diff --git a/.changeset/large-trainers-cross.md b/.changeset/large-trainers-cross.md
new file mode 100644
index 00000000000..4641567fed3
--- /dev/null
+++ b/.changeset/large-trainers-cross.md
@@ -0,0 +1,5 @@
+---
+"@smithy/experimental-identity-and-auth": patch
+---
+
+set identity&auth SRA active by default
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 2b9e65ceeab..0e9dc6ab26b 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -30,7 +30,7 @@ under development:
 
 Experimental Feature | Flag                          | Description
 ---------------------|-------------------------------|------------
-Identity & Auth      | `experimentalIdentityAndAuth` | Standardize identity and auth integrations to match the Smithy specification (see [Authentication Traits](https://smithy.io/2.0/spec/authentication-traits.html)). Newer capabilities include support for multiple auth schemes, `@optionalAuth`, and standardized identity interfaces for authentication schemes both in code generation and TypeScript packages. In `smithy-typescript`, `@httpApiKeyAuth` will be updated to use the new standardized interfaces. In `aws-sdk-js-v3` (`smithy-typescript`'s largest customer), this will affect `@aws.auth#sigv4` and `@httpBearerAuth` implementations, but is planned to be completely backwards-compatible.
+N/A                  | N/A                           | N/A
 
 ## Reporting Bugs/Feature Requests
 
diff --git a/README.md b/README.md
index 9264ce3099d..b10dda96c90 100644
--- a/README.md
+++ b/README.md
@@ -197,7 +197,7 @@ By default, the Smithy TypeScript code generators provide the code generation fr
 |`private`|No|Whether the package is `private` in `package.json`. The default value is `false`.|
 |`requiredMemberMode`|No|**NOT RECOMMENDED DUE TO BACKWARD COMPATIBILITY CONCERNS.** Sets whether members marked with the `@required` trait are allowed to be `undefined`. See more details on the risks in `TypeScriptSettings.RequiredMemberMode`. The default value is `nullable`.|
 |`createDefaultReadme`|No|Whether to generate a default `README.md` for the package. The default value is `false`.|
-|`experimentalIdentityAndAuth`|No|Experimental feature that standardizes identity and auth integrations to match the Smithy specification (see [Authentication Traits](https://smithy.io/2.0/spec/authentication-traits.html)). See [the experimental features section for more details](CONTRIBUTING.md#experimental-features).|
+|`useLegacyAuth`|No|**NOT RECOMMENDED, AVAILABLE ONLY FOR BACKWARD COMPATIBILITY CONCERNS.** Flag that enables using legacy auth. When in doubt, use the default identity and auth behavior (not configuring `useLegacyAuth`) as the golden path.|
 
 #### `typescript-client-codegen` plugin artifacts
 
diff --git a/packages/experimental-identity-and-auth/src/integration/httpApiKeyAuth.integ.spec.ts b/packages/experimental-identity-and-auth/src/integration/httpApiKeyAuth.integ.spec.ts
index 9ab8efa9805..496bd51236e 100644
--- a/packages/experimental-identity-and-auth/src/integration/httpApiKeyAuth.integ.spec.ts
+++ b/packages/experimental-identity-and-auth/src/integration/httpApiKeyAuth.integ.spec.ts
@@ -7,7 +7,7 @@ import {
 import { requireRequestsFrom } from "@smithy/util-test";
 
 describe("@httpApiKeyAuth integration tests", () => {
-  // TODO(experimentalIdentityAndAuth): should match `HttpApiKeyAuthService` `@httpApiKeyAuth` trait
+  // Match `HttpApiKeyAuthService` `@httpApiKeyAuth` trait
   const MOCK_API_KEY_NAME = "Authorization";
   const MOCK_API_KEY_SCHEME = "ApiKey";
   const MOCK_API_KEY = "APIKEY_123";
diff --git a/scripts/build-generated-test-packages.js b/scripts/build-generated-test-packages.js
index 65c378b8bb7..4797a7aa884 100644
--- a/scripts/build-generated-test-packages.js
+++ b/scripts/build-generated-test-packages.js
@@ -9,59 +9,39 @@ const { spawnProcess } = require("./utils/spawn-process");
 
 const root = path.join(__dirname, "..");
 
-const testProjectDir = path.join(
-    root,
-    "smithy-typescript-codegen-test",
-);
+const testProjectDir = path.join(root, "smithy-typescript-codegen-test");
 
-const codegenTestDir = path.join(
-    testProjectDir,
-    "build",
-    "smithyprojections",
-    "smithy-typescript-codegen-test",
-);
+const codegenTestDir = path.join(testProjectDir, "build", "smithyprojections", "smithy-typescript-codegen-test");
 
-const weatherClientDir = path.join(
-    codegenTestDir,
-    "source",
-    "typescript-client-codegen"
-);
+const weatherClientDir = path.join(codegenTestDir, "source", "typescript-client-codegen");
 
 const releasedClientDir = path.join(
-    testProjectDir,
-    "released-version-test",
-    "build",
-    "smithyprojections",
-    "released-version-test",
-    "source",
-    "typescript-codegen"
+  testProjectDir,
+  "released-version-test",
+  "build",
+  "smithyprojections",
+  "released-version-test",
+  "source",
+  "typescript-codegen"
 );
 
-// TODO(experimentalIdentityAndAuth): build generic client for integration tests
-const weatherExperimentalIdentityAndAuthClientDir = path.join(
-    codegenTestDir,
-    "client-experimental-identity-and-auth",
-    "typescript-client-codegen"
-);
+// Build generic legacy auth client for integration tests
+const weatherLegacyAuthClientDir = path.join(codegenTestDir, "client-legacy-auth", "typescript-client-codegen");
 
-const weatherSsdkDir = path.join(
-    codegenTestDir,
-    "ssdk-test",
-    "typescript-server-codegen"
-)
+const weatherSsdkDir = path.join(codegenTestDir, "ssdk-test", "typescript-server-codegen");
 
-// TODO(experimentalIdentityAndAuth): add `@httpApiKeyAuth` client for integration tests
+// Build `@httpApiKeyAuth` client for integration tests
 const httpApiKeyAuthClientDir = path.join(
-    codegenTestDir,
-    "identity-and-auth-http-api-key-auth",
-    "typescript-client-codegen"
+  codegenTestDir,
+  "identity-and-auth-http-api-key-auth",
+  "typescript-client-codegen"
 );
 
-// TODO(experimentalIdentityAndAuth): add `@httpBearerAuth` client for integration tests
+// Build `@httpBearerAuth` client for integration tests
 const httpBearerAuthClientDir = path.join(
-    codegenTestDir,
-    "identity-and-auth-http-bearer-auth",
-    "typescript-client-codegen"
+  codegenTestDir,
+  "identity-and-auth-http-bearer-auth",
+  "typescript-client-codegen"
 );
 
