diff --git a/AnkiDroid/src/androidTest/java/com/ichi2/anki/tests/ContentProviderTest.kt b/AnkiDroid/src/androidTest/java/com/ichi2/anki/tests/ContentProviderTest.kt
index 1ccd1a940765..f4a2a3779599 100644
--- a/AnkiDroid/src/androidTest/java/com/ichi2/anki/tests/ContentProviderTest.kt
+++ b/AnkiDroid/src/androidTest/java/com/ichi2/anki/tests/ContentProviderTest.kt
@@ -171,7 +171,7 @@ class ContentProviderTest : InstrumentedTest() {
             col.decks.count(),
         )
         // Delete test note type
-        col.modSchemaNoCheck()
+        col.modSchema(check = false)
         removeAllNoteTypesByName(col, BASIC_NOTE_TYPE_NAME)
         removeAllNoteTypesByName(col, TEST_NOTE_TYPE_NAME)
     }
@@ -642,7 +642,7 @@ class ContentProviderTest : InstrumentedTest() {
             }
         } finally {
             // Delete the note type (this will force a full-sync)
-            col.modSchemaNoCheck()
+            col.modSchema(check = false)
             try {
                 val noteType = col.notetypes.get(noteTypeId)
                 assertNotNull("Check note type", noteType)
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/CardTemplateEditor.kt b/AnkiDroid/src/main/java/com/ichi2/anki/CardTemplateEditor.kt
index 85f29417227b..af688b729dee 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/CardTemplateEditor.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/CardTemplateEditor.kt
@@ -1357,7 +1357,7 @@ open class CardTemplateEditor :
          */
         private fun executeWithSyncCheck(schemaChangingAction: Runnable) {
             try {
-                templateEditor.getColUnsafe.modSchema()
+                templateEditor.getColUnsafe.modSchema(check = true)
                 schemaChangingAction.run()
                 templateEditor.loadTemplatePreviewerFragmentIfFragmented()
             } catch (e: ConfirmModSchemaException) {
@@ -1366,7 +1366,7 @@ open class CardTemplateEditor :
                 d.setArgs(resources.getString(R.string.full_sync_confirmation))
                 val confirm =
                     Runnable {
-                        templateEditor.getColUnsafe.modSchemaNoCheck()
+                        templateEditor.getColUnsafe.modSchema(check = false)
                         schemaChangingAction.run()
                         templateEditor.dismissAllDialogFragments()
                     }
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/CoroutineHelpers.kt b/AnkiDroid/src/main/java/com/ichi2/anki/CoroutineHelpers.kt
index 2c01e7b67448..fc4800d912bb 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/CoroutineHelpers.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/CoroutineHelpers.kt
@@ -33,7 +33,6 @@ import androidx.lifecycle.coroutineScope
 import androidx.lifecycle.viewModelScope
 import anki.collection.Progress
 import com.ichi2.anki.CollectionManager.TR
-import com.ichi2.anki.CollectionManager.withCol
 import com.ichi2.anki.CrashReportData.Companion.throwIfDialogUnusable
 import com.ichi2.anki.CrashReportData.Companion.toCrashReportData
 import com.ichi2.anki.CrashReportData.HelpAction
@@ -41,17 +40,14 @@ import com.ichi2.anki.CrashReportData.HelpAction.AnkiBackendLink
 import com.ichi2.anki.CrashReportData.HelpAction.OpenDeckOptions
 import com.ichi2.anki.common.annotations.UseContextParameter
 import com.ichi2.anki.exception.StorageAccessException
-import com.ichi2.anki.libanki.Collection
 import com.ichi2.anki.pages.DeckOptionsDestination
 import com.ichi2.anki.snackbar.showSnackbar
 import com.ichi2.anki.utils.openUrl
 import com.ichi2.utils.create
 import com.ichi2.utils.message
-import com.ichi2.utils.negativeButton
 import com.ichi2.utils.neutralButton
 import com.ichi2.utils.positiveButton
 import com.ichi2.utils.setupEnterKeyHandler
-import com.ichi2.utils.show
 import com.ichi2.utils.title
 import kotlinx.coroutines.CancellableContinuation
 import kotlinx.coroutines.CancellationException
@@ -79,8 +75,6 @@ import org.jetbrains.annotations.VisibleForTesting
 import timber.log.Timber
 import kotlin.coroutines.CoroutineContext
 import kotlin.coroutines.EmptyCoroutineContext
-import kotlin.coroutines.resume
-import kotlin.coroutines.suspendCoroutine
 import kotlin.time.Duration
 
