Forget pushed event ids when Google Calendar is disconnected (Feature 16)

Disconnect deleted the connection but left every pushed plan synced with
its stored event ids, though no calendar was chosen any more. It now
deletes the connection and runs the same invalidation as choosing another
calendar (forgetEvents: MarkCalendarPlansEdited, ClearCalendarEvents) in
one transaction, under the account lock. A refused revoke still changes
nothing.

Tests push three weeks, disconnect, and check each is changed with no
event id; then connect again, choose a calendar and push the whole week
to it. Also: a refused revoke keeps every week synced, and a disconnect
during a push waits for its record and then forgets it.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/plan/push_test.go

@@ -631,3 +631,124 @@ func TestChoosingAnotherCalendarWaitsForAPush(t *testing.T) {
 	}
 	e.assertWeekOn(t, kitchenCal.ID, week, dates, fullWeek...)
 }
+
+// pushedWeeks are the weeks the disconnect tests push: the calendar and the
+// connection are the household's, so a disconnect concerns every one.
+var pushedWeeks = []store.LocalDate{week, mustDate("2026-10-19"), mustDate("2026-10-26")}
+
+// assertForgotten fails unless the plan of weekStart is changed and no day
+// keeps an event id.
+func (e *env) assertForgotten(t *testing.T, weekStart store.LocalDate, why string) {
+	t.Helper()
+	p, err := e.svc.Get(t.Context(), weekStart)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if p.Status != plan.StatusChanged {
+		t.Errorf("plan of %s %s = %s, want changed", weekStart, why, p.Status)
+	}
+	for date, id := range e.eventIDs(t, weekStart) {
+		if id != "" {
+			t.Errorf("%s kept event id %q %s", date, id, why)
+		}
+	}
+}
+
+func TestDisconnectForgetsEveryPushedWeek(t *testing.T) {
+	e := newEnv(t)
+	e.connectCalendar(t)
+	dates := map[store.LocalDate][]string{}
+	for _, w := range pushedWeeks {
+		dates[w] = e.storePlan(t, w, fullWeek...)
+		if _, err := e.svc.Push(t.Context(), w); err != nil {
+			t.Fatalf("Push %s: %v", w, err)
+		}
+	}
+	draftWeek := mustDate("2026-11-02")
+	e.storePlan(t, draftWeek, fullWeek...)
+
+	if err := e.gcal.Disconnect(t.Context()); err != nil {
+		t.Fatalf("Disconnect: %v", err)
+	}
+	for _, w := range pushedWeeks {
+		e.assertForgotten(t, w, "after disconnecting")
+	}
+	e.assertUnsynced(t, draftWeek, plan.StatusDraft)
+
+	// Connecting again chooses no calendar, so nothing is pushed until one
+	// is chosen; then a push writes the whole week to it.
+	e.google.Connect(t, e.gcal)
+	if _, err := e.svc.Push(t.Context(), week); !errors.Is(err, gcal.ErrNoCalendar) {
+		t.Fatalf("Push after connecting again = %v, want ErrNoCalendar", err)
+	}
+	e.google.SetCalendars(0, dinnersCal, kitchenCal)
+	if _, err := e.gcal.SelectCalendar(t.Context(), kitchenCal.ID); err != nil {
+		t.Fatal(err)
+	}
+	for _, w := range pushedWeeks {
+		e.assertForgotten(t, w, "after connecting again")
+		p, err := e.svc.Push(t.Context(), w)
+		if err != nil || p.Status != plan.StatusSynced {
+			t.Fatalf("Push %s = %s, %v; want synced", w, p.Status, err)
+		}
+		e.assertWeekOn(t, kitchenCal.ID, w, dates[w], fullWeek...)
+	}
+}
+
+// TestDisconnectRefusedKeepsPushedWeeks: a revoke Google refuses keeps the
+// connection and its calendar, so every pushed week stays synced to it.
+func TestDisconnectRefusedKeepsPushedWeeks(t *testing.T) {
+	e := newEnv(t)
+	e.connectCalendar(t)
+	dates := map[store.LocalDate][]string{}
+	for _, w := range pushedWeeks {
+		dates[w] = e.storePlan(t, w, fullWeek...)
+		if _, err := e.svc.Push(t.Context(), w); err != nil {
+			t.Fatalf("Push %s: %v", w, err)
+		}
+	}
+	e.google.AnswerRevoke(http.StatusServiceUnavailable, "")
+	var revokeErr *gcal.RevokeError
+	if err := e.gcal.Disconnect(t.Context()); !errors.As(err, &revokeErr) {
+		t.Fatalf("Disconnect = %v, want a *RevokeError", err)
+	}
+	for _, w := range pushedWeeks {
+		if p, err := e.svc.Get(t.Context(), w); err != nil || p.Status != plan.StatusSynced {
+			t.Errorf("plan of %s after a refused disconnect = %s, %v; want synced", w, p.Status, err)
+		}
+		e.assertWeekOn(t, dinnersCal.ID, w, dates[w], fullWeek...)
+	}
+}
+
+// TestDisconnectWaitsForAPush disconnects while a push is at Google: the
+// disconnect waits until the push is recorded, then forgets its events.
+func TestDisconnectWaitsForAPush(t *testing.T) {
+	e := newEnv(t)
+	e.connectCalendar(t)
+	e.storePlan(t, week, fullWeek...)
+	arrived, release := e.google.HoldEvents()
+	defer release()
+	pushed := make(chan error, 1)
+	go func() {
+		_, err := e.svc.Push(t.Context(), week)
+		pushed <- err
+	}()
+	<-arrived
+	disconnected := make(chan error, 1)
+	go func() {
+		disconnected <- e.gcal.Disconnect(t.Context())
+	}()
+	select {
+	case err := <-disconnected:
+		t.Fatalf("Disconnect finished (%v) while a push was at Google", err)
+	case <-time.After(200 * time.Millisecond):
+	}
+	release()
+	if err := <-pushed; err != nil {
+		t.Fatalf("Push: %v", err)
+	}
+	if err := <-disconnected; err != nil {
+		t.Fatalf("Disconnect: %v", err)
+	}
+	e.assertForgotten(t, week, "after disconnecting")
+}