 const nodeModulesDir = path.join(root, "node_modules");
@@ -82,10 +62,14 @@ const buildAndCopyToNodeModules = async (packageName, codegenDir, nodeModulesDir
       await spawnProcess("rm", ["-rf", packageName], { cwd: nodeModulesDir });
       await spawnProcess("mkdir", ["-p", packageName], { cwd: nodeModulesDir });
       const targetPackageDir = path.join(nodeModulesDir, packageName);
-      await spawnProcess("tar", ["-xf", "package.tgz", "-C", targetPackageDir, "--strip-components", "1"], { cwd: codegenDir });
+      await spawnProcess("tar", ["-xf", "package.tgz", "-C", targetPackageDir, "--strip-components", "1"], {
+        cwd: codegenDir,
+      });
     }
   } catch (e) {
-    console.log(`Building and copying package \`${packageName}\` in \`${codegenDir}\` to \`${nodeModulesDir}\` failed:`)
+    console.log(
+      `Building and copying package \`${packageName}\` in \`${codegenDir}\` to \`${nodeModulesDir}\` failed:`
+    );
     console.log(e);
     process.exit(1);
   }
@@ -94,12 +78,17 @@ const buildAndCopyToNodeModules = async (packageName, codegenDir, nodeModulesDir
 (async () => {
   await buildAndCopyToNodeModules("weather", weatherClientDir, nodeModulesDir);
   await buildAndCopyToNodeModules("weather-ssdk", weatherSsdkDir, nodeModulesDir);
-  // TODO(experimentalIdentityAndAuth): build generic client for integration tests
-  await buildAndCopyToNodeModules("@smithy/weather-experimental-identity-and-auth", weatherExperimentalIdentityAndAuthClientDir, nodeModulesDir);
-  // TODO(experimentalIdentityAndAuth): add `@httpApiKeyAuth` client for integration tests
-  await buildAndCopyToNodeModules("@smithy/identity-and-auth-http-api-key-auth-service", httpApiKeyAuthClientDir, nodeModulesDir);
-  // TODO(experimentalIdentityAndAuth): add `@httpBearerAuth` client for integration tests
-  await buildAndCopyToNodeModules("@smithy/identity-and-auth-http-bearer-auth-service", httpBearerAuthClientDir, nodeModulesDir);
-  // Test released version of smithy-typescript codegenerators, but
-  await buildAndCopyToNodeModules("released", releasedClientDir, undefined);
+  await buildAndCopyToNodeModules("@smithy/weather-legacy-auth", weatherLegacyAuthClientDir, nodeModulesDir);
+  await buildAndCopyToNodeModules(
+    "@smithy/identity-and-auth-http-api-key-auth-service",
+    httpApiKeyAuthClientDir,
+    nodeModulesDir
+  );
+  await buildAndCopyToNodeModules(
+    "@smithy/identity-and-auth-http-bearer-auth-service",
+    httpBearerAuthClientDir,
+    nodeModulesDir
+  );
+  // TODO(released-version-test): Test released version of smithy-typescript codegenerators, but currently is not working
+  // await buildAndCopyToNodeModules("released", releasedClientDir, undefined);
 })();
diff --git a/smithy-typescript-codegen-test/example-weather-customizations/src/main/java/example/weather/SupportWeatherSigV4Auth.java b/smithy-typescript-codegen-test/example-weather-customizations/src/main/java/example/weather/SupportWeatherSigV4Auth.java
new file mode 100644
index 00000000000..9384e44ba63
--- /dev/null
+++ b/smithy-typescript-codegen-test/example-weather-customizations/src/main/java/example/weather/SupportWeatherSigV4Auth.java
@@ -0,0 +1,133 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package example.weather;
+
+import java.util.Optional;
+import java.util.function.Consumer;
+import software.amazon.smithy.codegen.core.Symbol;
+import software.amazon.smithy.codegen.core.SymbolReference;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.typescript.codegen.ApplicationProtocol;
+import software.amazon.smithy.typescript.codegen.LanguageTarget;
+import software.amazon.smithy.typescript.codegen.TypeScriptDependency;
+import software.amazon.smithy.typescript.codegen.TypeScriptSettings;
+import software.amazon.smithy.typescript.codegen.TypeScriptWriter;
+import software.amazon.smithy.typescript.codegen.auth.http.ConfigField;
+import software.amazon.smithy.typescript.codegen.auth.http.HttpAuthOptionProperty;
+import software.amazon.smithy.typescript.codegen.auth.http.HttpAuthScheme;
+import software.amazon.smithy.typescript.codegen.auth.http.HttpAuthSchemeParameter;
+import software.amazon.smithy.typescript.codegen.auth.http.integration.HttpAuthTypeScriptIntegration;
+import software.amazon.smithy.utils.SmithyInternalApi;
+
+@SmithyInternalApi
+public final class SupportWeatherSigV4Auth implements HttpAuthTypeScriptIntegration {
+    static final Symbol AWS_CREDENTIAL_IDENTITY = Symbol.builder()
+        .name("AwsCredentialIdentity")
+        .namespace(TypeScriptDependency.SMITHY_TYPES.getPackageName(), "/")
+        .addDependency(TypeScriptDependency.SMITHY_TYPES)
+        .build();
+    static final Symbol AWS_CREDENTIAL_IDENTITY_PROVIDER = Symbol.builder()
+        .name("AwsCredentialIdentityProvider")
+        .namespace(TypeScriptDependency.SMITHY_TYPES.getPackageName(), "/")
+        .addDependency(TypeScriptDependency.SMITHY_TYPES)
+        .build();
+    static final ConfigField CREDENTIALS_CONFIG_FIELD = ConfigField.builder()
+        .name("credentials")
+        .type(ConfigField.Type.MAIN)
+        .docs(w -> w.write("The credentials used to sign requests."))
+        .inputType(Symbol.builder()
+            .name("AwsCredentialIdentity | AwsCredentialIdentityProvider")
+            .addReference(AWS_CREDENTIAL_IDENTITY)
+            .addReference(AWS_CREDENTIAL_IDENTITY_PROVIDER)
+            .build())
+        .resolvedType(Symbol.builder()
+            .name("AwsCredentialIdentityProvider")
+            .addReference(AWS_CREDENTIAL_IDENTITY)
+            .addReference(AWS_CREDENTIAL_IDENTITY_PROVIDER)
+            .build())
+        .configFieldWriter(ConfigField::defaultMainConfigFieldWriter)
+        .build();
+    private static final Consumer<TypeScriptWriter> AWS_SIGV4_AUTH_SIGNER = w -> {
+        w.addDependency(TypeScriptDependency.EXPERIMENTAL_IDENTITY_AND_AUTH);
+        w.addImport("SigV4Signer", null, TypeScriptDependency.EXPERIMENTAL_IDENTITY_AND_AUTH);
+        w.write("new SigV4Signer()");
+    };
+    private static final SymbolReference PROVIDER = SymbolReference.builder()
+        .symbol(Symbol.builder()
+            .name("Provider")
+            .namespace(TypeScriptDependency.SMITHY_TYPES.getPackageName(), "/")
+            .addDependency(TypeScriptDependency.SMITHY_TYPES)
+            .build())
+        .alias("__Provider")
+        .build();
+
+    @Override
+    public boolean matchesSettings(TypeScriptSettings settings) {
+        return !settings.useLegacyAuth();
+    }
+
+    @Override
+    public Optional<HttpAuthScheme> getHttpAuthScheme() {
+        return Optional.of(HttpAuthScheme.builder()
+                .schemeId(ShapeId.from("aws.auth#sigv4"))
+                .applicationProtocol(ApplicationProtocol.createDefaultHttpApplicationProtocol())
+                .putDefaultSigner(LanguageTarget.SHARED, AWS_SIGV4_AUTH_SIGNER)
+                .addConfigField(CREDENTIALS_CONFIG_FIELD)
+                .addConfigField(ConfigField.builder()
+                    .name("region")
+                    .type(ConfigField.Type.AUXILIARY)
+                    .docs(w -> w.write("The AWS region to which this client will send requests."))
+                    .inputType(Symbol.builder()
+                        .name("string | __Provider<string>")
+                        .addReference(PROVIDER)
+                        .build())
+                    .resolvedType(Symbol.builder()
+                        .name("__Provider<string>")
+                        .addReference(PROVIDER)
+                        .build())
+                    .configFieldWriter(ConfigField::defaultAuxiliaryConfigFieldWriter)
+                    .build())
+                .addHttpAuthSchemeParameter(HttpAuthSchemeParameter.builder()
+                    .name("region")
+                    .type(w -> w.write("string"))
+                    .source(w -> {
+                        w.addDependency(TypeScriptDependency.UTIL_MIDDLEWARE);
+                        w.addImport("normalizeProvider", null, TypeScriptDependency.UTIL_MIDDLEWARE);
+                        w.openBlock("await normalizeProvider(config.region)() || (() => {", "})()", () -> {
+                            w.write("throw new Error(\"expected `region` to be configured for `aws.auth#sigv4`\");");
+                        });
+                    })
+                    .build())
+                .addHttpAuthOptionProperty(HttpAuthOptionProperty.builder()
+                    .name("name")
+                    .type(HttpAuthOptionProperty.Type.SIGNING)
+                    .source(s -> w -> {
+                        w.write("$S", s.trait().toNode().expectObjectNode().getMember("name"));
+                    })
+                    .build())
+                .addHttpAuthOptionProperty(HttpAuthOptionProperty.builder()
+                    .name("region")
+                    .type(HttpAuthOptionProperty.Type.SIGNING)
+                    .source(t -> w -> {
+                        w.write("authParameters.region");
+                    })
+                    .build())
+                .propertiesExtractor(s -> w -> w
+                    .write("""
+                        (config, context) => {
+                          return {
+                            /**
+                             * @internal
+                             */
+                            signingProperties: {
+                              ...config,
+                              ...context,
+                            },
+                          };
+                        },"""))
+                .build());
+    }
+}
diff --git a/smithy-typescript-codegen-test/example-weather-customizations/src/main/resources/META-INF/services/software.amazon.smithy.typescript.codegen.integration.TypeScriptIntegration b/smithy-typescript-codegen-test/example-weather-customizations/src/main/resources/META-INF/services/software.amazon.smithy.typescript.codegen.integration.TypeScriptIntegration
index 93c3c677e46..17504f263bd 100644
--- a/smithy-typescript-codegen-test/example-weather-customizations/src/main/resources/META-INF/services/software.amazon.smithy.typescript.codegen.integration.TypeScriptIntegration
+++ b/smithy-typescript-codegen-test/example-weather-customizations/src/main/resources/META-INF/services/software.amazon.smithy.typescript.codegen.integration.TypeScriptIntegration
@@ -1 +1,2 @@
 example.weather.ExampleWeatherCustomEndpointsRuntimeConfig
+example.weather.SupportWeatherSigV4Auth
diff --git a/smithy-typescript-codegen-test/model/weather/main.smithy b/smithy-typescript-codegen-test/model/weather/main.smithy
index e8abc79201c..6446b1c9eb5 100644
--- a/smithy-typescript-codegen-test/model/weather/main.smithy
+++ b/smithy-typescript-codegen-test/model/weather/main.smithy
@@ -34,7 +34,7 @@ service Weather {
         GetCurrentTime
         // util-stream.integ.spec.ts
         Invoke
-        // experimentalIdentityAndAuth
+        // Identity and Auth
         OnlyHttpApiKeyAuth
         OnlyHttpApiKeyAuthOptional
         OnlyHttpBearerAuth
diff --git a/smithy-typescript-codegen-test/released-version-test/build.gradle.kts b/smithy-typescript-codegen-test/released-version-test/build.gradle.kts
index a46cf794210..38e874f58a0 100644
--- a/smithy-typescript-codegen-test/released-version-test/build.gradle.kts
+++ b/smithy-typescript-codegen-test/released-version-test/build.gradle.kts
@@ -3,6 +3,8 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
+// TODO(released-version-test): Test released version of smithy-typescript codegenerators, but currently is extremely flaky
+/*
 plugins {
     java
     id("software.amazon.smithy.gradle.smithy-base")
@@ -27,3 +29,4 @@ dependencies {
 }
 