 /** Overridable reference to [Dispatchers.IO]. Useful if tests can't use it */
@@ -549,53 +543,6 @@ private fun ProgressContext.updateDialog(dialog: android.app.ProgressDialog) {
     dialog.setMessage(text + progressText)
 }
 
-/**
- * If a one-way sync is not already required, confirm the user wishes to proceed.
- * If the user agrees, the schema is bumped and the routine will return true.
- * On false, calling routine should abort.
- */
-suspend fun AnkiActivity.userAcceptsSchemaChange(col: Collection): Boolean {
-    if (col.schemaChanged()) {
-        return true
-    }
-    return suspendCoroutine { coroutine ->
-        AlertDialog.Builder(this).show {
-            message(text = col.tr.deckConfigWillRequireFullSync()) // generic message
-            positiveButton(R.string.dialog_ok) {
-                col.modSchemaNoCheck()
-                coroutine.resume(true)
-            }
-            negativeButton(R.string.dialog_cancel) { coroutine.resume(false) }
-            setOnCancelListener { coroutine.resume(false) }
-        }
-    }
-}
-
-/**
- * Returns whether we are allowed to change the schema.
- *
- * If changing the schema would require the next sync to be a full sync, and it's not already required, ask
- * the user whether or not they still allow the schema change.
- */
-suspend fun AnkiActivity.userAcceptsSchemaChange(): Boolean {
-    if (withCol { schemaChanged() }) {
-        return true
-    }
-    val hasAcceptedSchemaChange =
-        suspendCoroutine { coroutine ->
-            AlertDialog.Builder(this).show {
-                message(text = TR.deckConfigWillRequireFullSync().replace("\\s+".toRegex(), " "))
-                positiveButton(R.string.dialog_ok) { coroutine.resume(true) }
-                negativeButton(R.string.dialog_cancel) { coroutine.resume(false) }
-                setOnCancelListener { coroutine.resume(false) }
-            }
-        }
-    if (hasAcceptedSchemaChange) {
-        withCol { modSchemaNoCheck() }
-    }
-    return hasAcceptedSchemaChange
-}
-
 /**
  * Ensures that current continuation is not [cancelled][CancellableContinuation.isCancelled].
  *
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt b/AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt
index 6e51e6a72df0..ec1335c598e9 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/DeckPicker.kt
@@ -163,6 +163,7 @@ import com.ichi2.anki.settings.Prefs
 import com.ichi2.anki.snackbar.BaseSnackbarBuilderProvider
 import com.ichi2.anki.snackbar.SnackbarBuilder
 import com.ichi2.anki.snackbar.showSnackbar
+import com.ichi2.anki.sync.launchCatchingRequiringOneWaySyncDiscardUndo
 import com.ichi2.anki.ui.ResizablePaneManager
 import com.ichi2.anki.ui.animations.fadeIn
 import com.ichi2.anki.ui.animations.fadeOut
@@ -686,7 +687,7 @@ open class DeckPicker :
             SchedulerUpgradeDialog(
                 activity = this,
                 onUpgrade = {
-                    launchCatchingRequiringOneWaySync {
+                    launchCatchingRequiringOneWaySyncDiscardUndo {
                         this@DeckPicker.withProgress { withCol { sched.upgradeToV2() } }
                         showThemedToast(this@DeckPicker, TR.schedulingUpdateDone(), false)
                     }
@@ -1727,7 +1728,7 @@ open class DeckPicker :
         if (recommendOneWaySync) {
             recommendOneWaySync = false
             try {
-                getColUnsafe.modSchema()
+                getColUnsafe.modSchema(check = true)
             } catch (e: ConfirmModSchemaException) {
                 Timber.w("Forcing one-way sync")
                 e.log()
@@ -2474,7 +2475,7 @@ class OneWaySyncDialog(
         val confirm =
             Runnable {
                 // Bypass the check once the user confirms
-                CollectionManager.getColUnsafe().modSchemaNoCheck()
+                CollectionManager.getColUnsafe().modSchema(check = false)
             }
         dialog.setConfirm(confirm)
         dialog.setArgs(message)
@@ -2492,30 +2493,5 @@ class OneWaySyncDialog(
     }
 }
 
