diff --git a/Assets/Tests/Editor/DynamicCodeToolTests/SharedRoslynCompilerWorkerHostTests.cs b/Assets/Tests/Editor/DynamicCodeToolTests/SharedRoslynCompilerWorkerHostTests.cs
index 950d57a2e0..51413deadf 100644
--- a/Assets/Tests/Editor/DynamicCodeToolTests/SharedRoslynCompilerWorkerHostTests.cs
+++ b/Assets/Tests/Editor/DynamicCodeToolTests/SharedRoslynCompilerWorkerHostTests.cs
@@ -2,6 +2,7 @@
 using System.Diagnostics;
 using System.IO;
 using System.Text;
+using System.Threading.Tasks;
 using NUnit.Framework;
 
 using io.github.hatayama.UnityCliLoop.FirstPartyTools;
@@ -27,6 +28,71 @@ public void ConfigureWorkerDotnetRuntimeEnvironment_WhenCalled_ShouldDisableMult
                 Is.EqualTo(SharedRoslynCompilerWorkerAssemblyBuilder.DotnetMultilevelLookupDisabledValue));
         }
 
+        /// <summary>
+        /// Verifies a pending compiler stream does not keep the bounded drain waiting.
+        /// </summary>
+        [Test]
+        public void WaitForCompilerStreamDrain_WhenStreamIsPending_ShouldReturnFalse()
+        {
+            TaskCompletionSource<string> pendingStream = new();
+
+            bool completed = SharedRoslynCompilerWorkerAssemblyBuilder.WaitForCompilerStreamDrain(
+                Task.FromResult("stdout"),
+                pendingStream.Task,
+                0);
+            pendingStream.SetResult("stderr");
+
+            Assert.That(completed, Is.False);
+        }
+
+        /// <summary>
+        /// Verifies completed compiler streams satisfy the bounded drain immediately.
+        /// </summary>
+        [Test]
+        public void WaitForCompilerStreamDrain_WhenStreamsAreCompleted_ShouldReturnTrue()
+        {
+            bool completed = SharedRoslynCompilerWorkerAssemblyBuilder.WaitForCompilerStreamDrain(
+                Task.FromResult("stdout"),
+                Task.FromResult("stderr"),
+                0);
+
+            Assert.That(completed, Is.True);
+        }
+
+        /// <summary>
+        /// Verifies a faulted compiler stream is treated as drained without escaping timeout recovery.
+        /// </summary>
+        [Test]
+        public void WaitForCompilerStreamDrain_WhenStreamFaults_ShouldReturnTrue()
+        {
+            Task<string> faultedStream = Task.FromException<string>(new IOException("stream read failed"));
+
+            bool completed = SharedRoslynCompilerWorkerAssemblyBuilder.WaitForCompilerStreamDrain(
+                Task.FromResult("stdout"),
+                faultedStream,
+                0);
+
+            Assert.That(completed, Is.True);
+        }
+
+        /// <summary>
+        /// Verifies one faulted stream does not make a still-pending drain appear complete.
+        /// </summary>
+        [Test]
+        public void WaitForCompilerStreamDrain_WhenFaultedStreamHasPendingPeer_ShouldReturnFalse()
+        {
+            TaskCompletionSource<string> pendingStream = new();
+            Task<string> faultedStream = Task.FromException<string>(new IOException("stream read failed"));
+
+            bool completed = SharedRoslynCompilerWorkerAssemblyBuilder.WaitForCompilerStreamDrain(
+                faultedStream,
+                pendingStream.Task,
+                0);
+            pendingStream.SetResult("stderr");
+
+            Assert.That(completed, Is.False);
+        }
+
         [Test]
         public void CreateCompileRequestCommand_WhenPathIsWindowsAbsolutePath_ShouldEncodeAsciiPayload()
         {
diff --git a/Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/SharedRoslynCompilerWorkerAssemblyBuilder.cs b/Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/SharedRoslynCompilerWorkerAssemblyBuilder.cs
index 468d84030a..dc67e1e254 100644
--- a/Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/SharedRoslynCompilerWorkerAssemblyBuilder.cs
+++ b/Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/SharedRoslynCompilerWorkerAssemblyBuilder.cs
@@ -16,6 +16,7 @@ namespace io.github.hatayama.UnityCliLoop.FirstPartyTools
     internal static class SharedRoslynCompilerWorkerAssemblyBuilder
     {
         private const int WorkerAssemblyBuildTimeoutMilliseconds = 30000;
+        private const int WorkerCompilerTerminationTimeoutMilliseconds = 500;
         internal const string DotnetMultilevelLookupEnvironmentVariableName = "DOTNET_MULTILEVEL_LOOKUP";
         internal const string DotnetMultilevelLookupDisabledValue = "0";
 
@@ -107,10 +108,13 @@ internal static WorkerAssemblyBuildResult CompileWorkerAssembly(
                 if (!process.HasExited)
                 {
                     process.Kill();
-                    process.WaitForExit(500);
+                    process.WaitForExit(WorkerCompilerTerminationTimeoutMilliseconds);
                 }
 
-                Task.WaitAll(stdoutTask, stderrTask);
+                WaitForCompilerStreamDrain(
+                    stdoutTask,
+                    stderrTask,
+                    WorkerCompilerTerminationTimeoutMilliseconds);
                 return WorkerAssemblyBuildResult.StartFailure(
                     "worker_compiler_timeout",
                     new
@@ -129,6 +133,33 @@ internal static WorkerAssemblyBuildResult CompileWorkerAssembly(
             return WorkerAssemblyBuildResult.Started(compilerMessages);
         }
 
+        internal static bool WaitForCompilerStreamDrain(
+            Task<string> stdoutTask,
+            Task<string> stderrTask,
+            int timeoutMilliseconds)
+        {
+            Debug.Assert(stdoutTask != null, "stdoutTask must not be null");
+            Debug.Assert(stderrTask != null, "stderrTask must not be null");
+            Debug.Assert(timeoutMilliseconds >= 0, "timeoutMilliseconds must not be negative");
+
+            Task streamDrainTask = Task.WhenAll(stdoutTask, stderrTask);
+            bool completed = Task.WaitAny(
+                new[] { streamDrainTask },
+                timeoutMilliseconds) == 0;
+            ObserveCompilerStreamFailure(stdoutTask);
+            ObserveCompilerStreamFailure(stderrTask);
+            ObserveCompilerStreamFailure(streamDrainTask);
+            return completed;
+        }
+
+        private static void ObserveCompilerStreamFailure(Task streamDrainTask)
+        {
+            // Why: disposing the process after a bounded drain can fault a pending read task later.
+            _ = streamDrainTask.ContinueWith(
+                task => { _ = task.Exception; },
+                TaskContinuationOptions.OnlyOnFaulted | TaskContinuationOptions.ExecuteSynchronously);
+        }
+
         private static List<string> BuildWorkerReferenceSet(ExternalCompilerPaths externalCompilerPaths)
         {
             string sharedRuntimeDirectoryPath = externalCompilerPaths.NetCoreRuntimeSharedDirectoryPath;