, parent, parentSub } = computeItemParams(y, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
+  toStruct (transaction, store, offset) {
+    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
     return parent === null
       ? new GC(this.id, this.length)
       : new ItemFormat(
diff --git a/src/structs/ItemJSON.js b/src/structs/ItemJSON.js
index aadb71e7..ceb0def3 100644
--- a/src/structs/ItemJSON.js
+++ b/src/structs/ItemJSON.js
@@ -9,7 +9,7 @@ import {
   splitItem,
   changeItemRefOffset,
   GC,
-  StructStore, Y, ID, AbstractType // eslint-disable-line
+  Transaction, StructStore, Y, ID, AbstractType // eslint-disable-line
 } from '../internals.js'
 
 import * as encoding from 'lib0/encoding.js'
@@ -54,14 +54,15 @@ export class ItemJSON extends AbstractItem {
     return this.content
   }
   /**
+   * @param {Transaction} transaction
    * @param {number} diff
    */
-  splitAt (diff) {
+  splitAt (transaction, diff) {
     /**
      * @type {ItemJSON}
      */
     // @ts-ignore
-    const right = splitItem(this, diff)
+    const right = splitItem(transaction, this, diff)
     right.content = this.content.splice(diff)
     return right
   }
@@ -118,17 +119,17 @@ export class ItemJSONRef extends AbstractItemRef {
     return this.content.length
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {ItemJSON|GC}
    */
-  toStruct (y, store, offset) {
+  toStruct (transaction, store, offset) {
     if (offset > 0) {
       changeItemRefOffset(this, offset)
       this.content = this.content.slice(offset)
     }
-    const { left, right, parent, parentSub } = computeItemParams(y, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
+    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
     return parent === null
       ? new GC(this.id, this.length)
       : new ItemJSON(
diff --git a/src/structs/ItemString.js b/src/structs/ItemString.js
index b0373c91..24e57f2f 100644
--- a/src/structs/ItemString.js
+++ b/src/structs/ItemString.js
@@ -8,7 +8,7 @@ import {
   splitItem,
   changeItemRefOffset,
   GC,
-  StructStore, Y, ID, AbstractType // eslint-disable-line
+  Transaction, StructStore, Y, ID, AbstractType // eslint-disable-line
 } from '../internals.js'
 
 import * as encoding from 'lib0/encoding.js'
@@ -53,15 +53,16 @@ export class ItemString extends AbstractItem {
     return this.string.length
   }
   /**
+   * @param {Transaction} transaction
    * @param {number} diff
    * @return {ItemString}
    */
-  splitAt (diff) {
+  splitAt (transaction, diff) {
     /**
      * @type {ItemString}
      */
     // @ts-ignore
-    const right = splitItem(this, diff)
+    const right = splitItem(transaction, this, diff)
     right.string = this.string.slice(diff)
     this.string = this.string.slice(0, diff)
     return right
@@ -104,18 +105,18 @@ export class ItemStringRef extends AbstractItemRef {
     return this.string.length
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {ItemString|GC}
    */
-  toStruct (y, store, offset) {
+  toStruct (transaction, store, offset) {
     if (offset > 0) {
       changeItemRefOffset(this, offset)
       this.string = this.string.slice(offset)
     }
 