-/**
- * [launchCatchingTask], showing a one-way sync dialog: [R.string.full_sync_confirmation]
- */
-fun AnkiActivity.launchCatchingRequiringOneWaySync(block: suspend () -> Unit) =
-    launchCatchingTask {
-        try {
-            block()
-        } catch (e: ConfirmModSchemaException) {
-            e.log()
-
-            // .also is used to ensure the activity is used as context
-            val confirmModSchemaDialog =
-                ConfirmationDialog().also { dialog ->
-                    dialog.setArgs(message = getString(R.string.full_sync_confirmation))
-                    dialog.setConfirm {
-                        launchCatchingTask {
-                            withCol { modSchemaNoCheck() }
-                            block()
-                        }
-                    }
-                }
-            showDialogFragment(confirmModSchemaDialog)
-        }
-    }
-
 val ActivityHomescreenBinding.studyoptionsFrame: FragmentContainerView?
     get() = studyoptionsFragment
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/NoteEditorFragment.kt b/AnkiDroid/src/main/java/com/ichi2/anki/NoteEditorFragment.kt
index 7f26df1ef013..64c20ab68604 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/NoteEditorFragment.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/NoteEditorFragment.kt
@@ -152,6 +152,7 @@ import com.ichi2.anki.servicelayer.NoteService
 import com.ichi2.anki.snackbar.BaseSnackbarBuilderProvider
 import com.ichi2.anki.snackbar.SnackbarBuilder
 import com.ichi2.anki.snackbar.showSnackbar
+import com.ichi2.anki.sync.userAcceptsSchemaChange
 import com.ichi2.anki.ui.setupNoteTypeSpinner
 import com.ichi2.anki.utils.RunOnlyOnce
 import com.ichi2.anki.utils.ext.sharedPrefs
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/NoteTypeFieldEditor.kt b/AnkiDroid/src/main/java/com/ichi2/anki/NoteTypeFieldEditor.kt
index 2d4210dbc6cd..e4f5383d2cf4 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/NoteTypeFieldEditor.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/NoteTypeFieldEditor.kt
@@ -238,9 +238,9 @@ class NoteTypeFieldEditor : AnkiActivity(R.layout.note_type_field_editor) {
         fieldName ?: return
         // Name is valid, now field is added
         if (modSchemaCheck) {
-            getColUnsafe.modSchema()
+            getColUnsafe.modSchema(check = true)
         } else {
-            getColUnsafe.modSchemaNoCheck()
+            getColUnsafe.modSchema(check = false)
         }
         launchCatchingTask {
             Timber.d("doInBackgroundAddField")
@@ -259,18 +259,21 @@ class NoteTypeFieldEditor : AnkiActivity(R.layout.note_type_field_editor) {
     private fun deleteFieldDialog() {
         val confirm =
             Runnable {
-                getColUnsafe.modSchemaNoCheck()
+                getColUnsafe.modSchema(check = false)
                 deleteField()
 
                 // This ensures that the context menu closes after the field has been deleted
-                supportFragmentManager.popBackStackImmediate(null, FragmentManager.POP_BACK_STACK_INCLUSIVE)
+                supportFragmentManager.popBackStackImmediate(
+                    null,
+                    FragmentManager.POP_BACK_STACK_INCLUSIVE,
+                )
             }
 
         if (fieldsLabels.size < 2) {
             showThemedToast(this, resources.getString(R.string.toast_last_field), true)
         } else {
             try {
-                getColUnsafe.modSchema()
+                getColUnsafe.modSchema(check = true)
                 val fieldName = noteFields[currentPos].name
                 ConfirmationDialog().let {
                     it.setArgs(
@@ -342,7 +345,7 @@ class NoteTypeFieldEditor : AnkiActivity(R.layout.note_type_field_editor) {
                         c.setArgs(resources.getString(R.string.full_sync_confirmation))
                         val confirm =
                             Runnable {
-                                getColUnsafe.modSchemaNoCheck()
+                                getColUnsafe.modSchema(check = false)
                                 try {
                                     renameField()
                                 } catch (e1: ConfirmModSchemaException) {
@@ -400,7 +403,7 @@ class NoteTypeFieldEditor : AnkiActivity(R.layout.note_type_field_editor) {
 
