a sev4 alarm stops when the service is back, or after two hours (V-535)

It repeated every five minutes for over two hours. WasAcked was the only
stop condition and nothing reachable from telegram can mark a nudge acked
— the only ack is a voice 'готово' on a box that runs no voice loop.

Two endings now. The condition cleared, which the rule answers through the
new Rule.StillTrue — deliberately not Predicate, which is edge-triggered
and reads false one tick after the alarm is raised, so building the stop on
it would cancel every alarm immediately. Or the alarm got old, which is the
bound that needs no cooperation from the rule. A rule with no StillTrue is
never read as resolved and stops only on age.

Covered by tests including the flap case, since none of it can be
reproduced by hand without waiting hours.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

cmd/mavend/tick.go

@@ -10,6 +10,7 @@ package main
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"log"
 	"os"
@@ -249,6 +250,7 @@ func (t *tickLoop) tick(ctx context.Context, now time.Time) {
 		return
 	}
 	keys = t.repeatableRules(keys)
+	keys = t.stopFinishedAlarms(ctx, keys, state, now)
 	if len(keys) == 0 {
 		return
 	}
@@ -260,6 +262,83 @@ func (t *tickLoop) tick(ctx context.Context, now time.Time) {
 	}
 }
 
+// maxAlarmAge — how long one un-acked telegram alarm may keep repeating.
+//
+// This is the floor brake and it applies to every rule, including one that
+// says nothing about its own condition (Vikunja #535). Nothing in the tree can
+// ack a telegram nudge: MarkAcked has no caller outside internal/store, and the
+// only ack that exists is a voice "готово" on a box that runs no voice loop. So
+// "repeat until acked" meant "repeat forever", and it did — every five minutes
+// for over two hours.
+//
+// Two hours at the five-minute default is about 24 messages, which is already
+// past the point of being read. An alarm nobody answered in two hours is not
+// one more repeat away from being answered, and the right move is to stop
+// talking, not to talk louder.
+const maxAlarmAge = 2 * time.Hour
+
+// stopFinishedAlarms returns the keys that may still repeat, and closes the
+// rest.
+//
+// Two ways an alarm ends without him. The condition cleared, which the rule
+// answers through StillTrue — deliberately NOT Predicate, which is
+// edge-triggered and reads false one tick after the alarm is raised, so using
+// it would cancel every alarm immediately. Or the alarm simply got old, which
+// is the bound that does not need the rule's cooperation.
+//
+// A rule with no StillTrue is not treated as resolved. Silence about the
+// condition is not evidence the condition cleared, so those keys only ever stop
+// on age.
+func (t *tickLoop) stopFinishedAlarms(ctx context.Context, keys []string, state loop.State, now time.Time) []string {
+	if len(keys) == 0 {
+		return nil
+	}
+	byName := make(map[string]loop.Rule, len(t.rules))
+	for _, r := range t.rules {
+		byName[r.Name] = r
+	}
+	live := keys[:0:0]
+	for _, key := range keys {
+		outcome := ""
+		switch r := byName[key]; {
+		case r.StillTrue != nil && !r.StillTrue(state):
+			outcome = store.NudgeResolved
+		case t.alarmIsOlderThan(ctx, key, maxAlarmAge, now):
+			// Not "resolved": nothing says the thing got better. This is her
+			// giving up on being answered, and /notifications should say so.
+			outcome = store.NudgeIgnored
+		}
+		if outcome == "" {
+			live = append(live, key)
+			continue
+		}
+		n, err := t.store.ResolvePendingTelegram(ctx, key, outcome, now)
+		if err != nil {
+			// Could not close it, so do not drop it either: repeating is the
+			// lesser fault against losing the alarm entirely.
+			log.Printf("tick: stop alarm %s: %v", key, err)
+			live = append(live, key)
+			continue
+		}
+		log.Printf("tick: alarm %s ended (%s), %d pending nudge(s) closed", key, outcome, n)
+	}
+	return live
+}
+
+// alarmIsOlderThan reports whether the oldest un-acked send for this rule is
+// past the cap. A read failure answers false: an alarm that repeats one more
+// time is better than one silenced by a transient store error.
+func (t *tickLoop) alarmIsOlderThan(ctx context.Context, rule string, age time.Duration, now time.Time) bool {
+	oldest, err := t.store.OldestPendingTelegram(ctx, rule)
+	if err != nil {
+		if !errors.Is(err, store.ErrNudgeNotFound) {
+			log.Printf("tick: oldest pending %s: %v", rule, err)
+		}
+		return false
+	}
+	return now.Sub(oldest) >= age
+}
+
 // repeatableRules drops keys whose rule is not wired any more.
 //
 // The repeat path reads the nudges table, not the rule set: any sev4 telegram