diff --git a/go/parts/bus.go b/go/parts/bus.go
index 13f67cf..6dc9d4d 100644
--- a/go/parts/bus.go
+++ b/go/parts/bus.go
@@ -101,9 +101,11 @@ func BusArm(state string) func(id string, ttl time.Duration) error {
 
 // FollowIdle follows the holder's idle state (the one BusArm writes) once the bundle serves, and hands the end of each
 // key (the bus's marker, OpExpire) to expired, a Receiver's Expired: the event drops an idle transfer, no timer runs.
-// said is told each outcome (dropped, or the error that stopped it) for the holder's log. It blocks; run it in its own
-// goroutine.
-func FollowIdle(state string, expired func(id string) (bool, error), said func(id string, dropped bool, err error)) {
+// Once the watch is taken it hands every transfer open (open, such as IDs of the holder's Transfers) to expired too, so
+// a key that ended while the bundle was down, whose marker no watch saw, still drops its transfer, and a key lost is
+// armed again. said is told each outcome (dropped, or the error that stopped it) for the holder's log. It returns
+// once the start's look is done; run it in its own goroutine.
+func FollowIdle(state string, open func() ([]string, error), expired func(id string) (bool, error), said func(id string, dropped bool, err error)) {
 	<-stdio.Served()
 	stdio.State(state).Follow("", func(ch stdio.StateChange) error {
 		if ch.Op != stdio.OpExpire {
@@ -115,4 +117,38 @@ func FollowIdle(state string, expired func(id string) (bool, error), said func(i
 		}
 		return err
 	})
+	expireOpen(state, open, expired, said)
+}
+
+// expireOpen is FollowIdle's look at its start: every open transfer handed to expired, as its key's end would.
+func expireOpen(state string, open func() ([]string, error), expired func(id string) (bool, error), said func(id string, dropped bool, err error)) {
+	say := func(id string, dropped bool, err error) {
+		if said != nil && (dropped || err != nil) {
+			said(id, dropped, err)
+		}
+	}
+	ids, err := open()
+	if err != nil {
+		say("", false, fmt.Errorf("the open transfers cannot be read at the start of %s's watch, so one whose idle key ended while the bundle was down waits for a look by hand: %w", state, err))
+		return
+	}
+	for _, id := range ids {
+		dropped, err := expired(id)
+		say(id, dropped, err)
+	}
+}
+
+// IDs answers the ids of the transfers open in t: FollowIdle's open.
+func IDs[M any](t Transfers[M]) func() ([]string, error) {
+	return func() ([]string, error) {
+		all, err := t.List()
+		if err != nil {
+			return nil, err
+		}
+		out := make([]string, 0, len(all))
+		for _, x := range all {
+			out = append(out, x.ID)
+		}
+		return out, nil
+	}
 }
diff --git a/go/parts/receive_test.go b/go/parts/receive_test.go
index 760c35a..d4ee5df 100644
--- a/go/parts/receive_test.go
+++ b/go/parts/receive_test.go
@@ -273,5 +273,33 @@ func aHolderTakesAFileInParts(t *testing.T) {
 		if pkg.Bound = func() (uint64, error) { return 0, errors.New("no binding") }; pkg.CapNow() != pkg.Cap {
 			t.Errorf("CapNow with no binding read = %d, want Cap %d", pkg.CapNow(), pkg.Cap)
 		}
+		pkg.Bound = nil
+		// At the start of the idle watch every open transfer is looked at (expireOpen): one whose key ended while the
+		// bundle was down is dropped, one still within its bound is armed again for the rest.
+		pkg.Arm = func(id string, ttl time.Duration) error { armed[id] = ttl; return nil }
+		for id := range pkg.Transfers.(memTransfers[packageShape]) {
+			_, _ = pkg.Drop(id)
+		}
+		_, _ = pkg.Open("t9", "builder", []Want{part}, packageShape{"m", "1"})
+		now = now.Add(IdleAfter + time.Hour)
+		_, _ = pkg.Open("t10", "builder", []Want{part}, packageShape{"m", "1"})
+		now = now.Add(time.Hour)
+		var dropped []string
+		expireOpen("idle", IDs(pkg.Transfers), pkg.Expired, func(id string, d bool, err error) {
+			if err != nil {
+				t.Errorf("start's look at %s: %v", id, err)
+			}
+			if d {
+				dropped = append(dropped, id)
+			}
+		})
+		if !reflect.DeepEqual(dropped, []string{"t9"}) || armed["t10"] != IdleAfter-time.Hour {
+			t.Errorf("at the start: dropped %v, t10 armed for %s; want t9 dropped and t10 armed for %s", dropped, armed["t10"], IdleAfter-time.Hour)
+		}
+		var said error
+		expireOpen("idle", func() ([]string, error) { return nil, errors.New("bus down") }, pkg.Expired, func(_ string, _ bool, err error) { said = err })
+		if said == nil || !strings.Contains(said.Error(), "bus down") {
+			t.Errorf("start's look with no list said %v, want the failure", said)
+		}
 	})
 }