Enable UserAgentPolicy in generated client libraries (#8983)

Copilot · JoshLove-msft · web-flow · commit b2b6044d121a · 2025-11-20T21:53:03.000Z
## Enable UserAgentPolicy in Generated Libraries ### Completed Work - [x] Research UserAgentPolicy API and usage patterns - [x] Modify `ClientProvider` to create UserAgentPolicy through abstraction layer - [x] Verify all tests pass successfully - [x] Address feedback: Make UserAgentPolicy a virtual method with default null value - [x] Address feedback: Use nameof(System.Type.Assembly) for property reference - [x] Address feedback: Remove optional null parameter from UserAgentPolicy constructor - [x] Address feedback: Refactor variable names for clarity ### Implementation Details The UserAgentPolicy is now automatically added to the pipeline for all generated clients: - Added `UserAgentPolicy` as a **virtual method** in `ClientPipelineApi` with default return value of `null` - Implemented in `ClientPipelineProvider` to return `new UserAgentPolicy(typeof(ClientType).Assembly)` - `ClientProvider` builds a list of per-retry policies, conditionally adding UserAgentPolicy first if not null, then auth policies - Uses `nameof(System.Type.Assembly)` for compile-time safety - Omits optional applicationId parameter (cleaner code) - Policy is added as the first item in the `perRetryPolicies` array, before authentication policies - Works for clients with no auth, API key auth, and OAuth2 auth - No configuration option needed - always enabled by default - **Optional via abstractions** - implementations can override the virtual method to return null and disable UserAgentPolicy ### Code Structure The refactored code uses a `perRetryPoliciesList` that is built up conditionally: 1. UserAgentPolicy is added first (if not null) 2. Authentication policies are added based on the auth type 3. The list is converted to an array for the pipeline This makes it clear that all policies in the list are per-retry policies, not just auth-specific policies. ### Generated Code Example ```csharp Pipeline = ClientPipeline.Create( options, Array.Empty<PipelinePolicy>(), new PipelinePolicy[] { new UserAgentPolicy(typeof(SampleClient).Assembly), ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<PipelinePolicy>()); ``` - Fixes #7863  <details> <summary>Original prompt</summary> > > ---- > > *This section details on the original issue you should resolve* > > <issue_title>Enable UserAgentPolicy once SCM ships</issue_title> > <issue_description>Once Azure/azure-sdk-for-net#51113 ships, we should integrate the UserAgentPolicy into generated libraries. We should add an option so that users can opt out of it, but this can be on by default so users don't have to know to turn it on. We can document this behavior clearly.</issue_description> > > ## Comments on the Issue (you are @copilot in this section) > > <comments> > <comment_new><author>@JoshLove-msft</author><body> > For Azure, we would just turn it off as the Azure.Core pipeline has its own UserAgentPolicy.</body></comment_new> > <comment_new><author>@JoshLove-msft</author><body> > > For Azure, we would just turn it off as the Azure.Core pipeline has its own UserAgentPolicy. > > Actually, we don't need to add config for this until we hear feedback that users don't want it on. For Azure, it will not use the same pipeline so there is no need to turn it off.</body></comment_new> > </comments> > </details> - Fixes #7863  --- 💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more [Copilot coding agent tips](https://gh.io/copilot-coding-agent-tips) in the docs. --------- Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com> Co-authored-by: JoshLove-msft <54595583+JoshLove-msft@users.noreply.github.com>
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/Abstractions/ClientPipelineApi.cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/Abstractions/ClientPipelineApi.cs
@@ -36,6 +36,7 @@ public abstract MethodBodyStatement[] CreateMessage(
 
         public abstract ValueExpression KeyAuthorizationPolicy(ValueExpression credential, ValueExpression headerName, ValueExpression? keyPrefix = null);
         public abstract ValueExpression TokenAuthorizationPolicy(ValueExpression credential, ValueExpression scopes);
+        public virtual ValueExpression? UserAgentPolicy(CSharpType clientType) => null;
         public abstract ClientPipelineApi FromExpression(ValueExpression expression);
         public abstract ClientPipelineApi ToExpression();
     }
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientPipelineProvider.cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientPipelineProvider.cs
@@ -58,6 +58,9 @@ public override ValueExpression KeyAuthorizationPolicy(ValueExpression credentia
         public override ValueExpression TokenAuthorizationPolicy(ValueExpression credential, ValueExpression scopes)
             => New.Instance(typeof(BearerTokenPolicy), credential, scopes);
 
