eval: a verb governed by "ты" is his, not her drift (V-462)

CheckFeminine flagged "ты заплатил за домен" as a masculine self-reference.
The second pass reads a masculine past-tense verb before "тебе", "тебя" or
"за" as her speaking with the pronoun dropped, and it checked neither the
subject nor what "за" pointed at. He is male, so a verb governed by "ты"
must be masculine, and "за домен" is a price rather than a favour.

The talk fixture was under-reporting by a point whenever a reply addressed
him in the past tense, which is common.

cmd/mavend/clarify_test.go

@@ -465,3 +465,39 @@ func TestExpiryNoticeSurvivesAConfirmTurn(t *testing.T) {
 		t.Fatal("the expired question must be gone")
 	}
 }
+
+// The other half of the subject question: his answer must fill the empty slot,
+// not replace the request. Slots.Text used to be the whole raw utterance for
+// every intent, so the branch that fills a text slot could only ever overwrite
+// (Vikunja #383). Here the parked request holds the hour and the answer holds
+// what to say at it, and the reminder that lands has both.
+func TestClarifySubjectAnswerFillsRatherThanClobbers(t *testing.T) {
+	ctx := context.Background()
+	h, st, _ := newClarifyHandler(t)
+	at := h.now().Add(2 * time.Hour)
+
+	question, asked := h.askClarify(clarifyDec(router.IntentReminder,
+		router.Slots{Time: at, HasTime: true}, "напомни в 11"))
+	if !asked || question != "О чём напомнить?" {
+		t.Fatalf("expected the subject question, got %q asked=%v", question, asked)
+	}
+
+	reply, handled := h.resolveClarifyAnswer(ctx, "позвонить маме")
+	if !handled {
+		t.Fatal("the answer to an open question must be consumed as an answer")
+	}
+	if reply == clarifyGaveUp {
+		t.Fatalf("a good answer must not drop the request: %q", reply)
+	}
+
+	reminders, err := st.DueReminders(ctx, h.now().Add(48*time.Hour))
+	if err != nil || len(reminders) != 1 {
+		t.Fatalf("clarified reminder was not created: reminders=%v err=%v", reminders, err)
+	}
+	if !strings.Contains(reminders[0].Payload, "маме") {
+		t.Fatalf("the answer never reached the reminder: %q", reminders[0].Payload)
+	}
+	if !strings.Contains(reminders[0].Payload, "11") {
+		t.Fatalf("the answer clobbered the original request: %q", reminders[0].Payload)
+	}
+}

cmd/mavgpud/runner.go

@@ -24,7 +24,12 @@ type runner struct {
 	mu    sync.Mutex
 	cmd   *exec.Cmd
 	ready bool
-	http  *http.Client
+	// yielding — stop() has sent the signal and the exit that follows is ours.
+	// llama-server aborts on SIGTERM (its static teardown throws, upstream
+	// ggml-org/llama.cpp), so a routine yield and a real crash produce the same
+	// "signal: aborted" and used to log identically (Vikunja #491).
+	yielding bool
+	http     *http.Client
 }
 
 func newRunner(bin string, args []string, readyURL string) *runner {
@@ -70,13 +75,18 @@ func (r *runner) start() error {
 	if err := cmd.Start(); err != nil {
 		return err
 	}
-	r.cmd, r.ready = cmd, false
+	r.cmd, r.ready, r.yielding = cmd, false, false
 	log.Printf("mavgpud: started llama-server pid=%d", cmd.Process.Pid)
 	go func() {
 		err := cmd.Wait()
 		r.mu.Lock()
-		r.cmd, r.ready = nil, false
+		yielded := r.yielding
+		r.cmd, r.ready, r.yielding = nil, false, false
 		r.mu.Unlock()
+		if yielded {
+			log.Printf("mavgpud: llama-server stopped, card yielded (%v)", err)
+			return
+		}
 		log.Printf("mavgpud: llama-server exited: %v", err)
 	}()
 	return nil
@@ -90,6 +100,10 @@ func (r *runner) stop(grace time.Duration) {
 	r.mu.Lock()
 	cmd := r.cmd
 	r.ready = false
+	if cmd != nil && cmd.Process != nil {
+		// The exit that follows is ours, not a crash.
+		r.yielding = true
+	}
 	r.mu.Unlock()
 	if cmd == nil || cmd.Process == nil {
 		return

