diff --git a/dotnet/EcencyApi.Tests/CurationDeskPayloadTests.cs b/dotnet/EcencyApi.Tests/CurationDeskPayloadTests.cs
index c7035402..336d4fec 100644
--- a/dotnet/EcencyApi.Tests/CurationDeskPayloadTests.cs
+++ b/dotnet/EcencyApi.Tests/CurationDeskPayloadTests.cs
@@ -887,16 +887,29 @@ public void TheQueueTakesAStateAndALimitAndNothingElse()
     }
 
     [Theory]
-    [InlineData("{}", "open must be true or false")]
-    [InlineData("{\"message\":\"back soon\"}", "open must be true or false")]
     [InlineData("{\"open\":\"false\"}", "open must be true or false")]
     [InlineData("{\"open\":0}", "open must be true or false")]
     [InlineData("{\"open\":null}", "open must be true or false")]
+    // Nothing at all is a client bug rather than a no-op, and upstream refuses it too.
+    [InlineData("{}", "nothing to set")]
     public void AWindowWithoutABooleanIsRefused(string json, string expected)
     {
         Assert.Equal(expected, Rejected(CurationDeskWrites.ApplicationWindow, json));
     }
 
+    [Fact]
+    public void ASaveAboutOneFieldDoesNotHaveToCarryTheWindow()
+    {
+        // `open` decides whether readers can apply. A save about the wording or the
+        // numbers that carried it too could undo another admin's close, so absent has to
+        // be allowed here and read upstream as "leave it".
+        Assert.Equal(new[] { "username", "message" },
+            Ok(CurationDeskWrites.ApplicationWindow, "{\"message\":\"back soon\"}")
+                .Select(kv => kv.Key).ToArray());
+        Assert.Equal(new[] { "username", "quorum" },
+            Ok(CurationDeskWrites.ApplicationWindow, "{\"quorum\":4}").Select(kv => kv.Key).ToArray());
+    }
+
     [Fact]
     public void AClosedWindowMessageIsCappedAtTheColumn()
     {
diff --git a/dotnet/EcencyApi/Handlers/PrivateApi.CurationDesk.cs b/dotnet/EcencyApi/Handlers/PrivateApi.CurationDesk.cs
index ed7bf078..20e76baa 100644
--- a/dotnet/EcencyApi/Handlers/PrivateApi.CurationDesk.cs
+++ b/dotnet/EcencyApi/Handlers/PrivateApi.CurationDesk.cs
@@ -1283,10 +1283,21 @@ private static void Truncate(JsonObject payload, string key, int max)
         }
         if (ReferenceEquals(route, ApplicationWindow))
         {
-            if (body.Field("open")?.GetValueKind() is not (JsonValueKind.True or JsonValueKind.False))
+            // Every field here is optional and absent means "leave it" upstream. One
+            // screen carries four controls that all land on one settings row, so a save
+            // about the quorum that also sent `open` could undo another admin's close and
+            // reopen applications to readers who act on it.
+            if (body.ContainsKey("open")
+                && body.Field("open")?.GetValueKind() is not (JsonValueKind.True or JsonValueKind.False))
             {
                 return "open must be true or false";
             }
+            // A call that sets nothing is a client bug, and upstream refuses it too.
+            if (!body.ContainsKey("open") && !body.ContainsKey("message")
+                && !body.ContainsKey("quorum") && !body.ContainsKey("term_days"))
+            {
+                return "nothing to set";
+            }
             if (body.TryGetPropertyValue("message", out var message) && message is not null
                 && (body.Str("message") is not { } messageText
                     || messageText.EnumerateRunes().Count() > MaxApplicationMessageLength))