             Timber.i("Repositioning field from %d to %d", currentPos, newPosition)
             try {
-                getColUnsafe.modSchema()
+                getColUnsafe.modSchema(check = true)
                 repositionField(newPosition - 1)
             } catch (e: ConfirmModSchemaException) {
                 e.log()
@@ -411,7 +414,7 @@ class NoteTypeFieldEditor : AnkiActivity(R.layout.note_type_field_editor) {
                 val confirm =
                     Runnable {
                         try {
-                            getColUnsafe.modSchemaNoCheck()
+                            getColUnsafe.modSchema(check = false)
                             repositionField(newPosition - 1)
                         } catch (e1: JSONException) {
                             throw RuntimeException(e1)
@@ -466,7 +469,7 @@ class NoteTypeFieldEditor : AnkiActivity(R.layout.note_type_field_editor) {
      */
     private fun sortByField() {
         try {
-            getColUnsafe.modSchema()
+            getColUnsafe.modSchema(check = true)
             launchCatchingTask { changeSortField(notetype, currentPos) }
         } catch (e: ConfirmModSchemaException) {
             e.log()
@@ -475,7 +478,7 @@ class NoteTypeFieldEditor : AnkiActivity(R.layout.note_type_field_editor) {
             c.setArgs(resources.getString(R.string.full_sync_confirmation))
             val confirm =
                 Runnable {
-                    getColUnsafe.modSchemaNoCheck()
+                    getColUnsafe.modSchema(check = false)
                     launchCatchingTask { changeSortField(notetype, currentPos) }
                 }
             c.setConfirm(confirm)
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeDialog.kt b/AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeDialog.kt
index e5ad2234a29f..25907aa935f8 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeDialog.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeDialog.kt
@@ -62,13 +62,13 @@ import com.ichi2.anki.dialogs.ConversionType.CLOZE_TO_CLOZE
 import com.ichi2.anki.dialogs.ConversionType.CLOZE_TO_REGULAR
 import com.ichi2.anki.dialogs.ConversionType.REGULAR_TO_CLOZE
 import com.ichi2.anki.dialogs.ConversionType.REGULAR_TO_REGULAR
-import com.ichi2.anki.launchCatchingRequiringOneWaySync
 import com.ichi2.anki.launchCatchingTask
 import com.ichi2.anki.libanki.NoteId
 import com.ichi2.anki.libanki.NoteTypeId
 import com.ichi2.anki.requireAnkiActivity
 import com.ichi2.anki.showError
 import com.ichi2.anki.snackbar.showSnackbar
+import com.ichi2.anki.sync.launchCatchingRequiringOneWaySync
 import com.ichi2.anki.ui.BasicItemSelectedListener
 import com.ichi2.anki.ui.internationalization.toSentenceCase
 import com.ichi2.anki.utils.InitStatus
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeViewModel.kt b/AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeViewModel.kt
index 0d1783beabcd..0f0769d83ee7 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeViewModel.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/dialogs/ChangeNoteTypeViewModel.kt
@@ -316,8 +316,6 @@ class ChangeNoteTypeViewModel(
             Timber.d("Field map: %s", fieldChangeMap)
             Timber.d("Card map: %s", templateChangeMap)
 
