diff --git a/cmd/mavend/alarm_stop_test.go b/cmd/mavend/alarm_stop_test.go
index 81d9242..cc57d7f 100644
--- a/cmd/mavend/alarm_stop_test.go
+++ b/cmd/mavend/alarm_stop_test.go
@@ -72,7 +72,7 @@ func TestAlarmStopsWhenTheServiceComesBackUp(t *testing.T) {
 	st := newTestStore(t)
 	ctx := context.Background()
 	now := refNow()
-	seedDown(t, st, ctx, "down", now)
+	seedDown(t, st, ctx, "down", now.Add(-5*time.Minute))
 
 	sink := &fakeSink{}
 	tl := newAlarmTickLoop(t, st, sink)
@@ -101,7 +101,7 @@ func TestAlarmStopsAtTheAgeCapWhileStillDown(t *testing.T) {
 	st := newTestStore(t)
 	ctx := context.Background()
 	now := refNow()
-	seedDown(t, st, ctx, "down", now)
+	seedDown(t, st, ctx, "down", now.Add(-5*time.Minute))
 
 	sink := &fakeSink{}
 	tl := newAlarmTickLoop(t, st, sink)
@@ -132,7 +132,7 @@ func TestAFlapRaisesAFreshAlarmRatherThanReviveTheClosedOne(t *testing.T) {
 	st := newTestStore(t)
 	ctx := context.Background()
 	now := refNow()
-	seedDown(t, st, ctx, "down", now)
+	seedDown(t, st, ctx, "down", now.Add(-5*time.Minute))
 
 	sink := &fakeSink{}
 	tl := newAlarmTickLoop(t, st, sink)
@@ -145,7 +145,7 @@ func TestAFlapRaisesAFreshAlarmRatherThanReviveTheClosedOne(t *testing.T) {
 		t.Fatalf("closing the run changed the row count: %d → %d", first, len(got))
 	}
 
-	seedDown(t, st, ctx, "down", now.Add(30*time.Minute))
+	seedDown(t, st, ctx, "down", now.Add(25*time.Minute))
 	sink.sends = nil
 	tl.tick(ctx, now.Add(31*time.Minute))
 
diff --git a/cmd/mavend/tick_test.go b/cmd/mavend/tick_test.go
index c2c4ac9..43646ee 100644
--- a/cmd/mavend/tick_test.go
+++ b/cmd/mavend/tick_test.go
@@ -584,7 +584,9 @@ func TestDigestSev4BypassesQueue(t *testing.T) {
 	ctx := context.Background()
 	now := refNow()
 	markPresent(t, st, ctx, now)
-	if _, err := st.SetValue(ctx, store.KindSelf, "service_down:db", "poll:uptimekuma", "down", now); err != nil {
+	// Older than loop.MinDownAge, so this tests the digest bypass and not the
+	// flap debounce (Vikunja #536).