+        public override ValueExpression? UserAgentPolicy(CSharpType clientType)
+            => New.Instance(typeof(System.ClientModel.Primitives.UserAgentPolicy), [TypeOf(clientType).Property(nameof(System.Type.Assembly))]);
+
         public override ClientPipelineApi ToExpression() => this;
 
         public override MethodBodyStatement[] SendMessage(HttpMessageApi message, HttpRequestOptionsApi options)
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientProvider.cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/ClientProvider.cs
@@ -570,18 +570,28 @@ private MethodBodyStatement[] BuildPrimaryConstructorBody(IReadOnlyList<Paramete
             }
 
             // handle pipeline property
+            var userAgentPolicy = This.ToApi<ClientPipelineApi>().UserAgentPolicy(Type);
+
+            List<ValueExpression> perRetryPoliciesList = [];
+            if (userAgentPolicy != null)
+            {
+                perRetryPoliciesList.Add(userAgentPolicy);
+            }
+
             ValueExpression perRetryPolicies;
             switch (authFields)
             {
                 case ApiKeyFields keyAuthFields:
                     ValueExpression? keyPrefixExpression = keyAuthFields.AuthorizationApiKeyPrefixField != null ? (ValueExpression)keyAuthFields.AuthorizationApiKeyPrefixField : null;
-                    perRetryPolicies = New.Array(ScmCodeModelGenerator.Instance.TypeFactory.ClientPipelineApi.PipelinePolicyType, isInline: true, This.ToApi<ClientPipelineApi>().KeyAuthorizationPolicy(keyAuthFields.AuthField, keyAuthFields.AuthorizationHeaderField, keyPrefixExpression));
+                    perRetryPoliciesList.Add(This.ToApi<ClientPipelineApi>().KeyAuthorizationPolicy(keyAuthFields.AuthField, keyAuthFields.AuthorizationHeaderField, keyPrefixExpression));
+                    perRetryPolicies = New.Array(ScmCodeModelGenerator.Instance.TypeFactory.ClientPipelineApi.PipelinePolicyType, isInline: true, [.. perRetryPoliciesList]);
                     break;
                 case OAuth2Fields oauth2AuthFields:
-                    perRetryPolicies = New.Array(ScmCodeModelGenerator.Instance.TypeFactory.ClientPipelineApi.PipelinePolicyType, isInline: true, This.ToApi<ClientPipelineApi>().TokenAuthorizationPolicy(oauth2AuthFields.AuthField, oauth2AuthFields.AuthorizationScopesField));
+                    perRetryPoliciesList.Add(This.ToApi<ClientPipelineApi>().TokenAuthorizationPolicy(oauth2AuthFields.AuthField, oauth2AuthFields.AuthorizationScopesField));
+                    perRetryPolicies = New.Array(ScmCodeModelGenerator.Instance.TypeFactory.ClientPipelineApi.PipelinePolicyType, isInline: true, [.. perRetryPoliciesList]);
                     break;
                 default:
-                    perRetryPolicies = New.Array(ScmCodeModelGenerator.Instance.TypeFactory.ClientPipelineApi.PipelinePolicyType);
+                    perRetryPolicies = New.Array(ScmCodeModelGenerator.Instance.TypeFactory.ClientPipelineApi.PipelinePolicyType, isInline: true, [.. perRetryPoliciesList]);
                     break;
             }
 
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,False,False,0).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,False,False,0).cs
@@ -3,4 +3,4 @@
 options ??= new global::Sample.TestClientOptions();
 
 _endpoint = endpoint;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,False,True,0).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,False,True,0).cs
@@ -5,4 +5,4 @@
 
 _endpoint = endpoint;
 _tokenProvider = tokenProvider;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly), new global::System.ClientModel.Primitives.BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,True,False,0).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,True,False,0).cs
@@ -5,4 +5,4 @@
 
 _endpoint = endpoint;
 _keyCredential = credential;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { global::System.ClientModel.Primitives.ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly), global::System.ClientModel.Primitives.ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,True,True,0).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,True,True,0).cs
@@ -5,4 +5,4 @@
 
 _endpoint = endpoint;
 _keyCredential = credential;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { global::System.ClientModel.Primitives.ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly), global::System.ClientModel.Primitives.ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,True,True,1).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithDefault,True,True,1).cs
@@ -5,4 +5,4 @@
 
 _endpoint = endpoint;
 _tokenProvider = tokenProvider;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly), new global::System.ClientModel.Primitives.BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,False,False,0).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,False,False,0).cs
@@ -3,4 +3,4 @@
 options ??= new global::Sample.TestClientOptions();
 
 _endpoint = endpoint;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,False,True,0).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,False,True,0).cs
@@ -5,4 +5,4 @@
 