 tasks["jar"].enabled = false
+*/
\ No newline at end of file
diff --git a/smithy-typescript-codegen-test/smithy-build.json b/smithy-typescript-codegen-test/smithy-build.json
index a5251a5e386..704f8eb617b 100644
--- a/smithy-typescript-codegen-test/smithy-build.json
+++ b/smithy-typescript-codegen-test/smithy-build.json
@@ -29,7 +29,7 @@
                 }
             }
         },
-        "client-experimental-identity-and-auth": {
+        "client-identity-and-auth": {
             "transforms": [
                 {
                     "name": "includeServices",
@@ -41,17 +41,16 @@
             "plugins": {
                 "typescript-client-codegen": {
                     "service": "example.weather#Weather",
-                    "package": "@smithy/weather-experimental-identity-and-auth",
+                    "package": "weather",
                     "packageVersion": "0.0.1",
                     "packageJson": {
                         "license": "Apache-2.0",
                         "private": true
-                    },
-                    "experimentalIdentityAndAuth": true
+                    }
                 }
             }
         },
-        "control-experimental-identity-and-auth": {
+        "client-legacy-auth": {
             "transforms": [
                 {
                     "name": "includeServices",
@@ -63,12 +62,13 @@
             "plugins": {
                 "typescript-client-codegen": {
                     "service": "example.weather#Weather",
-                    "package": "weather",
+                    "package": "@smithy/weather-legacy-auth",
                     "packageVersion": "0.0.1",
                     "packageJson": {
                         "license": "Apache-2.0",
                         "private": true
-                    }
+                    },
+                    "useLegacyAuth": true
                 }
             }
         },
@@ -89,8 +89,7 @@
                     "packageJson": {
                         "license": "Apache-2.0",
                         "private": true
-                    },
-                    "experimentalIdentityAndAuth": true
+                    }
                 }
             }
         },
@@ -111,8 +110,7 @@
                     "packageJson": {
                         "license": "Apache-2.0",
                         "private": true
-                    },
-                    "experimentalIdentityAndAuth": true
+                    }
                 }
             }
         }
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/CommandGenerator.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/CommandGenerator.java
index 0f4011f1966..aa3305e2f2d 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/CommandGenerator.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/CommandGenerator.java
@@ -30,6 +30,7 @@
 import java.util.Optional;
 import java.util.Set;
 import java.util.TreeSet;
+import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 import software.amazon.smithy.build.FileManifest;
@@ -56,7 +57,9 @@
 import software.amazon.smithy.typescript.codegen.sections.CommandBodyExtraCodeSection;
 import software.amazon.smithy.typescript.codegen.sections.CommandConstructorCodeSection;
 import software.amazon.smithy.typescript.codegen.sections.CommandPropertiesCodeSection;
+import software.amazon.smithy.typescript.codegen.sections.PreCommandClassCodeSection;
 import software.amazon.smithy.typescript.codegen.sections.SmithyContextCodeSection;
+import software.amazon.smithy.typescript.codegen.util.CommandWriterConsumer;
 import software.amazon.smithy.typescript.codegen.validation.SensitiveDataFinder;
 import software.amazon.smithy.utils.SmithyInternalApi;
 
@@ -154,6 +157,17 @@ private void generateClientCommand() {
             );
         }
 
+        // Section of items like TypeScript @ts-ignore
+        writer.injectSection(PreCommandClassCodeSection.builder()
+            .settings(settings)
+            .model(model)
+            .service(service)
+            .operation(operation)
+            .symbolProvider(symbolProvider)
+            .runtimeClientPlugins(runtimePlugins)
+            .protocolGenerator(protocolGenerator)
+            .applicationProtocol(applicationProtocol)
+            .build());
         writer.openBlock(
             "export class $L extends $$Command.classBuilder<$T, $T, $L, ServiceInputTypes, ServiceOutputTypes>()",
             ".build() {", // class open bracket.
@@ -459,10 +473,7 @@ private void addCommandSpecificPlugins() {
                 // Construct additional parameters string
                 Map<String, Object> paramsMap = plugin.getAdditionalPluginFunctionParameters(
                         model, service, operation);
-                List<String> additionalParameters = CodegenUtils.getFunctionParametersList(paramsMap);
-                String additionalParamsString = additionalParameters.isEmpty()
-                        ? ""
-                        : ", { " + String.join(", ", additionalParameters) + " }";
+
 
                 // Construct writer context
                 Map<String, Object> symbolMap = new HashMap<>();
@@ -474,7 +485,33 @@ private void addCommandSpecificPlugins() {
                 }
                 writer.pushState();
                 writer.putContext(symbolMap);
-                writer.write("$pluginFn:T(config" + additionalParamsString + "),");
+                writer.openBlock("$pluginFn:T(config", "),", () -> {
+                    List<String> additionalParameters = CodegenUtils.getFunctionParametersList(paramsMap);
+                    Map<String, CommandWriterConsumer> clientAddParamsWriterConsumers =
+                        plugin.getOperationAddParamsWriterConsumers();
+                    if (additionalParameters.isEmpty() && clientAddParamsWriterConsumers.isEmpty()) {
+                        return;
+                    }
+                    writer.openBlock(", { ", " }", () -> {
+                        writer
+                            .pushState()
+                            .putContext("params", additionalParameters)
+                            .writeInline("${#params}${value:L}, ${/params}")
+                            .popState();
+                        clientAddParamsWriterConsumers.forEach((key, consumer) -> {
+                            writer.writeInline("$L: $C,", key, (Consumer<TypeScriptWriter>) (w -> {
+                                consumer.accept(w, CommandConstructorCodeSection.builder()
+                                    .settings(settings)
+                                    .model(model)
+                                    .service(service)
+                                    .symbolProvider(symbolProvider)
+                                    .runtimeClientPlugins(runtimePlugins)
+                                    .applicationProtocol(applicationProtocol)
+                                    .build());
+                            }));
+                        });
+                    });
+                });
                 writer.popState();
             });
         }
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/DirectedTypeScriptCodegen.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/DirectedTypeScriptCodegen.java
index f70ab9cc58b..fea50a6e42d 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/DirectedTypeScriptCodegen.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/DirectedTypeScriptCodegen.java
@@ -102,6 +102,11 @@ public TypeScriptCodegenContext createContext(CreateContextDirective<TypeScriptS
             });
         });
 
+        directive.integrations().forEach(integration -> {
+            LOGGER.info(() -> "Mutating plugins from TypeScriptIntegration: " + integration.name());
+            integration.mutateClientPlugins(runtimePlugins);
+        });
+
         ProtocolGenerator protocolGenerator = resolveProtocolGenerator(
                 directive.integrations(),
                 directive.model(),
@@ -236,9 +241,7 @@ private void generateClient(GenerateServiceDirective<TypeScriptCodegenContext, T
         delegator.useShapeWriter(service, writer -> new ServiceBareBonesClientGenerator(
                 settings, model, symbolProvider, writer, integrations, runtimePlugins, applicationProtocol).run());
 