-    const { left, right, parent, parentSub } = computeItemParams(y, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
+    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
     return parent === null
       ? new GC(this.id, this.length)
       : new ItemString(
diff --git a/src/structs/ItemType.js b/src/structs/ItemType.js
index 8d16016a..67c11e90 100644
--- a/src/structs/ItemType.js
+++ b/src/structs/ItemType.js
@@ -150,13 +150,13 @@ export class ItemTypeRef extends AbstractItemRef {
     this.type = typeRefs[typeRef](decoder)
   }
   /**
-   * @param {Y} y
+   * @param {Transaction} transaction
    * @param {StructStore} store
    * @param {number} offset
    * @return {ItemType|GC}
    */
-  toStruct (y, store, offset) {
-    const { left, right, parent, parentSub } = computeItemParams(y, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
+  toStruct (transaction, store, offset) {
+    const { left, right, parent, parentSub } = computeItemParams(transaction, store, this.left, this.right, this.parent, this.parentSub, this.parentYKey)
     return parent === null
       ? new GC(this.id, this.length)
       : new ItemType(
diff --git a/src/types/AbstractType.js b/src/types/AbstractType.js
index e39f36fe..76625ab1 100644
--- a/src/types/AbstractType.js
+++ b/src/types/AbstractType.js
@@ -381,7 +381,7 @@ export const typeArrayInsertGenerics = (transaction, parent, index, content) =>
       if (index <= n.length) {
         if (index < n.length) {
           // insert in-between
-          getItemCleanStart(transaction.y.store, createID(n.id.client, n.id.clock + index))
+          getItemCleanStart(transaction, transaction.y.store, createID(n.id.client, n.id.clock + index))
         }
         break
       }
@@ -405,7 +405,7 @@ export const typeArrayDelete = (transaction, parent, index, length) => {
     if (!n.deleted && n.countable) {
       if (index <= n.length) {
         if (index < n.length && index > 0) {
-          n = getItemCleanStart(transaction.y.store, createID(n.id.client, n.id.clock + index))
+          n = getItemCleanStart(transaction, transaction.y.store, createID(n.id.client, n.id.clock + index))
         }
         break
       }
@@ -416,7 +416,7 @@ export const typeArrayDelete = (transaction, parent, index, length) => {
   while (length > 0 && n !== null) {
     if (!n.deleted) {
       if (length < n.length) {
-        getItemCleanStart(transaction.y.store, createID(n.id.client, n.id.clock + length))
+        getItemCleanStart(transaction, transaction.y.store, createID(n.id.client, n.id.clock + length))
       }
       n.delete(transaction)
       length -= n.length
diff --git a/src/types/YText.js b/src/types/YText.js
index 0c397960..aa0f8fb1 100644
--- a/src/types/YText.js
+++ b/src/types/YText.js
@@ -39,7 +39,7 @@ const findNextPosition = (transaction, store, currentAttributes, left, right, co
         if (!right.deleted) {
           if (count < right.length) {
             // split right
-            getItemCleanStart(store, createID(right.id.client, right.id.clock + count))
+            getItemCleanStart(transaction, store, createID(right.id.client, right.id.clock + count))
           }
           count -= right.length
         }
@@ -251,7 +251,7 @@ const formatText = (transaction, parent, left, right, currentAttributes, length,
         case ItemEmbed:
         case ItemString:
           if (length < right.length) {
-            getItemCleanStart(transaction.y.store, createID(right.id.client, right.id.clock + length))
+            getItemCleanStart(transaction, transaction.y.store, createID(right.id.client, right.id.clock + length))
           }
           length -= right.length
           break
@@ -284,7 +284,7 @@ const deleteText = (transaction, parent, left, right, currentAttributes, length)
         case ItemEmbed:
         case ItemString:
           if (length < right.length) {
-            getItemCleanStart(transaction.y.store, createID(right.id.client, right.id.clock + length))
+            getItemCleanStart(transaction, transaction.y.store, createID(right.id.client, right.id.clock + length))
           }
           length -= right.length
           right.delete(transaction)
diff --git a/src/utils/DeleteSet.js b/src/utils/DeleteSet.js
index 03c52c54..44417d19 100644
--- a/src/utils/DeleteSet.js
+++ b/src/utils/DeleteSet.js
@@ -193,7 +193,7 @@ export const readDeleteSet = (decoder, transaction, store) => {
         let struct = structs[index]
         // split the first item if necessary
         if (!struct.deleted && struct.id.clock < clock) {
-          structs.splice(index + 1, 0, struct.splitAt(clock - struct.id.clock))
+          structs.splice(index + 1, 0, struct.splitAt(transaction, clock - struct.id.clock))
           index++ // increase we now want to use the next struct
         }
         while (index < structs.length) {
@@ -202,7 +202,7 @@ export const readDeleteSet = (decoder, transaction, store) => {
           if (struct.id.clock < clock + len) {
             if (!struct.deleted) {
               if (clock + len < struct.id.clock + struct.length) {
-                structs.splice(index, 0, struct.splitAt(clock + len - struct.id.clock))
+                structs.splice(index, 0, struct.splitAt(transaction, clock + len - struct.id.clock))
               }
               struct.delete(transaction)
             }
diff --git a/src/utils/StructStore.js b/src/utils/StructStore.js
index ce382e39..3061d5eb 100644
--- a/src/utils/StructStore.js
+++ b/src/utils/StructStore.js
@@ -2,7 +2,7 @@
 
 import {
   GC,
-  AbstractRef, ID, ItemType, AbstractItem, AbstractStruct // eslint-disable-line
+  Transaction, AbstractRef, ID, ItemType, AbstractItem, AbstractStruct // eslint-disable-line
 } from '../internals.js'
 
 import * as math from 'lib0/math.js'
@@ -167,13 +167,15 @@ export const getItemType = (store, id) => find(store, id)
 
