diff --git a/eng/pipelines/extra-platforms/runtime-extra-platforms-wasm.yml b/eng/pipelines/extra-platforms/runtime-extra-platforms-wasm.yml
index e6be56a9307d60..0efe765230720f 100644
--- a/eng/pipelines/extra-platforms/runtime-extra-platforms-wasm.yml
+++ b/eng/pipelines/extra-platforms/runtime-extra-platforms-wasm.yml
@@ -119,7 +119,7 @@ jobs:
       alwaysRun: ${{ parameters.isWasmOnlyBuild }}
 
       # NOTE - Since threading is experimental, we don't want to block mainline work
-      shouldContinueOnError: true
+      # TODO put back shouldContinueOnError: true
       scenarios:
         - WasmTestOnBrowser
         #- WasmTestOnNodeJS - this is not supported yet, https://github.com/dotnet/runtime/issues/85592
diff --git a/src/libraries/Microsoft.Extensions.Logging.Console/tests/Microsoft.Extensions.Logging.Console.Tests/ConsoleFormatterTests.cs b/src/libraries/Microsoft.Extensions.Logging.Console/tests/Microsoft.Extensions.Logging.Console.Tests/ConsoleFormatterTests.cs
index 573006673d8889..6da081c4e86ab0 100644
--- a/src/libraries/Microsoft.Extensions.Logging.Console/tests/Microsoft.Extensions.Logging.Console.Tests/ConsoleFormatterTests.cs
+++ b/src/libraries/Microsoft.Extensions.Logging.Console/tests/Microsoft.Extensions.Logging.Console.Tests/ConsoleFormatterTests.cs
@@ -74,7 +74,6 @@ internal static (ConsoleLogger Logger, ConsoleSink Sink, ConsoleSink ErrorSink,
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_TimeStampFormat_IsReloaded()
         {
             // Arrange
@@ -88,7 +87,6 @@ public void ConsoleLoggerOptions_TimeStampFormat_IsReloaded()
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatterNames))]
         public void InvalidLogLevel_Throws(string formatterName)
         {
@@ -103,7 +101,6 @@ public void InvalidLogLevel_Throws(string formatterName)
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatterNamesAndLevels))]
         public void NoMessageOrException_Noop(string formatterName, LogLevel level)
         {
@@ -123,7 +120,6 @@ public void NoMessageOrException_Noop(string formatterName, LogLevel level)
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatterNamesAndLevels))]
         public void Log_LogsCorrectTimestamp(string formatterName, LogLevel level)
         {
diff --git a/src/libraries/Microsoft.Extensions.Logging.Console/tests/Microsoft.Extensions.Logging.Console.Tests/ConsoleLoggerTest.cs b/src/libraries/Microsoft.Extensions.Logging.Console/tests/Microsoft.Extensions.Logging.Console.Tests/ConsoleLoggerTest.cs
index f0ef3d6cd7e1d1..0994980590122b 100644
--- a/src/libraries/Microsoft.Extensions.Logging.Console/tests/Microsoft.Extensions.Logging.Console.Tests/ConsoleLoggerTest.cs
+++ b/src/libraries/Microsoft.Extensions.Logging.Console/tests/Microsoft.Extensions.Logging.Console.Tests/ConsoleLoggerTest.cs
@@ -174,7 +174,6 @@ internal static string GetJsonLogLevelString(LogLevel logLevel)
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void LogsWhenMessageIsNotProvided()
         {
             // Arrange
@@ -207,7 +206,6 @@ public void LogsWhenMessageIsNotProvided()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void DoesNotLog_NewLine_WhenNoExceptionIsProvided()
         {
             // Arrange
@@ -236,7 +234,6 @@ public void DoesNotLog_NewLine_WhenNoExceptionIsProvided()
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [InlineData(null, 0)]
         [InlineData(null, 1)]
         [InlineData("missingFormatter", 0)]
@@ -279,7 +276,6 @@ public void Options_FormatterNameNull_UsesDeprecatedProperties(string formatterN
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [InlineData("Route with name 'Simple' was not found.")]
         public void Writes_NewLine_WhenExceptionIsProvided(string message)
         {
@@ -304,7 +300,6 @@ public void Writes_NewLine_WhenExceptionIsProvided(string message)
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ThrowsException_WhenNoFormatterIsProvided()
         {
             // Arrange
@@ -316,7 +311,6 @@ public void ThrowsException_WhenNoFormatterIsProvided()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void LogsWhenNullFilterGiven()
         {
             // Arrange
@@ -338,7 +332,6 @@ public void LogsWhenNullFilterGiven()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void WriteCritical_LogsCorrectColors()
         {
             // Arrange
@@ -360,7 +353,6 @@ public void WriteCritical_LogsCorrectColors()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void WriteError_LogsCorrectColors()
         {
             // Arrange
@@ -382,7 +374,6 @@ public void WriteError_LogsCorrectColors()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void WriteWarning_LogsCorrectColors()
         {
             // Arrange
@@ -404,7 +395,6 @@ public void WriteWarning_LogsCorrectColors()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void WriteInformation_LogsCorrectColors()
         {
             // Arrange
@@ -456,7 +446,6 @@ public void AddConsole_IsOutputRedirected_ColorDisabled()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void WriteDebug_LogsCorrectColors()
         {
             // Arrange
@@ -478,7 +467,6 @@ public void WriteDebug_LogsCorrectColors()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void WriteTrace_LogsCorrectColors()
         {
             // Arrange
@@ -500,7 +488,6 @@ public void WriteTrace_LogsCorrectColors()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void WriteAllLevelsDisabledColors_LogsNoColors()
         {
             // Arrange
@@ -525,7 +512,6 @@ public void WriteAllLevelsDisabledColors_LogsNoColors()
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatsAndLevels))]
         public void Log_LogsCorrectTimestamp(ConsoleLoggerFormat format, LogLevel level)
         {
@@ -567,7 +553,6 @@ public void Log_LogsCorrectTimestamp(ConsoleLoggerFormat format, LogLevel level)
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatsAndLevels))]
         public void WriteCore_LogsCorrectTimestampInUtc(ConsoleLoggerFormat format, LogLevel level)
         {
@@ -609,7 +594,6 @@ public void WriteCore_LogsCorrectTimestampInUtc(ConsoleLoggerFormat format, LogL
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatsAndLevels))]
         public void WriteCore_LogsCorrectMessages(ConsoleLoggerFormat format, LogLevel level)
         {
@@ -654,7 +638,6 @@ public void WriteCore_LogsCorrectMessages(ConsoleLoggerFormat format, LogLevel l
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void NoLogScope_DoesNotWriteAnyScopeContentToOutput()
         {
             // Arrange
@@ -676,7 +659,6 @@ public void NoLogScope_DoesNotWriteAnyScopeContentToOutput()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void WritingScopes_LogsWithCorrectColors()
         {
             // Arrange
@@ -703,7 +685,6 @@ public void WritingScopes_LogsWithCorrectColors()
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(Formats))]
         public void WritingScopes_LogsExpectedMessage(ConsoleLoggerFormat format)
         {
@@ -755,7 +736,6 @@ public void WritingScopes_LogsExpectedMessage(ConsoleLoggerFormat format)
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(Formats))]
         public void WritingNestedScope_LogsNullScopeName(ConsoleLoggerFormat format)
         {
@@ -805,7 +785,6 @@ public void WritingNestedScope_LogsNullScopeName(ConsoleLoggerFormat format)
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(Formats))]
         public void WritingNestedScopes_LogsExpectedMessage(ConsoleLoggerFormat format)
         {
@@ -864,7 +843,6 @@ public void WritingNestedScopes_LogsExpectedMessage(ConsoleLoggerFormat format)
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(Formats))]
         public void WritingMultipleScopes_LogsExpectedMessage(ConsoleLoggerFormat format)
         {
@@ -934,7 +912,6 @@ public void WritingMultipleScopes_LogsExpectedMessage(ConsoleLoggerFormat format
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void CallingBeginScopeOnLogger_AlwaysReturnsNewDisposableInstance()
         {
             // Arrange
@@ -953,7 +930,6 @@ public void CallingBeginScopeOnLogger_AlwaysReturnsNewDisposableInstance()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void CallingBeginScopeOnLogger_ReturnsNonNullableInstance()
         {
             // Arrange
@@ -969,7 +945,6 @@ public void CallingBeginScopeOnLogger_ReturnsNonNullableInstance()
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(Formats))]
         public void ConsoleLoggerLogsToError_WhenOverErrorLevel(ConsoleLoggerFormat format)
         {
@@ -1020,7 +995,6 @@ public void ConsoleLoggerLogsToError_WhenOverErrorLevel(ConsoleLoggerFormat form
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatsAndLevels))]
         public void WriteCore_NullMessageWithException(ConsoleLoggerFormat format, LogLevel level)
         {
@@ -1065,7 +1039,6 @@ public void WriteCore_NullMessageWithException(ConsoleLoggerFormat format, LogLe
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatsAndLevels))]
         public void WriteCore_EmptyMessageWithException(ConsoleLoggerFormat format, LogLevel level)
         {
@@ -1109,7 +1082,6 @@ public void WriteCore_EmptyMessageWithException(ConsoleLoggerFormat format, LogL
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(FormatsAndLevels))]
         public void WriteCore_MessageWithNullException(ConsoleLoggerFormat format, LogLevel level)
         {
@@ -1150,7 +1122,6 @@ public void WriteCore_MessageWithNullException(ConsoleLoggerFormat format, LogLe
         }
 