-        if (directive.settings().getExperimentalIdentityAndAuth()) {
-            // feat(experimentalIdentityAndAuth): allow configuring custom HttpAuthSchemeProviderGenerator
-            LOGGER.fine("experimentalIdentityAndAuth: Generating auth scheme resolver");
+        if (!directive.settings().useLegacyAuth()) {
             new HttpAuthSchemeProviderGenerator(
                 delegator,
                 settings,
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/RuntimeConfigGenerator.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/RuntimeConfigGenerator.java
index bc1ba5a35fd..9fce5fa7693 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/RuntimeConfigGenerator.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/RuntimeConfigGenerator.java
@@ -195,10 +195,9 @@ void generate(LanguageTarget target) {
                         integration.getRuntimeConfigWriters(settings, model, symbolProvider, target)
                     );
                 }
-                // feat(experimentalIdentityAndAuth): add config writers for httpAuthScheme and httpAuthSchemes
                 // Needs a separate integration point since not all the information is accessible in
                 // {@link TypeScriptIntegration#getRuntimeConfigWriters()}
-                if (applicationProtocol.isHttpProtocol() && settings.getExperimentalIdentityAndAuth()) {
+                if (applicationProtocol.isHttpProtocol() && !settings.useLegacyAuth()) {
                     generateHttpAuthSchemeConfig(configs, writer, target);
                 }
                 int indentation = target.equals(LanguageTarget.SHARED) ? 1 : 2;
@@ -229,7 +228,6 @@ private void generateHttpAuthSchemeConfig(
     ) {
         SupportedHttpAuthSchemesIndex authIndex = new SupportedHttpAuthSchemesIndex(integrations, model, settings);
 
-        // feat(experimentalIdentityAndAuth): write the default imported HttpAuthSchemeProvider
         if (target.equals(LanguageTarget.SHARED)) {
             configs.put("httpAuthSchemeProvider", w -> {
                 w.write("$T", Symbol.builder()
@@ -241,7 +239,6 @@ private void generateHttpAuthSchemeConfig(
             });
         }
 
-        // feat(experimentalIdentityAndAuth): gather HttpAuthSchemes to generate
         ServiceIndex serviceIndex = ServiceIndex.of(model);
         TopDownIndex topDownIndex = TopDownIndex.of(model);
         Map<ShapeId, HttpAuthScheme> allEffectiveHttpAuthSchemes =
@@ -268,7 +265,6 @@ private void generateHttpAuthSchemeConfig(
             return;
         }
 
-        // feat(experimentalIdentityAndAuth): write the default httpAuthSchemes
         configs.put("httpAuthSchemes", w -> {
             w.addDependency(TypeScriptDependency.SMITHY_TYPES);
             w.addImport("IdentityProviderConfig", null, TypeScriptDependency.SMITHY_TYPES);
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/ServiceBareBonesClientGenerator.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/ServiceBareBonesClientGenerator.java
index 3d5feebe53f..e872e05b59a 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/ServiceBareBonesClientGenerator.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/ServiceBareBonesClientGenerator.java
@@ -41,6 +41,7 @@
 import software.amazon.smithy.typescript.codegen.sections.ClientConstructorCodeSection;
 import software.amazon.smithy.typescript.codegen.sections.ClientDestroyCodeSection;
 import software.amazon.smithy.typescript.codegen.sections.ClientPropertiesCodeSection;
+import software.amazon.smithy.typescript.codegen.util.ClientWriterConsumer;
 import software.amazon.smithy.utils.OptionalUtils;
 import software.amazon.smithy.utils.SmithyInternalApi;
 
@@ -63,13 +64,13 @@ public final class ServiceBareBonesClientGenerator implements Runnable {
     private final ApplicationProtocol applicationProtocol;
 
     ServiceBareBonesClientGenerator(
-            TypeScriptSettings settings,
-            Model model,
-            SymbolProvider symbolProvider,
-            TypeScriptWriter writer,
-            List<TypeScriptIntegration> integrations,
-            List<RuntimeClientPlugin> runtimePlugins,
-            ApplicationProtocol applicationProtocol
+        TypeScriptSettings settings,
+        Model model,
+        SymbolProvider symbolProvider,
+        TypeScriptWriter writer,
+        List<TypeScriptIntegration> integrations,
+        List<RuntimeClientPlugin> runtimePlugins,
+        ApplicationProtocol applicationProtocol
     ) {
         this.settings = settings;
         this.model = model;
@@ -438,10 +439,6 @@ private void generateConstructor() {
                     // Construct additional parameters string
                     Map<String, Object> paramsMap = plugin.getAdditionalPluginFunctionParameters(
                             model, service, null);
-                    List<String> additionalParameters = CodegenUtils.getFunctionParametersList(paramsMap);
-                    String additionalParamsString = additionalParameters.isEmpty()
-                            ? ""
-                            : ", { " + String.join(", ", additionalParameters) + " }";
 
                     // Construct writer context
                     Map<String, Object> symbolMap = new HashMap<>();
@@ -453,11 +450,39 @@ private void generateConstructor() {
                     }
                     writer.pushState();
                     writer.putContext(symbolMap);
-                    writer.write("this.middlewareStack.use($pluginFn:T(this.config" + additionalParamsString + "));");
+                    writer.openBlock("this.middlewareStack.use($pluginFn:T(this.config", "));", () -> {
+                        List<String> additionalParameters = CodegenUtils.getFunctionParametersList(paramsMap);
+                        Map<String, ClientWriterConsumer> clientAddParamsWriterConsumers =
+                            plugin.getClientAddParamsWriterConsumers();
+
+                        if (additionalParameters.isEmpty() && clientAddParamsWriterConsumers.isEmpty()) {
+                            return;
+                        }
+
+                        writer.openBlock(", {", " }", () -> {
+                            writer
+                                .pushState()
+                                .putContext("params", additionalParameters)
+                                .writeInline("${#params}${value:L}, ${/params}")
+                                .popState();
+                            clientAddParamsWriterConsumers.forEach((key, consumer) -> {
+                                writer.writeInline("$L: $C,", key, (Consumer<TypeScriptWriter>) (w -> {
+                                    consumer.accept(w, ClientBodyExtraCodeSection.builder()
+                                        .settings(settings)
+                                        .model(model)
+                                        .service(service)
+                                        .symbolProvider(symbolProvider)
+                                        .integrations(integrations)
+                                        .runtimeClientPlugins(runtimePlugins)
+                                        .applicationProtocol(applicationProtocol)
+                                        .build());
+                                }));
+                            });
+                        });
+                    });
                     writer.popState();
                 });
             }
-
             writer.popState();
         });
     }
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptDependency.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptDependency.java
index dbdbab0a99b..0faaff2c523 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptDependency.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptDependency.java
@@ -124,7 +124,6 @@ public enum TypeScriptDependency implements Dependency {
     // Conditionally added when @aws.auth#sigv4 is used
     SIGNATURE_V4("dependencies", "@smithy/signature-v4", false),
 
-    // feat(experimentalIdentityAndAuth): Conditionally added dependencies for `experimentalIdentityAndAuth`.
     // This package should never have a major version, and should only use minor and patch versions in development.
     // Exports are located between @smithy/types and @smithy/core
     @Deprecated EXPERIMENTAL_IDENTITY_AND_AUTH("dependencies", "@smithy/experimental-identity-and-auth", false),
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptSettings.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptSettings.java
index a64da907a3d..0ed8bff53d7 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptSettings.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/TypeScriptSettings.java
@@ -57,7 +57,7 @@ public final class TypeScriptSettings {
     private static final String PRIVATE = "private";
     private static final String PACKAGE_MANAGER = "packageManager";
     private static final String CREATE_DEFAULT_README = "createDefaultReadme";
-    private static final String EXPERIMENTAL_IDENTITY_AND_AUTH = "experimentalIdentityAndAuth";
+    private static final String USE_LEGACY_AUTH = "useLegacyAuth";
     private static final String GENERATE_TYPEDOC = "generateTypeDoc";
 
     private String packageName;
@@ -75,7 +75,7 @@ public final class TypeScriptSettings {
         RequiredMemberMode.NULLABLE;
     private PackageManager packageManager = PackageManager.YARN;
     private boolean createDefaultReadme = false;
-    private boolean experimentalIdentityAndAuth = false;
+    private boolean useLegacyAuth = false;
     private boolean generateTypeDoc = false;
 
     @Deprecated
@@ -110,8 +110,8 @@ public static TypeScriptSettings from(Model model, ObjectNode config, ArtifactTy
         settings.setPrivate(config.getBooleanMember(PRIVATE).map(BooleanNode::getValue).orElse(false));
         settings.setCreateDefaultReadme(
                 config.getBooleanMember(CREATE_DEFAULT_README).map(BooleanNode::getValue).orElse(false));
-        settings.setExperimentalIdentityAndAuth(
-                config.getBooleanMemberOrDefault(EXPERIMENTAL_IDENTITY_AND_AUTH, false));
+        settings.useLegacyAuth(
+                config.getBooleanMemberOrDefault(USE_LEGACY_AUTH, false));
         settings.setGenerateTypeDoc(
                 config.getBooleanMember(GENERATE_TYPEDOC).map(BooleanNode::getValue).orElse(false));
         settings.setPackageManager(
@@ -360,28 +360,27 @@ public void setPackageManager(PackageManager packageManager) {
     }
 