cmd/mavgpud/runner_test.go

@@ -0,0 +1,59 @@
+package main
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+)
+
+// fakeServer writes an executable standing in for llama-server: it ignores
+// SIGTERM the way the real one effectively does — by dying messily rather than
+// cleanly — and reports a non-zero status.
+func fakeServer(t *testing.T, body string) string {
+	t.Helper()
+	path := filepath.Join(t.TempDir(), "fake-llama-server")
+	if err := os.WriteFile(path, []byte("#!/bin/sh\n"+body+"\n"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+	return path
+}
+
+// A deliberate stop is a yield, and the log has to say so.
+//
+// llama-server aborts inside its own static teardown on SIGTERM, so the exit
+// status of a routine yield is identical to that of a real crash. Reading the
+// mavgpud log, the two were indistinguishable (Vikunja #491).
+func TestStopMarksTheExitAsAYield(t *testing.T) {
+	r := newRunner(fakeServer(t, "while : ; do sleep 1 ; done"), nil, "")
+	if err := r.start(); err != nil {
+		t.Fatalf("start: %v", err)
+	}
+	r.mu.Lock()
+	if r.yielding {
+		t.Error("a freshly started server is already marked as yielding")
+	}
+	r.mu.Unlock()
+
+	r.stop(2 * time.Second)
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		if !r.running() {
+			return
+		}
+		time.Sleep(10 * time.Millisecond)
+	}
+	t.Fatal("the child outlived stop")
+}
+
+// Stopping when nothing is running must not arm the flag for the next child.
+// The next exit after that would be a real crash logged as a yield.
+func TestStopWithNoChildDoesNotArmTheFlag(t *testing.T) {
+	r := newRunner("/nonexistent", nil, "")
+	r.stop(10 * time.Millisecond)
+	r.mu.Lock()
+	defer r.mu.Unlock()
+	if r.yielding {
+		t.Error("stop armed the yield flag with no child running")
+	}
+}

deploy/mavgpud.service

@@ -19,6 +19,10 @@ RestartSec=5
 # llama-server on SIGTERM, so give it longer than stop_grace to do that.
 KillSignal=SIGTERM
 TimeoutStopSec=60
+# llama-server aborts inside its own static teardown on SIGTERM, so every
+# routine yield used to write a multi-gigabyte core into systemd-coredump
+# (Vikunja #491). Yielding is meant to happen several times a day.
+LimitCORE=0
 
 [Install]
 WantedBy=default.target

internal/calendar/calendar.go

@@ -18,6 +18,7 @@ import (
 	"sort"
 	"strings"
 	"time"
+	"unicode"
 )
 
 // Fact sources. A calendar event reaches the store as a
@@ -153,14 +154,20 @@ func Overlapping(events []Event, from, to time.Time) []Event {
 	return out
 }
 
-// safeKey makes a summary safe to use inside a fact key (ASCII alphanumerics
-// and dashes). Non-Latin summaries collapse to their punctuation, which is why
-// the day prefix carries the identity and this only disambiguates within a day.
+// safeKey makes a summary safe to use inside a fact key: letters and digits in
+// any script, plus dashes, with space and underscore folded to a dash.
+//
+// It kept ASCII only until 04-08-2026, and dropped everything else. His
+// calendar is Russian, so "Встреча с Аней" and "Обед с мамой" both reduced to
+// "--" and produced the same key on the same day — the second event of the day
+// silently overwrote the first (Vikunja #443). Letting the letters through is
+// what makes the key identify the event. Migration #18 drops the keys written
+// under the old rule; they are re-derived on the next poll.
 func safeKey(s string) string {
 	var b strings.Builder
 	for _, r := range s {
 		switch {
-		case (r >= 'a' && r <= 'z') || (r >= 'A' && r <= 'Z') || (r >= '0' && r <= '9') || r == '-':
+		case unicode.IsLetter(r) || unicode.IsDigit(r) || r == '-':
 			b.WriteRune(r)
 		case r == ' ' || r == '_':
 			b.WriteRune('-')

