diff --git a/hub/CHANGELOG.md b/hub/CHANGELOG.md
index f7924ac..416f959 100644
--- a/hub/CHANGELOG.md
+++ b/hub/CHANGELOG.md
@@ -1,3 +1,40 @@
+## v0.81.0 — E-2: the absent backup target gets its own signal (2026-07-29)
+
+**Hub half of E-2, and it ships FIRST by necessity:** an event type the hub does not allowlist makes
+`POST /event` return 400 and the event vanishes (the R-97a failure). The controller cannot emit
+`backup_target_absent` until this is live.
+
+E-2's Phase 0 established that an absent backup target has **no prompt signal today**. The drive-gate
+path stops apps and logs a WARN but emits nothing — `NotifyStorageDisconnected` is defined and never
+called anywhere in the controller (verified against the gitignored-`cmd/` trap with a positive
+control). A drive that is *only* a backup target has no apps to stop, so it is entirely silent. The
+sole signal is the tier's own failure at its next due cycle, i.e. **up to ~24 h** on the daily local
+tier — the R-100 shape, where a real fault is visible only after a deadline elapses.
+
+Added to BOTH registers, because each half fails differently and the second failure is the quiet one:
+
+- `allowedEventTypes` (`internal/api/handler.go`) — without it the event is lost at the door;
+- `customerMessages` (`internal/notify/templates.go`) — without it the event IS delivered, but the
+  customer receives the controller's raw operator English instead of Hungarian, and nothing looks
+  broken.
+
+`backup_target_absent` is deliberately **not** folded into `storage_disconnected`. That one says "a
+drive went away and some apps may have stopped"; this one says "the thing that makes your backup
+survive a disk failure is gone" — a different customer action and a different operator urgency.
+
+Hungarian copy states the CONSEQUENCE, not just the fact:
+> „A rendszermentés meghajtója nem érhető el — amíg vissza nem csatlakoztatod, a teljes rendszermentés nem készül el."
+
+`backup_target_restored` is the paired recovery (`info` severity — the existing recovery pattern;
+`severityNotifies` is untouched and NOT widened).
+
+**Tests + red-proofs.** `api.TestBackupTargetEventTypesAreAllowlisted` and
+`notify.TestBackupTargetCustomerMessagesArePresent` pin the pair; a third test pins that the copy
+names what is at risk and what happens, so a future shortening to a bare „Meghajtó hiányzik." cannot
+pass. All three red-proofed with the mutation VERIFIED to have landed first — the initial attempt
+silently no-op'd (gofmt had realigned the map to three spaces) and the test "passed", which would
+have been a false proof.
+
 ## v0.80.0 — R-100: staleness counts from the last SUCCESS (2026-07-28)
 
 `OffsiteChecker.isStale` counted from `last_run`, which the controller writes **unconditionally** at the
diff --git a/hub/internal/api/backup_target_event_test.go b/hub/internal/api/backup_target_event_test.go
new file mode 100644
index 0000000..e62384b
--- /dev/null
+++ b/hub/internal/api/backup_target_event_test.go
@@ -0,0 +1,25 @@
+package api
+
+import "testing"
+
+// E-2 — the absent-backup-target signal needs BOTH registers, not one.
+//
+// Phase 0 of E-2 established that an absent backup target has no prompt signal today: the drive-gate
+// path stops apps and logs, but emits nothing, and the tier's own failure only lands at its next due
+// cycle (up to ~24 h on the daily local tier). `backup_target_absent` is that missing signal.
+//
+// A new event type is a PAIR, and each half fails differently:
+//   - missing from allowedEventTypes  → POST /event returns 400 and the event VANISHES (R-97a);
+//   - missing from customerMessages   → it is delivered, but the customer gets the controller's raw
+//     English operator string instead of Hungarian.
+//
+// The second failure is the quiet one — delivery "works", so nothing looks broken. Both are pinned
+// here, in the same test, because fixing one and not the other is the realistic mistake.
+func TestBackupTargetEventTypesAreAllowlisted(t *testing.T) {
+	for _, et := range []string{"backup_target_absent", "backup_target_restored"} {
+		if !allowedEventTypes[et] {
+			t.Fatalf("%s must be in allowedEventTypes, or POST /event 400s and the absent backup "+
+				"target goes silent until the tier misses its deadline", et)
+		}
+	}
+}
diff --git a/hub/internal/api/handler.go b/hub/internal/api/handler.go
index 9ee92f9..f41b0bc 100644
--- a/hub/internal/api/handler.go
+++ b/hub/internal/api/handler.go
@@ -1595,8 +1595,16 @@ var allowedEventTypes = map[string]bool{
 	"offbox_repo_reset":    true,
 	"storage_disconnected": true,
 	"storage_reconnected":  true,
-	"disk_warning":         true,
-	"disk_critical":        true,
+	// controller v0.184.0 (E-2) — the assigned whole-guest backup TARGET drive is absent. Distinct
+	// from storage_disconnected on purpose: that one says "a drive went away and some apps may have
+	// stopped"; this one says "the thing that makes a backup survive a disk failure is gone", which
+	// is a different action for the customer and a different urgency for the operator. Before this
+	// the only signal was the tier's own failure at its next due cycle — up to ~24 h on the daily
+	// local tier — i.e. the R-100 shape: a real fault visible only after a deadline elapsed.
+	"backup_target_absent":   true,
+	"backup_target_restored": true,
+	"disk_warning":           true,
+	"disk_critical":          true,
 	// controller v0.169.0 — per-disk SMART degradation (Rendben→Figyelmeztetés/Hiba). The controller
 	// sends a dynamic Hungarian message (disk label + the triggering attribute names), so — like
 	// offbox_enlarge_blocked — there is deliberately NO customerMessages entry (which would discard the
diff --git a/hub/internal/notify/backup_target_message_test.go b/hub/internal/notify/backup_target_message_test.go
new file mode 100644
index 0000000..3346d87
--- /dev/null
+++ b/hub/internal/notify/backup_target_message_test.go
@@ -0,0 +1,38 @@
+package notify
+
+import (
+	"strings"
+	"testing"
+)
+
+// E-2 — the Hungarian half of the backup_target_absent pair.
