fix(scheduler): 'deck not found in limits map'

A 'Check database' action is shown on the error message, which resolves
the issue.

The error is no longer sent to ACRA

Fixes 15195

Assisted-by: Claude Opus 4.7 - initial debugging, wrote code which I
designed

Author: david-allison

AnkiDroid/src/main/java/com/ichi2/anki/CoroutineHelpers.kt

@@ -19,6 +19,7 @@ package com.ichi2.anki
 import android.app.Activity
 import android.app.Dialog
 import android.content.Context
+import android.content.ContextWrapper
 import android.content.DialogInterface
 import android.database.sqlite.SQLiteDatabaseCorruptException
 import android.net.Uri
@@ -37,9 +38,6 @@ import anki.collection.Progress
 import com.ichi2.anki.CollectionManager.TR
 import com.ichi2.anki.CrashReportData.Companion.throwIfDialogUnusable
 import com.ichi2.anki.CrashReportData.Companion.toCrashReportData
-import com.ichi2.anki.CrashReportData.HelpAction
-import com.ichi2.anki.CrashReportData.HelpAction.AnkiBackendLink
-import com.ichi2.anki.CrashReportData.HelpAction.OpenDeckOptions
 import com.ichi2.anki.android.AnkiBroadcastReceiver
 import com.ichi2.anki.common.annotations.UseContextParameter
 import com.ichi2.anki.common.coroutines.applicationScope
@@ -49,6 +47,7 @@ import com.ichi2.anki.dialogs.DatabaseErrorDialog.DatabaseErrorDialogType
 import com.ichi2.anki.exception.StorageAccessException
 import com.ichi2.anki.pages.DeckOptionsDestination
 import com.ichi2.anki.snackbar.showSnackbar
+import com.ichi2.anki.ui.internationalization.sentenceCase
 import com.ichi2.anki.utils.openUrl
 import com.ichi2.utils.create
 import com.ichi2.utils.message
@@ -282,16 +281,16 @@ fun Context.showError(
 
     Timber.i("Error dialog displayed")
 
+    val helpAction = crashReportData?.helpAction?.takeIf { it.canExecute(this) }
+
     try {
         AlertDialog
             .Builder(this)
             .create {
                 title(R.string.vague_error)
                 message(text = message)
                 positiveButton(R.string.dialog_ok)
-                if (crashReportData?.helpAction != null) {
-                    neutralButton(R.string.help)
-                }
+                helpAction?.let { neutralButton(text = it.buttonText(this@showError)) }
                 if (crashReportData?.reportableException == true) {
                     Timber.w("sending crash report on close")
                     setOnDismissListener { crashReportData.sendCrashReport() }
@@ -301,10 +300,7 @@ fun Context.showError(
                 setOnShowListener {
                     neutralButton?.setOnClickListener {
                         lifecycle.coroutineScope.launch {
-                            val shouldDismiss = crashReportData!!.helpAction!!.execute(context = context)
-                            if (shouldDismiss) {
-                                dismiss()
-                            }
+                            if (helpAction!!.execute(this@showError)) dismiss()
                         }
                     }
                 }
@@ -318,25 +314,13 @@ fun Context.showError(
     }
 }
 
-/**
- * @return Whether the dialog should be dismissed
- */
-suspend fun HelpAction.execute(context: Context): Boolean {
+/** The dialog's [Context] is wrapped (e.g. ContextThemeWrapper); walk the chain to find the activity. */
+internal tailrec fun Context.findAnkiActivity(): AnkiActivity? =
     when (this) {
-        is AnkiBackendLink -> {
-            context.openUrl(this.link)
-            return false
-        }
-        OpenDeckOptions -> {
-            // if we're in the error dialog, we have no context of the deck which caused the exception
-            // assume it's the current deck
-            val openCurrentDeckOptions = DeckOptionsDestination.fromCurrentDeck()
-            context.startActivity(openCurrentDeckOptions.toIntent(context))
-            // dismiss the dialog - the user should have resolved the issue
-            return true
-        }
+        is AnkiActivity -> this
+        is ContextWrapper -> baseContext.findAnkiActivity()
+        else -> null
     }
-}
 