+	if _, err := st.SetValue(ctx, store.KindSelf, "service_down:db", "poll:uptimekuma", "down", now.Add(-5*time.Minute)); err != nil {
 		t.Fatalf("seed service_down: %v", err)
 	}
 	sink := &fakeSink{}
diff --git a/internal/loop/explain_test.go b/internal/loop/explain_test.go
index 1110106..603e238 100644
--- a/internal/loop/explain_test.go
+++ b/internal/loop/explain_test.go
@@ -103,7 +103,7 @@ func TestExplainGate_PresenceAway(t *testing.T) {
 func TestExplainGate_PresenceAwayOpsBypass(t *testing.T) {
 	now := refTime()
 	s := State{Now: now, Presence: store.Away,
-		Facts: map[string]store.Fact{"service_down:db": factAt("service_down:db", "poll:uptimekuma", `"down"`, now.Add(-1*time.Minute))},
+		Facts: map[string]store.Fact{"service_down:db": factAt("service_down:db", "poll:uptimekuma", `"down"`, now.Add(-5*time.Minute))},
 	}
 	r := ServiceDownRule() // Sev4 ops
 	passed, blocked, d := ExplainGate(s, r)
@@ -260,7 +260,7 @@ func TestExplainTick_WinnerRecorded(t *testing.T) {
 		Presence: store.Present,
 		Facts: map[string]store.Fact{
 			"water":           factAt("water", "tap:water", `"250ml"`, now.Add(-4*time.Hour)),
-			"service_down:db": factAt("service_down:db", "poll:uptimekuma", `"down"`, now.Add(-1*time.Minute)),
+			"service_down:db": factAt("service_down:db", "poll:uptimekuma", `"down"`, now.Add(-5*time.Minute)),
 		},
 	}
 	cand, trace := ExplainTick(s, DefaultRules())
diff --git a/internal/loop/gate_test.go b/internal/loop/gate_test.go
index 4ad6e90..c8195ed 100644
--- a/internal/loop/gate_test.go
+++ b/internal/loop/gate_test.go
@@ -202,7 +202,7 @@ func TestTickNeverDogpilesAndPicksLoudest(t *testing.T) {
 			"meal":            ago("meal", "voice", `"lunch"`, 8*time.Hour),
 			"desk_active":     ago("desk_active", "infer:hyprland", "1", 30*time.Second),
 			"break":           ago("break", "voice", `"walk"`, 3*time.Hour),
-			"service_down:db": ago("service_down:db", "poll:uptimekuma", `"down"`, time.Minute),
+			"service_down:db": ago("service_down:db", "poll:uptimekuma", `"down"`, 5*time.Minute),
 			"netdata_alarm":   ago("netdata_alarm", "poll:netdata", `"critical"`, time.Minute),
 		},
 	}
diff --git a/internal/loop/gather_test.go b/internal/loop/gather_test.go
index c854eba..b4bc97c 100644
--- a/internal/loop/gather_test.go
+++ b/internal/loop/gather_test.go
@@ -25,7 +25,9 @@ func TestGatherStateLoadsPrefixFamilies(t *testing.T) {
 		"service_down:db":  "down",
 		"service_down:web": "up",
 	} {
-		if _, err := s.SetValue(ctx, store.KindEnv, key, ServiceDownSource, val, now.Add(-time.Minute)); err != nil {
+		// Older than MinDownAge, so this tests the gather path and not the
+		// flap debounce.
+		if _, err := s.SetValue(ctx, store.KindEnv, key, ServiceDownSource, val, now.Add(-5*time.Minute)); err != nil {
 			t.Fatalf("SetValue %s: %v", key, err)
 		}
 	}
diff --git a/internal/loop/loop_test.go b/internal/loop/loop_test.go
index 0f5cf1a..14d3451 100644
--- a/internal/loop/loop_test.go
+++ b/internal/loop/loop_test.go
@@ -82,7 +82,7 @@ func TestTickOpsHardSurvivesAwayAndQuiet(t *testing.T) {
 		Presence:   store.Away,
 		QuietHours: true,
 		Facts: map[string]store.Fact{
-			"service_down:db": factAt("service_down:db", "poll:uptimekuma", `"down"`, now.Add(-1*time.Minute)),
+			"service_down:db": factAt("service_down:db", "poll:uptimekuma", `"down"`, now.Add(-5*time.Minute)),
 		},
 	}
 	got := Tick(s, DefaultRules())
@@ -99,7 +99,7 @@ func TestTickServiceSourceTrustRefusesForgedTrigger(t *testing.T) {
 		Now:      now,
 		Presence: store.Present,
 		Facts: map[string]store.Fact{
-			"service_down:db": factAt("service_down:db", "ambient", `"down"`, now.Add(-1*time.Minute)),
+			"service_down:db": factAt("service_down:db", "ambient", `"down"`, now.Add(-5*time.Minute)),
 		},
 	}
 	if got := Tick(s, DefaultRules()); got != nil {
@@ -116,7 +116,7 @@ func TestTickOneNudgePerTickMaxSeverityWins(t *testing.T) {
 		Presence: store.Present,
 		Facts: map[string]store.Fact{
 			"water":           factAt("water", "tap:water", `"250ml"`, now.Add(-4*time.Hour)),
-			"service_down:db": factAt("service_down:db", "poll:uptimekuma", `"down"`, now.Add(-1*time.Minute)),
+			"service_down:db": factAt("service_down:db", "poll:uptimekuma", `"down"`, now.Add(-5*time.Minute)),
 		},
 	}
 	got := Tick(s, DefaultRules())
diff --git a/internal/loop/rules.go b/internal/loop/rules.go
index e062df6..aa6ed21 100644
--- a/internal/loop/rules.go
+++ b/internal/loop/rules.go
@@ -144,6 +144,44 @@ func DownServices(s State) []string {
 	return out
 }
 
+// MinDownAge — how long a monitor must have read "down" before it is worth
+// waking him (Vikunja #536).