+//
+// Companion to api.TestBackupTargetEventTypesAreAllowlisted, which pins the allowlist half. They are
+// deliberately two tests in two packages because the registers live in two packages, and the failure
+// modes differ: an allowlist miss makes POST /event 400 (loud, the event is lost); a customerMessages
+// miss delivers the event but falls back to the controller's raw operator English
+// (templates.go FormatCustomerEmail: hunMessage == "" → message). The customer would receive
+// "Backup target drive absent: ..." in English and nothing would look broken.
+func TestBackupTargetCustomerMessagesArePresent(t *testing.T) {
+	for _, et := range []string{"backup_target_absent", "backup_target_restored"} {
+		msg, ok := customerMessages[et]
+		if !ok || strings.TrimSpace(msg) == "" {
+			t.Fatalf("customerMessages[%q] is missing — the event would be delivered to the customer "+
+				"in the controller's operator English instead of Hungarian", et)
+		}
+	}
+}
+
+// The absent message must name the CONSEQUENCE, not just the fact. "A drive is missing" is a fact the
+// customer can do nothing with; "the whole-system backup will not be made until you reconnect it" is
+// the thing that makes them act. This pins the distinction the copy was written for — a future
+// shortening to a bare "Meghajtó hiányzik." would pass the presence test above and lose the point.
+func TestBackupTargetAbsentMessageNamesTheConsequence(t *testing.T) {
+	msg := customerMessages["backup_target_absent"]
+	if !strings.Contains(msg, "rendszermentés") {
+		t.Errorf("backup_target_absent must name WHAT is at risk (the rendszermentés), got: %q", msg)
+	}
+	if !strings.Contains(strings.ToLower(msg), "nem készül") {
+		t.Errorf("backup_target_absent must state the consequence (the backup will not be made), got: %q", msg)
+	}
+}
diff --git a/hub/internal/notify/templates.go b/hub/internal/notify/templates.go
index 9c225e1..5716105 100644
--- a/hub/internal/notify/templates.go
+++ b/hub/internal/notify/templates.go
@@ -59,14 +59,14 @@ var customerMessages = map[string]string{
 	// Customer-claim arc (v0.50.0)
 	"claim_lockout": "Túl sok hibás beállító/visszaállító kód próbálkozás történt — a beállító oldal 15 percre zárolva lett. Ha nem te próbálkoztál, jelezd az üzemeltetőnek.",
 	// Backup events
-	"backup_completed":          "A biztonsági mentés sikeresen elkészült.",
-	"backup_failed":             "A biztonsági mentés sikertelen! Kérjük, ellenőrizd a rendszert.",
-	"db_dump_completed":         "Az adatbázis mentés sikeresen elkészült.",
-	"db_dump_failed":            "Az adatbázis mentés sikertelen!",
-	"backup_integrity_ok":       "A mentés integritás ellenőrzés sikeres.",
-	"backup_integrity_failed":   "A mentés integritás ellenőrzés hibát talált!",
-	"crossdrive_completed":      "A másodlagos mentés sikeresen elkészült.",
-	"crossdrive_failed":         "A másodlagos mentés sikertelen!",
+	"backup_completed":        "A biztonsági mentés sikeresen elkészült.",
+	"backup_failed":           "A biztonsági mentés sikertelen! Kérjük, ellenőrizd a rendszert.",
+	"db_dump_completed":       "Az adatbázis mentés sikeresen elkészült.",
+	"db_dump_failed":          "Az adatbázis mentés sikertelen!",
+	"backup_integrity_ok":     "A mentés integritás ellenőrzés sikeres.",
+	"backup_integrity_failed": "A mentés integritás ellenőrzés hibát talált!",
+	"crossdrive_completed":    "A másodlagos mentés sikeresen elkészült.",
+	"crossdrive_failed":       "A másodlagos mentés sikertelen!",
 	// Offsite-repo continuity (controller v0.142.0)
 	"offbox_repo_orphaned": "A távoli mentési tároló elárvult: a benne lévő mentések egy korábbi, már nem elérhető kulccsal készültek (jellemzően újratelepítés után). Új mentés a tároló visszaállításáig nem készül — nyisd meg a Távoli mentés oldalt.",
 	"offbox_repo_reset":    "A távoli mentési tároló visszaállítva: a régi előzmény félretéve (nem törölve), és egy üres, új tároló jött létre a mostani kulccsal.",
@@ -87,6 +87,12 @@ var customerMessages = map[string]string{
 	"storage_disconnected": "Egy meghajtó leválasztva — a mentések szünetelhetnek.",
 	"storage_reconnected":  "A meghajtó újra csatlakoztatva.",
 
+	// E-2 — the drive the whole-system backup is written to is gone. Deliberately NOT folded into
+	// storage_disconnected: the customer action differs (reconnect THIS drive, or the system backup
+	// stops surviving a disk failure), and the fallback is honest about what still protects them.
+	"backup_target_absent":   "A rendszermentés meghajtója nem érhető el — amíg vissza nem csatlakoztatod, a teljes rendszermentés nem készül el.",
+	"backup_target_restored": "A rendszermentés meghajtója újra elérhető — a mentés folytatódik.",
+
 	// Staleness events (Hub-generated)
 	"node_stale":     "A szerver nem küldött jelentést az elmúlt időszakban.",
 	"node_down":      "A szerver nem elérhető!",