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [MemberData(nameof(Levels))]
         public void WriteCore_NullMessageWithNullException(LogLevel level)
         {
@@ -1169,7 +1140,6 @@ public void WriteCore_NullMessageWithNullException(LogLevel level)
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void IsEnabledReturnsCorrectValue()
         {
             var logger = SetUp().Logger;
@@ -1184,7 +1154,6 @@ public static void IsEnabledReturnsCorrectValue()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_DisableColors_IsAppliedToLoggers()
         {
             // Arrange
@@ -1219,7 +1188,6 @@ public void ConsoleLoggerOptions_SetInvalidBufferMode_Throws()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_DisableColors_IsReadFromLoggingConfiguration()
         {
             var configuration = new ConfigurationBuilder().AddInMemoryCollection(new[] { new KeyValuePair<string, string>("Console:DisableColors", "true") }).Build();
@@ -1237,7 +1205,6 @@ public void ConsoleLoggerOptions_DisableColors_IsReadFromLoggingConfiguration()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_TimeStampFormat_IsReloaded()
         {
             // Arrange
@@ -1252,7 +1219,6 @@ public void ConsoleLoggerOptions_TimeStampFormat_IsReloaded()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_TimeStampFormat_IsReadFromLoggingConfiguration()
         {
             var configuration = new ConfigurationBuilder().AddInMemoryCollection(new[] { new KeyValuePair<string, string>("Console:TimeStampFormat", "yyyyMMddHHmmss") }).Build();
@@ -1270,7 +1236,6 @@ public void ConsoleLoggerOptions_TimeStampFormat_IsReadFromLoggingConfiguration(
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_TimeStampFormat_MultipleReloads()
         {
             var monitor = new TestOptionsMonitor(new ConsoleLoggerOptions());
@@ -1285,7 +1250,6 @@ public void ConsoleLoggerOptions_TimeStampFormat_MultipleReloads()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_IncludeScopes_IsAppliedToLoggers()
         {
             // Arrange
@@ -1300,7 +1264,6 @@ public void ConsoleLoggerOptions_IncludeScopes_IsAppliedToLoggers()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_LogAsErrorLevel_IsReadFromLoggingConfiguration()
         {
             var configuration = new ConfigurationBuilder().AddInMemoryCollection(new[] { new KeyValuePair<string, string>("Console:LogToStandardErrorThreshold", "Warning") }).Build();
@@ -1318,7 +1281,6 @@ public void ConsoleLoggerOptions_LogAsErrorLevel_IsReadFromLoggingConfiguration(
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_LogAsErrorLevel_IsAppliedToLoggers()
         {
             // Arrange
@@ -1333,7 +1295,6 @@ public void ConsoleLoggerOptions_LogAsErrorLevel_IsAppliedToLoggers()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_UpdateQueueOptions_UpdatesConsoleLoggerProcessorProperties()
         {
             // Arrange
@@ -1353,7 +1314,6 @@ public void ConsoleLoggerOptions_UpdateQueueOptions_UpdatesConsoleLoggerProcesso
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_UseUtcTimestamp_IsAppliedToLoggers()
         {
             // Arrange
@@ -1368,7 +1328,6 @@ public void ConsoleLoggerOptions_UseUtcTimestamp_IsAppliedToLoggers()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public void ConsoleLoggerOptions_IncludeScopes_IsReadFromLoggingConfiguration()
         {
             var configuration = new ConfigurationBuilder().AddInMemoryCollection(new[] { new KeyValuePair<string, string>("Console:IncludeScopes", "true") }).Build();
diff --git a/src/libraries/Microsoft.Extensions.Logging/tests/DI.Common/Common/tests/Microsoft.Extensions.Logging.Testing.Tests.csproj b/src/libraries/Microsoft.Extensions.Logging/tests/DI.Common/Common/tests/Microsoft.Extensions.Logging.Testing.Tests.csproj
index 49e334b679eebb..7dc147ea8fe4b7 100644
--- a/src/libraries/Microsoft.Extensions.Logging/tests/DI.Common/Common/tests/Microsoft.Extensions.Logging.Testing.Tests.csproj
+++ b/src/libraries/Microsoft.Extensions.Logging/tests/DI.Common/Common/tests/Microsoft.Extensions.Logging.Testing.Tests.csproj
@@ -4,6 +4,10 @@
     <EnableDefaultItems>true</EnableDefaultItems>
   </PropertyGroup>
 
+  <PropertyGroup Condition="'$(TargetOS)' == 'browser'">
+    <WasmXHarnessMonoArgs>--setenv=XHARNESS_LOG_TEST_START=true --no-memory-snapshot</WasmXHarnessMonoArgs>
+  </PropertyGroup>
+
   <ItemGroup>
     <Compile Include="..\src\LogLevelAttribute.cs"
              Link="tests\DI.Common\Common\src\LogLevelAttribute.cs" />
diff --git a/src/libraries/System.Diagnostics.TraceSource/tests/System.Diagnostics.TraceSource.Config.Tests/System.Diagnostics.TraceSource.Config.Tests.csproj b/src/libraries/System.Diagnostics.TraceSource/tests/System.Diagnostics.TraceSource.Config.Tests/System.Diagnostics.TraceSource.Config.Tests.csproj
index cd36a59ecae62a..7a8bdffe6d237d 100644
--- a/src/libraries/System.Diagnostics.TraceSource/tests/System.Diagnostics.TraceSource.Config.Tests/System.Diagnostics.TraceSource.Config.Tests.csproj
+++ b/src/libraries/System.Diagnostics.TraceSource/tests/System.Diagnostics.TraceSource.Config.Tests/System.Diagnostics.TraceSource.Config.Tests.csproj
@@ -3,6 +3,9 @@
     <IncludeRemoteExecutor>true</IncludeRemoteExecutor>
     <TargetFramework>$(NetCoreAppCurrent)</TargetFramework>
   </PropertyGroup>
+  <PropertyGroup Condition="'$(TargetOS)' == 'browser'">
+    <WasmXHarnessMonoArgs>--setenv=XHARNESS_LOG_TEST_START=true --no-memory-snapshot</WasmXHarnessMonoArgs>
+  </PropertyGroup>
   <ItemGroup>
     <Compile Include="$(CommonTestPath)TestUtilities\System\DisableParallelization.cs" Link="Common\TestUtilities\System\DisableParallelization.cs" />
   </ItemGroup>
diff --git a/src/libraries/System.IO.Pipelines/tests/PipeWriterTests.cs b/src/libraries/System.IO.Pipelines/tests/PipeWriterTests.cs
index 2913efbe3cdf6c..85070e1534a8ee 100644
--- a/src/libraries/System.IO.Pipelines/tests/PipeWriterTests.cs
+++ b/src/libraries/System.IO.Pipelines/tests/PipeWriterTests.cs
@@ -294,7 +294,6 @@ public async Task WritesUsingGetMemoryWorks()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91547", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public async Task CompleteWithLargeWriteThrows()
         {
             var completeDelay = TimeSpan.FromMilliseconds(10);
diff --git a/src/libraries/System.Linq.Parallel/tests/ExchangeTests.cs b/src/libraries/System.Linq.Parallel/tests/ExchangeTests.cs
index 5c36f46c5d2073..6c99c02ccdfa5d 100644
--- a/src/libraries/System.Linq.Parallel/tests/ExchangeTests.cs
+++ b/src/libraries/System.Linq.Parallel/tests/ExchangeTests.cs
@@ -116,6 +116,7 @@ public static void Partitioning_Default_Longrunning(Labeled<ParallelQuery<int>>
 
         [ConditionalTheory]
         [MemberData(nameof(PartitioningData), new[] { 0, 1, 2, 16, 1024 })]
+        [ActiveIssue("https://github.com/dotnet/runtime/issues/91541", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void Partitioning_Striped(Labeled<ParallelQuery<int>> labeled, int count, int partitions)
         {
             if (partitions > 1 && !PlatformDetection.IsThreadingSupported)
diff --git a/src/libraries/System.Threading.Tasks.Parallel/tests/System.Threading.Tasks.Parallel.Tests.csproj b/src/libraries/System.Threading.Tasks.Parallel/tests/System.Threading.Tasks.Parallel.Tests.csproj
index 4be608cc6847ac..7a599ea739d7cb 100644
--- a/src/libraries/System.Threading.Tasks.Parallel/tests/System.Threading.Tasks.Parallel.Tests.csproj
+++ b/src/libraries/System.Threading.Tasks.Parallel/tests/System.Threading.Tasks.Parallel.Tests.csproj
@@ -6,6 +6,9 @@
   <PropertyGroup>
     <StartupObject />
   </PropertyGroup>
+  <PropertyGroup Condition="'$(TargetOS)' == 'browser'">
+    <WasmXHarnessMonoArgs>--setenv=XHARNESS_LOG_TEST_START=true --no-memory-snapshot</WasmXHarnessMonoArgs>
+  </PropertyGroup>
   <ItemGroup>
     <Compile Include="$(CommonTestPath)System\Diagnostics\Tracing\TestEventListener.cs" Link="Common\System\Diagnostics\Tracing\TestEventListener.cs" />
     <Compile Include="BreakTests.cs" />
diff --git a/src/libraries/System.Threading.Tasks/tests/System.Threading.Tasks.Tests.csproj b/src/libraries/System.Threading.Tasks/tests/System.Threading.Tasks.Tests.csproj
index dfd17dfa6e6d45..c16ca8af166263 100644
--- a/src/libraries/System.Threading.Tasks/tests/System.Threading.Tasks.Tests.csproj
+++ b/src/libraries/System.Threading.Tasks/tests/System.Threading.Tasks.Tests.csproj
@@ -5,6 +5,9 @@
     <TargetFramework>$(NetCoreAppCurrent)</TargetFramework>
     <_WasmPThreadPoolSize Condition="'$(MonoWasmBuildVariant)' == 'multithread'">64</_WasmPThreadPoolSize>
   </PropertyGroup>
+  <PropertyGroup Condition="'$(TargetOS)' == 'browser'">
+    <WasmXHarnessMonoArgs>--setenv=XHARNESS_LOG_TEST_START=true --no-memory-snapshot</WasmXHarnessMonoArgs>
+  </PropertyGroup>
   <ItemGroup>
     <Compile Include="Helpers.cs" />
     <Compile Include="Task\TaskArgumentValidationTests.cs" />
diff --git a/src/libraries/System.Threading/tests/SemaphoreSlimTests.cs b/src/libraries/System.Threading/tests/SemaphoreSlimTests.cs
index 4c2c5cc53a5249..4c0655795409d6 100644
--- a/src/libraries/System.Threading/tests/SemaphoreSlimTests.cs
+++ b/src/libraries/System.Threading/tests/SemaphoreSlimTests.cs
@@ -72,7 +72,6 @@ public static void RunSemaphoreSlimTest1_Wait_NegativeCases()
         }
 
