From 3003f753332d44b5f1764dc131261b2d22cf3758 Mon Sep 17 00:00:00 2001
From: Jean-Luc Makiola <business@jeanlucmakiola.de>
Date: Wed, 21 Oct 2026 17:37:11 +0200
Subject: [PATCH] fix: keep the built-in timer presets when a backup has none

A backup without the timer_presets field decoded it as an empty list,
which means "the user removed them all", so restoring it wiped the
built-in presets. A missing field now keeps them. BACKUP.md describes
this and the per-alarm clamps.
---
 .../clockula/data/backup/BackupCodec.kt             |  4 ++--
 .../clockula/data/backup/BackupDto.kt               |  7 ++++++-
 .../clockula/data/backup/BackupCodecTest.kt         | 13 +++++++++++++
 docs/BACKUP.md                                      |  6 ++++++
 4 files changed, 27 insertions(+), 3 deletions(-)

diff --git a/app/src/main/java/de/jeanlucmakiola/clockula/data/backup/BackupCodec.kt b/app/src/main/java/de/jeanlucmakiola/clockula/data/backup/BackupCodec.kt
index f0b0795..b1b2d60 100644
--- a/app/src/main/java/de/jeanlucmakiola/clockula/data/backup/BackupCodec.kt
+++ b/app/src/main/java/de/jeanlucmakiola/clockula/data/backup/BackupCodec.kt
@@ -189,7 +189,7 @@ object BackupCodec {
         val settingsDto = settings
         if ((settingsDto.alarmRingtoneUri?.length ?: 0) > MAX_URI_CHARS ||
             (settingsDto.timerRingtoneUri?.length ?: 0) > MAX_URI_CHARS ||
-            settingsDto.timerPresets.size > 1_000
+            (settingsDto.timerPresets?.size ?: 0) > 1_000
         ) {
             return BackupResult.Failure("settings contain oversized values")
         }
@@ -206,7 +206,7 @@ object BackupCodec {
                 dismissChallenge = settingsDto.dismissChallenge.toEnum(DismissChallenge.NONE),
                 homeZoneId = settingsDto.homeZoneId?.let(Zones::normalise),
             ),
-            timerPresets = settingsDto.timerPresets.map { it.milliseconds },
+            timerPresets = settingsDto.timerPresets?.map { it.milliseconds } ?: TimerPresets.BUILT_IN,
         )
 
         return BackupResult.Success(
diff --git a/app/src/main/java/de/jeanlucmakiola/clockula/data/backup/BackupDto.kt b/app/src/main/java/de/jeanlucmakiola/clockula/data/backup/BackupDto.kt
index 35c15c5..118e99e 100644
--- a/app/src/main/java/de/jeanlucmakiola/clockula/data/backup/BackupDto.kt
+++ b/app/src/main/java/de/jeanlucmakiola/clockula/data/backup/BackupDto.kt
@@ -71,5 +71,10 @@ data class SettingsDto(
     @SerialName("default_timer_ringtone_uri") val timerRingtoneUri: String? = null,
     @SerialName("default_dismiss_challenge") val dismissChallenge: String = "NONE",
     @SerialName("home_zone_id") val homeZoneId: String? = null,
-    @SerialName("timer_presets") val timerPresets: List<Long> = emptyList(),
+    /**
+     * Absent is not empty: an empty list is a user who removed every preset,
+     * while a file without the field (an older or hand-written one) keeps the
+     * built-in ones.
+     */
+    @SerialName("timer_presets") val timerPresets: List<Long>? = null,
 )
diff --git a/app/src/test/java/de/jeanlucmakiola/clockula/data/backup/BackupCodecTest.kt b/app/src/test/java/de/jeanlucmakiola/clockula/data/backup/BackupCodecTest.kt
index 2f3f13b..db57734 100644
--- a/app/src/test/java/de/jeanlucmakiola/clockula/data/backup/BackupCodecTest.kt
+++ b/app/src/test/java/de/jeanlucmakiola/clockula/data/backup/BackupCodecTest.kt
@@ -257,6 +257,19 @@ class BackupCodecTest {
         assertThat(timers.map { it.duration }).containsExactly(TimerPresets.MIN, TimerPresets.MAX).inOrder()
     }
 
+    @Test
+    fun `a file without timer presets keeps the built-in ones`() {
+        val settings = (BackupCodec.decode(minimalDocument()) as BackupResult.Success).content.settings
+        assertThat(settings.timerPresets).isEqualTo(TimerPresets.BUILT_IN)
+    }
+
+    @Test
+    fun `an empty preset list is honoured as all removed`() {
+        val json = minimalDocument().replace("\"settings\": {}", "\"settings\": {\"timer_presets\": []}")
+        val settings = (BackupCodec.decode(json) as BackupResult.Success).content.settings
+        assertThat(settings.timerPresets).isEmpty()
+    }
+
     @Test
     fun `garbage text fails rather than throwing`() {
         assertThat(BackupCodec.decode("not json at all")).isInstanceOf(BackupResult.Failure::class.java)
diff --git a/docs/BACKUP.md b/docs/BACKUP.md
index 28dda94..e8536de 100644
--- a/docs/BACKUP.md
+++ b/docs/BACKUP.md
@@ -38,6 +38,12 @@ written here.
   `ClockPrefs`/`SettingsPrefs` already apply on every write, so a value from
   a future, more permissive version degrades to the nearest valid one instead
   of failing the import.
+- An alarm's own `snooze_minutes`, `snooze_limit` and `volume_ramp_seconds`
+  are clamped at parse time to the same ranges as the defaults they
+  override, and a timer's `duration_millis` to the setup range (1 second to
+  24 hours). Room has no clamp of its own, so this is where it happens.
+- A missing `timer_presets` keeps the built-in presets. An empty list is a
+  user who removed them all, and is imported as such.
 - An enum field with a name this version does not recognise (a `dismiss_
   challenge` or `theme_mode` from a future version, say) degrades to that
   field's default, the same forgiving-read posture `AlarmMapper` already uses