+//
+// Technitium read down on one kuma poll and up on the next, sixty seconds
+// apart, and the alarm arrived after the service was already back. mavpoll
+// writes a service_down fact only when the state CHANGES, so the fact's
+// timestamp is the instant the monitor went down and its age is how long it
+// has stayed there. That is the whole debounce: no history to keep, no counter
+// to persist.
+//
+// Ninety seconds is one poll interval plus room for jitter, so a monitor must
+// survive at least one further poll as down. The cost is up to ninety seconds
+// of alarm latency on a real outage, against never being paged for a blip.
+//
+// It bounds the alarm, not the truth: DownServices still reports a monitor the
+// instant it goes down, because /dash showing a fresh outage is right even
+// when phoning him about it is not.
+const MinDownAge = 90 * time.Second
+
+// downLongEnough — the newest down fact that has aged past MinDownAge, or the
+// zero time when no monitor has. The rule fires off this and not off the
+// newest down fact outright.
+func downLongEnough(s State, now time.Time) time.Time {
+	var newest time.Time
+	for _, f := range s.FactsUnder(ServiceDownPrefix) {
+		if f.Source != ServiceDownSource || f.Value != `"down"` {
+			continue
+		}
+		if now.Sub(f.Ts) < MinDownAge {
+			continue
+		}
+		if f.Ts.After(newest) {
+			newest = f.Ts
+		}
+	}
+	return newest
+}
+
 // ServiceDownRule — sev4 ops hard: at least one kuma monitor reads "down".
 //
 // It used to read one aggregate `service_down` fact, which is why it was
@@ -160,17 +198,11 @@ func ServiceDownRule() Rule {
 		Cooldown:     Cooldown{Base: 15 * time.Minute, Min: 5 * time.Minute, Max: 1 * time.Hour},
 		WantPrefixes: []string{ServiceDownPrefix},
 		Predicate: func(s State) bool {
-			var newest time.Time
-			for _, f := range s.FactsUnder(ServiceDownPrefix) {
-				if f.Source != ServiceDownSource || f.Value != `"down"` {
-					continue
-				}
-				if f.Ts.After(newest) {
-					newest = f.Ts
-				}
-			}
+			newest := downLongEnough(s, s.Now)
 			if newest.IsZero() {
-				return false // nothing down, or no data at all → shut up
+				// Nothing down, no data at all, or nothing down long enough
+				// to be more than a flap → shut up. See MinDownAge.