     /**
-     * Returns whether to use experimental identity and auth.
+     * Returns whether to use legacy auth integrations.
      *
-     * @return if experimental identity and auth should used. Default: false
+     * @return if legacy auth should used. Default: false
      */
-    public boolean getExperimentalIdentityAndAuth() {
-        return experimentalIdentityAndAuth;
+    public boolean useLegacyAuth() {
+        return useLegacyAuth;
     }
 
     /**
-     * Sets whether experimental identity and auth should be used.
+     * Sets whether legacy auth should be used.
      *
-     * @param experimentalIdentityAndAuth whether experimental identity and auth should be used.
+     * @param useLegacyAuth whether legacy auth should be used.
      */
-    public void setExperimentalIdentityAndAuth(boolean experimentalIdentityAndAuth) {
-        if (experimentalIdentityAndAuth) {
+    public void useLegacyAuth(boolean useLegacyAuth) {
+        if (useLegacyAuth) {
             LOGGER.warning("""
-                Experimental identity and auth is in development, and is subject to \
-                breaking changes. Behavior may NOT have the same feature parity as \
-                non-experimental behavior. This setting is also subject to removal \
-                when the feature is completed.""");
+                Legacy auth is considered deprecated and is no longer in development,
+                and should only be used for backward compatibility concerns. Consider
+                migrating to the default identity and auth behavior.""");
         }
-        this.experimentalIdentityAndAuth = experimentalIdentityAndAuth;
+        this.useLegacyAuth = useLegacyAuth;
     }
 
     /**
@@ -490,7 +489,7 @@ public enum ArtifactType {
         CLIENT(SymbolVisitor::new,
                 Arrays.asList(PACKAGE, PACKAGE_DESCRIPTION, PACKAGE_JSON, PACKAGE_VERSION, PACKAGE_MANAGER,
                               SERVICE, PROTOCOL, PRIVATE, REQUIRED_MEMBER_MODE,
-                              CREATE_DEFAULT_README, EXPERIMENTAL_IDENTITY_AND_AUTH, GENERATE_TYPEDOC)),
+                              CREATE_DEFAULT_README, USE_LEGACY_AUTH, GENERATE_TYPEDOC)),
         SSDK((m, s) -> new ServerSymbolVisitor(m, new SymbolVisitor(m, s)),
                 Arrays.asList(PACKAGE, PACKAGE_DESCRIPTION, PACKAGE_JSON, PACKAGE_VERSION, PACKAGE_MANAGER,
                               SERVICE, PROTOCOL, PRIVATE, REQUIRED_MEMBER_MODE,
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/ConfigField.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/ConfigField.java
index 50a53478544..e99965ab3a1 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/ConfigField.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/ConfigField.java
@@ -19,7 +19,7 @@
 /**
  * Definition of a Config field.
  *
- * Currently used to populate the ClientDefaults interface in `experimentalIdentityAndAuth`.
+ * Currently used to populate the ClientDefaults interface.
  *
  * @param name name of the config field
  * @param type whether the config field is main or auxiliary
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthScheme.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthScheme.java
index 2078c34171a..ce5607b1c3d 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthScheme.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthScheme.java
@@ -22,7 +22,7 @@
 import software.amazon.smithy.utils.ToSmithyBuilder;
 
 /**
- * feat(experimentalIdentityAndAuth): Defines an HttpAuthScheme used in code generation.
+ * Defines an HttpAuthScheme used in code generation.
  *
  * HttpAuthScheme defines everything needed to generate an HttpAuthSchemeProvider,
  * HttpAuthOptions, and registered HttpAuthSchemes in the IdentityProviderConfiguration.
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthSchemeParameter.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthSchemeParameter.java
index 7c7c58d89bb..e83fed5bdf5 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthSchemeParameter.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthSchemeParameter.java
@@ -14,7 +14,7 @@
 /**
  * Definition of an HttpAuthSchemeParameter.
  *
- * Currently this is used to generate the the HttpAuthSchemeParameters interface in `experimentalIdentityAndAuth`.
+ * Currently this is used to generate the the HttpAuthSchemeParameters interface.
  *
  * @param name name of the auth scheme parameter
  * @param type writer for the type of the auth scheme parameter
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthSchemeProviderGenerator.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthSchemeProviderGenerator.java
index fa629113874..32bdc2c8218 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthSchemeProviderGenerator.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/HttpAuthSchemeProviderGenerator.java
@@ -41,7 +41,7 @@
 import software.amazon.smithy.utils.StringUtils;
 
 /**
- * feat(experimentalIdentityAndAuth): Generator for {@code HttpAuthSchemeProvider} and corresponding interfaces.
+ * Generator for {@code HttpAuthSchemeProvider} and corresponding interfaces.
  *
  * Code generated includes:
  *
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/SupportedHttpAuthSchemesIndex.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/SupportedHttpAuthSchemesIndex.java
index 333d2f70c76..cc51c7b2c04 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/SupportedHttpAuthSchemesIndex.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/SupportedHttpAuthSchemesIndex.java
@@ -20,9 +20,6 @@
  *
  * Integrations may mutate this index to customize {@link HttpAuthScheme}
  * implementations.
- *
- * This class is currently under the `experimentalIdentityAgitndAuth` experimental
- * flag, and is subject to breaking changes.
  */
 @SmithyInternalApi
 public final class SupportedHttpAuthSchemesIndex {
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddHttpAuthSchemePlugin.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddHttpAuthSchemePlugin.java
index bcb0db1a66d..30b4775b0eb 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddHttpAuthSchemePlugin.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddHttpAuthSchemePlugin.java
@@ -33,8 +33,7 @@
 import software.amazon.smithy.typescript.codegen.integration.RuntimeClientPlugin;
 import software.amazon.smithy.typescript.codegen.integration.RuntimeClientPlugin.Convention;
 import software.amazon.smithy.typescript.codegen.sections.ClientBodyExtraCodeSection;
-import software.amazon.smithy.utils.CodeInterceptor;
-import software.amazon.smithy.utils.CodeSection;
+import software.amazon.smithy.typescript.codegen.util.ClientWriterConsumer;
 import software.amazon.smithy.utils.SmithyInternalApi;
 
 /**
@@ -43,15 +42,19 @@
 @SmithyInternalApi
 public final class AddHttpAuthSchemePlugin implements HttpAuthTypeScriptIntegration {
     /**
-     * Integration should only be used if `experimentalIdentityAndAuth` flag is true.
+     * Integration should be skipped if the `useLegacyAuth` flag is true.
      */
     @Override
     public boolean matchesSettings(TypeScriptSettings settings) {
-        return settings.getExperimentalIdentityAndAuth();
+        return !settings.useLegacyAuth();
     }
 
     @Override
     public List<RuntimeClientPlugin> getClientPlugins() {
+        Map<String, ClientWriterConsumer> httpAuthSchemeParametersProvider = Map.of(
+            "httpAuthSchemeParametersProvider", AddHttpAuthSchemePlugin::httpAuthSchemeParametersProvider,
+            "identityProviderConfigProvider", AddHttpAuthSchemePlugin::identityProviderConfigProvider
+        );
         return List.of(
             RuntimeClientPlugin.builder()
                 .servicePredicate((m, s) -> s.hasTrait(EndpointRuleSetTrait.ID))
@@ -59,14 +62,7 @@ public List<RuntimeClientPlugin> getClientPlugins() {
                     TypeScriptDependency.SMITHY_CORE.dependency,
                     "HttpAuthSchemeEndpointRuleSet",
                     Convention.HAS_MIDDLEWARE)
-                .additionalPluginFunctionParamsSupplier((model, service, operation) -> Map.of(
-                    "httpAuthSchemeParametersProvider", Symbol.builder()
-                        .name("this.getDefaultHttpAuthSchemeParametersProvider()")
-                        .build(),
-                    "identityProviderConfigProvider", Symbol.builder()
-                        .name("this.getIdentityProviderConfigProvider()")
-                        .build()
-                ))
+                .withAdditionalClientParams(httpAuthSchemeParametersProvider)
                 .build(),
             RuntimeClientPlugin.builder()
                 .servicePredicate((m, s) -> !s.hasTrait(EndpointRuleSetTrait.ID))
@@ -74,14 +70,7 @@ public List<RuntimeClientPlugin> getClientPlugins() {
                     TypeScriptDependency.SMITHY_CORE.dependency,
                     "HttpAuthScheme",
                     Convention.HAS_MIDDLEWARE)
-                .additionalPluginFunctionParamsSupplier((model, service, operation) -> Map.of(
-                    "httpAuthSchemeParametersProvider", Symbol.builder()
-                        .name("this.getDefaultHttpAuthSchemeParametersProvider()")
-                        .build(),
-                    "identityProviderConfigProvider", Symbol.builder()
-                        .name("this.getIdentityProviderConfigProvider()")
-                        .build()
-                ))
+                .withAdditionalClientParams(httpAuthSchemeParametersProvider)
                 .build(),
             RuntimeClientPlugin.builder()
                 .inputConfig(Symbol.builder()
@@ -100,74 +89,10 @@ public List<RuntimeClientPlugin> getClientPlugins() {
         );
     }
 