internal/calendar/calendar_test.go

@@ -139,6 +139,9 @@ func TestSafeKey(t *testing.T) {
 		{"Hello_World", "Hello-World"},
 		{"special@#$chars!!", "specialchars"},
 		{"ALL_CAPS_123", "ALL-CAPS-123"},
+		// His calendar is Russian. These reduced to "--" and "--" (Vikunja #443).
+		{"Встреча с Аней", "Встреча-с-Аней"},
+		{"Обед с мамой", "Обед-с-мамой"},
 	}
 	for _, tt := range tests {
 		if got := safeKey(tt.in); got != tt.want {
@@ -263,3 +266,19 @@ func TestSourceTrust(t *testing.T) {
 		t.Errorf("Sources() = %v", Sources())
 	}
 }
+
+// Two Russian events on one day must not share a key. They did: safeKey kept
+// ASCII only, so both summaries collapsed to their spaces and the second event
+// overwrote the first in the store (Vikunja #443).
+func TestFactKeyDistinguishesRussianEventsOnOneDay(t *testing.T) {
+	day := time.Date(2026, 8, 4, 0, 0, 0, 0, time.UTC)
+	a := Event{Summary: "Встреча с Аней", Start: day.Add(10 * time.Hour), End: day.Add(11 * time.Hour)}
+	b := Event{Summary: "Обед с мамой", Start: day.Add(13 * time.Hour), End: day.Add(14 * time.Hour)}
+	if FactKeyIn(a, time.UTC) == FactKeyIn(b, time.UTC) {
+		t.Fatalf("both events keyed as %q", FactKeyIn(a, time.UTC))
+	}
+	// The day prefix still has to survive, because the store range-scans on it.
+	if !strings.HasPrefix(FactKeyIn(a, time.UTC), KeyPrefixForDay(day)) {
+		t.Fatalf("key %q lost the day prefix %q", FactKeyIn(a, time.UTC), KeyPrefixForDay(day))
+	}
+}

internal/phraser/eval/checks.go

@@ -173,12 +173,23 @@ func checkFeminine(body string) Result {
 	// Second pass: self-reference with the pronoun dropped — "напомнил тебе",
 	// "проверил за тебя". A masculine past-tense verb whose object is HIM can
 	// only be her speaking about herself.
+	//
+	// Two guards, both from a false positive on the talk fixture: "ты заплатил
+	// за домен до марта" scored as her drift and cost the run a point it had
+	// earned (Vikunja #462). He is male, so a past-tense verb governed by "ты"
+	// must be masculine. And a bare "за" is not evidence of anything — "за
+	// домен" is a price, "за тебя" is her doing something on his behalf — so it
+	// only counts when he is the one it points at.
 	for i, w := range words {
-		if !masculinePast(w) || i+1 >= len(words) {
+		if !masculinePast(w) || i+1 >= len(words) || governedByYou(words, i) {
 			continue
 		}
 		next := words[i+1]
-		if next == "тебе" || next == "тебя" || next == "за" {
+		aboutHim := next == "тебе" || next == "тебя"
+		if next == "за" && i+2 < len(words) && (words[i+2] == "тебя" || words[i+2] == "тебе") {
+			aboutHim = true
+		}
+		if aboutHim {
 			return Result{CheckFeminine, false,
 				fmt.Sprintf("masculine self-reference %q before %q", w, next)}
 		}
@@ -652,3 +663,19 @@ func checkEllipsis(body string) Result {
 	}
 	return Result{CheckEllipsis, true, ""}
 }
+
+// governedByYou reports whether "ты" stands close enough in front of the verb
+// at index i to be its subject. Three words, the same window checkFeminine's
+// first pass uses after "я", and it stops at a first-person pronoun so "ты
+// просил, я напомнил" still trips.
+func governedByYou(words []string, i int) bool {
+	for j := i - 1; j >= 0 && j >= i-3; j-- {
+		switch words[j] {
+		case "ты":
+			return true
+		case "я":
+			return false
+		}
+	}
+	return false
+}

internal/phraser/eval/eval_test.go

@@ -106,6 +106,12 @@ func TestChecksCatchWhatTheyClaim(t *testing.T) {
 		{"masculine predicative", "я должен сказать: попей воды.", CheckFeminine},
 		// The other direction: HE is male, so second-person masculine is right.
 		{"second person masculine ok", "ты не пил воду четыре часа.", ""},
+		// The recorded false positive: "заплатил" sits before "за", and the
+		// second pass read that as her dropping the pronoun. The subject is
+		// "ты" and he is male, so the reply is right (Vikunja #462).
+		{"second person masculine before за", "ты заплатил за домен до марта, а воду пить всё равно надо.", ""},
+		// The same shape she really does get wrong still trips.
+		{"masculine on his behalf", "проверил за тебя — воды не было четыре часа.", CheckFeminine},
 		// The real observed failure: she addressed him as a woman.
 		{"feminine second person", "ты давно не отдыхала — попей воды.", CheckHisGender},
 		{"feminine second person no dash", "ты пила воду четыре часа назад.", CheckHisGender},