         [ConditionalFact(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91541", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         public static void RunSemaphoreSlimTest1_WaitAsync()
         {
             // Infinite timeout
@@ -464,7 +463,6 @@ private static void RunSemaphoreSlimTest7_AvailableWaitHandle_Helper(int initial
         /// <param name="finalCount">The final semaphore count</param>
         /// <returns>True if the test succeeded, false otherwise</returns>
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91538", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [InlineData(5, 1000, 50, 50, 50, 0, 5, 1000)]
         [InlineData(0, 1000, 50, 25, 25, 25, 0, 500)]
         [InlineData(0, 1000, 50, 0, 0, 50, 0, 100)]
@@ -531,7 +529,6 @@ public static void RunSemaphoreSlimTest8_ConcWaitAndRelease(int initial, int max
         /// <param name="finalCount">The final semaphore count</param>
         /// <returns>True if the test succeeded, false otherwise</returns>
         [ConditionalTheory(typeof(PlatformDetection), nameof(PlatformDetection.IsThreadingSupported))]
-        [ActiveIssue("https://github.com/dotnet/runtime/issues/91541", typeof(PlatformDetection), nameof(PlatformDetection.IsWasmThreadingSupported))]
         [InlineData(5, 1000, 50, 50, 50, 0, 5, 500)]
         [InlineData(0, 1000, 50, 25, 25, 25, 0, 500)]
         [InlineData(0, 1000, 50, 0, 0, 50, 0, 100)]
diff --git a/src/libraries/tests.proj b/src/libraries/tests.proj
index 88ac0d5f0aac1e..a1de1433304181 100644
--- a/src/libraries/tests.proj
+++ b/src/libraries/tests.proj
@@ -61,6 +61,14 @@
     <ProjectExclusions Include="$(MonoProjectRoot)sample\wasm\browser-minimal-config\Wasm.Browser.Config.Sample.csproj" />
   </ItemGroup>
 
+  <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(MonoWasmBuildVariant)' == 'multithread'" >
+    <!-- until we fix JS interop with deputy -->
+    <ProjectExclusions Include="$(MonoProjectRoot)sample\wasm\browser-threads\Wasm.Browser.Threads.Sample.csproj" />
+    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Runtime.InteropServices.JavaScript\tests\System.Runtime.InteropServices.JavaScript.Legacy.UnitTests\System.Runtime.InteropServices.JavaScript.Legacy.Tests.csproj" />
+    <ProjectExclusions Include="$(MSBuildThisFileDirectory)System.Runtime.InteropServices.JavaScript\tests\System.Runtime.InteropServices.JavaScript.UnitTests\System.Runtime.InteropServices.JavaScript.Tests.csproj" />
+  </ItemGroup>
+
+
   <!-- wasm EAT/AOT -->
   <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(RunDisabledWasmTests)' != 'true' and '$(EnableAggressiveTrimming)' == 'true'">
   </ItemGroup>
@@ -568,7 +576,9 @@
   <ItemGroup Condition="'$(TargetOS)' == 'browser' and '$(MonoWasmBuildVariant)' == 'multithread'">
     <!-- Don't want the default smoke tests - just verify that threading works -->
     <SmokeTestProject Remove="@(SmokeTestProject)" />
+    <!-- TODO deputy JS interop 
     <SmokeTestProject Include="$(MonoProjectRoot)sample\wasm\browser-threads\Wasm.Browser.Threads.Sample.csproj" />
+    -->
     <!-- this sample is messy sandbox right now
     <SmokeTestProject Include="$(MonoProjectRoot)sample\wasm\browser-threads-minimal\Wasm.Browser.Threads.Minimal.Sample.csproj" />
     -->
diff --git a/src/mono/mono/component/diagnostics_server.c b/src/mono/mono/component/diagnostics_server.c
index 4bea3d722625c5..e32499ea1e408a 100644
--- a/src/mono/mono/component/diagnostics_server.c
+++ b/src/mono/mono/component/diagnostics_server.c
@@ -250,7 +250,7 @@ queue_push_sync (WasmIpcStreamQueue *q, const uint8_t *buf, uint32_t buf_size, u
 		gboolean is_browser_thread = FALSE;
 		while (mono_atomic_load_i32 (&q->buf_full) != 0) {
 			if (G_UNLIKELY (!is_browser_thread_inited)) {
-					is_browser_thread = mono_threads_wasm_is_ui_thread ();
+					is_browser_thread = mono_threads_wasm_is_deputy_thread ();
 					is_browser_thread_inited = TRUE;
 			}
 			if (G_UNLIKELY (is_browser_thread)) {
diff --git a/src/mono/mono/metadata/sgen-stw.c b/src/mono/mono/metadata/sgen-stw.c
index daaafba2aef7c3..b27699434f3987 100644
--- a/src/mono/mono/metadata/sgen-stw.c
+++ b/src/mono/mono/metadata/sgen-stw.c
@@ -503,7 +503,8 @@ mono_wasm_gc_lock(void)
 	MONO_ENTER_GC_UNSAFE;
 #ifndef DISABLE_THREADS
 	/* only the browser thread is allowed to take the GC lock */
-	g_assert (mono_threads_wasm_is_ui_thread ());
+	// FIXME, to make it work for deputy
+	g_assert (mono_threads_wasm_is_deputy_thread ());
 	LOCK_GC;
 	acquire_gc_locks();
 #else
diff --git a/src/mono/mono/metadata/threads.c b/src/mono/mono/metadata/threads.c
index dbed9f92e7f883..b177dc33a84295 100644
--- a/src/mono/mono/metadata/threads.c
+++ b/src/mono/mono/metadata/threads.c
@@ -99,8 +99,11 @@ mono_native_thread_join_handle (HANDLE thread_handle, gboolean close_handle);
 
 #include "icall-decl.h"
 
-/*#define THREAD_DEBUG(a) do { a; } while (0)*/
+#ifdef DEBUG
+#define THREAD_DEBUG(a) do { a; } while (0)
+#else
 #define THREAD_DEBUG(a)
+#endif // DEBUG
 /*#define THREAD_WAIT_DEBUG(a) do { a; } while (0)*/
 #define THREAD_WAIT_DEBUG(a)
 /*#define LIBGC_DEBUG(a) do { a; } while (0)*/
diff --git a/src/mono/mono/utils/mono-threads-debug.h b/src/mono/mono/utils/mono-threads-debug.h
index ded80a96f3ab1b..359b91626501b0 100644
--- a/src/mono/mono/utils/mono-threads-debug.h
+++ b/src/mono/mono/utils/mono-threads-debug.h
@@ -15,7 +15,7 @@
 
 #define MOSTLY_ASYNC_SAFE_PRINTF(...) MOSTLY_ASYNC_SAFE_FPRINTF(1, __VA_ARGS__);
 
-#if 1
+#ifndef DEBUG
 #define THREADS_DEBUG(...)
 #else
 #define THREADS_DEBUG MOSTLY_ASYNC_SAFE_PRINTF
@@ -27,7 +27,7 @@
 #define THREADS_STW_DEBUG MOSTLY_ASYNC_SAFE_PRINTF
 #endif
 
-#if 1
+#ifndef DEBUG
 #define THREADS_SUSPEND_DEBUG(...)
 #else
 #define THREADS_SUSPEND_DEBUG MOSTLY_ASYNC_SAFE_PRINTF
diff --git a/src/mono/mono/utils/mono-threads-wasm.c b/src/mono/mono/utils/mono-threads-wasm.c
index b31faae8e1173f..3a1a3672237036 100644
--- a/src/mono/mono/utils/mono-threads-wasm.c
+++ b/src/mono/mono/utils/mono-threads-wasm.c
@@ -471,6 +471,30 @@ mono_threads_wasm_ui_thread_tid (void)
 #endif
 }
 
+#ifndef DISABLE_THREADS
+static pthread_t deputy_thread_tid;
+#endif
+
+gboolean
+mono_threads_wasm_is_deputy_thread (void)
+{
+#ifdef DISABLE_THREADS
+	return TRUE;
+#else
+	return pthread_self () == deputy_thread_tid;
+#endif
+}
+
+MonoNativeThreadId
+mono_threads_wasm_deputy_thread_tid (void)
+{
+#ifdef DISABLE_THREADS
+	return (MonoNativeThreadId)1;
+#else
+	return (MonoNativeThreadId) deputy_thread_tid;
+#endif
+}
+
 #ifndef DISABLE_THREADS
 extern void mono_wasm_pthread_on_pthread_attached (MonoNativeThreadId pthread_id);
 extern void mono_wasm_pthread_on_pthread_detached (MonoNativeThreadId pthread_id);
@@ -549,6 +573,47 @@ mono_threads_wasm_async_run_in_target_thread_vii (pthread_t target_thread, void
 	emscripten_dispatch_to_thread_async (target_thread, EM_FUNC_SIG_VII, func, NULL, user_data1, user_data2);
 }
 