+				return false
 			}
 			return !s.NudgedSince("service_down", newest)
 		},
diff --git a/internal/loop/rules_test.go b/internal/loop/rules_test.go
index 70cc11c..0c081bc 100644
--- a/internal/loop/rules_test.go
+++ b/internal/loop/rules_test.go
@@ -193,13 +193,13 @@ func TestOpsRulePredicates(t *testing.T) {
 		{
 			name:  "service_down fires on a kuma down fact",
 			rule:  ServiceDownRule(),
-			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:uptimekuma", `"down"`, time.Minute)},
+			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:uptimekuma", `"down"`, 5*time.Minute)},
 			want:  true,
 		},
 		{
 			name:  "service_down quiet when kuma says up",
 			rule:  ServiceDownRule(),
-			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:uptimekuma", `"up"`, time.Minute)},
+			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:uptimekuma", `"up"`, 5*time.Minute)},
 			want:  false,
 		},
 		{
@@ -218,31 +218,31 @@ func TestOpsRulePredicates(t *testing.T) {
 		{
 			name:  "service_down refuses a forgery from the netdata poller",
 			rule:  ServiceDownRule(),
-			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:netdata", `"down"`, time.Minute)},
+			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:netdata", `"down"`, 5*time.Minute)},
 			want:  false,
 		},
 		{
 			name:  "service_down refuses a forgery from ambient audio",
 			rule:  ServiceDownRule(),
-			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "ambient:other", `"down"`, time.Minute)},
+			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "ambient:other", `"down"`, 5*time.Minute)},
 			want:  false,
 		},
 		{
 			name:  "service_down refuses a forgery from the user's own voice",
 			rule:  ServiceDownRule(),
-			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "voice", `"down"`, time.Minute)},
+			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "voice", `"down"`, 5*time.Minute)},
 			want:  false,
 		},
 		{
 			name:  "service_down refuses a source that only looks like kuma",
 			rule:  ServiceDownRule(),
-			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:uptimekuma-staging", `"down"`, time.Minute)},
+			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:uptimekuma-staging", `"down"`, 5*time.Minute)},
 			want:  false,
 		},
 		{
 			name:  "service_down refuses an unquoted down value",
 			rule:  ServiceDownRule(),
-			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:uptimekuma", `down`, time.Minute)},
+			facts: map[string]store.Fact{"service_down:db": ago("service_down:db", "poll:uptimekuma", `down`, 5*time.Minute)},
 			want:  false,
 		},
 
@@ -383,7 +383,7 @@ func TestPredicatesArePure(t *testing.T) {
 		"meal":            ago("meal", "voice", `"lunch"`, 7*time.Hour),
 		"desk_active":     ago("desk_active", "infer:hyprland", "1", 30*time.Second),
 		"break":           ago("break", "voice", `"walk"`, 2*time.Hour),
-		"service_down:db": ago("service_down:db", "poll:uptimekuma", `"down"`, time.Minute),
+		"service_down:db": ago("service_down:db", "poll:uptimekuma", `"down"`, 5*time.Minute),
 	})
 	for _, r := range DefaultRules() {
 		first := r.Predicate(s)
@@ -445,12 +445,12 @@ func TestDownServicesNamesOnlyTheDownOnes(t *testing.T) {
 	s := State{
 		Now: refTime(),
 		Facts: map[string]store.Fact{
-			"service_down:web":     ago("service_down:web", ServiceDownSource, `"up"`, time.Minute),
-			"service_down:db":      ago("service_down:db", ServiceDownSource, `"down"`, time.Minute),
-			"service_down:vault":   ago("service_down:vault", ServiceDownSource, `"down"`, time.Minute),
-			"service_down:paused":  ago("service_down:paused", ServiceDownSource, `"maintenance"`, time.Minute),
-			"service_down:forged":  ago("service_down:forged", "voice", `"down"`, time.Minute),
-			"service_down:missing": ago("service_down:missing", ServiceDownSource, `"unknown"`, time.Minute),
+			"service_down:web":     ago("service_down:web", ServiceDownSource, `"up"`, 5*time.Minute),
+			"service_down:db":      ago("service_down:db", ServiceDownSource, `"down"`, 5*time.Minute),
+			"service_down:vault":   ago("service_down:vault", ServiceDownSource, `"down"`, 5*time.Minute),
+			"service_down:paused":  ago("service_down:paused", ServiceDownSource, `"maintenance"`, 5*time.Minute),
+			"service_down:forged":  ago("service_down:forged", "voice", `"down"`, 5*time.Minute),
+			"service_down:missing": ago("service_down:missing", ServiceDownSource, `"unknown"`, 5*time.Minute),
 		},
 	}
 	got := DownServices(s)
@@ -469,8 +469,8 @@ func TestDownServicesNamesOnlyTheDownOnes(t *testing.T) {
 // the aggregate stayed "down" and pausing achieved nothing.
