Add managedSettings.clearCache RPC bindings (force-clear managed settings cache)

dotnet/test/E2E/RpcServerE2ETests.cs

@@ -125,6 +125,15 @@ public async Task Should_Call_Rpc_Ping_With_Typed_Params_And_Result()
         Assert.NotEqual(default, result.Timestamp);
     }
 
+    [Fact]
+    [Trait(E2ETestTraits.Backend, E2ETestTraits.CapiOnly)]
+    public async Task Should_Clear_The_Managed_Settings_Cache()
+    {
+        await Client.StartAsync();
+
+        await Client.Rpc.ManagedSettings.ClearCacheAsync();
+    }
+
     [Fact]
     public async Task Should_Reject_Llm_Inference_Response_Frames_For_Missing_Request()
     {

dotnet/test/Unit/SerializationTests.cs

@@ -1156,6 +1156,35 @@ public void QueuePendingItems_MessageId_UsesCamelCaseAndIsOptional(string? messa
     }
 #pragma warning restore GHCP001
 
+    [Fact]
+    public void ModelSwitchRequests_DistinguishRequiredNullFromOmittedOptionalValue()
+    {
+        var options = GetSerializerOptions();
+        var assembly = typeof(CopilotClient).Assembly;
+
+        var switchAutoTierType = assembly.GetType("GitHub.Copilot.Rpc.ModelSwitchAutoTierRequest");
+        Assert.NotNull(switchAutoTierType);
+        var switchAutoTierRequest = CreateInternalRequest(
+            switchAutoTierType!,
+            ("SessionId", "session-id"),
+            ("AutoTier", null));
+        using var switchAutoTierDocument = JsonDocument.Parse(
+            JsonSerializer.Serialize(switchAutoTierRequest, switchAutoTierType!, options));
+        Assert.True(switchAutoTierDocument.RootElement.TryGetProperty("autoTier", out var requiredAutoTier));
+        Assert.Equal(JsonValueKind.Null, requiredAutoTier.ValueKind);
+
+        var switchToType = assembly.GetType("GitHub.Copilot.Rpc.ModelSwitchToRequest");
+        Assert.NotNull(switchToType);
+        var switchToRequest = CreateInternalRequest(
+            switchToType!,
+            ("SessionId", "session-id"),
+            ("ModelId", "auto"),
+            ("AutoTier", null));
+        using var switchToDocument = JsonDocument.Parse(
+            JsonSerializer.Serialize(switchToRequest, switchToType!, options));
+        Assert.False(switchToDocument.RootElement.TryGetProperty("autoTier", out _));
+    }
+
     private static JsonSerializerOptions GetSerializerOptions()
     {
         var prop = typeof(CopilotClient)

go/internal/e2e/rpc_server_e2e_test.go

@@ -17,6 +17,21 @@ import (
 // Mirrors dotnet/test/RpcServerTests.cs (snapshot category "rpc_server").
 // Tests server-scoped (non-session) RPCs.
 func TestRPCServerE2E(t *testing.T) {
+	t.Run("should clear the managed settings cache", func(t *testing.T) {
+		ctx := testharness.NewTestContext(t)
+		ctx.ConfigureForTest(t)
+		client := ctx.NewClient()
+		t.Cleanup(func() { client.ForceStop() })
+
+		if err := client.Start(t.Context()); err != nil {
+			t.Fatalf("Start failed: %v", err)
+		}
+
+		if _, err := client.RPC.ManagedSettings.ClearCache(t.Context()); err != nil {
+			t.Fatalf("ManagedSettings.ClearCache failed: %v", err)
+		}
+	})
+
 	t.Run("should call rpc ping with typed params and result", func(t *testing.T) {
 		ctx := testharness.NewTestContext(t)
 		ctx.ConfigureForTest(t)