-    @Override
-    public List<? extends CodeInterceptor<? extends CodeSection, TypeScriptWriter>> interceptors(
-        TypeScriptCodegenContext codegenContext
-    ) {
-        return List.of(CodeInterceptor.appender(ClientBodyExtraCodeSection.class, (w, s) -> {
-            if (!s.getSettings().generateClient()
-                || !s.getSettings().getExperimentalIdentityAndAuth()
-                || !s.getApplicationProtocol().isHttpProtocol()) {
-                return;
-            }
-
-            /*
-            private getDefaultHttpAuthSchemeParametersProvider() {
-              return defaultWeatherHttpAuthSchemeParametersProvider;
-            }
-            */
-            w.openBlock("private getDefaultHttpAuthSchemeParametersProvider() {", "}", () -> {
-                String httpAuthSchemeParametersProviderName = "default"
-                    + CodegenUtils.getServiceName(s.getSettings(), s.getModel(), s.getSymbolProvider())
-                    + "HttpAuthSchemeParametersProvider";
-                w.addImport(httpAuthSchemeParametersProviderName, null, AuthUtils.AUTH_HTTP_PROVIDER_DEPENDENCY);
-                w.write("return " + httpAuthSchemeParametersProviderName + ";");
-            });
-
-            /*
-            private getIdentityProviderConfigProvider() {
-              return async (config: WeatherClientResolvedConfig) => new DefaultIdentityProviderConfig({
-                "aws.auth#sigv4": config.credentials,
-                "smithy.api#httpApiKeyAuth": config.apiKey,
-                "smithy.api#httpBearerAuth": config.token,
-              });
-            }
-            */
-            w.openBlock("private getIdentityProviderConfigProvider() {", "}", () -> {
-                w.addDependency(TypeScriptDependency.SMITHY_CORE);
-                w.addImport("DefaultIdentityProviderConfig", null, TypeScriptDependency.SMITHY_CORE);
-                w.openBlock("""
-                    return async (config: $LResolvedConfig) => \
-                    new DefaultIdentityProviderConfig({""", "});",
-                    s.getSymbolProvider().toSymbol(s.getService()).getName(),
-                    () -> {
-                    SupportedHttpAuthSchemesIndex authIndex = new SupportedHttpAuthSchemesIndex(
-                        s.getIntegrations(),
-                        s.getModel(),
-                        s.getSettings());
-                    ServiceIndex serviceIndex = ServiceIndex.of(s.getModel());
-                    TopDownIndex topDownIndex = TopDownIndex.of(s.getModel());
-                    Map<ShapeId, HttpAuthScheme> httpAuthSchemes = AuthUtils.getAllEffectiveNoAuthAwareAuthSchemes(
-                        s.getService(), serviceIndex, authIndex, topDownIndex);
-                    for (HttpAuthScheme scheme : httpAuthSchemes.values()) {
-                        if (scheme == null) {
-                            continue;
-                        }
-                        for (ConfigField configField : scheme.getConfigFields()) {
-                            if (configField.type().equals(ConfigField.Type.MAIN)) {
-                                w.write("$S: config.$L,", scheme.getSchemeId().toString(), configField.name());
-                            }
-                        }
-                    }
-                });
-            });
-        }));
-    }
-
     @Override
     public void customize(TypeScriptCodegenContext codegenContext) {
         if (!codegenContext.settings().generateClient()
-            || !codegenContext.settings().getExperimentalIdentityAndAuth()
+            || codegenContext.settings().useLegacyAuth()
             || !codegenContext.applicationProtocol().isHttpProtocol()) {
             return;
         }
@@ -217,6 +142,71 @@ public void customize(TypeScriptCodegenContext codegenContext) {
         });
     }
 
+    /**
+     * Writes the httpAuthSchemeParametersProvider for input to middleware additional parameters.
+     * Example:
+     * ```typescript
+     * defaultWeatherHttpAuthSchemeParametersProvider;
+     * ```
+     */
+    private static void httpAuthSchemeParametersProvider(TypeScriptWriter w,
+                                                         ClientBodyExtraCodeSection clientBodySection) {
+        String httpAuthSchemeParametersProviderName = "default"
+            + CodegenUtils.getServiceName(
+            clientBodySection.getSettings(),
+            clientBodySection.getModel(),
+            clientBodySection.getSymbolProvider()
+        )
+            + "HttpAuthSchemeParametersProvider";
+        w.addImport(httpAuthSchemeParametersProviderName, null, AuthUtils.AUTH_HTTP_PROVIDER_DEPENDENCY);
+        w.writeInline(httpAuthSchemeParametersProviderName);
+    }
+
+    /**
+     * Writes the identityProviderConfigProvider for input to middleware additional parameters.
+     * Example:
+     * ```typescript
+     * async (config: WeatherClientResolvedConfig) => new DefaultIdentityProviderConfig({
+     *   "aws.auth#sigv4": config.credentials,
+     *   "smithy.api#httpApiKeyAuth": config.apiKey,
+     *   "smithy.api#httpBearerAuth": config.token,
+     * })
+     * ```
+     */
+    private static void identityProviderConfigProvider(TypeScriptWriter w,
+                                                       ClientBodyExtraCodeSection s) {
+        w.addDependency(TypeScriptDependency.SMITHY_CORE);
+        w.addImport("DefaultIdentityProviderConfig", null, TypeScriptDependency.SMITHY_CORE);
+        w.openBlock("""
+                        async (config: $LResolvedConfig) => \
+                        new DefaultIdentityProviderConfig({""", "})",
+            s.getSymbolProvider().toSymbol(s.getService()).getName(),
+            () -> {
+                SupportedHttpAuthSchemesIndex authIndex = new SupportedHttpAuthSchemesIndex(
+                    s.getIntegrations(),
+                    s.getModel(),
+                    s.getSettings());
+                ServiceIndex serviceIndex = ServiceIndex.of(s.getModel());
+                TopDownIndex topDownIndex = TopDownIndex.of(s.getModel());
+                Map<ShapeId, HttpAuthScheme> httpAuthSchemes = AuthUtils.getAllEffectiveNoAuthAwareAuthSchemes(
+                    s.getService(), serviceIndex, authIndex, topDownIndex);
+                for (HttpAuthScheme scheme : httpAuthSchemes.values()) {
+                    if (scheme == null) {
+                        continue;
+                    }
+                    for (ConfigField configField : scheme.getConfigFields()) {
+                        if (configField.type().equals(ConfigField.Type.MAIN)) {
+                            w.writeInline(
+                                "$S: config.$L,",
+                                scheme.getSchemeId().toString(),
+                                configField.name()
+                            );
+                        }
+                    }
+                }
+            });
+    }
+
     /*
     export interface HttpAuthSchemeInputConfig {
       httpAuthSchemes?: HttpAuthScheme[];
@@ -260,14 +250,14 @@ private void generateHttpAuthSchemeInputConfigInterface(
         w.addDependency(TypeScriptDependency.SMITHY_TYPES);
         w.addImport("HttpAuthScheme", null, TypeScriptDependency.SMITHY_TYPES);
         w.writeDocs("""
-            experimentalIdentityAndAuth: Configuration of HttpAuthSchemes for a client which provides \
+            Configuration of HttpAuthSchemes for a client which provides \
             default identity providers and signers per auth scheme.
             @internal""");
         w.write("httpAuthSchemes?: HttpAuthScheme[];\n");
 
         String httpAuthSchemeProviderName = serviceName + "HttpAuthSchemeProvider";
         w.writeDocs("""
-            experimentalIdentityAndAuth: Configuration of an HttpAuthSchemeProvider for a client which \
+            Configuration of an HttpAuthSchemeProvider for a client which \
             resolves which HttpAuthScheme to use.
             @internal""");
         w.write("httpAuthSchemeProvider?: $L;\n", httpAuthSchemeProviderName);
@@ -326,14 +316,14 @@ private void generateHttpAuthSchemeResolvedConfigInterface(
         w.addDependency(TypeScriptDependency.SMITHY_TYPES);
         w.addImport("HttpAuthScheme", null, TypeScriptDependency.SMITHY_TYPES);
         w.writeDocs("""
-            experimentalIdentityAndAuth: Configuration of HttpAuthSchemes for a client which provides \
+            Configuration of HttpAuthSchemes for a client which provides \
             default identity providers and signers per auth scheme.
             @internal""");
         w.write("readonly httpAuthSchemes: HttpAuthScheme[];\n");
 
