diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/server/Lib.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/server/Lib.cs
index f1d6c1aa9e..a0c02aa9d0 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/server/Lib.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/server/Lib.cs
@@ -2,6 +2,7 @@
 using SpacetimeDB;
 
 #pragma warning disable CA1050 // Declare types in namespaces - this is a test fixture, no need for a namespace.
+#pragma warning disable STDB_UNSTABLE // Enable experimental SpacetimeDB features
 
 [SpacetimeDB.Type]
 public partial struct CustomStruct
diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#MultiTableRow.InsertMultiData.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#MultiTableRow.InsertMultiData.verified.cs
index 645e0cf939..6641f96fd4 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#MultiTableRow.InsertMultiData.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#MultiTableRow.InsertMultiData.verified.cs
@@ -4,6 +4,7 @@
 
 partial struct MultiTableRow
 {
+    [System.Diagnostics.CodeAnalysis.Experimental("STDB_UNSTABLE")]
     public static void VolatileNonatomicScheduleImmediateInsertMultiData(MultiTableRow data)
     {
         using var stream = new MemoryStream();
diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Reducers.InsertData.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Reducers.InsertData.verified.cs
index add5f82302..4be5a0da72 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Reducers.InsertData.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Reducers.InsertData.verified.cs
@@ -4,6 +4,7 @@
 
 partial class Reducers
 {
+    [System.Diagnostics.CodeAnalysis.Experimental("STDB_UNSTABLE")]
     public static void VolatileNonatomicScheduleImmediateInsertData(PublicTable data)
     {
         using var stream = new MemoryStream();
diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Reducers.ScheduleImmediate.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Reducers.ScheduleImmediate.verified.cs
index 94063a3acf..aa20a22ef0 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Reducers.ScheduleImmediate.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Reducers.ScheduleImmediate.verified.cs
@@ -4,6 +4,7 @@
 
 partial class Reducers
 {
+    [System.Diagnostics.CodeAnalysis.Experimental("STDB_UNSTABLE")]
     public static void VolatileNonatomicScheduleImmediateScheduleImmediate(PublicTable data)
     {
         using var stream = new MemoryStream();
diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Test.NestingNamespaces.AndClasses.InsertData2.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Test.NestingNamespaces.AndClasses.InsertData2.verified.cs
index 9d7e1ea917..732c40a809 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Test.NestingNamespaces.AndClasses.InsertData2.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Test.NestingNamespaces.AndClasses.InsertData2.verified.cs
@@ -6,6 +6,7 @@ namespace Test.NestingNamespaces
 {
     partial class AndClasses
     {
+        [System.Diagnostics.CodeAnalysis.Experimental("STDB_UNSTABLE")]
         public static void VolatileNonatomicScheduleImmediateInsertData2(PublicTable data)
         {
             using var stream = new MemoryStream();
diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Timers.Init.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Timers.Init.verified.cs
index 9a30e7939d..7cb0c5b60e 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Timers.Init.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Timers.Init.verified.cs
@@ -4,6 +4,7 @@
 
 partial class Timers
 {
+    [System.Diagnostics.CodeAnalysis.Experimental("STDB_UNSTABLE")]
     public static void VolatileNonatomicScheduleImmediateInit()
     {
         using var stream = new MemoryStream();
diff --git a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Timers.SendScheduledMessage.verified.cs b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Timers.SendScheduledMessage.verified.cs
index 0cea55149e..eefbfb2a66 100644
--- a/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Timers.SendScheduledMessage.verified.cs
+++ b/crates/bindings-csharp/Codegen.Tests/fixtures/server/snapshots/Module#Timers.SendScheduledMessage.verified.cs
@@ -4,6 +4,7 @@
 
 partial class Timers
 {
+    [System.Diagnostics.CodeAnalysis.Experimental("STDB_UNSTABLE")]
     public static void VolatileNonatomicScheduleImmediateSendScheduledMessage(
         Timers.SendMessageTimer arg
     )
diff --git a/crates/bindings-csharp/Codegen/Module.cs b/crates/bindings-csharp/Codegen/Module.cs
index 08061be464..0cda108d68 100644
--- a/crates/bindings-csharp/Codegen/Module.cs
+++ b/crates/bindings-csharp/Codegen/Module.cs
@@ -451,8 +451,13 @@ public Scope.Extensions GenerateSchedule()
     {
         var extensions = new Scope.Extensions(Scope, FullName);
 
+        // Mark the API as unstable. We use name `STDB_UNSTABLE` because:
+        // 1. It's a close equivalent of the `unstable` Cargo feature in Rust.
+        // 2. Our diagnostic IDs use either BSATN or STDB prefix depending on the package.
+        // 3. We don't expect to mark individual experimental features with numeric IDs, so we don't use the standard 1234 suffix.
         extensions.Contents.Append(
             $$"""
+            [System.Diagnostics.CodeAnalysis.Experimental("STDB_UNSTABLE")]
             public static void VolatileNonatomicScheduleImmediate{{Name}}({{string.Join(
                 ", ",
                 Args.Select(a => $"{a.Type} {a.Name}")