 func TestPausedMonitorSilencesOnlyItself(t *testing.T) {
 	base := map[string]store.Fact{
-		"service_down:db":  ago("service_down:db", ServiceDownSource, `"maintenance"`, time.Minute),
-		"service_down:web": ago("service_down:web", ServiceDownSource, `"down"`, time.Minute),
+		"service_down:db":  ago("service_down:db", ServiceDownSource, `"maintenance"`, 5*time.Minute),
+		"service_down:web": ago("service_down:web", ServiceDownSource, `"down"`, 5*time.Minute),
 	}
 	if !ServiceDownRule().Predicate(State{Now: refTime(), Facts: base}) {
 		t.Fatal("web is still down, the rule must fire")
@@ -494,8 +494,48 @@ func TestServiceDownFiresOncePerTransition(t *testing.T) {
 		t.Fatal("already told about this transition, must be quiet")
 	}
 	// A second service goes down after that nudge — a new edge, so it fires.
-	s.Facts["service_down:web"] = ago("service_down:web", ServiceDownSource, `"down"`, time.Minute)
+	s.Facts["service_down:web"] = ago("service_down:web", ServiceDownSource, `"down"`, 5*time.Minute)
 	if !ServiceDownRule().Predicate(s) {
 		t.Fatal("a later transition must fire again")
 	}
 }
+
+// A monitor that reads down on one poll and up on the next raises nothing
+// (Vikunja #536). Technitium did exactly that at 01:27:59 on 05-08-2026, and
+// the alarm arrived after the service was already back.
+func TestAFlappingMonitorRaisesNothing(t *testing.T) {
+	fresh := ago("service_down:dns", ServiceDownSource, `"down"`, 10*time.Second)
+	s := State{Now: refTime(), Facts: map[string]store.Fact{"service_down:dns": fresh}}
+	if ServiceDownRule().Predicate(s) {
+		t.Fatal("a monitor down for ten seconds must not wake him")
+	}
+	// It stays down. mavpoll writes only on change, so the fact does not move
+	// and its age is how long the outage has run.
+	s.Now = fresh.Ts.Add(MinDownAge)
+	if !ServiceDownRule().Predicate(s) {
+		t.Fatal("past MinDownAge this is a real outage and must fire")
+	}
+}
+
+// The debounce bounds the alarm, not the truth. /dash reads DownServices and
+// showing a fresh outage there is right even when phoning him about it is not.
+func TestDownServicesReportsAFreshOutage(t *testing.T) {
+	s := State{
+		Now:   refTime(),
+		Facts: map[string]store.Fact{"service_down:dns": ago("service_down:dns", ServiceDownSource, `"down"`, 10*time.Second)},
+	}
+	if got := DownServices(s); len(got) != 1 || got[0] != "dns" {
+		t.Fatalf("DownServices = %v, want [dns]", got)
+	}
+}
+
+// One monitor flapping must not hide another that has been down for an hour.
+func TestAFlapDoesNotMaskARealOutage(t *testing.T) {
+	s := State{Now: refTime(), Facts: map[string]store.Fact{
+		"service_down:dns": ago("service_down:dns", ServiceDownSource, `"down"`, 10*time.Second),
+		"service_down:db":  ago("service_down:db", ServiceDownSource, `"down"`, time.Hour),
+	}}
+	if !ServiceDownRule().Predicate(s) {
+		t.Fatal("db has been down an hour, the rule must fire")
+	}
+}