         String httpAuthSchemeProviderName = serviceName + "HttpAuthSchemeProvider";
         w.writeDocs("""
-            experimentalIdentityAndAuth: Configuration of an HttpAuthSchemeProvider for a client which \
+            Configuration of an HttpAuthSchemeProvider for a client which \
             resolves which HttpAuthScheme to use.
             @internal""");
         w.write("readonly httpAuthSchemeProvider: $L;\n", httpAuthSchemeProviderName);
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddHttpSigningPlugin.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddHttpSigningPlugin.java
index fbdc5c99223..9b8a43e258d 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddHttpSigningPlugin.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/AddHttpSigningPlugin.java
@@ -16,17 +16,15 @@
 
 /**
  * Add middleware for {@code httpSigningMiddleware}.
- *
- * This is the experimental behavior for `experimentalIdentityAndAuth`.
  */
 @SmithyInternalApi
 public class AddHttpSigningPlugin implements TypeScriptIntegration {
     /**
-     * Integration should only be used if `experimentalIdentityAndAuth` flag is true.
+     * Integration should be skipped if the `useLegacyAuth` flag is true.
      */
     @Override
     public boolean matchesSettings(TypeScriptSettings settings) {
-        return settings.getExperimentalIdentityAndAuth();
+        return !settings.useLegacyAuth();
     }
 
     @Override
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthExtensionConfigurationInterface.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthExtensionConfigurationInterface.java
index db90da40c42..c91190a0b43 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthExtensionConfigurationInterface.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthExtensionConfigurationInterface.java
@@ -13,8 +13,6 @@
 
 /**
  * Adds the corresponding interface and functions for {@code HttpAuthExtensionConfiguration}.
- *
- * This is experimental for `experimentalIdentityAndAuth`.
  */
 @SmithyInternalApi
 public class HttpAuthExtensionConfigurationInterface implements ExtensionConfigurationInterface {
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthRuntimeExtensionIntegration.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthRuntimeExtensionIntegration.java
index ea39877ae3b..d3a0481d914 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthRuntimeExtensionIntegration.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthRuntimeExtensionIntegration.java
@@ -28,18 +28,16 @@
 
 /**
  * Adds {@link HttpAuthExtensionConfigurationInterface} to a client.
- *
- * This is the experimental behavior for `experimentalIdentityAndAuth`.
  */
 @SmithyInternalApi
 public class HttpAuthRuntimeExtensionIntegration implements TypeScriptIntegration {
 
     /**
-     * Integration should only be used if `experimentalIdentityAndAuth` flag is true.
+     * Integration should be skipped if the `useLegacyAuth` flag is true.
      */
     @Override
     public boolean matchesSettings(TypeScriptSettings settings) {
-        return settings.getExperimentalIdentityAndAuth();
+        return !settings.useLegacyAuth();
     }
 
     @Override
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthTypeScriptIntegration.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthTypeScriptIntegration.java
index 77d4006972a..bbd936eef52 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthTypeScriptIntegration.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/HttpAuthTypeScriptIntegration.java
@@ -14,15 +14,13 @@
 import software.amazon.smithy.utils.SmithyInternalApi;
 
 /**
- * Java SPI for customizing TypeScript code generation for `experimentalIdentityAndAuth`.
- *
- * This should NOT be used as it is highly susceptible to breaking changes.
+ * Java SPI for customizing TypeScript code generation for Identity and Authentication.
  */
 @SmithyInternalApi
 public interface HttpAuthTypeScriptIntegration extends TypeScriptIntegration {
     /**
-     * feat(experimentalIdentityAndAuth): Register an {@link HttpAuthScheme} that is used to generate the
-     * {@code HttpAuthSchemeProvider} and corresponding config field and runtime config values.
+     * Register an {@link HttpAuthScheme} that is used to generate the {@code HttpAuthSchemeProvider}
+     * and corresponding config field and runtime config values.
      * @return an empty optional.
      */
     default Optional<HttpAuthScheme> getHttpAuthScheme() {
@@ -30,8 +28,8 @@ default Optional<HttpAuthScheme> getHttpAuthScheme() {
     }
 
     /**
-     * feat(experimentalIdentityAndAuth): Mutate an {@link SupportedHttpAuthSchemesIndex} to mutate registered
-     * {@link HttpAuthScheme}s, e.g. default {@code IdentityProvider}s and {@code HttpSigner}s.
+     * Mutate an {@link SupportedHttpAuthSchemesIndex} to mutate registered {@link HttpAuthScheme}s,
+     * e.g. default {@code IdentityProvider}s and {@code HttpSigner}s.
      * @param supportedHttpAuthSchemesIndex index to mutate.
      * @param model model
      * @param settings settings
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportHttpApiKeyAuth.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportHttpApiKeyAuth.java
index 00b32335122..8ce8d9db999 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportHttpApiKeyAuth.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportHttpApiKeyAuth.java
@@ -23,8 +23,6 @@
 
 /**
  * Support for @httpApiKeyAuth.
- *
- * This is the experimental behavior for `experimentalIdentityAndAuth`.
  */
 @SmithyInternalApi
 public class SupportHttpApiKeyAuth implements HttpAuthTypeScriptIntegration {
@@ -51,11 +49,11 @@ public class SupportHttpApiKeyAuth implements HttpAuthTypeScriptIntegration {
         .build();
 
     /**
-     * Integration should only be used if `experimentalIdentityAndAuth` flag is true.
+     * Integration should be skipped if the `useLegacyAuth` flag is true.
      */
     @Override
     public boolean matchesSettings(TypeScriptSettings settings) {
-        return settings.getExperimentalIdentityAndAuth();
+        return !settings.useLegacyAuth();
     }
 
     @Override
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportHttpBearerAuth.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportHttpBearerAuth.java
index f5ff5d94482..0879f3e7c5d 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportHttpBearerAuth.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportHttpBearerAuth.java
@@ -21,8 +21,6 @@
 
 /**
  * Support for @httpBearerAuth.
- *
- * This is the experimental behavior for `experimentalIdentityAndAuth`.
  */
 @SmithyInternalApi
 public final class SupportHttpBearerAuth implements HttpAuthTypeScriptIntegration {
@@ -44,11 +42,11 @@ public final class SupportHttpBearerAuth implements HttpAuthTypeScriptIntegratio
         .build();
 
     /**
-     * Integration should only be used if `experimentalIdentityAndAuth` flag is true.
+     * Integration should be skipped if the `useLegacyAuth` flag is true.
      */
     @Override
     public boolean matchesSettings(TypeScriptSettings settings) {
-        return settings.getExperimentalIdentityAndAuth();
+        return !settings.useLegacyAuth();
     }
 
     @Override
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportNoAuth.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportNoAuth.java
index 5025c26b18c..0c86191c808 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportNoAuth.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/auth/http/integration/SupportNoAuth.java
@@ -32,11 +32,11 @@ public final class SupportNoAuth implements HttpAuthTypeScriptIntegration {
             .build());
 
     /**
-     * Integration should only be used if `experimentalIdentityAndAuth` flag is true.
+     * Integration should be skipped if the `useLegacyAuth` flag is true.
      */
     @Override
     public boolean matchesSettings(TypeScriptSettings settings) {
-        return settings.getExperimentalIdentityAndAuth();
+        return !settings.useLegacyAuth();
     }
 
     @Override
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/AddEventStreamDependency.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/AddEventStreamDependency.java
index 03144e11a93..ab8df8808a2 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/AddEventStreamDependency.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/AddEventStreamDependency.java
@@ -44,6 +44,13 @@
 @SmithyInternalApi
 public final class AddEventStreamDependency implements TypeScriptIntegration {
 
+    @Override
+    public List<String> runAfter() {
+        return List.of(
+            new AddBuiltinPlugins().name()
+        );
+    }
+
     @Override
     public List<RuntimeClientPlugin> getClientPlugins() {
         return ListUtils.of(
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/AddHttpApiKeyAuthPlugin.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/AddHttpApiKeyAuthPlugin.java
index 40e8cf54ed6..a40cf61acbb 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/AddHttpApiKeyAuthPlugin.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/AddHttpApiKeyAuthPlugin.java
@@ -30,7 +30,7 @@
 /**
  * Add config and middleware to support a service with the @httpApiKeyAuth trait.
  *
- * This is the existing control behavior for `experimentalIdentityAndAuth`.
+ * This is legacy auth behavior, and is no longer in development.
  */
 @SmithyInternalApi
 public final class AddHttpApiKeyAuthPlugin implements TypeScriptIntegration {
@@ -38,11 +38,11 @@ public final class AddHttpApiKeyAuthPlugin implements TypeScriptIntegration {
     public static final String INTEGRATION_NAME = "HttpApiKeyAuth";
 