-            withCol { modSchema() }
-
             val changes =
                 changeNoteTypeOfNotes(
                     noteIds = noteIds,
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/notetype/ManageNotetypes.kt b/AnkiDroid/src/main/java/com/ichi2/anki/notetype/ManageNotetypes.kt
index 86b1b576b38f..cec573f936d3 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/notetype/ManageNotetypes.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/notetype/ManageNotetypes.kt
@@ -41,7 +41,7 @@ import com.ichi2.anki.dialogs.showLoadingDialog
 import com.ichi2.anki.launchCatchingTask
 import com.ichi2.anki.notetype.ManageNoteTypesState.UserMessage
 import com.ichi2.anki.snackbar.showSnackbar
-import com.ichi2.anki.userAcceptsSchemaChange
+import com.ichi2.anki.sync.userAcceptsSchemaChange
 import com.ichi2.anki.utils.Destination
 import com.ichi2.ui.AccessibleSearchView
 import com.ichi2.utils.getInputField
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/preferences/SyncSettingsFragment.kt b/AnkiDroid/src/main/java/com/ichi2/anki/preferences/SyncSettingsFragment.kt
index 5c457be4b37b..ce67ce319109 100644
--- a/AnkiDroid/src/main/java/com/ichi2/anki/preferences/SyncSettingsFragment.kt
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/preferences/SyncSettingsFragment.kt
@@ -68,7 +68,7 @@ class SyncSettingsFragment : SettingsFragment() {
                     setMessage(TR.preferencesOnNextSyncForceChangesIn())
                     setPositiveButton(R.string.dialog_ok) { _, _ ->
                         launchCatchingTask {
-                            withCol { modSchemaNoCheck() }
+                            withCol { modSchema(check = false) }
                             showSnackbar(R.string.one_way_sync_confirmation, Snackbar.LENGTH_SHORT)
                         }
                     }
diff --git a/AnkiDroid/src/main/java/com/ichi2/anki/sync/SchemaChanges.kt b/AnkiDroid/src/main/java/com/ichi2/anki/sync/SchemaChanges.kt
new file mode 100644
index 000000000000..a3acec5d7e13
--- /dev/null
+++ b/AnkiDroid/src/main/java/com/ichi2/anki/sync/SchemaChanges.kt
@@ -0,0 +1,112 @@
+/*
+ *  Copyright (c) 2026 David Allison <davidallisongithub@gmail.com>
+ *
+ *  This program is free software; you can redistribute it and/or modify it under
+ *  the terms of the GNU General Public License as published by the Free Software
+ *  Foundation; either version 3 of the License, or (at your option) any later
+ *  version.
+ *
+ *  This program is distributed in the hope that it will be useful, but WITHOUT ANY
+ *  WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
+ *  PARTICULAR PURPOSE. See the GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package com.ichi2.anki.sync
+
+import androidx.appcompat.app.AlertDialog
+import com.ichi2.anki.AnkiActivity
+import com.ichi2.anki.CollectionManager.TR
+import com.ichi2.anki.CollectionManager.withCol
+import com.ichi2.anki.R
+import com.ichi2.anki.dialogs.ConfirmationDialog
+import com.ichi2.anki.launchCatchingTask
+import com.ichi2.anki.libanki.Collection
+import com.ichi2.anki.libanki.exception.ConfirmModSchemaException
+import com.ichi2.anki.utils.ext.showDialogFragment
+import com.ichi2.utils.message
+import com.ichi2.utils.negativeButton
+import com.ichi2.utils.positiveButton
+import com.ichi2.utils.show
+import kotlin.coroutines.resume
+import kotlin.coroutines.suspendCoroutine
+
+/**
+ * [launchCatchingTask], showing a one-way sync dialog: [R.string.full_sync_confirmation]
+ *
+ * @param block calls a backend method which unconditionally performs a schema change,
+ *  such as [Collection.changeNotetypeRaw]
+ */
+fun AnkiActivity.launchCatchingRequiringOneWaySync(block: suspend () -> Unit) =
+    launchCatchingTask {
+        if (withCol { !schemaChanged() }) {
+            // .also is used to ensure the activity is used as context
+            val confirmModSchemaDialog =
+                ConfirmationDialog().also { dialog ->
+                    dialog.setArgs(message = getString(R.string.full_sync_confirmation))
+                    dialog.setConfirm {
+                        launchCatchingTask {
+                            block()
+                        }
+                    }
+                }
+            showDialogFragment(confirmModSchemaDialog)
+            return@launchCatchingTask
+        }
+        // TODO: use context(SchemaChangedConfirmed) after bug #20247 is fixed (upstream-issue)
+        block()
+    }
+
+/**
+ * [launchCatchingTask], showing a one-way sync dialog: [R.string.full_sync_confirmation]
+ *
+ * **This method discards the undo and study queues when consent is provided**
+ */
+fun AnkiActivity.launchCatchingRequiringOneWaySyncDiscardUndo(block: suspend () -> Unit) =
+    launchCatchingTask {
+        try {
+            block()
+        } catch (e: ConfirmModSchemaException) {
+            e.log()
+
+            // .also is used to ensure the activity is used as context
+            val confirmModSchemaDialog =
+                ConfirmationDialog().also { dialog ->
+                    dialog.setArgs(message = getString(R.string.full_sync_confirmation))
+                    dialog.setConfirm {
+                        launchCatchingTask {
+                            withCol { modSchema(check = false) }
+                            block()
+                        }
+                    }
+                }
+            showDialogFragment(confirmModSchemaDialog)
+        }
+    }
+
+/**
+ * Returns whether we are allowed to change the schema.
+ *
+ * If changing the schema would require the next sync to be a full sync, and it's not already required, ask
+ * the user whether or not they still allow the schema change.
+ */
+suspend fun AnkiActivity.userAcceptsSchemaChange(): Boolean {
+    if (withCol { schemaChanged() }) {
+        return true
+    }
+    val hasAcceptedSchemaChange =
+        suspendCoroutine { coroutine ->
+            AlertDialog.Builder(this).show {
+                message(text = TR.deckConfigWillRequireFullSync().replace("\\s+".toRegex(), " "))
+                positiveButton(R.string.dialog_ok) { coroutine.resume(true) }
+                negativeButton(R.string.dialog_cancel) { coroutine.resume(false) }
+                setOnCancelListener { coroutine.resume(false) }
+            }
+        }
+    if (hasAcceptedSchemaChange) {
+        withCol { modSchema(check = false) }
+    }
+    return hasAcceptedSchemaChange
+}
diff --git a/libanki/src/main/java/com/ichi2/anki/libanki/Collection.kt b/libanki/src/main/java/com/ichi2/anki/libanki/Collection.kt
index 5a1305abfd39..5913f69093a9 100644
--- a/libanki/src/main/java/com/ichi2/anki/libanki/Collection.kt
+++ b/libanki/src/main/java/com/ichi2/anki/libanki/Collection.kt
@@ -337,14 +337,14 @@ class Collection(
         config = Config(backend)
     }
 