 /** In most cases, you'll want [AnkiActivity.withProgress]
  * instead. This lower-level routine can be used to integrate your own
@@ -679,6 +663,7 @@ data class CrashReportData(
     fun shouldReportException(): Boolean {
         if (!reportableException) return false
         if (exception.isInvalidFsrsParametersException()) return false
+        if (exception.isDeckNotFoundInLimitsMapException()) return false
         if (exception is BackendInvalidInputException && exception.message == "missing template") return false
         return true
     }
@@ -699,12 +684,50 @@ data class CrashReportData(
      * - Open the deck options
      */
     sealed class HelpAction {
+        /** Label for the 'help' button on the error dialog. Defaults to "Help". */
+        open fun buttonText(context: Context): CharSequence = context.getString(R.string.help)
+
+        /** `false` hides the help button. */
+        open fun canExecute(context: Context): Boolean = true
+
+        /** Perform the action. @return whether the error dialog should be dismissed. */
+        abstract suspend fun execute(context: Context): Boolean
+
         data class AnkiBackendLink(
             val link: Uri,
-        ) : HelpAction()
+        ) : HelpAction() {
+            override suspend fun execute(context: Context): Boolean {
+                context.openUrl(link)
+                return false
+            }
+        }
 
         /** Open the deck options for the current deck */
-        data object OpenDeckOptions : HelpAction()
+        data object OpenDeckOptions : HelpAction() {
+            override suspend fun execute(context: Context): Boolean {
+                // if we're in the error dialog, we have no context of the deck which caused the exception
+                // assume it's the current deck
+                val openCurrentDeckOptions = DeckOptionsDestination.fromCurrentDeck()
+                context.startActivity(openCurrentDeckOptions.toIntent(context))
+                // dismiss the dialog - the user should have resolved the issue
+                return true
+            }
+        }
+
+        /** Opens 'Check Database' */
+        data object OpenCheckDatabase : HelpAction() {
+            override fun buttonText(context: Context): CharSequence = with(context) { TR.sentenceCase.checkDatabase }
+
+            override fun canExecute(context: Context): Boolean = context.findAnkiActivity() != null
+
+            override suspend fun execute(context: Context): Boolean {
+                Timber.i("Opening 'Check Database'")
+                context.findAnkiActivity()!!.showDatabaseErrorDialog(
+                    errorDialogType = DatabaseErrorDialogType.DIALOG_CONFIRM_DATABASE_CHECK,
+                )
+                return true
+            }
+        }
 
         companion object {
             fun from(e: Throwable): HelpAction? {
@@ -720,6 +743,7 @@ data class CrashReportData(
 
                 if (link != null) return AnkiBackendLink(link)
                 if (e.isInvalidFsrsParametersException()) return OpenDeckOptions
+                if (e.isDeckNotFoundInLimitsMapException()) return OpenCheckDatabase
 
                 return null
             }
@@ -768,5 +792,9 @@ data class CrashReportData(
             } catch (_: Throwable) {
                 false
             }
+
+        @VisibleForTesting
+        internal fun Throwable.isDeckNotFoundInLimitsMapException(): Boolean =
+            this is BackendInvalidInputException && message == "deck not found in limits map"
     }
 }

AnkiDroid/src/test/java/com/ichi2/anki/CrashReportDataTest.kt

@@ -0,0 +1,34 @@
+// SPDX-FileCopyrightText: 2026 David Allison <davidallisongithub@gmail.com>
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package com.ichi2.anki
+
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import com.ichi2.anki.CrashReportData.Companion.isDeckNotFoundInLimitsMapException
+import com.ichi2.anki.libanki.QueueType
+import com.ichi2.testutils.EmptyApplication
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.annotation.Config
+import kotlin.test.assertFailsWith
+import kotlin.test.assertTrue
+
+@RunWith(AndroidJUnit4::class)
+@Config(application = EmptyApplication::class)
+class CrashReportDataTest : RobolectricTest() {
+    /** #15195: corrupt deck hierarchy raises 'deck not found in limits map' */
+    @Test
+    fun `deck not found in limits map regression test`() {
+        addDeck("A::B::C").withNote(QueueType.New)
+        val deckBDid = col.decks.idForName("A::B")!!
+        val deckADid = col.decks.idForName("A")!!
+
+        // Drop A::B -> A::B::C is under 'A', but has no entry in the limits map
+        col.db.execute("delete from decks where id = ?", deckBDid)
+
+        col.decks.select(deckADid)
+
+        val ex = assertFailsWith<Exception> { col.sched.counts() }
+        assertTrue(ex.isDeckNotFoundInLimitsMapException())
+    }
+}