diff --git a/lib/l10n/app_de.arb b/lib/l10n/app_de.arb
index 43872bb2a..744868aaf 100644
--- a/lib/l10n/app_de.arb
+++ b/lib/l10n/app_de.arb
@@ -183,6 +183,10 @@
   "@devicesOuraProtocolTimeout": {
     "description": "Snackbar: Oura-Sync fehlgeschlagen — Protokoll-Timeout / unvollständige Antwort."
   },
+  "devicesOuraWriteRefused": "Ein Befehl konnte nicht an den Ring gesendet werden. Bitte synchronisiere erneut.",
+  "@devicesOuraWriteRefused": {
+    "description": "Snackbar: Oura-Sync fehlgeschlagen — die Verbindung hat einen Befehl abgelehnt."
+  },
   "devicesOuraCheckpointUnconfirmed": "Die Synchronisation konnte nicht abgeschlossen werden. Bitte synchronisiere erneut.",
   "devicesSyncingTheRing": "Ring wird synchronisiert…",
   "devicesSynced": "Synchronisiert.",
@@ -1375,7 +1379,7 @@
   "healthCatMovementLoad": "Bewegung & Belastung",
   "healthCatBodyWear": "Körper & Tragezeit",
   "healthBlurbRestingHr": "Der niedrigste anhaltende Puls der Nacht",
-  "healthBlurbHrv": "Mittlerer RMSSD über die 5-Minuten-Fenster der Nacht",
+  "healthBlurbHrv": "RMSSD der Schlag-zu-Schlag-Intervalle im Schlaf",
   "healthBlurbHrvCv": "SDNN als Anteil des mittleren Schlagintervalls, innerhalb einer Nacht",
   "healthBlurbLfHf": "Wie sich die Herzschlag-Variabilität auf die Frequenzbereiche verteilt",
   "healthBlurbDip": "Wie stark deine Herzfrequenz im Schlaf sinkt",
diff --git a/lib/l10n/app_en.arb b/lib/l10n/app_en.arb
index 2e949e79d..e8c2ddc83 100644
--- a/lib/l10n/app_en.arb
+++ b/lib/l10n/app_en.arb
@@ -780,6 +780,10 @@
   "@devicesOuraProtocolTimeout": {
     "description": "Snackbar: Oura sync failed — protocol timeout / incomplete answer."
   },
+  "devicesOuraWriteRefused": "Could not send a command to the ring. Please try syncing again.",
+  "@devicesOuraWriteRefused": {
+    "description": "Snackbar: Oura sync failed — the link refused a command write."
+  },
   "devicesOuraCheckpointUnconfirmed": "The sync could not be completed. Please try syncing again.",
   "@devicesOuraCheckpointUnconfirmed": {
     "description": "Snackbar: Oura sync failed — a batch checkpoint was not confirmed in time."
@@ -6803,7 +6807,7 @@
   "@healthBlurbRestingHr": {
     "description": "Explore catalogue one-line description for resting heart rate"
   },
-  "healthBlurbHrv": "Mean RMSSD across the night's 5-minute windows",
+  "healthBlurbHrv": "RMSSD of beat-to-beat intervals during sleep",
   "@healthBlurbHrv": {
     "description": "Explore catalogue one-line description for HRV: the nightly mean of the RMSSDs of the sleep session's 5-minute windows"
   },
diff --git a/lib/l10n/app_es.arb b/lib/l10n/app_es.arb
index fe84b4c9d..cb9af1212 100644
--- a/lib/l10n/app_es.arb
+++ b/lib/l10n/app_es.arb
@@ -177,6 +177,10 @@
   "@devicesOuraProtocolTimeout": {
     "description": "Aviso: la sincronización de Oura falló — tiempo de espera agotado / respuesta incompleta."
   },
+  "devicesOuraWriteRefused": "No se pudo enviar un comando al anillo. Vuelve a sincronizar.",
+  "@devicesOuraWriteRefused": {
+    "description": "Aviso: la sincronización de Oura falló — la conexión rechazó un comando."
