diff --git a/modules/mesh-delivery-checker/cmd/mesh-delivery-checker-tools/main.go b/modules/mesh-delivery-checker/cmd/mesh-delivery-checker-tools/main.go
index 4422450..0bc71c9 100644
--- a/modules/mesh-delivery-checker/cmd/mesh-delivery-checker-tools/main.go
+++ b/modules/mesh-delivery-checker/cmd/mesh-delivery-checker-tools/main.go
@@ -105,7 +105,7 @@ func TryTools(tr Trying) []stdio.Tool {
 		{Name: check.TryTool,
 			Description: "Try a pushed head before its pull request is opened: the checker judges it as it judges a pull request's head, merged onto its trunk's head, " +
 				"its unit and integration levels through the build modules, and owes the forge nothing. Answers the try's id at once; " + check.TryReadTool + " reads " +
-				"where it stands. A try of the same head that waits or runs is the answer to a second ask; at most 4 wait or run at once, mesh-wide. A repository " +
+				"where it stands. A try of the same head that waits or runs is the answer to a second ask; at most 4 run on a build node and 8 wait for one at once, mesh-wide (a try queued behind the seat's checks holds no node). A repository " +
 				"the checker checks no level of (one whose trunk the gate does not name) is refused. A try whose ask no build node took within the step " +
 				"bound ends as error; its ask stays in the build seat's stream and may still run later, judged by nobody (issue 734).",
 			Input: map[string]any{"type": "object", "required": []string{"repository", "head"}, "properties": map[string]any{
diff --git a/modules/mesh-delivery-checker/internal/check/try.go b/modules/mesh-delivery-checker/internal/check/try.go
index a44b3b4..c008011 100644
--- a/modules/mesh-delivery-checker/internal/check/try.go
+++ b/modules/mesh-delivery-checker/internal/check/try.go
@@ -30,8 +30,13 @@ const (
 	// TriesState is the checker's state of tries: the bucket mesh-delivery-checker_tries, keys try-<unix nanoseconds>.
 	TriesState  = "tries"
 	TriesBucket = delivery.CheckerModule + "_" + TriesState
-	// MaxTries is how many tries may wait or run at once, mesh-wide: each holds a build node for minutes.
+	// MaxTries is how many tries may hold a build node at once, mesh-wide: each holds one for minutes. A try whose asks no
+	// node has taken yet waits behind the seat's other asks and holds none, so it counts toward MaxTriesWaiting instead
+	// (issue 1890: at 19:53 on 2026-10-26 four tries sat queued behind 44 checks for up to 47 minutes and no fifth could be
+	// asked).
 	MaxTries = 4
+	// MaxTriesWaiting is how many tries may wait at once, queued or with their asks not yet taken by a node.
+	MaxTriesWaiting = 8
 	// TryScan is how many of the newest tries a new ask reads to find the ones that wait or run (issue 1827).
 	TryScan = 64
 	// TryKeep is how long an ended try's key is kept before the checker removes it.
@@ -166,6 +171,18 @@ func (w *tryWriter) end() (Try, uint64) {
 	return w.t, w.rev
 }
 
+// HoldsANode says whether the try holds a build node now: it runs, and a step of its asks runs on a node, or it names
+// no step (a checker that writes its asks only at the end, or one about to put its first).
+func (t Try) HoldsANode() bool {
+	if t.State != TryRunning {
+		return false
+	}
+	if len(t.Steps) == 0 {
+		return true
+	}
+	return slices.ContainsFunc(t.Steps, func(s TryStep) bool { return s.State == delivery.StepRunning })
+}
+
 // Over says whether the try came to its end.
 func (t Try) Over() bool { return t.State == TryPass || t.State == TryFail || t.State == TryError }
 
@@ -269,7 +286,7 @@ func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (
 	}); err != nil {
 		return "", err
 	}
-	var open []string
+	var holding, waiting []string
 	for i, cur := range tries {
 		if !live[i] {
 			continue
@@ -277,10 +294,17 @@ func AskTry(store TryStore, trunks map[string]string, a TryAsk, now time.Time) (
 		if cur.Repository == t.Repository && cur.Head == t.Head && cur.Trunk == t.Trunk && cur.Tests == t.Tests && cur.Level == t.Level {
 			return cur.ID, nil
 		}
-		open = append(open, fmt.Sprintf("%s (%s@%.12s, %s)", cur.ID, cur.Repository, cur.Head, cur.State))
+		said := fmt.Sprintf("%s (%s@%.12s, %s)", cur.ID, cur.Repository, cur.Head, cur.State)
+		if cur.HoldsANode() {
+			holding = append(holding, said)
+		} else {
+			waiting = append(waiting, said)
+		}
 	}
-	if len(open) >= MaxTries {
-		return "", fmt.Errorf("%d tries wait or run, the most at once: %s; ask again when one ends", len(open), strings.Join(open, ", "))
+	// Tries on a build node and tries waiting for one are bounded apart: a try queued behind the seat's checks holds no node.
