Fix two CombinationResultsConverter edge cases

docs/combinations.md

@@ -198,6 +198,7 @@ public class CombinationResultsConverter :
         var items = results.Items;
         if (items.Count == 0)
         {
+            writer.WriteEndObject();
             return;
         }
 
@@ -363,16 +364,19 @@ public class CombinationResultsConverter :
             builder.Append(trimmed);
             if (!trimmed.EndsWith('.'))
             {
-                builder.Append(". ");
+                builder.Append('.');
             }
+
+            // separate from the next line even when the sentence was already terminated
+            builder.Append(' ');
         }
 
         builder.TrimEnd();
         return builder.ToString();
     }
 }
 ```
-<sup><a href='/src/Verify/Combinations/CombinationResultsConverter.cs#L1-L185' title='Snippet source file'>snippet source</a> | <a href='#snippet-CombinationResultsConverter.cs' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/Verify/Combinations/CombinationResultsConverter.cs#L1-L189' title='Snippet source file'>snippet source</a> | <a href='#snippet-CombinationResultsConverter.cs' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 

src/Verify.Tests/CombinationTests.EmptyResults.verified.txt

@@ -0,0 +1 @@
+{}

src/Verify.Tests/CombinationTests.EmptyResultsNested.verified.txt

@@ -0,0 +1,4 @@
+{
+  results: {},
+  after: TheValue
+}

src/Verify.Tests/CombinationTests.MultiLineArgumentException.verified.txt

@@ -0,0 +1,4 @@
+{
+   1: ArgumentException: Value cannot be null. Parameter name: p.,
+  10: ArgumentException: Value cannot be null. Parameter name: p.
+}

src/Verify.Tests/CombinationTests.cs

@@ -159,6 +159,38 @@ public Task RecordingWithExceptionPausedTest()
             .IgnoreStackTrace();
     }
 
+    static string ThrowMultiLine(int value) =>
+        throw new ArgumentException(
+            """
+            Value cannot be null.
+            Parameter name: p
+            """);
+
+    // ArgumentException messages are flattened onto one line, so the parts of the
+    // message need a separator between them
+    [Fact]
+    public Task MultiLineArgumentException() =>
+        Combination(captureExceptions: true)
+            .Verify(
+                ThrowMultiLine,
+                params1);
+
+    // Only reachable by constructing the results directly, since the runner requires
+    // every list to have at least one item
+    [Fact]
+    public Task EmptyResults() =>
+        Verify(new CombinationResults([], [], null));
+
+    // an unclosed object would swallow everything written after it
+    [Fact]
+    public Task EmptyResultsNested() =>
+        Verify(
+            new
+            {
+                results = new CombinationResults([], [], null),
+                after = "TheValue"
+            });
+
     [Fact]
     public Task RecordingPausedTest()
     {

src/Verify/Combinations/CombinationResultsConverter.cs

@@ -10,6 +10,7 @@ public override void Write(VerifyJsonWriter writer, CombinationResults results)
         var items = results.Items;
         if (items.Count == 0)
         {
+            writer.WriteEndObject();
             return;
         }
 
@@ -175,8 +176,11 @@ static string FlattenMessage(string message)
             builder.Append(trimmed);
             if (!trimmed.EndsWith('.'))
             {
-                builder.Append(". ");
+                builder.Append('.');
             }
+
+            // separate from the next line even when the sentence was already terminated
+            builder.Append(' ');
         }
 
         builder.TrimEnd();

src/todo.md

@@ -67,10 +67,10 @@ All six resolved 2026-08-16 (five fixed here; the inline item resolved as by-des
 - [ ] **MSTest source generator ignores `record` test classes.**
   `Verify.MSTest.SourceGenerator/UsesVerifyGenerator.cs:125-126` — only `ClassDeclarationSyntax` is eligible; `[UsesVerify] [TestClass] partial record` compiles then fails at runtime with the misleading "TestContext is null" error. `Parser.GetParentClasses` similarly stops at a `record struct` parent.
 
-- [ ] **Unclosed JSON object for empty `CombinationResults`.**
+- [x] **Unclosed JSON object for empty `CombinationResults`.**
   `Verify/Combinations/CombinationResultsConverter.cs:8-14` — `WriteStartObject()` then early `return` with no `WriteEndObject()`. Only reachable by constructing `CombinationResults([], ...)` directly.
 
-- [ ] **`FlattenMessage` omits the joining space after a line ending in `.`.**
+- [x] **`FlattenMessage` omits the joining space after a line ending in `.`.**
   `Verify/Combinations/CombinationResultsConverter.cs:168-183` — two-line messages (net48 `ArgumentNullException`) render as `"Value cannot be null.Parameter name: p"`.
 
 - [ ] **Negative sub-hour offsets render unsigned.**