feat(headless): complete deterministic bot command parity

tests/AcDream.Headless.Tests/HeadlessProcessSchedulerTests.cs

@@ -113,6 +113,33 @@ public sealed class HeadlessProcessSchedulerTests
         Assert.True(session.Runtime.Session.IsInWorld);
     }
 
+    [Fact]
+    public void IdleDispatchBeforeDeadlineAllocatesNothingAndDoesNotTick()
+    {
+        var time = new ManualTimeProvider();
+        var operations = new FixtureSessionOperations();
+        using HeadlessSessionHost session =
+            CreateSession("idle", time, operations);
+        Assert.Equal(
+            RuntimeSessionStartStatus.Connected,
+            session.Start().Status);
+        var scheduler = new HeadlessProcessScheduler([session], time);
+
+        for (int index = 0; index < 32; index++)
+            Assert.False(scheduler.DispatchDue(time.GetTimestamp()));
+        long before = GC.GetAllocatedBytesForCurrentThread();
+        for (int index = 0; index < 100_000; index++)
+        {
+            if (scheduler.DispatchDue(time.GetTimestamp()))
+                throw new InvalidOperationException("Idle session ticked.");
+        }
+        long allocated = GC.GetAllocatedBytesForCurrentThread() - before;
+
+        Assert.Equal(0L, allocated);
+        Assert.Equal(0UL, session.Runtime.Clock.FrameNumber);
+        Assert.Equal(0L, scheduler.CaptureSnapshot().TurnCount);
+    }
+
     [Fact]
     public async Task ProcessHostRunsMultipleSessionsOnOneScheduler()
     {
@@ -134,7 +161,7 @@ public sealed class HeadlessProcessSchedulerTests
         using var host = new HeadlessProcessHost(
             configuration,
             HeadlessPathSet.Resolve(new HeadlessPathOverrides()),
-            new StringReader(
+            new System.IO.StringReader(
                 "first-password"
                 + Environment.NewLine
                 + "second-password"