+extern void mono_wasm_setup_deputy_thread (void);
+
+// this is running in deputy thread
+static void*
+deputy_thread_fn (void* unused_arg G_GNUC_UNUSED)
+{
+	mono_wasm_setup_deputy_thread();
+	
+	// "exit" from server_thread, but keep the pthread alive and responding to events
+	emscripten_exit_with_live_runtime ();
+}
+
+EMSCRIPTEN_KEEPALIVE gboolean
+mono_wasm_create_deputy_thread (pthread_t *out_thread_id)
+{
+	if (!pthread_create (&deputy_thread_tid, NULL, deputy_thread_fn, NULL)) {
+		*out_thread_id = deputy_thread_tid;
+		return TRUE;
+	}
+	memset(out_thread_id, 0, sizeof(pthread_t));
+	return FALSE;
+}
+
+void
+mono_threads_wasm_async_run_in_deputy_thread (void (*func) (void))
+{
+	mono_threads_wasm_async_run_in_target_thread (deputy_thread_tid, func);
+}
+
+void
+mono_threads_wasm_async_run_in_deputy_thread_vi (void (*func) (gpointer), gpointer user_data)
+{
+	mono_threads_wasm_async_run_in_target_thread_vi (deputy_thread_tid, func, user_data);
+}
+
+void
+mono_threads_wasm_async_run_in_deputy_thread_vii (void (*func) (gpointer, gpointer), gpointer user_data1, gpointer user_data2)
+{
+	mono_threads_wasm_async_run_in_target_thread_vii (deputy_thread_tid, func, user_data1, user_data2);
+}
+
 
 #endif /* DISABLE_THREADS */
 
diff --git a/src/mono/mono/utils/mono-threads-wasm.h b/src/mono/mono/utils/mono-threads-wasm.h
index 157fc22af8859a..046f6aae9c5a3b 100644
--- a/src/mono/mono/utils/mono-threads-wasm.h
+++ b/src/mono/mono/utils/mono-threads-wasm.h
@@ -23,9 +23,15 @@
 gboolean
 mono_threads_wasm_is_ui_thread (void);
 
+gboolean
+mono_threads_wasm_is_deputy_thread (void);
+
 MonoNativeThreadId
 mono_threads_wasm_ui_thread_tid (void);
 
+MonoNativeThreadId
+mono_threads_wasm_deputy_thread_tid (void);
+
 #ifndef DISABLE_THREADS
 /**
  * Runs the given function asynchronously on the main thread.
@@ -52,6 +58,19 @@ mono_threads_wasm_async_run_in_target_thread_vi (pthread_t target_thread, void (
 void
 mono_threads_wasm_async_run_in_target_thread_vii (pthread_t target_thread, void (*func) (gpointer, gpointer), gpointer user_data1, gpointer user_data2);
 
+gboolean
+mono_wasm_create_deputy_thread (pthread_t *out_thread_id);
+
+void
+mono_threads_wasm_async_run_in_deputy_thread (void (*func) (void));
+
+void
+mono_threads_wasm_async_run_in_deputy_thread_vi (void (*func)(gpointer), gpointer user_data);
+
+void
+mono_threads_wasm_async_run_in_deputy_thread_vii (void (*func)(gpointer, gpointer), gpointer user_data1, gpointer user_data2);
+
+
 static inline
 int32_t
 mono_wasm_atomic_wait_i32 (volatile int32_t *addr, int32_t expected, int32_t timeout_ns)
diff --git a/src/mono/sample/wasm/browser-threads-minimal/Wasm.Browser.Threads.Minimal.Sample.csproj b/src/mono/sample/wasm/browser-threads-minimal/Wasm.Browser.Threads.Minimal.Sample.csproj
index bd8644d2fefd30..ddcf9116e02213 100644
--- a/src/mono/sample/wasm/browser-threads-minimal/Wasm.Browser.Threads.Minimal.Sample.csproj
+++ b/src/mono/sample/wasm/browser-threads-minimal/Wasm.Browser.Threads.Minimal.Sample.csproj
@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
     <WasmEnableThreads>true</WasmEnableThreads>
+    <MonoWasmBuildVariant>multithread</MonoWasmBuildVariant>
   </PropertyGroup>
   <Import Project="..\DefaultBrowserSample.targets" />
 
diff --git a/src/mono/sample/wasm/browser-threads-minimal/main.js b/src/mono/sample/wasm/browser-threads-minimal/main.js
index 72631334586fb6..329a45aa99b429 100644
--- a/src/mono/sample/wasm/browser-threads-minimal/main.js
+++ b/src/mono/sample/wasm/browser-threads-minimal/main.js
@@ -12,9 +12,6 @@ try {
     const { getAssemblyExports, runMain } = await dotnet
         //.withEnvironmentVariable("MONO_LOG_LEVEL", "debug")
         //.withDiagnosticTracing(true)
-        .withConfig({
-            pthreadPoolSize: 6,
-        })
         .withElementOnExit()
         .withExitCodeLogging()
         .create();
diff --git a/src/mono/sample/wasm/browser/Program.cs b/src/mono/sample/wasm/browser/Program.cs
index ce542da6201921..47b9c726349104 100644
--- a/src/mono/sample/wasm/browser/Program.cs
+++ b/src/mono/sample/wasm/browser/Program.cs
@@ -2,6 +2,8 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Threading;
+using System.Threading.Tasks;
 using System.Runtime.InteropServices.JavaScript;
 using System.Runtime.InteropServices;
 
@@ -9,13 +11,46 @@ namespace Sample
 {
     public partial class Test
     {
-        public static int Main(string[] args)
+        public static async Task<int> Main(string[] args)
         {
-            DisplayMeaning(42);
+            Console.WriteLine($"smoke: TestCanStartThread 0 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+            var are = new AutoResetEvent(false);
+            /*
+            var t = new Thread(() =>
+            {
+                Console.WriteLine($"smoke: TestCanStartThread 2 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+                are.Set();
+                Console.WriteLine($"smoke: TestCanStartThread 3 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+            });
+            */
+            /*
+            var factory = new TaskFactory();
+            await factory.StartNew(() =>
+            {
+                Console.WriteLine($"smoke: TestCanStartThread 2 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+                are.Set();
+                Console.WriteLine($"smoke: TestCanStartThread 3 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+            }, TaskCreationOptions.LongRunning);
+            */
+            var p = Task.Run(async ()=>{
+                Console.WriteLine($"smoke: TestCanStartThread 1 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+                await Task.Delay(1000);
+                Console.WriteLine($"smoke: TestCanStartThread 2 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+                are.Set();
+                Console.WriteLine($"smoke: TestCanStartThread 3 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+            });
+
+            Console.WriteLine($"smoke: TestCanStartThread 4 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+
+            are.WaitOne();
+
+            Console.WriteLine($"smoke: TestCanStartThread 5 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+
+            await p;
+
+            Console.WriteLine($"smoke: TestCanStartThread 6 ManagedThreadId:{Thread.CurrentThread.ManagedThreadId}, SynchronizationContext: {SynchronizationContext.Current?.GetType().FullName ?? "null"}");
+
             return 0;
         }
-
-        [JSImport("Sample.Test.displayMeaning", "main.js")]
-        internal static partial void DisplayMeaning(int meaning);
     }
 }
diff --git a/src/mono/sample/wasm/browser/Wasm.Browser.Sample.csproj b/src/mono/sample/wasm/browser/Wasm.Browser.Sample.csproj
index 365ba7276cb0b9..4f97a682fbb1b7 100644
--- a/src/mono/sample/wasm/browser/Wasm.Browser.Sample.csproj
+++ b/src/mono/sample/wasm/browser/Wasm.Browser.Sample.csproj
@@ -1,4 +1,8 @@
 <Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <WasmEnableThreads>true</WasmEnableThreads>
+    <MonoWasmBuildVariant>multithread</MonoWasmBuildVariant>
+  </PropertyGroup>
   <Import Project="..\DefaultBrowserSample.targets" />
   <ItemGroup>
     <WasmExtraFilesToDeploy Include="main.js" />
diff --git a/src/mono/sample/wasm/browser/main.js b/src/mono/sample/wasm/browser/main.js
index ba84cca682189b..a199f107319dd4 100644
--- a/src/mono/sample/wasm/browser/main.js
+++ b/src/mono/sample/wasm/browser/main.js
@@ -3,23 +3,15 @@
 
 import { dotnet, exit } from './_framework/dotnet.js'
 
-function displayMeaning(meaning) {
-    document.getElementById("out").innerHTML = `${meaning}`;
-}
+setInterval(() => {
+    console.log("UI thread is alive!");
+}, 1000);
 
 try {
-    const { setModuleImports } = await dotnet
+    await dotnet
         .withElementOnExit()
         .create();
 
