diff --git a/internal/agent/dsh.go b/internal/agent/dsh.go
index 9173e158..6e82bbe3 100644
--- a/internal/agent/dsh.go
+++ b/internal/agent/dsh.go
@@ -114,10 +114,11 @@ func dsh(home string) *Agent {
 			Get: func() string { return dshGetEffort(dir) },
 			Set: func(v string) error { return dshSetEffort(dir, v) },
 			Options: func(cur map[string]string) []Option {
+				// a model through magpie that lists no levels has none in
+				// dsh (its route gives it no reasoningEfforts), so none is
+				// offered: dsh's own four were, and each was turned away
 				if ref, ok := strings.CutPrefix(cur["model"], magpieID+"/"); ok && len(dshProfiles(dir)) > 0 {
-					if levels := dshLevels(ref); len(levels) > 0 {
-						return static(levels...)
-					}
+					return static(dshLevels(ref)...)
 				}
 				return static(dshEfforts...)
 			},
@@ -1125,6 +1126,9 @@ func dshSetEffort(dir, v string) error {
 		if viaGateway {
 			levels = dshLevels(ref)
 		}
+		if v != "" && len(levels) == 0 {
+			return fmt.Errorf("DeepSeek Harness has no thinking levels for %s: magpie knows of none the model takes", ref)
+		}
 		if v != "" && !contains(levels, v) {
 			return fmt.Errorf("DeepSeek Harness takes an effort of %s for this model, not %q", strings.Join(levels, ", "), v)
 		}
diff --git a/internal/agent/effort_test.go b/internal/agent/effort_test.go
index 7674d0ea..a0270b90 100644
--- a/internal/agent/effort_test.go
+++ b/internal/agent/effort_test.go
@@ -151,6 +151,49 @@ func TestCommandCodeEffort(t *testing.T) {
 	}
 }
 
+// #473: a model through magpie listing no levels (LongCat-2.5-Preview) had
+// dsh's own off, low, high and max offered on the Agents page, and each was
+// turned away with "takes an effort of  for this model". It has none in dsh:
+// none is offered, and one asked for says so.
+func TestDshEffortModelWithoutLevels(t *testing.T) {
+	home := effortHome(t)
+	if err := catalog.SaveLive("deepseek", "https://api.deepseek.com/v1", []catalog.Model{
+		{ID: "pro", Name: "pro", Efforts: []string{"none", "low", "high", "max"}},
+		{ID: "plain", Name: "plain"},
+	}); err != nil {
+		t.Fatal(err)
+	}
+	patch := filepath.Join(home, ".dsh", "profiles", "web", "cordis.patch.yml")
+	writeFile(t, patch, "[]\n")
+	a := dsh(home)
+	f := a.Field("effort")
+	if err := a.Field("model").Set("magpie/deepseek/plain"); err != nil {
+		t.Fatal(err)
+	}
+	cur := map[string]string{"model": "magpie/deepseek/plain"}
+	if got := f.Options(cur); len(got) != 0 {
+		t.Fatalf("offered %+v for a model with no levels", got)
+	}
+	err := f.Set("low")
+	if err == nil || strings.Contains(err.Error(), "of  for") || !strings.Contains(err.Error(), "deepseek/plain") {
+		t.Fatalf("low: %v", err)
+	}
+	if err := f.Set(""); err != nil || f.Get() != "" {
+		t.Fatalf("default: %v %q", err, f.Get())
+	}
+	// every level offered for any model is one dsh takes
+	for _, m := range []string{"magpie/deepseek/pro", "magpie/deepseek/plain", "deepseek-v4-pro"} {
+		if err := a.Field("model").Set(m); err != nil {
+			t.Fatal(err)
+		}
+		for _, o := range f.Options(map[string]string{"model": m}) {
+			if err := f.Set(o.Value); err != nil {
+				t.Fatalf("%s offered %q and turned it away: %v", m, o.Value, err)
+			}
+		}
+	}
+}
+
 func TestDshEffort(t *testing.T) {
 	home := effortHome(t)
 	if err := catalog.SaveLive("deepseek", "https://api.deepseek.com/v1", []catalog.Model{