internal/router/agenda_test.go

@@ -75,3 +75,47 @@ func TestAgendaGrammarSparesStatements(t *testing.T) {
 		}
 	}
 }
+
+// The tomorrow form and the bare event noun. Both were measured answering
+// "пока не умею" on the deployed daemon, 02-08-2026, while the same question
+// about today worked — the first rule set needed "у меня" or a calendar noun
+// and these phrasings carry neither (Vikunja #471).
+func TestAgendaCoversOtherDaysAndNamedEvents(t *testing.T) {
+	r := agendaRouter(t)
+	for _, u := range []string{
+		"какие планы на завтра?",
+		"какие планы на послезавтра",
+		"что по делам в среду",
+		"какие планы на выходные",
+		"когда планёрка?",
+		"во сколько созвон",
+		"когда будет совещание",
+	} {
+		d, err := r.Route(context.Background(), u, refNow())
+		if err != nil {
+			t.Fatalf("route(%q): %v", u, err)
+		}
+		if d.Intent != IntentQuery {
+			t.Errorf("route(%q) = %s, want query", u, d.Intent)
+		}
+	}
+}
+
+// The two new rules are narrow on purpose. A world question that opens with
+// "когда" is not an agenda question, and telling her about a plan is not
+// asking about one.
+func TestAgendaGrammarsLeaveTheWorldAlone(t *testing.T) {
+	r := agendaRouter(t)
+	for _, u := range []string{
+		"когда была битва при ватерлоо",
+		"когда изобрели телефон",
+	} {
+		d, err := r.Route(context.Background(), u, refNow())
+		if err != nil {
+			t.Fatalf("route(%q): %v", u, err)
+		}
+		if d.Stage == 0 {
+			t.Errorf("route(%q) was claimed at stage 0 as %s", u, d.Intent)
+		}
+	}
+}

internal/router/eval/ru_routing_v1.json

@@ -23,6 +23,8 @@
     { "id": "ru-query-012", "utterance": "какие заметки я оставил про полив", "lang": "ru", "intent": "query", "tags": ["recall"] },
     { "id": "ru-query-013", "utterance": "во сколько у меня встреча", "lang": "ru", "intent": "query", "tags": ["calendar"] },
     { "id": "ru-query-019", "utterance": "что у меня стоит в календаре на послезавтра", "lang": "ru", "intent": "query", "tags": ["calendar", "hard"], "note": "agenda, not the clock: the daemon answers this from CalendarEvents inside the query branch, so the clock/date system rule must not swallow it" },
+    { "id": "ru-query-022", "utterance": "какие планы на завтра?", "lang": "ru", "intent": "query", "tags": ["calendar"], "note": "the same agenda question as ru-query-019 aimed at another day; it answered \u043f\u043e\u043a\u0430 \u043d\u0435 \u0443\u043c\u0435\u044e on the deployed daemon while the today form worked (Vikunja #471)" },
+    { "id": "ru-query-023", "utterance": "\u043a\u043e\u0433\u0434\u0430 \u043f\u043b\u0430\u043d\u0451\u0440\u043a\u0430?", "lang": "ru", "intent": "query", "tags": ["calendar", "hard"], "note": "a named event with no calendar word — the noun is the only signal that this is a question about his day" },
     { "id": "ru-query-014", "utterance": "я успеваю до дедлайна", "lang": "ru", "intent": "query", "tags": ["hard", "no-question-word"] },
     { "id": "ru-query-015", "utterance": "сколько я прошёл шагов", "lang": "ru", "intent": "query", "tags": ["aggregate"] },
     { "id": "ru-query-016", "utterance": "покажи давление за неделю", "lang": "ru", "intent": "query", "tags": ["hard", "imperative"], "note": "imperative form but a read — must not route to act" },

internal/router/llmrouter.go

@@ -210,7 +210,11 @@ func (lr *LLMRouter) Route(ctx context.Context, utterance string, now time.Time)
 		d.Slots.HasKey = a.Key != ""
 	case IntentReminder:
 		d.Intent = IntentReminder
-		d.Slots.Text = firstNonEmpty(a.Text, utterance)
+		// No utterance fallback here, unlike every other intent below. The
+		// model returning no text for a reminder means it found no subject,
+		// and "напомни в 11" is not a subject. Leaving Text empty is what
+		// lets the gate turn that into a question (Vikunja #383).
+		d.Slots.Text = a.Text
 	case IntentNote:
 		d.Intent = IntentNote
 		d.Slots.Text = firstNonEmpty(a.Text, utterance)