-    /** Mark schema modified to force a full
-     * sync, but with the confirmation checking function disabled This
-     * is equivalent to `modSchema(False)` in Anki. A distinct method
-     * is used so that the type does not states that an exception is
-     * thrown when in fact it is never thrown.
+    /**
+     * Marks the schema as modified to cause a one-way sync.
+     *
+     * **This method discards the undo and study queues when returning successfully**
      */
-    @NotInPyLib
-    fun modSchemaNoCheck() {
+    @LibAnkiAlias("set_schema_modified")
+    @RustCleanup("Anki only sets scm, not mod")
+    fun setSchemaModified() {
         db.execute(
             "update col set scm=?, mod=?",
             TimeManager.time.intTimeMS(),
@@ -352,23 +352,31 @@ class Collection(
         )
     }
 
-    /** Mark schema modified to cause a one-way sync.
-     * ConfirmModSchemaException will be thrown if the user needs to be prompted to confirm the action.
-     * If the user chooses to confirm then modSchemaNoCheck should be called, after which the exception can
-     * be safely ignored, and the outer code called again.
+    /**
+     * Marks the schema as modified to cause a one-way sync, throwing [ConfirmModSchemaException]
+     * when [check] is `true` and a one-way sync was not previously required
+     * (the schema was not previously modified).
      *
-     * @throws ConfirmModSchemaException
+     * **This method discards the undo and study queues when returning successfully**
+     * ([check] == `false` OR [check] == `true` and the schema was previously modified).
+     *
+     * @param check whether to throw [ConfirmModSchemaException] if the schema is unchanged.
+     * Use `false` after catching the exception and obtaining user consent.
+     *
+     * @throws ConfirmModSchemaException if the schema is currently unchanged and [check] is `true`
      */
     @LibAnkiAlias("mod_schema")
-    fun modSchema() {
+    fun modSchema(check: Boolean) {
         if (!schemaChanged()) {
-            /* In Android we can't show a dialog which blocks the main UI thread
-             Therefore we can't wait for the user to confirm if they want to do
-             a one-way sync here, and we instead throw an exception asking the outer
-             code to handle the user's choice */
-            throw ConfirmModSchemaException()
+            if (check) {
+                /* In Android we can't show a dialog which blocks the main UI thread
+                   Therefore we can't wait for the user to confirm if they want to do
+                   a one-way sync here, and we instead throw an exception asking the outer
+                   code to handle the user's choice */
+                throw ConfirmModSchemaException()
+            }
         }
-        modSchemaNoCheck()
+        setSchemaModified()
     }
 