-    setModuleImports("main.js", {
-        Sample: {
-            Test: {
-                displayMeaning
-            }
-        }
-    });
-
     await dotnet.run();
 }
 catch (err) {
diff --git a/src/mono/wasm/Wasm.Build.Tests/Blazor/SimpleMultiThreadedTests.cs b/src/mono/wasm/Wasm.Build.Tests/Blazor/SimpleMultiThreadedTests.cs
index c28f18a3c57469..9f7acf6a6ea666 100644
--- a/src/mono/wasm/Wasm.Build.Tests/Blazor/SimpleMultiThreadedTests.cs
+++ b/src/mono/wasm/Wasm.Build.Tests/Blazor/SimpleMultiThreadedTests.cs
@@ -12,7 +12,7 @@
 #nullable enable
 
 namespace Wasm.Build.Tests.MT.Blazor;
-
+/* until JS interop in deputy
 public class SimpleMultiThreadedTests : BlazorWasmTestBase
 {
     public SimpleMultiThreadedTests(ITestOutputHelper output, SharedBuildPerTestClassFixture buildContext)
@@ -76,3 +76,4 @@ await BlazorRunForPublishWithWebServer(
             throw new XunitException($"Errors found in browser console output:\n{errorOutput}");
     }
 }
+*/
diff --git a/src/mono/wasm/debugger/Wasm.Debugger.Tests/wasm.helix.targets b/src/mono/wasm/debugger/Wasm.Debugger.Tests/wasm.helix.targets
index e645a2c42c4d5d..38adf24927ab05 100644
--- a/src/mono/wasm/debugger/Wasm.Debugger.Tests/wasm.helix.targets
+++ b/src/mono/wasm/debugger/Wasm.Debugger.Tests/wasm.helix.targets
@@ -12,19 +12,6 @@
   <Target Name="_AddWorkItemsForWasmDebuggerTests">
     <!-- remove the existing item -->
     <HelixWorkItem Remove="@(HelixWorkItem)" Condition="'%(HelixWorkItem.Identity)' == 'Wasm.Debugger.Tests'" />
-
-    <ReadLinesFromFile File="$(TestArchiveTestsDir)DebuggerTestSuite.tests.list">
-      <Output TaskParameter="Lines" ItemName="_DebuggerTestsClassName" />
-    </ReadLinesFromFile>
-
-    <ItemGroup>
-      <HelixWorkItem Include="@(_DebuggerTestsClassName -> '$(DebuggerHost)-%(Identity)')">
-        <PayloadArchive>$(TestArchiveTestsDir)Wasm.Debugger.Tests.zip</PayloadArchive>
-        <Command>$(HelixCommand)</Command>
-        <Timeout>$(_DebuggerTestsWorkItemTimeout)</Timeout>
-        <PreCommands Condition="'$(OS)' == 'Windows_NT'">set &quot;TEST_ARGS=--filter category^^!=failing^&amp;FullyQualifiedName~%(Identity)&quot;</PreCommands>
-        <PreCommands Condition="'$(OS)' != 'Windows_NT'">export &quot;TEST_ARGS=--filter category!=failing&amp;FullyQualifiedName~%(Identity)&quot;</PreCommands>
-      </HelixWorkItem>
-    </ItemGroup>
+    <!-- TODO not ready for deputy yet -->
   </Target>
 </Project>
diff --git a/src/mono/wasm/runtime/cwraps.ts b/src/mono/wasm/runtime/cwraps.ts
index 4026be432c3004..f64a822648257f 100644
--- a/src/mono/wasm/runtime/cwraps.ts
+++ b/src/mono/wasm/runtime/cwraps.ts
@@ -41,6 +41,7 @@ const threading_cwraps: SigLine[] = MonoWasmThreads ? [
     [true, "mono_wasm_diagnostic_server_thread_attach_to_runtime", "void", []],
     [true, "mono_wasm_diagnostic_server_post_resume_runtime", "void", []],
     [true, "mono_wasm_diagnostic_server_create_stream", "number", []],
+    [true, "mono_wasm_create_deputy_thread", "bool", ["number"]],
 ] : [];
 
 // when the method is assigned/cached at usage, instead of being invoked directly from cwraps, it can't be marked lazy, because it would be re-bound on each call
@@ -181,6 +182,7 @@ export interface t_ThreadingCwraps {
     mono_wasm_diagnostic_server_thread_attach_to_runtime(): void;
     mono_wasm_diagnostic_server_post_resume_runtime(): void;
     mono_wasm_diagnostic_server_create_stream(): VoidPtr;
+    mono_wasm_create_deputy_thread(threadIdOutPtr: VoidPtr): boolean;
 }
 
 export interface t_ProfilerCwraps {
diff --git a/src/mono/wasm/runtime/driver.c b/src/mono/wasm/runtime/driver.c
index b3bac44d0d6858..4d2c56c7562363 100644
--- a/src/mono/wasm/runtime/driver.c
+++ b/src/mono/wasm/runtime/driver.c
@@ -662,6 +662,20 @@ mono_wasm_invoke_method_bound (MonoMethod *method, void* args /*JSMarshalerArgum
 	return is_err;
 }
 
+#ifndef DISABLE_THREADS
+// this is running in deputy thread
+EMSCRIPTEN_KEEPALIVE void
+mono_wasm_invoke_method_bound_deputy (MonoMethod *method, void* args /*JSMarshalerArguments*/)
+{
+	mono_wasm_invoke_method_bound(method, args, NULL);
+	free(args);
+}
+
+void
+mono_threads_wasm_async_run_in_deputy_thread_vii (void (*func)(gpointer, gpointer), gpointer user_data1, gpointer user_data2);
+
+#endif
+
 EMSCRIPTEN_KEEPALIVE MonoMethod*
 mono_wasm_assembly_get_entry_point (MonoAssembly *assembly, int auto_insert_breakpoint)
 {
@@ -1185,7 +1199,8 @@ mono_wasm_exec_regression (int verbose_level, char *image)
 EMSCRIPTEN_KEEPALIVE int
 mono_wasm_exit (int exit_code)
 {
-	mono_jit_cleanup (root_domain);
+	// TODO!!!!! call this on deputy thread
+	// mono_jit_cleanup (root_domain);
 	fflush (stdout);
 	fflush (stderr);
 	emscripten_force_exit (exit_code);
diff --git a/src/mono/wasm/runtime/exports-binding.ts b/src/mono/wasm/runtime/exports-binding.ts
index 5fbfc421a9a570..663884039069a7 100644
--- a/src/mono/wasm/runtime/exports-binding.ts
+++ b/src/mono/wasm/runtime/exports-binding.ts
@@ -25,6 +25,7 @@ import { mono_wasm_change_case, mono_wasm_change_case_invariant } from "./hybrid
 import { mono_wasm_compare_string, mono_wasm_ends_with, mono_wasm_starts_with, mono_wasm_index_of } from "./hybrid-globalization/collations";
 import { mono_wasm_get_calendar_info } from "./hybrid-globalization/calendar";
 import { mono_wasm_install_js_worker_interop, mono_wasm_uninstall_js_worker_interop } from "./pthreads/shared";
+import { mono_wasm_setup_deputy_thread } from "./pthreads/browser/deputy";
 
 import {
     mono_wasm_invoke_js_blazor, mono_wasm_invoke_js_with_args_ref, mono_wasm_get_object_property_ref, mono_wasm_set_object_property_ref,
@@ -51,6 +52,7 @@ export const mono_wasm_threads_imports = !MonoWasmThreads ? [] : [
     mono_wasm_diagnostic_server_stream_signal_work_available,
 
     // corebindings.c
+    mono_wasm_setup_deputy_thread,
     mono_wasm_install_js_worker_interop,
     mono_wasm_uninstall_js_worker_interop,
 ];
diff --git a/src/mono/wasm/runtime/globals.ts b/src/mono/wasm/runtime/globals.ts
index 5554344dd5b11e..bbcdcb126ae66a 100644
--- a/src/mono/wasm/runtime/globals.ts
+++ b/src/mono/wasm/runtime/globals.ts
@@ -71,6 +71,8 @@ export function setRuntimeGlobals(globalObjects: GlobalObjects) {
         afterPreInit: createPromiseController<void>(),
         afterPreRun: createPromiseController<void>(),
         beforeOnRuntimeInitialized: createPromiseController<void>(),
+        afterStartMonoVM: createPromiseController<void>(),
+        runMainResult: createPromiseController<void>(),
         afterOnRuntimeInitialized: createPromiseController<void>(),
         afterPostRun: createPromiseController<void>(),
         mono_wasm_exit: () => {
diff --git a/src/mono/wasm/runtime/loader/config.ts b/src/mono/wasm/runtime/loader/config.ts
index e805223074bccd..a0e89798bf6369 100644
--- a/src/mono/wasm/runtime/loader/config.ts
+++ b/src/mono/wasm/runtime/loader/config.ts
@@ -190,7 +190,7 @@ export function normalizeConfig() {
 
     if (MonoWasmThreads && !Number.isInteger(config.pthreadPoolSize)) {
         // ActiveIssue https://github.com/dotnet/runtime/issues/91538
-        config.pthreadPoolSize = 40;
+        config.pthreadPoolSize = 1;
     }
 