 _endpoint = endpoint;
 _tokenProvider = tokenProvider;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly), new global::System.ClientModel.Primitives.BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,True,False,0).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,True,False,0).cs
@@ -5,4 +5,4 @@
 
 _endpoint = endpoint;
 _keyCredential = credential;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { global::System.ClientModel.Primitives.ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly), global::System.ClientModel.Primitives.ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,True,True,0).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,True,True,0).cs
@@ -5,4 +5,4 @@
 
 _endpoint = endpoint;
 _keyCredential = credential;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { global::System.ClientModel.Primitives.ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly), global::System.ClientModel.Primitives.ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,True,True,1).cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/TestBuildConstructors_PrimaryConstructor(WithRequired,True,True,1).cs
@@ -5,4 +5,4 @@
 
 _endpoint = endpoint;
 _tokenProvider = tokenProvider;
-Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly), new global::System.ClientModel.Primitives.BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/ValidateConstructorsWhenUnsupportedAuth.cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/ValidateConstructorsWhenUnsupportedAuth.cs
@@ -18,7 +18,7 @@ internal TestClient(global::System.Uri endpoint, global::Sample.TestClientOption
             options ??= new global::Sample.TestClientOptions();
 
             _endpoint = endpoint;
-            Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+            Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
         }
     }
 }
diff --git a/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/XmlDocsAreWritten.cs b/packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/test/Providers/ClientProviders/TestData/ClientProviderTests/XmlDocsAreWritten.cs
@@ -45,7 +45,7 @@ public TestClient(global::System.Uri endpoint, string queryParam, global::Sample
 
             _endpoint = endpoint;
             _queryParam = queryParam;
-            Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
+            Pipeline = global::System.ClientModel.Primitives.ClientPipeline.Create(options, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>(), new global::System.ClientModel.Primitives.PipelinePolicy[] { new global::System.ClientModel.Primitives.UserAgentPolicy(typeof(global::Sample.TestClient).Assembly) }, Array.Empty<global::System.ClientModel.Primitives.PipelinePolicy>());
         }
 
         /// <summary> The HTTP pipeline for sending and receiving REST requests and responses. </summary>
diff --git a/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClient.cs b/packages/http-client-csharp/generator/TestProjects/Local/Sample-TypeSpec/src/Generated/SampleTypeSpecClient.cs
@@ -64,7 +64,7 @@ public SampleTypeSpecClient(Uri endpoint, ApiKeyCredential credential, SampleTyp
 
             _endpoint = endpoint;
             _keyCredential = credential;
-            Pipeline = ClientPipeline.Create(options, Array.Empty<PipelinePolicy>(), new PipelinePolicy[] { ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<PipelinePolicy>());
+            Pipeline = ClientPipeline.Create(options, Array.Empty<PipelinePolicy>(), new PipelinePolicy[] { new UserAgentPolicy(typeof(SampleTypeSpecClient).Assembly), ApiKeyAuthenticationPolicy.CreateHeaderApiKeyPolicy(_keyCredential, AuthorizationHeader) }, Array.Empty<PipelinePolicy>());
             _apiVersion = options.Version;
         }
 
@@ -82,7 +82,7 @@ public SampleTypeSpecClient(Uri endpoint, AuthenticationTokenProvider tokenProvi
 
             _endpoint = endpoint;
             _tokenProvider = tokenProvider;
-            Pipeline = ClientPipeline.Create(options, Array.Empty<PipelinePolicy>(), new PipelinePolicy[] { new BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<PipelinePolicy>());
+            Pipeline = ClientPipeline.Create(options, Array.Empty<PipelinePolicy>(), new PipelinePolicy[] { new UserAgentPolicy(typeof(SampleTypeSpecClient).Assembly), new BearerTokenPolicy(_tokenProvider, _flows) }, Array.Empty<PipelinePolicy>());
             _apiVersion = options.Version;
         }
 

Original file line number	Diff line number	Diff line change
`@@ -36,6 +36,7 @@ public abstract MethodBodyStatement[] CreateMessage(`
`36`	`36`
`37`	`37`	`public abstract ValueExpression KeyAuthorizationPolicy(ValueExpression credential, ValueExpression headerName, ValueExpression? keyPrefix = null);`
`38`	`38`	`public abstract ValueExpression TokenAuthorizationPolicy(ValueExpression credential, ValueExpression scopes);`
	`39`	`+ public virtual ValueExpression? UserAgentPolicy(CSharpType clientType) => null;`
`39`	`40`	`public abstract ClientPipelineApi FromExpression(ValueExpression expression);`
`40`	`41`	`public abstract ClientPipelineApi ToExpression();`
`41`	`42`	`}`