internal/router/llmrouter_test.go

@@ -356,3 +356,35 @@ func TestRouterLLMFactWithResolvedKeyStaysConfident(t *testing.T) {
 		t.Fatalf("a fact the parser could key must not clarify: %+v", d)
 	}
 }
+
+// A reminder with a time and no subject must come back empty and gated, not
+// backfilled with the raw words. "напомни в 11" carries an hour and nothing to
+// say at that hour; parking the utterance in Text made the request look
+// complete, so the daemon set a reminder that fires saying "напомни в 11"
+// (Vikunja #383).
+func TestLLMReminderWithoutSubjectAsksInsteadOfGuessing(t *testing.T) {
+	r := newLLMTestRouter(t, `{"intent":"reminder"}`)
+	d, err := r.Route(context.Background(), "напомни в 11", refNow())
+	if err != nil {
+		t.Fatalf("route: %v", err)
+	}
+	if d.Slots.Text != "" {
+		t.Fatalf("subject backfilled from the utterance: %q", d.Slots.Text)
+	}
+	if !d.Clarify {
+		t.Fatalf("a subjectless reminder was accepted, confidence %v", d.Confidence)
+	}
+}
+
+// The gate is about the subject, not about reminders in general: one that has
+// both halves still runs without a question.
+func TestLLMReminderWithSubjectIsNotGated(t *testing.T) {
+	r := newLLMTestRouter(t, `{"intent":"reminder","text":"позвонить маме"}`)
+	d, err := r.Route(context.Background(), "напомни в 11 позвонить маме", refNow())
+	if err != nil {
+		t.Fatalf("route: %v", err)
+	}
+	if d.Clarify {
+		t.Fatalf("a complete reminder was sent back as a question: %+v", d.Slots)
+	}
+}

internal/router/router.go

@@ -147,7 +147,15 @@ func (r *Router) fillSlots(ctx context.Context, d *Decision, now time.Time) {
 			d.Slots.Fn, d.Slots.Args, d.Slots.HasFn = fn, args, true
 		}
 	}
-	if d.Slots.Text == "" {
+	// The extractor's Text is the raw utterance, which is the payload for a
+	// note, a query or a chat turn but not for a reminder — there Text is the
+	// subject, what she says at the hour. Backfilling it made Text impossible
+	// to be empty, so StillMissing never reported SlotText and "О чём
+	// напомнить?" was unaskable; the answer to a question she did manage to
+	// ask then overwrote the whole request instead of filling one gap
+	// (Vikunja #383). A reminder with no subject stays empty and is gated
+	// below into a question.
+	if d.Slots.Text == "" && d.Intent != IntentReminder {
 		d.Slots.Text = ex.Text
 	}
 	// Stage stays 1: it says who decided the route, and that was the LLM.
@@ -177,6 +185,12 @@ func (r *Router) gateLLMDecision(d *Decision) {
 	if d.Intent == IntentAct && !d.Slots.HasFn && d.Confidence > llmThinConfidence {
 		d.Confidence = llmThinConfidence
 	}
+	// A reminder with no subject: she knows when but not what to say then.
+	// Setting it anyway fires an empty reminder at the hour, which reads as a
+	// bug to him and cannot be repaired after the fact. Ask (Vikunja #383).
+	if d.Intent == IntentReminder && d.Slots.Text == "" && d.Confidence > llmThinConfidence {
+		d.Confidence = llmThinConfidence
+	}
 	if d.Confidence < r.threshold {
 		d.Clarify = true
 	}

internal/router/stage0.go

@@ -182,9 +182,38 @@ func AgendaQueryGrammars() []Grammar {
 			Pattern: regexp.MustCompile(`(?i)^\s*(что|чего|какие|сколько|во\s+сколько|когда)\s+у\s+меня(\s|[?!.]|$)`),
 			Build:   agendaQueryBuild,
 		},
+		{
+			// A plan noun aimed at a named day, with no possessive to anchor
+			// on: "какие планы на завтра", "что по делам в среду". The rule
+			// above wants "у меня" and this phrasing never has it, so
+			// "какие планы на завтра" answered "пока не умею" while "какие
+			// планы на сегодня" worked (Vikunja #471). The day word is what
+			// makes it an agenda question rather than a topic.
+			Name: "plan-day-query",
+			// Only "план" and "дел". A verb stem like "встреч" would take
+			// "встречаемся в среду", which is him telling her something, not
+			// asking.
+			Pattern: regexp.MustCompile(`(?i)(^|\s)(план|дел)[а-я]*\s+(на|в|во|по)\s+` + dayWordPattern + `(\s|[?!.]|$)`),
+			Build:   agendaQueryBuild,
+		},
+		{
+			// A named event with no calendar word at all: "когда планёрка?",
+			// "во сколько созвон". He is asking when something on his calendar
+			// happens, and the noun is the only signal. Closed list, so "когда
+			// битва при Ватерлоо" is still a world question.
+			Name:    "event-time-query",
+			Pattern: regexp.MustCompile(`(?i)^\s*(когда|во\s+сколько|в\s+котором\s+часу)\s+(будет\s+|у\s+нас\s+)?(планёрк|планерк|встреч|созвон|митинг|совещани|звонок|созвон|приём|прием|интервью|собеседовани|тренировк|урок|занятие|пара)[а-я]*(\s|[?!.]|$)`),
+			Build:   agendaQueryBuild,
+		},
 	}
 }
 