     // Default values (when WasmDebugLevel is not set)
diff --git a/src/mono/wasm/runtime/profiler.ts b/src/mono/wasm/runtime/profiler.ts
index af4775f66fe974..b49d0ad044a4f7 100644
--- a/src/mono/wasm/runtime/profiler.ts
+++ b/src/mono/wasm/runtime/profiler.ts
@@ -43,7 +43,7 @@ export const enum MeasuredBlock {
     preRunWorker = "mono.preRunWorker",
     onRuntimeInitialized = "mono.onRuntimeInitialized",
     postRun = "mono.postRun",
-    memorySnapshot = "mono.memorySnapshot",
+    startMonoVM = "mono.startMonoVM",
     loadRuntime = "mono.loadRuntime",
     bindingsInit = "mono.bindingsInit",
     bindJsFunction = "mono.bindJsFunction:",
diff --git a/src/mono/wasm/runtime/pthreads/browser/deputy.ts b/src/mono/wasm/runtime/pthreads/browser/deputy.ts
new file mode 100644
index 00000000000000..fd4ac33b4b5958
--- /dev/null
+++ b/src/mono/wasm/runtime/pthreads/browser/deputy.ts
@@ -0,0 +1,101 @@
+import MonoWasmThreads from "consts:monoWasmThreads";
+
+import { threads_c_functions as cwraps } from "../../cwraps";
+import { forceThreadMemoryViewRefresh, getI32, withStackAlloc } from "../../memory";
+import { Module, mono_assert, runtimeHelpers } from "../../globals";
+import { Thread, waitForThread } from ".";
+import { mono_log_info } from "../../logging";
+import { start_mono_vm } from "../../startup";
+import { pthread_self } from "../worker";
+import { MonoThreadMessage, mono_wasm_install_js_worker_interop } from "../shared";
+import { mono_run_main_impl } from "../../run";
+
+export let deputyThread: Thread | undefined;
+
+export async function startDeputyThread(): Promise<void> {
+    if (!MonoWasmThreads) {
+        return;
+    }
+    const sizeOfPthreadT = 4;
+    const result: number | undefined = withStackAlloc(sizeOfPthreadT, (pthreadIdPtr) => {
+        if (!cwraps.mono_wasm_create_deputy_thread(pthreadIdPtr))
+            return undefined;
+        const pthreadId = getI32(pthreadIdPtr);
+        return pthreadId;
+    });
+    mono_assert(result, "failed to create deputy thread");
+    // have to wait until the message port is created
+    deputyThread = await waitForThread(result);
+    // wait until mono VM started
+    await runtimeHelpers.afterStartMonoVM.promise;
+}
+
+export async function deputy_run_main(main_assembly_name: string, args: string[]) {
+    deputyThread?.postMessageToWorker({
+        type: "deputy",
+        cmd: "run_main",
+        main_assembly_name,
+        args
+    });
+    return runtimeHelpers.runMainResult.promise;
+}
+
+export function mono_wasm_setup_deputy_thread() {
+    mono_assert(MonoWasmThreads, "Expected MT build");
+    if (globalThis.setInterval) globalThis.setInterval(() => {
+        mono_log_info("Deputy thread is alive!");
+    }, 3000);
+
+    runtimeHelpers.isDeputyThread = true;
+
+    //TODO pop on exit
+    Module.runtimeKeepalivePush();
+
+    pthread_self.addEventListenerFromBrowser(async (event: MessageEvent<MonoThreadMessage>) => {
+        if (event.data.type == "deputy" && event.data.cmd == "run_main") {
+            try {
+                forceThreadMemoryViewRefresh();
+                const { main_assembly_name, args } = event.data as any;
+                const result = await mono_run_main_impl(main_assembly_name, args);
+                pthread_self.postMessageToBrowser({
+                    type: "deputy",
+                    cmd: "run_main_result",
+                    result
+                });
+            }
+            catch (ex: any) {
+                pthread_self.postMessageToBrowser({
+                    type: "deputy",
+                    cmd: "run_main_error",
+                    reason: "" + ex
+                });
+            }
+        }
+    });
+
+
+    // because this is synchronous method, we will postpone mono startup to the next event loop
+    Module.safeSetTimeout(async () => {
+        try {
+            forceThreadMemoryViewRefresh();
+            await start_mono_vm();
+
+            mono_wasm_install_js_worker_interop(1);
+            runtimeHelpers.javaScriptExports.install_synchronization_context();
+
+            // tell UI thread that we are ready
+            pthread_self.postMessageToBrowser({
+                type: "deputy",
+                cmd: "ready"
+            });
+        }
+        catch (ex: any) {
+            pthread_self.postMessageToBrowser({
+                type: "deputy",
+                cmd: "abort",
+                reason: "" + ex
+            });
+            runtimeHelpers.abort(ex);
+        }
+    }, 0);
+}
diff --git a/src/mono/wasm/runtime/pthreads/browser/index.ts b/src/mono/wasm/runtime/pthreads/browser/index.ts
index 89c84baf78836e..dbcd79c85b5155 100644
--- a/src/mono/wasm/runtime/pthreads/browser/index.ts
+++ b/src/mono/wasm/runtime/pthreads/browser/index.ts
@@ -1,13 +1,17 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
-import { isMonoWorkerMessageChannelCreated, monoSymbol, makeMonoThreadMessageApplyMonoConfig, isMonoWorkerMessagePreload, MonoWorkerMessage } from "../shared";
+import MonoWasmThreads from "consts:monoWasmThreads";
+
+import { isMonoWorkerMessageChannelCreated, monoSymbol, makeMonoThreadMessageApplyMonoConfig, isMonoWorkerMessagePreload, MonoWorkerMessage, getBrowserThreadID } from "../shared";
 import { pthreadPtr } from "../shared/types";
 import { MonoThreadMessage } from "../shared";
 import Internals from "../shared/emscripten-internals";
 import { createPromiseController, runtimeHelpers } from "../../globals";
 import { PromiseController } from "../../types/internal";
-import { mono_log_debug } from "../../logging";
+import { mono_log_debug, mono_set_thread_id } from "../../logging";
+import { mono_wasm_init_diagnostics } from "../../diagnostics";
+import { startDeputyThread } from "./deputy";
 
 const threads: Map<pthreadPtr, Thread> = new Map();
 
@@ -80,8 +84,23 @@ export function getThread(pthreadPtr: pthreadPtr): Thread | undefined {
 export const getThreadIds = (): IterableIterator<pthreadPtr> => threads.keys();
 
 function monoDedicatedChannelMessageFromWorkerToMain(event: MessageEvent<unknown>, thread: Thread): void {
-    // TODO: add callbacks that will be called from here
-    mono_log_debug("got message from worker on the dedicated channel", event.data, thread);
+    const data = event.data as MonoThreadMessage;
+    if (data.type == "deputy") {
+        if (data.cmd == "ready") {
+            runtimeHelpers.afterStartMonoVM.promise_control.resolve();
+            return;
+        } else if (data.cmd == "abort") {
+            runtimeHelpers.afterStartMonoVM.promise_control.reject((data as any).reason);
+            return;
+        } else if (data.cmd == "run_main_result") {
+            runtimeHelpers.runMainResult.promise_control.resolve((data as any).result);
+            return;
+        } else if (data.cmd == "run_main_error") {
+            runtimeHelpers.runMainResult.promise_control.reject((data as any).reason);
+            return;
+        }
+    }
+    mono_log_debug("got unexpected message from worker on the dedicated channel", event.data, thread);
 }
 
 // handler that runs in the main thread when a message is received from a pthread worker
@@ -132,3 +151,17 @@ export async function instantiateWasmPThreadWorkerPool(): Promise<void> {
         await Promise.all(promises);
     }
 }
+
+export async function mono_wasm_init_threads() {
+    if (!MonoWasmThreads) {
+        return;
+    }
+    const tid = getBrowserThreadID();
+    mono_set_thread_id(`0x${tid.toString(16)}-UI`);
+
+    await instantiateWasmPThreadWorkerPool();
+
+    await mono_wasm_init_diagnostics();
+
+    await startDeputyThread();
+}
diff --git a/src/mono/wasm/runtime/pthreads/shared/index.ts b/src/mono/wasm/runtime/pthreads/shared/index.ts
index c8557755062a2f..24a24bad4aa003 100644
--- a/src/mono/wasm/runtime/pthreads/shared/index.ts
+++ b/src/mono/wasm/runtime/pthreads/shared/index.ts
@@ -2,7 +2,6 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 import MonoWasmThreads from "consts:monoWasmThreads";
-import BuildConfiguration from "consts:configuration";
 
 import { Module, mono_assert, runtimeHelpers } from "../../globals";
 import { MonoConfig } from "../../types";
@@ -47,6 +46,11 @@ export interface MonoThreadMessage {
     cmd: string;
 }
 
+export interface DeputyMessage extends MonoThreadMessage {
+    type: "deputy";
+    cmd: string;
+}
+
 export function isMonoThreadMessage(x: unknown): x is MonoThreadMessage {
     if (typeof (x) !== "object" || x === null) {
         return false;
@@ -147,7 +151,7 @@ export function mono_wasm_install_js_worker_interop(install_js_synchronization_c
         Module.runtimeKeepalivePush();
     }
 
-    set_thread_info(pthread_self ? pthread_self.pthreadId : 0, true, true, !!install_js_synchronization_context);
+    set_thread_info(pthread_self ? pthread_self.pthreadId : 0, true, true, !!install_js_synchronization_context, !!runtimeHelpers.isDeputyThread);
 }
 
 export function mono_wasm_uninstall_js_worker_interop(uninstall_js_synchronization_context: number): void {
@@ -162,7 +166,7 @@ export function mono_wasm_uninstall_js_worker_interop(uninstall_js_synchronizati
 
     runtimeHelpers.jsSynchronizationContextInstalled = false;
     runtimeHelpers.mono_wasm_bindings_is_ready = false;
-    set_thread_info(pthread_self ? pthread_self.pthreadId : 0, true, false, false);
+    set_thread_info(pthread_self ? pthread_self.pthreadId : 0, true, false, false, false);
 }
 
 export function assert_synchronization_context(): void {
@@ -171,14 +175,18 @@ export function assert_synchronization_context(): void {
     }
 }
 