 /**
  * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
+ *
+ * @param {Transaction} transaction
  * @param {StructStore} store
  * @param {ID} id
  * @return {AbstractItem}
  *
  * @private
  */
-export const getItemCleanStart = (store, id) => {
+export const getItemCleanStart = (transaction, store, id) => {
   /**
    * @type {Array<AbstractItem>}
    */
@@ -185,7 +187,7 @@ export const getItemCleanStart = (store, id) => {
    */
   let struct = structs[index]
   if (struct.id.clock < id.clock && struct.constructor !== GC) {
-    struct = struct.splitAt(id.clock - struct.id.clock)
+    struct = struct.splitAt(transaction, id.clock - struct.id.clock)
     structs.splice(index + 1, 0, struct)
   }
   return struct
@@ -193,13 +195,15 @@ export const getItemCleanStart = (store, id) => {
 
 /**
  * Expects that id is actually in store. This function throws or is an infinite loop otherwise.
+ *
+ * @param {Transaction} transaction
  * @param {StructStore} store
  * @param {ID} id
  * @return {AbstractItem}
  *
  * @private
  */
-export const getItemCleanEnd = (store, id) => {
+export const getItemCleanEnd = (transaction, store, id) => {
   /**
    * @type {Array<AbstractItem>}
    */
@@ -208,7 +212,7 @@ export const getItemCleanEnd = (store, id) => {
   const index = findIndexSS(structs, id.clock)
   const struct = structs[index]
   if (id.clock !== struct.id.clock + struct.length - 1 && struct.constructor !== GC) {
-    structs.splice(index + 1, 0, struct.splitAt(id.clock - struct.id.clock + 1))
+    structs.splice(index + 1, 0, struct.splitAt(transaction, id.clock - struct.id.clock + 1))
   }
   return struct
 }
diff --git a/src/utils/Transaction.js b/src/utils/Transaction.js
index 43a2625b..17441505 100644
--- a/src/utils/Transaction.js
+++ b/src/utils/Transaction.js
@@ -170,7 +170,7 @@ export const transact = (y, f) => {
           const deleteItem = deleteItems[di]
           for (let si = findIndexSS(structs, deleteItem.clock); si < structs.length; si++) {
             const struct = structs[si]
-            if (deleteItem.clock + deleteItem.len < struct.id.clock) {
+            if (deleteItem.clock + deleteItem.len <= struct.id.clock) {
               break
             }
             if (struct.deleted && struct instanceof AbstractItem && (struct.constructor !== ItemDeleted || (struct.parent._item !== null && struct.parent._item.deleted))) {
diff --git a/src/utils/structEncoding.js b/src/utils/structEncoding.js
index 7bd220d1..1a800ab0 100644
--- a/src/utils/structEncoding.js
+++ b/src/utils/structEncoding.js
@@ -207,7 +207,7 @@ const resumeStructIntegration = (transaction, store) => {
     }
     if (m.length === 0) {
       if (offset < ref.length) {
-        ref.toStruct(transaction.y, store, offset).integrate(transaction)
+        ref.toStruct(transaction, store, offset).integrate(transaction)
       }
       stack.pop()
     }
diff --git a/tests/y-array.tests.js b/tests/y-array.tests.js
index 3953a883..06c7d5e5 100644
--- a/tests/y-array.tests.js
+++ b/tests/y-array.tests.js
@@ -306,6 +306,8 @@ const arrayTransactions = [
   }
 ]
 
+// TODO: http://127.0.0.1:3443/?filter=\[22/&seed=1943600076
+
 /**
  * @param {t.TestCase} tc
  */
diff --git a/tests/y-map.tests.js b/tests/y-map.tests.js
index 5cfe0a2f..586a5f0d 100644
--- a/tests/y-map.tests.js
+++ b/tests/y-map.tests.js
@@ -348,7 +348,7 @@ const mapTransactions = [
  * @param {t.TestCase} tc
  */
 export const testRepeatGeneratingYmapTests10 = tc => {
-  applyRandomTests(tc, mapTransactions, 4)
+  applyRandomTests(tc, mapTransactions, 10)
 }
 
 /**