     /** `true` if schema changed since last sync. */
diff --git a/libanki/src/main/java/com/ichi2/anki/libanki/DB.kt b/libanki/src/main/java/com/ichi2/anki/libanki/DB.kt
index ba561bceb86e..124ee78a3b33 100644
--- a/libanki/src/main/java/com/ichi2/anki/libanki/DB.kt
+++ b/libanki/src/main/java/com/ichi2/anki/libanki/DB.kt
@@ -120,20 +120,27 @@ class DB(
         return results
     }
 
+    /**
+     * Execute a single SQL statement that does not return data.
+     *
+     * This method discards the undo and study queues unless the statement is a `SELECT`.
+     */
     fun execute(
         sql: String,
         vararg `object`: Any?,
     ) {
-        val s = sql.trim().lowercase()
-        // mark modified?
-        for (mo in MOD_SQL_STATEMENTS) {
-            if (s.startsWith(mo)) {
-                break
-            }
+        // permalink: https://github.com/ankitects/anki/blob/83c615cc7f9aef3c336936fa797671965538f89c/rslib/src/backend/dbproxy.rs#L170-L178
+        if (!sql.lowercase().trim().startsWith("select")) {
+            Timber.i("clearing undo and study queues")
         }
         database.execSQL(sql, `object`)
     }
 
+    /**
+     * Executes a collection of ';'-delimited SQL statements which do not return data.
+     *
+     * This method discards the undo and study queues unless all statements are `SELECT`.
+     */
     @KotlinCleanup("""Use Kotlin string. Change split so that there is no empty string after last ";".""")
     fun executeScript(sql: String) {
         val queries = sql.split(";")
diff --git a/libanki/src/main/java/com/ichi2/anki/libanki/Notetypes.kt b/libanki/src/main/java/com/ichi2/anki/libanki/Notetypes.kt
index 79edc1a278e2..25e852aaacc8 100644
--- a/libanki/src/main/java/com/ichi2/anki/libanki/Notetypes.kt
+++ b/libanki/src/main/java/com/ichi2/anki/libanki/Notetypes.kt
@@ -561,10 +561,12 @@ class Notetypes(
      *
      * Each value represents the index in the previous notetype.
      * -1 indicates the original value will be discarded.
+     *
+     * **This method updates the schema without confirmation**
      */
     @LibAnkiAlias("change_notetype_of_notes")
     fun changeNotetypeOfNotes(input: ChangeNotetypeRequest): OpChanges {
-        val opBytes = this.col.backend.changeNotetypeRaw(input.toByteArray())
+        val opBytes = col.backend.changeNotetypeRaw(input.toByteArray())
         return OpChanges.parseFrom(opBytes)
     }
 
diff --git a/libanki/src/main/java/com/ichi2/anki/libanki/sched/Scheduler.kt b/libanki/src/main/java/com/ichi2/anki/libanki/sched/Scheduler.kt
index b8281e3a714f..cd959e55aac1 100644
--- a/libanki/src/main/java/com/ichi2/anki/libanki/sched/Scheduler.kt
+++ b/libanki/src/main/java/com/ichi2/anki/libanki/sched/Scheduler.kt
@@ -229,7 +229,7 @@ open class Scheduler(
      * @throws com.ichi2.anki.libanki.exception.ConfirmModSchemaException
      */
     fun upgradeToV2() {
-        col.modSchema()
+        col.modSchema(check = true)
         col.backend.upgradeScheduler()
         col._loadScheduler()
     }