+let info_counter = 0;
 // this is just for Debug build of the runtime, making it easier to debug worker threads
-export function set_thread_info(pthread_ptr: number, isAttached: boolean, hasInterop: boolean, hasSynchronization: boolean): void {
-    if (MonoWasmThreads && BuildConfiguration === "Debug" && !runtimeHelpers.cspPolicy) {
+export function set_thread_info(pthread_ptr: number, isAttached: boolean, hasInterop: boolean, hasSynchronization: boolean, isDeputy: boolean): void {
+    // TODO && BuildConfiguration === "Debug"
+    if (MonoWasmThreads && !runtimeHelpers.cspPolicy) {
+        const id = "0x" + pthread_ptr.toString(16);
         try {
-            (globalThis as any).monoThreadInfo = new Function(`//# sourceURL=https://WorkerInfo/\r\nconsole.log("tid:0x${pthread_ptr.toString(16)} isAttached:${isAttached} hasInterop:${!!hasInterop} hasSynchronization:${hasSynchronization}" );`);
+            (globalThis as any).monoThreadInfo = new Function(`//# sourceURL=https://WorkerInfo-${info_counter}-${id}/\r\nreturn("id:${id} isAttached:${isAttached} hasInterop:${!!hasInterop} hasSynchronization:${hasSynchronization} isDeputy:${isDeputy}" );`);
         }
         catch (ex) {
             runtimeHelpers.cspPolicy = true;
         }
     }
+    info_counter++;
 }
diff --git a/src/mono/wasm/runtime/pthreads/worker/index.ts b/src/mono/wasm/runtime/pthreads/worker/index.ts
index 2ac8feb10a9a54..3d595afdc48e2b 100644
--- a/src/mono/wasm/runtime/pthreads/worker/index.ts
+++ b/src/mono/wasm/runtime/pthreads/worker/index.ts
@@ -18,7 +18,7 @@ import {
     WorkerThreadEventTarget
 } from "./events";
 import { postRunWorker, preRunWorker } from "../../startup";
-import { mono_log_debug } from "../../logging";
+import { mono_log_debug, mono_log_info } from "../../logging";
 import { mono_set_thread_id } from "../../logging";
 import { jiterpreter_allocate_tables } from "../../jiterpreter-support";
 
@@ -85,23 +85,36 @@ function setupChannelToMainThread(pthread_ptr: pthreadPtr): PThreadSelf {
 
 /// This is an implementation detail function.
 /// Called in the worker thread (not main thread) from mono when a pthread becomes attached to the mono runtime.
+let inter: number | undefined;
 export function mono_wasm_pthread_on_pthread_attached(pthread_id: number): void {
     const self = pthread_self;
     mono_assert(self !== null && self.pthreadId == pthread_id, "expected pthread_self to be set already when attaching");
-    mono_set_thread_id("0x" + pthread_id.toString(16));
-    mono_log_debug("attaching pthread to mono runtime 0x" + pthread_id.toString(16));
+    const id = "0x" + pthread_id.toString(16);
+    mono_set_thread_id(id);
+    mono_log_info("attaching pthread to mono runtime " + id);
     preRunWorker();
-    set_thread_info(pthread_id, true, false, false);
+    set_thread_info(pthread_id, true, false, false, false);
     jiterpreter_allocate_tables(Module);
     currentWorkerThreadEvents.dispatchEvent(makeWorkerThreadEvent(dotnetPthreadAttached, self));
+    if (globalThis.setInterval) {
+        const info = (globalThis as any).monoThreadInfo ?
+            (globalThis as any).monoThreadInfo() : "" + id;
+        inter = globalThis.setInterval(() => {
+            mono_log_info("Worker is alive! " + info);
+        }, 3000); // keep the worker alive
+    }
 }
 
 /// Called in the worker thread (not main thread) from mono when a pthread becomes detached from the mono runtime.
 export function mono_wasm_pthread_on_pthread_detached(pthread_id: number): void {
-    mono_log_debug("detaching pthread from mono runtime 0x" + pthread_id.toString(16));
+    mono_log_info("detaching pthread from mono runtime 0x" + pthread_id.toString(16));
     postRunWorker();
-    set_thread_info(pthread_id, false, false, false);
+    set_thread_info(pthread_id, false, false, false, false);
     mono_set_thread_id("");
+    if (inter && (globalThis as any).clearInterval) {
+        clearInterval(inter);
+        inter = undefined;
+    }
 }
 
 /// This is an implementation detail function.
diff --git a/src/mono/wasm/runtime/run.ts b/src/mono/wasm/runtime/run.ts
index 41444a5251f8cb..7455071e4b5cf0 100644
--- a/src/mono/wasm/runtime/run.ts
+++ b/src/mono/wasm/runtime/run.ts
@@ -1,6 +1,8 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+import MonoWasmThreads from "consts:monoWasmThreads";
+
 import { ENVIRONMENT_IS_NODE, loaderHelpers, runtimeHelpers } from "./globals";
 import { mono_wasm_wait_for_debugger } from "./debug";
 import { mono_wasm_set_main_args } from "./startup";
@@ -8,6 +10,7 @@ import cwraps from "./cwraps";
 import { assembly_load } from "./class-loader";
 import { mono_log_info } from "./logging";
 import { assert_bindings } from "./invoke-js";
+import { deputy_run_main } from "./pthreads/browser/deputy";
 
 /**
  * Possible signatures are described here  https://docs.microsoft.com/en-us/dotnet/csharp/fundamentals/program-structure/main-command-line
@@ -54,6 +57,15 @@ export async function mono_run_main(main_assembly_name: string, args?: string[])
         mono_log_info("waiting for debugger...");
         await mono_wasm_wait_for_debugger();
     }
+    if (MonoWasmThreads) {
+        return deputy_run_main(main_assembly_name, args);
+    }
+    else {
+        return mono_run_main_impl(main_assembly_name, args);
+    }
+}
+
+export async function mono_run_main_impl(main_assembly_name: string, args: string[]) {
     const method = find_entry_point(main_assembly_name);
 
     const res = await runtimeHelpers.javaScriptExports.call_entry_point(method, args);
diff --git a/src/mono/wasm/runtime/startup.ts b/src/mono/wasm/runtime/startup.ts
index 7fec1577dedc94..1fee0065ec7349 100644
--- a/src/mono/wasm/runtime/startup.ts
+++ b/src/mono/wasm/runtime/startup.ts
@@ -6,7 +6,8 @@ import WasmEnableLegacyJsInterop from "consts:wasmEnableLegacyJsInterop";
 
 import { DotnetModuleInternal, CharPtrNull } from "./types/internal";
 import { linkerDisableLegacyJsInterop, ENVIRONMENT_IS_PTHREAD, exportedRuntimeAPI, INTERNAL, loaderHelpers, Module, runtimeHelpers, createPromiseController, mono_assert, linkerWasmEnableSIMD, linkerWasmEnableEH, ENVIRONMENT_IS_WORKER } from "./globals";
-import cwraps, { init_c_exports } from "./cwraps";
+import { init_c_exports } from "./cwraps";
+import { threads_c_functions as cwraps } from "./cwraps";
 import { mono_wasm_raise_debug_event, mono_wasm_runtime_ready } from "./debug";
 import { toBase64StringImpl } from "./base64";
 import { mono_wasm_init_aot_profiler, mono_wasm_init_browser_profiler } from "./profiler";
@@ -18,17 +19,15 @@ import { init_managed_exports } from "./managed-exports";
 import { cwraps_internal } from "./exports-internal";
 import { CharPtr, InstantiateWasmCallBack, InstantiateWasmSuccessCallback } from "./types/emscripten";
 import { wait_for_all_assets } from "./assets";
-import { mono_wasm_init_diagnostics } from "./diagnostics";
 import { replace_linker_placeholders } from "./exports-binding";
 import { endMeasure, MeasuredBlock, startMeasure } from "./profiler";
 import { checkMemorySnapshotSize, getMemorySnapshot, storeMemorySnapshot } from "./snapshot";
 import { interp_pgo_load_data, interp_pgo_save_data } from "./interp-pgo";
-import { mono_log_debug, mono_log_error, mono_log_warn, mono_set_thread_id } from "./logging";
+import { mono_log_debug, mono_log_error, mono_log_warn } from "./logging";
 
 // threads
-import { preAllocatePThreadWorkerPool, instantiateWasmPThreadWorkerPool } from "./pthreads/browser";
+import { mono_wasm_init_threads, preAllocatePThreadWorkerPool } from "./pthreads/browser";
 import { currentWorkerThreadEvents, dotnetPthreadCreated, initWorkerThreadEvents } from "./pthreads/worker";
-import { getBrowserThreadID } from "./pthreads/shared";
 import { jiterpreter_allocate_tables } from "./jiterpreter-support";
 
 // legacy
@@ -145,6 +144,9 @@ function preInit(userPreInit: (() => void)[]) {
         mono_wasm_pre_init_essential(false);
         mono_log_debug("preInit");
         runtimeHelpers.beforePreInit.promise_control.resolve();
+        if (!ENVIRONMENT_IS_WORKER) {
+            Module.runtimeKeepalivePush();
+        }
         // all user Module.preInit callbacks
         userPreInit.forEach(fn => fn());
     } catch (err) {
@@ -237,33 +239,23 @@ async function onRuntimeInitializedAsync(userOnRuntimeInitialized: () => void) {
 
         await wait_for_all_assets();
 
-        // Threads early are not supported with memory snapshot. See below how we enable them later.
-        // Please disable startupMemoryCache in order to be able to diagnose or pause runtime startup.
-        if (MonoWasmThreads && !runtimeHelpers.config.startupMemoryCache) {
-            await mono_wasm_init_threads();
-        }
-
-        // load runtime and apply environment settings (if necessary)
-        await mono_wasm_before_memory_snapshot();
-
-        if (runtimeHelpers.config.interpreterPgo) {
-            await interp_pgo_load_data();
-        }
+        mono_assert(!MonoWasmThreads || !runtimeHelpers.config.startupMemoryCache, "Threads are not supported with memory snapshot.");
 