+  },
   "devicesOuraCheckpointUnconfirmed": "No se pudo completar la sincronización. Vuelve a sincronizar.",
   "devicesSyncingTheRing": "Sincronizando el anillo…",
   "devicesSynced": "Sincronizado.",
@@ -1331,7 +1335,7 @@
   "healthCatMovementLoad": "Movimiento y carga",
   "healthCatBodyWear": "Cuerpo y uso",
   "healthBlurbRestingHr": "El ritmo sostenido más bajo de la noche",
-  "healthBlurbHrv": "RMSSD medio de las ventanas de 5 minutos de la noche",
+  "healthBlurbHrv": "RMSSD de los intervalos latido a latido durante el sueño",
   "healthBlurbHrvCv": "SDNN como fracción del intervalo medio entre latidos, dentro de una noche",
   "healthBlurbLfHf": "Dónde se concentra la potencia del ritmo cardíaco entre frecuencias",
   "healthBlurbDip": "Cuánto baja tu frecuencia cardíaca mientras duermes",
diff --git a/lib/l10n/app_fr.arb b/lib/l10n/app_fr.arb
index d95de114d..6b2495e1e 100644
--- a/lib/l10n/app_fr.arb
+++ b/lib/l10n/app_fr.arb
@@ -177,6 +177,10 @@
   "@devicesOuraProtocolTimeout": {
     "description": "Snackbar : échec de la synchronisation Oura — délai dépassé / réponse incomplète."
   },
+  "devicesOuraWriteRefused": "Impossible d'envoyer une commande à la bague. Resynchronisez.",
+  "@devicesOuraWriteRefused": {
+    "description": "Snackbar : échec de la synchronisation Oura — la liaison a refusé une commande."
+  },
   "devicesOuraCheckpointUnconfirmed": "La synchronisation n'a pas pu être terminée. Resynchronisez.",
   "devicesSyncingTheRing": "Synchronisation de la bague…",
   "devicesSynced": "Synchronisé.",
@@ -1331,7 +1335,7 @@
   "healthCatMovementLoad": "Mouvement et charge",
   "healthCatBodyWear": "Corps et port",
   "healthBlurbRestingHr": "Le rythme soutenu le plus bas de la nuit",
-  "healthBlurbHrv": "RMSSD moyen sur les fenêtres de 5 minutes de la nuit",
+  "healthBlurbHrv": "RMSSD des intervalles battement à battement pendant le sommeil",
   "healthBlurbHrvCv": "SDNN en proportion de l'intervalle moyen entre battements, sur une nuit",
   "healthBlurbLfHf": "Où se situe la puissance du rythme cardiaque selon les fréquences",
   "healthBlurbDip": "De combien votre fréquence cardiaque baisse pendant votre sommeil",
diff --git a/lib/l10n/app_hi.arb b/lib/l10n/app_hi.arb
index 837a029df..b852c0b80 100644
--- a/lib/l10n/app_hi.arb
+++ b/lib/l10n/app_hi.arb
@@ -177,6 +177,10 @@
   "@devicesOuraProtocolTimeout": {
     "description": "स्नैकबार: Oura सिंक विफल — प्रोटोकॉल टाइमआउट / अपूर्ण उत्तर।"
   },
+  "devicesOuraWriteRefused": "रिंग को कमांड नहीं भेजा जा सका। कृपया फिर से सिंक करें।",
+  "@devicesOuraWriteRefused": {
+    "description": "स्नैकबार: Oura सिंक विफल — लिंक ने कमांड लिखना अस्वीकार किया।"
+  },
   "devicesOuraCheckpointUnconfirmed": "सिंक पूर्ण नहीं हो पाई। कृपया फिर से सिंक करें।",
   "devicesSyncingTheRing": "रिंग सिंक हो रही है…",
   "devicesSynced": "सिंक हो गया।",
@@ -1331,7 +1335,7 @@
   "healthCatMovementLoad": "गतिविधि और भार",
   "healthCatBodyWear": "शरीर और पहनावा",
   "healthBlurbRestingHr": "रात की सबसे कम स्थिर दर",
-  "healthBlurbHrv": "रात की 5-मिनट की खिड़कियों पर औसत RMSSD",
+  "healthBlurbHrv": "नींद के दौरान धड़कन-दर-धड़कन अंतराल का RMSSD",
   "healthBlurbHrvCv": "एक रात के भीतर, औसत धड़कन-अंतराल के अनुपात में SDNN",
   "healthBlurbLfHf": "धड़कन-समय की ऊर्जा विभिन्न आवृत्तियों में कहाँ है",
   "healthBlurbDip": "सोते समय आपकी हृदय गति कितनी गिरती है",
diff --git a/lib/l10n/app_zh.arb b/lib/l10n/app_zh.arb
index e8621b898..46c33f878 100644
--- a/lib/l10n/app_zh.arb