+	if len(holding) >= MaxTries || len(waiting) >= MaxTriesWaiting {
+		return "", fmt.Errorf("%d tries run on a build node (the most at once: %d) and %d wait for one (the most: %d): running %s; waiting %s; ask again when one ends",
+			len(holding), MaxTries, len(waiting), MaxTriesWaiting, orNone(holding), orNone(waiting))
 	}
 	t.ID = "try-" + strconv.FormatInt(now.UnixNano(), 10)
 	data, err := encodeTry(t)
@@ -553,3 +577,11 @@ func judgeWithin(ctx context.Context, j Judge, cs *Case, bound time.Duration) (O
 	}
 	return out, true
 }
+
+// orNone joins the tries said, or says none.
+func orNone(said []string) string {
+	if len(said) == 0 {
+		return "none"
+	}
+	return strings.Join(said, ", ")
+}
diff --git a/modules/mesh-delivery-checker/internal/check/try_test.go b/modules/mesh-delivery-checker/internal/check/try_test.go
index cee1241..e6b2427 100644
--- a/modules/mesh-delivery-checker/internal/check/try_test.go
+++ b/modules/mesh-delivery-checker/internal/check/try_test.go
@@ -3,6 +3,7 @@ package check
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"strings"
 	"testing"
 	"time"
@@ -67,14 +68,38 @@ func TestATryIsAskedQueuedOncePerHeadAndAtMostFourAtOnce(t *testing.T) { // ADR
 	if err != nil || again != id {
 		t.Errorf("a second ask of the same head answered %q, %v, want %q", again, err, id)
 	}
-	heads := []string{head2, trunkA2, trunkS2}
-	for i, h := range heads {
-		if _, err := AskTry(store, tryTrunks, TryAsk{Repository: repoA, Head: h, Trunk: trunkA}, at.Add(time.Duration(i+2)*time.Second)); err != nil {
-			t.Fatalf("try %d: %v", i+2, err)
-		}
+	// Issue 1890: tries on a build node (a step of theirs running, or none named yet) and tries waiting for one (queued, or
+	// their asks not taken) are bounded apart, MaxTries and MaxTriesWaiting; the refusal names both counts.
+	onNode := func(i int) Try {
+		return Try{ID: fmt.Sprintf("try-%d", i), Repository: repoA, Head: fmt.Sprintf("%040x", i), Trunk: trunkA, State: TryRunning,
+			Steps: []TryStep{{Ask: "a", State: delivery.StepRunning}}}
 	}
-	if _, err := AskTry(store, tryTrunks, TryAsk{Repository: repoSDK, Head: head1}, at.Add(time.Minute)); err == nil || !strings.Contains(err.Error(), "4 tries wait or run") {
-		t.Errorf("a fifth try answered %v, want refused naming the four", err)
+	waitingFor := func(i int) Try {
+		return Try{ID: fmt.Sprintf("try-%d", i), Repository: repoA, Head: fmt.Sprintf("%040x", i), Trunk: trunkA, State: TryRunning,
+			Steps: []TryStep{{Ask: "a", State: TryAsked}}}
+	}
+	for _, c := range []struct {
+		what          string
+		holding, wait int
+		refused       string
+	}{
+		{"four queued behind the checks, none on a node: a fifth is taken", 0, 4, ""},
+		{"four on a node", MaxTries, 0, "4 tries run on a build node (the most at once: 4) and 0 wait"},
+		{"three on a node, eight waiting", 3, MaxTriesWaiting, "3 tries run on a build node (the most at once: 4) and 8 wait for one (the most: 8)"},
+	} {
+		kv := newMemKV()
+		for i := range c.holding + c.wait {
+			tr := waitingFor(i + 1)
+			if i < c.holding {
+				tr = onNode(i + 1)
+			}
+			data, _ := encodeTry(tr)
+			_, _ = kv.Create(context.Background(), tr.ID, data)
+		}
+		_, err := AskTry(memTries{kv}, tryTrunks, TryAsk{Repository: repoSDK, Head: head1}, at.Add(time.Minute))
+		if (c.refused == "") != (err == nil) || (err != nil && !strings.Contains(err.Error(), c.refused)) {
+			t.Errorf("%s: answered %v, want refused %q", c.what, err, c.refused)
+		}
 	}
 }