-        if (runtimeHelpers.config.exitAfterSnapshot) {
-            const reason = runtimeHelpers.ExitStatus
-                ? new runtimeHelpers.ExitStatus(0)
-                : new Error("Snapshot taken, exiting because exitAfterSnapshot was set.");
-            reason.silent = true;
+        if (MonoWasmThreads) {
+            await mono_wasm_init_threads();
+        } else {
+            await start_mono_vm();
 
-            loaderHelpers.mono_exit(0, reason);
-            return;
-        }
+            if (runtimeHelpers.config.exitAfterSnapshot) {
+                const reason = runtimeHelpers.ExitStatus
+                    ? new runtimeHelpers.ExitStatus(0)
+                    : new Error("Snapshot taken, exiting because exitAfterSnapshot was set.");
+                reason.silent = true;
 
-        if (!ENVIRONMENT_IS_WORKER) {
-            Module.runtimeKeepalivePush();
+                loaderHelpers.mono_exit(0, reason);
+                return;
+            }
         }
-        runtimeHelpers.runtimeReady = true;
 
         if (runtimeHelpers.config.virtualWorkingDirectory) {
             const FS = Module.FS;
@@ -276,17 +268,8 @@ async function onRuntimeInitializedAsync(userOnRuntimeInitialized: () => void) {
             FS.chdir(cwd);
         }
 
-        if (MonoWasmThreads && runtimeHelpers.config.startupMemoryCache) {
-            await mono_wasm_init_threads();
-        }
-
-        bindings_init();
-        jiterpreter_allocate_tables(Module);
+        runtimeHelpers.runtimeReady = true;
 
-        if (MonoWasmThreads) {
-            runtimeHelpers.javaScriptExports.install_synchronization_context();
-            runtimeHelpers.jsSynchronizationContextInstalled = true;
-        }
 
         if (!runtimeHelpers.mono_wasm_runtime_is_ready) mono_wasm_runtime_ready();
 
@@ -348,16 +331,6 @@ export function postRunWorker() {
     runtimeHelpers.afterPreRun = createPromiseController<void>();
 }
 
-async function mono_wasm_init_threads() {
-    if (!MonoWasmThreads) {
-        return;
-    }
-    const tid = getBrowserThreadID();
-    mono_set_thread_id(`0x${tid.toString(16)}-main`);
-    await instantiateWasmPThreadWorkerPool();
-    await mono_wasm_init_diagnostics();
-}
-
 function mono_wasm_pre_init_essential(isWorker: boolean): void {
     if (!isWorker)
         Module.addRunDependency("mono_wasm_pre_init_essential");
@@ -377,11 +350,6 @@ function mono_wasm_pre_init_essential(isWorker: boolean): void {
         cwraps_mono_api(MONO);
         cwraps_binding_api(BINDING);
     }
-    // removeRunDependency triggers the dependenciesFulfilled callback (runCaller) in
-    // emscripten - on a worker since we don't have any other dependencies that causes run() to get
-    // called too soon; and then it will get called a second time when dotnet.native.js calls it directly.
-    // on a worker run() short-cirtcuits and just calls   readyPromiseResolve, initRuntime and postMessage.
-    // sending postMessage twice will break instantiateWasmPThreadWorkerPool on the main thread.
     if (!isWorker)
         Module.removeRunDependency("mono_wasm_pre_init_essential");
 }
@@ -512,7 +480,7 @@ async function ensureUsedWasmFeatures() {
     }
 }
 
-async function mono_wasm_before_memory_snapshot() {
+export async function start_mono_vm() {
     const mark = startMeasure();
     if (runtimeHelpers.loadedMemorySnapshotSize) {
         // get the bytes after we re-sized the memory, so that we don't have too much memory in use at the same time
@@ -550,13 +518,19 @@ async function mono_wasm_before_memory_snapshot() {
         runtimeHelpers.storeMemorySnapshotPending = false;
     }
 
-    if (runtimeHelpers.config.interpreterPgo)
+    if (runtimeHelpers.config.interpreterPgo) {
+        await interp_pgo_load_data();
+
         setTimeout(maybeSaveInterpPgoTable, (runtimeHelpers.config.interpreterPgoSaveDelay || 15) * 1000);
+    }
+
+    bindings_init();
+    jiterpreter_allocate_tables(Module);
 
-    endMeasure(mark, MeasuredBlock.memorySnapshot);
+    endMeasure(mark, MeasuredBlock.startMonoVM);
 }
 
-async function maybeSaveInterpPgoTable () {
+async function maybeSaveInterpPgoTable() {
     // If the application exited abnormally, don't save the table. It probably doesn't contain useful data,
     //  and saving would overwrite any existing table from a previous successful run.
     // We treat exiting with a code of 0 as equivalent to if the app is still running - it's perfectly fine
diff --git a/src/mono/wasm/runtime/types/internal.ts b/src/mono/wasm/runtime/types/internal.ts
index 53fb458d6a4323..d1fe89ef256a2d 100644
--- a/src/mono/wasm/runtime/types/internal.ts
+++ b/src/mono/wasm/runtime/types/internal.ts
@@ -191,6 +191,7 @@ export type RuntimeHelpers = {
     subtle: SubtleCrypto | null,
     updateMemoryViews: () => void
     runtimeReady: boolean,
+    isDeputyThread: boolean,
     jsSynchronizationContextInstalled: boolean,
     cspPolicy: boolean,
 
@@ -201,9 +202,12 @@ export type RuntimeHelpers = {
     afterPreInit: PromiseAndController<void>,
     afterPreRun: PromiseAndController<void>,
     beforeOnRuntimeInitialized: PromiseAndController<void>,
+    afterStartMonoVM: PromiseAndController<void>,
     afterOnRuntimeInitialized: PromiseAndController<void>,
     afterPostRun: PromiseAndController<void>,
 
+    runMainResult: PromiseAndController<number>,
+
     featureWasmEh: boolean,
     featureWasmSimd: boolean,
 
diff --git a/src/mono/wasm/test-main.js b/src/mono/wasm/test-main.js
index 4467dc20ce204e..ffb2e0536c1bb4 100644
--- a/src/mono/wasm/test-main.js
+++ b/src/mono/wasm/test-main.js
@@ -277,7 +277,7 @@ function configureRuntime(dotnet, runArgs) {
         .withInteropCleanupOnExit()
         .withAssertAfterExit()
         .withConfig({
-            loadAllSatelliteResources: true
+            loadAllSatelliteResources: true,
         });
 
     if (ENVIRONMENT_IS_NODE) {
@@ -326,7 +326,6 @@ async function dry_run(runArgs) {
             appendElementOnExit: false,
             logExitCode: false,
             virtualWorkingDirectory: undefined,
-            pthreadPoolSize: 0,
             interopCleanupOnExit: false,
             // this just means to not continue startup after the snapshot is taken.
             // If there was previously a matching snapshot, it will be used.
@@ -343,6 +342,13 @@ async function dry_run(runArgs) {
     return true;
 }
 
+let alive;
+if (globalThis.setInterval) {
+    alive = globalThis.setInterval(() => {
+        console.log("UI thread is alive!");
+    }, 3000);
+}
+
 async function run() {
     try {
         const runArgs = await getArgs();
@@ -350,11 +356,11 @@ async function run() {
 
         if (ENVIRONMENT_IS_WEB && runArgs.memorySnapshot) {
             if (globalThis.isSecureContext) {
-            const dryOk = await dry_run(runArgs);
-            if (!dryOk) {
-                mono_exit(1, "Failed during dry run");
-                return;
-            }
+                const dryOk = await dry_run(runArgs);
+                if (!dryOk) {
+                    mono_exit(1, "Failed during dry run");
+                    return;
+                }
             } else {
                 console.log("Skipping dry run as the context is not secure and the snapshot would be not trusted.");
             }
@@ -411,6 +417,9 @@ async function run() {
                 const app_args = runArgs.applicationArguments.slice(2);
                 const result = await App.runtime.runMain(main_assembly_name, app_args);
                 console.log(`test-main.js exiting ${app_args.length > 1 ? main_assembly_name + " " + app_args[0] : main_assembly_name} with result ${result}`);
+                if (alive && globalThis.clearInterval) {
+                    globalThis.clearInterval(alive);
+                }
                 mono_exit(result);
             } catch (error) {
                 if (error.name != "ExitStatus") {
@@ -425,4 +434,5 @@ async function run() {
     }
 }
 
+
 await run();
diff --git a/src/mono/wasm/wasm.proj b/src/mono/wasm/wasm.proj
index 6ed392341e6b66..e537019944009d 100644
--- a/src/mono/wasm/wasm.proj
+++ b/src/mono/wasm/wasm.proj
@@ -274,7 +274,7 @@
       <_EmccCommonFlags Condition="'$(MonoWasmThreads)' == 'true'" Include="-s USE_PTHREADS=1" />
       <_EmccLinkFlags Condition="'$(MonoWasmThreads)' == 'true'" Include="-Wno-pthreads-mem-growth" />
       <_EmccLinkFlags Condition="'$(MonoWasmThreads)' == 'true'" Include="-s PTHREAD_POOL_SIZE=0" />
-      <_EmccLinkFlags Condition="'$(MonoWasmThreads)' == 'true'" Include="-s PTHREAD_POOL_SIZE_STRICT=2" /> <!-- hard error if worker pool is exhausted -->
+      <_EmccLinkFlags Condition="'$(MonoWasmThreads)' == 'true'" Include="-s PTHREAD_POOL_SIZE_STRICT=0" /> <!-- UI thread should be not blocked in deputy design -->
       <_EmccLinkFlags Include="-s ALLOW_MEMORY_GROWTH=1" />
       <!-- for jiterpreter -->
       <_EmccLinkFlags Include="-s ALLOW_TABLE_GROWTH=1" />