+++ b/lib/l10n/app_zh.arb
@@ -177,6 +177,10 @@
   "@devicesOuraProtocolTimeout": {
     "description": "快讯条：Oura 同步失败 — 协议超时 / 回应不完整。"
   },
+  "devicesOuraWriteRefused": "无法向戒指发送指令。请重新同步。",
+  "@devicesOuraWriteRefused": {
+    "description": "快讯条：Oura 同步失败 — 连接拒绝了指令写入。"
+  },
   "devicesOuraCheckpointUnconfirmed": "同步无法完成。请重新同步。",
   "devicesSyncingTheRing": "正在同步戒指…",
   "devicesSynced": "已同步。",
@@ -1331,7 +1335,7 @@
   "healthCatMovementLoad": "运动与负荷",
   "healthCatBodyWear": "身体与佩戴",
   "healthBlurbRestingHr": "整夜持续保持的最低心率",
-  "healthBlurbHrv": "整晚各 5 分钟窗口 RMSSD 的平均值",
+  "healthBlurbHrv": "睡眠期间逐搏间期的 RMSSD",
   "healthBlurbHrvCv": "单晚内 SDNN 占平均心跳间期的比例",
   "healthBlurbLfHf": "心跳间期功率在各频段的分布",
   "healthBlurbDip": "睡眠期间心率下降的幅度",
diff --git a/lib/ui2/profile/devices.dart b/lib/ui2/profile/devices.dart
index d8a7b1cac..b711395c1 100644
--- a/lib/ui2/profile/devices.dart
+++ b/lib/ui2/profile/devices.dart
@@ -2030,10 +2030,12 @@ Future<void> _syncRing(BuildContext c, String? family) async {
             (l?.devicesOuraProtocolTimeout ??
                 'The ring stopped answering mid-sync. Please try syncing '
                     'again.'),
+          // A refused write does not say WHY (range, another app, transport),
+          // so the message claims only that the command was not sent.
           OuraSyncCategory.writeRefused =>
-            (l?.devicesCouldNotReachRing ??
-                'Could not reach the ring. It has to be nearby, and not '
-                    'connected to another app.'),
+            (l?.devicesOuraWriteRefused ??
+                'Could not send a command to the ring. Please try syncing '
+                    'again.'),
           _ => (l?.devicesCouldNotReachRing ??
               'Could not reach the ring. It has to be nearby, and not '
                   'connected to another app.'),
diff --git a/lib/ui2/screens/health_screen.dart b/lib/ui2/screens/health_screen.dart
index a722d0e5b..1391190b7 100644
--- a/lib/ui2/screens/health_screen.dart
+++ b/lib/ui2/screens/health_screen.dart
@@ -357,7 +357,7 @@ class _Cat {
 const _catalogue = <_Cat>[
   _Cat('Heart & rhythm', [
     _CatRow('resting_hr', 'rhr', 'The lowest sustained rate of the night'),
-    _CatRow('hrv', 'rmssd', 'Mean RMSSD across the night\'s 5-minute windows'),
+    _CatRow('hrv', 'rmssd', 'RMSSD of beat-to-beat intervals during sleep'),
     _CatRow('hrv_cv', 'hrv_cv',
         'SDNN as a share of the average beat interval, within one night'),
     _CatRow('lf_hf', 'lf_hf', 'Where beat-timing power sits across frequencies'),
diff --git a/lib/ui2/screens/metric_detail.dart b/lib/ui2/screens/metric_detail.dart
index e464aff5e..e5274e47e 100644
--- a/lib/ui2/screens/metric_detail.dart
+++ b/lib/ui2/screens/metric_detail.dart
@@ -121,7 +121,9 @@ const _specs = <String, MetricSpec>{
         'median, are dropped first. On a night whose beat timing looks noisy, '
         'only windows that pass the jitter check on their own, or that sit on '
         'a steady breathing line, count; a window, or a night, whose beats '
-        'add up to more time than passed is left out. '
+        'add up to more time than passed is left out. Older nights whose raw '
+        'beats are gone keep the value an earlier version of this method gave '
+        'them. '
         'Pulse-derived, so this is PRV: real and trendable, but not ECG HRV.',
     citation: 'Task Force 1996 · 20% local-median ectopic filter, after Malik',
     requires: {InputSignal.rrIntervals},