+// dayWordPattern — the day words an agenda question can name. Weekdays appear
+// in the accusative and prepositional forms the questions actually use ("в
+// среду", "на среде"), which is why the stems carry an inflection tail rather
+// than a fixed ending.
+const dayWordPattern = `(сегодня|завтра|послезавтра|выходн[а-я]+|недел[а-я]+|понедельник[а-я]*|вторник[а-я]*|сред[ауые][а-я]*|четверг[а-я]*|пятниц[ауые][а-я]*|суббот[ауые][а-я]*|воскресень[ея][а-я]*)`
+
 // agendaQueryBuild — shared Build for the agenda grammars. Confidence 1.0 on
 // the intent only: the utterance travels intact and the query chain's own
 // matchers decide the rest.

internal/store/migrations.go

@@ -208,6 +208,17 @@ ALTER TABLE reminders ADD COLUMN next_fire_ts INTEGER;`, // #2
 	// list_tasks into something that writes without the row changing by one
 	// byte. The fingerprint is the declared shape at approval time, so a
 	// redefinition is a re-approval instead of a silent upgrade.
+	`DELETE FROM facts
+	  WHERE key LIKE 'calendar_event_%'
+	    AND replace(substr(key, 25), '-', '') = '';`,
+	// #18 — drop the calendar keys written while safeKey dropped Cyrillic
+	// (Vikunja #443). Everything after the date prefix was punctuation, so
+	// every Russian event on one day shared one key and only the last one
+	// survived. Deleting rather than rewriting: a calendar fact is derived
+	// data, the next poll writes the day again under keys that identify the
+	// event, and the old rows would otherwise be recited as extra meetings.
+	// The filter is exact — it keeps any key whose summary part still has a
+	// letter or a digit in it.
 }
 
 // migrate applies every migration with a number greater than the DB's current

internal/store/migrations_test.go

@@ -47,3 +47,36 @@ func TestMigrateAppliesOnceAndIsIdempotent(t *testing.T) {
 		t.Fatalf("after re-migrate user_version = %d, want %d", v, want)
 	}
 }
+
+// Migration #18 clears the calendar keys written while safeKey dropped
+// Cyrillic. Those rows are indistinguishable from real events on read, so
+// leaving them would recite one meeting as several (Vikunja #443).
+func TestCollapsedCalendarKeysAreDropped(t *testing.T) {
+	ctx := context.Background()
+	s := newTestStore(t)
+
+	rows := []string{
+		"calendar_event_20260804_--",             // "Встреча с Аней" under the old rule
+		"calendar_event_20260804_",               // a one-word Russian summary
+		"calendar_event_20260804_Встреча-с-Аней", // the new format
+		"calendar_event_20260804_Standup",        // an ASCII summary, always fine
+	}
+	for _, key := range rows {
+		if _, err := s.db.ExecContext(ctx,
+			`INSERT INTO facts (ts, kind, key, value, source, confidence) VALUES (0, 'env', ?, 'x', 'poll:caldav', 1.0)`,
+			key); err != nil {
+			t.Fatalf("seed %q: %v", key, err)
+		}
+	}
+	if _, err := s.db.ExecContext(ctx, migrations[17]); err != nil {
+		t.Fatalf("migration 18: %v", err)
+	}
+
+	var got int
+	if err := s.db.QueryRowContext(ctx, `SELECT count(*) FROM facts WHERE key LIKE 'calendar_event_%'`).Scan(&got); err != nil {
+		t.Fatal(err)
+	}
+	if got != 2 {
+		t.Fatalf("%d calendar rows left, want the 2 that identify their event", got)
+	}
+}