style: minor review reminder comments and reorganization

Some minor changes requested at ankidroid#20325 by David and Ashish.

Author: ericli3690

AnkiDroid/src/main/java/com/ichi2/anki/reviewreminders/ReviewReminderGroup.kt

@@ -19,6 +19,11 @@ package com.ichi2.anki.reviewreminders
 import kotlinx.serialization.SerializationException
 import kotlinx.serialization.json.Json
 
+/**
+ * Convenience typealias for the mutation functions passed to editors of [ReviewReminderGroup].
+ */
+typealias ReviewReminderGroupEditor = (ReviewReminderGroup) -> ReviewReminderGroup
+
 /**
  * A group of review reminders, all for the same [ReviewReminderScope],
  * persisted as a single JSON string in SharedPreferences.
@@ -27,6 +32,9 @@ import kotlinx.serialization.json.Json
  * explicitly defined to restrict what can be done with the interface and to eliminate the
  * need to verbosely type out "HashMap<ReviewReminderId, ReviewReminder>" everywhere.
  *
+ * Edits to instances of this class are not automatically persisted to SharedPreferences;
+ * that functionality is provided by [ReviewRemindersDatabase].
+ *
  * A HashMap is used to allow for O(1) access to individual reminders by [ReviewReminderId].
  */
 class ReviewReminderGroup(
@@ -39,9 +47,7 @@ class ReviewReminderGroup(
     /**
      * Manually construct a [ReviewReminderGroup] from key-value pairs.
      */
-    constructor(vararg pairs: Pair<ReviewReminderId, ReviewReminder>) : this(
-        buildMap { pairs.forEach { put(it.first, it.second) } },
-    )
+    constructor(vararg pairs: Pair<ReviewReminderId, ReviewReminder>) : this(hashMapOf(*pairs))
 
     /**
      * Merge multiple [ReviewReminderGroup]s into one.
@@ -112,8 +118,3 @@ class ReviewReminderGroup(
  * Convenience extension constructor for merging a list of [ReviewReminderGroup]s into one.
  */
 fun List<ReviewReminderGroup>.mergeAll() = ReviewReminderGroup(*this.toTypedArray())
-
-/**
- * Convenience typealias for the mutation functions passed to editors of [ReviewReminderGroup].
- */
-typealias ReviewReminderGroupEditor = (ReviewReminderGroup) -> ReviewReminderGroup

AnkiDroid/src/main/java/com/ichi2/anki/reviewreminders/ReviewReminderSchema.kt

@@ -115,6 +115,9 @@ data class ReviewReminderSchemaV2(
 /**
  * Schema migration settings for testing purposes.
  * Consult this as an example of how to save old schemas and define their [ReviewReminderSchema.migrate] methods.
+ * Also see the unit tests for [ReviewRemindersDatabase], where these classes are exercised.
+ * These classes cannot be moved directly to the test file because [ReviewReminderSchema] is a sealed interface,
+ * meaning all implementations of it must be within the same module.
  */
 object TestingReviewReminderMigrationSettings {
     /**

AnkiDroid/src/main/java/com/ichi2/anki/reviewreminders/ReviewRemindersDatabase.kt

@@ -22,6 +22,7 @@ import androidx.annotation.VisibleForTesting
 import androidx.core.content.edit
 import com.ichi2.anki.AnkiDroidApp
 import com.ichi2.anki.CrashReportService
+import com.ichi2.anki.common.utils.ellipsize
 import com.ichi2.anki.libanki.DeckId
 import com.ichi2.anki.settings.Prefs
 import com.ichi2.anki.showError
@@ -108,9 +109,9 @@ object ReviewRemindersDatabase {
     /**
      * Current [ReviewReminder] schema version. Whenever [ReviewReminder] is modified, this integer MUST be incremented.
      *
-     * Version 1: 3 August 2025 - Initial version
-     * Version 2: 25 January 2026 - Added [ReviewReminder.onlyNotifyIfNoReviews]
-     * Version 3: 8 February 2026 - Added [ReviewReminder.latestNotifTime]
+     * - Version 1: [ReviewReminderSchemaV1]: 3 August 2025 -  Initial version
+     * - Version 2: [ReviewReminderSchemaV2]: 25 January 2026 - Added [ReviewReminder.onlyNotifyIfNoReviews]
+     * - Version 3: [ReviewReminder]: 8 February 2026 - Added [ReviewReminder.latestNotifTime]
      *
      * @see [oldReviewReminderSchemasForMigration]
      * @see [ReviewReminder]
@@ -275,6 +276,8 @@ object ReviewRemindersDatabase {
      * Get the [ReviewReminder]s for a specific key.
      * Deletes the stored review reminders and returns an empty [ReviewReminderGroup] if deserialization fails
      * and no valid schema migrations exist.
+     *
+     * @see decodeJson
      */
     private fun getRemindersForKey(key: String): ReviewReminderGroup {
         val jsonString = remindersSharedPrefs.getString(key, null) ?: return ReviewReminderGroup()
@@ -320,6 +323,8 @@ object ReviewRemindersDatabase {
      * @param expectedScope The expected scope of all review reminders in the resulting map.
      *
      * @throws IllegalArgumentException If the result of applying the [editor] contains review reminders of a scope other than [expectedScope].
+     *
+     * @see getRemindersForKey
      */
     private fun editRemindersForKey(
         key: String,
@@ -380,15 +385,15 @@ object ReviewRemindersDatabase {
      */
     fun checkDeserializationErrors(context: Context) {
         Prefs.reviewReminderDeserializationErrors?.let { errorString ->
-            if (errorString.isNotEmpty()) {
-                context.showError(
-                    message =
-                        "An error occurred while loading your review reminders, corrupted reminders have been deleted. " +
-                            "Details:\n\n$errorString",
-                    crashReportData = null, // Crash reports are sent when the error is first encountered
-                )
-                Prefs.reviewReminderDeserializationErrors = ""
-            }
+            if (errorString.isEmpty()) return
+
+            context.showError(
+                message =
+                    "An error occurred while loading your review reminders, corrupted reminders have been deleted. " +
+                        "Details:\n\n${errorString.ellipsize(1000)}",
+                crashReportData = null, // Crash reports are sent when the error is first encountered
+            )
+            Prefs.reviewReminderDeserializationErrors = ""
         }
     }
 }

AnkiDroid/src/test/java/com/ichi2/anki/reviewreminders/ReviewRemindersDatabaseTest.kt

@@ -32,6 +32,7 @@ import org.hamcrest.Matchers.equalTo
 import org.hamcrest.Matchers.hasItem
 import org.hamcrest.Matchers.not
 import org.hamcrest.TypeSafeMatcher
+import org.intellij.lang.annotations.Language
 import org.junit.After
 import org.junit.Before
 import org.junit.Test
@@ -445,6 +446,7 @@ class ReviewRemindersDatabaseTest : RobolectricTest() {
      */
     @Test
     fun `raw ReviewReminder string can be deserialized without throwing`() {
+        @Language("JSON")
         val rawString =
             """
             {