     /**
-     * Integration should only be used if `experimentalIdentityAndAuth` flag is false.
+     * Integration should be used only if the `useLegacyAuth` flag is true.
      */
     @Override
     public boolean matchesSettings(TypeScriptSettings settings) {
-        return !settings.getExperimentalIdentityAndAuth();
+        return settings.useLegacyAuth();
     }
 
     /**
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/RuntimeClientPlugin.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/RuntimeClientPlugin.java
index c48f730c4ad..04adc6cb21a 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/RuntimeClientPlugin.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/RuntimeClientPlugin.java
@@ -15,6 +15,7 @@
 
 package software.amazon.smithy.typescript.codegen.integration;
 
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Objects;
@@ -29,6 +30,8 @@
 import software.amazon.smithy.model.shapes.ServiceShape;
 import software.amazon.smithy.typescript.codegen.TypeScriptDependency;
 import software.amazon.smithy.typescript.codegen.TypeScriptSettings;
+import software.amazon.smithy.typescript.codegen.util.ClientWriterConsumer;
+import software.amazon.smithy.typescript.codegen.util.CommandWriterConsumer;
 import software.amazon.smithy.utils.SmithyBuilder;
 import software.amazon.smithy.utils.SmithyUnstableApi;
 import software.amazon.smithy.utils.StringUtils;
@@ -56,6 +59,8 @@ public final class RuntimeClientPlugin implements ToSmithyBuilder<RuntimeClientP
     private final BiPredicate<Model, ServiceShape> servicePredicate;
     private final OperationPredicate operationPredicate;
     private final SettingsPredicate settingsPredicate;
+    private final Map<String, ClientWriterConsumer> writeAdditionalClientParams;
+    private final Map<String, CommandWriterConsumer> writeAdditionalOperationParams;
 
     private RuntimeClientPlugin(Builder builder) {
         inputConfig = builder.inputConfig;
@@ -68,6 +73,8 @@ private RuntimeClientPlugin(Builder builder) {
         operationPredicate = builder.operationPredicate;
         servicePredicate = builder.servicePredicate;
         settingsPredicate = builder.settingsPredicate;
+        writeAdditionalClientParams = builder.writeAdditionalClientParams;
+        writeAdditionalOperationParams = builder.writeAdditionalOperationParams;
 
         boolean allNull = (inputConfig == null) && (resolvedConfig == null) && (resolveFunction == null);
         boolean allSet = (inputConfig != null) && (resolvedConfig != null) && (resolveFunction != null);
@@ -258,7 +265,30 @@ public Map<String, Object> getAdditionalPluginFunctionParameters(
         if (additionalPluginFunctionParamsSupplier != null) {
             return additionalPluginFunctionParamsSupplier.apply(model, service, operation);
         }
-        return new HashMap<String, Object>();
+        return new HashMap<>();
+    }
+
+    /**
+     * Gets a list of additional parameters to be supplied to the
+     * plugin function. These parameters are to be supplied to plugin
+     * function as second argument. The map is empty if there are
+     * no additional parameters.
+     *
+     * @param model Model the operation belongs to.
+     * @param service Service the operation belongs to.
+     * @param operation Operation to test against.
+     * @return Returns the optionally present map of parameters. The key is the key
+     * for a parameter, and value is the value for a parameter.
+     */
+    public Map<String, Object> getAdditionalPluginFunctionParameterWriterConsumers(
+        Model model,
+        ServiceShape service,
+        OperationShape operation
+    ) {
+        if (additionalPluginFunctionParamsSupplier != null) {
+            return additionalPluginFunctionParamsSupplier.apply(model, service, operation);
+        }
+        return new HashMap<>();
     }
 
     /**
@@ -326,6 +356,22 @@ public boolean matchesSettings(Model model, ServiceShape service, TypeScriptSett
         return settingsPredicate.test(model, service, settings);
     }
 
+    /**
+     * @return the map of additional client level plugin params and their writer consumers used
+     * to populate the param values.
+     */
+    public Map<String, ClientWriterConsumer> getClientAddParamsWriterConsumers() {
+        return this.writeAdditionalClientParams;
+    }
+
+    /**
+     * @return the map of additional operation level plugin params and their writer consumers used
+     * to populate the param values.
+     */
+    public Map<String, CommandWriterConsumer> getOperationAddParamsWriterConsumers() {
+        return this.writeAdditionalOperationParams;
+    }
+
     public static Builder builder() {
         return new Builder();
     }
@@ -398,6 +444,8 @@ public static final class Builder implements SmithyBuilder<RuntimeClientPlugin>
         private BiPredicate<Model, ServiceShape> servicePredicate = (model, service) -> true;
         private OperationPredicate operationPredicate = (model, service, operation) -> false;
         private SettingsPredicate settingsPredicate = (model, service, settings) -> true;
+        private Map<String, ClientWriterConsumer> writeAdditionalClientParams = Collections.emptyMap();
+        private Map<String, CommandWriterConsumer> writeAdditionalOperationParams = Collections.emptyMap();
 
         @Override
         public RuntimeClientPlugin build() {
@@ -746,6 +794,24 @@ public Builder servicePredicate(BiPredicate<Model, ServiceShape> servicePredicat
             return this;
         }
 
+        /**
+         * Enables access to the writer for adding imports/dependencies.
+         */
+        public Builder withAdditionalClientParams(Map<String, ClientWriterConsumer> writeAdditionalClientParams) {
+            this.writeAdditionalClientParams = writeAdditionalClientParams;
+            return this;
+        }
+
+        /**
+         * Enables access to the writer for adding imports/dependencies.
+         */
+        public Builder withAdditionalOperationParams(
+            Map<String, CommandWriterConsumer> writeAdditionalOperationParams
+        ) {
+            this.writeAdditionalOperationParams = writeAdditionalOperationParams;
+            return this;
+        }
+
         /**
          * Configures various aspects of the builder based on naming conventions
          * defined by the provided {@link Convention} values.
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java
index 83dd240eee1..75dda21d0e1 100644
--- a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/integration/TypeScriptIntegration.java
@@ -64,6 +64,13 @@ default List<RuntimeClientPlugin> getClientPlugins() {
         return Collections.emptyList();
     }
 
+    /**
+     * Mutates in place the loaded list of plugins to apply to the generated client.
+     */
+    default void mutateClientPlugins(List<RuntimeClientPlugin> plugins) {
+        // defaults to no mutation
+    }
+
     /**
      * Gets a list of protocol generators to register.
      *
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/sections/PreCommandClassCodeSection.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/sections/PreCommandClassCodeSection.java
new file mode 100644
index 00000000000..06b3aa6317f
--- /dev/null
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/sections/PreCommandClassCodeSection.java
@@ -0,0 +1,135 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.typescript.codegen.sections;
+
+import java.util.List;
+import java.util.Optional;
+import software.amazon.smithy.codegen.core.SymbolProvider;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.shapes.OperationShape;
+import software.amazon.smithy.model.shapes.ServiceShape;
+import software.amazon.smithy.typescript.codegen.ApplicationProtocol;
+import software.amazon.smithy.typescript.codegen.TypeScriptSettings;
+import software.amazon.smithy.typescript.codegen.integration.ProtocolGenerator;
+import software.amazon.smithy.typescript.codegen.integration.RuntimeClientPlugin;
+import software.amazon.smithy.utils.CodeSection;
+import software.amazon.smithy.utils.SmithyBuilder;
+import software.amazon.smithy.utils.SmithyUnstableApi;
+
+@SmithyUnstableApi
+public final class PreCommandClassCodeSection implements CodeSection {
+    private final TypeScriptSettings settings;
+    private final Model model;
+    private final ServiceShape service;
+    private final OperationShape operation;
+    private final SymbolProvider symbolProvider;
+    private final List<RuntimeClientPlugin> runtimeClientPlugins;
+    private final ProtocolGenerator protocolGenerator;
+    private final ApplicationProtocol applicationProtocol;
+
+    private PreCommandClassCodeSection(Builder builder) {
+        settings = SmithyBuilder.requiredState("settings", builder.settings);
+        model = SmithyBuilder.requiredState("model", builder.model);
+        service = SmithyBuilder.requiredState("service", builder.service);
+        operation = SmithyBuilder.requiredState("operation", builder.operation);
+        symbolProvider = SmithyBuilder.requiredState("symbolProvider", builder.symbolProvider);
+        runtimeClientPlugins = SmithyBuilder.requiredState("runtimeClientPlugins", builder.runtimeClientPlugins);
+        protocolGenerator = builder.protocolGenerator;
+        applicationProtocol = SmithyBuilder.requiredState("applicationProtocol", builder.applicationProtocol);
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public TypeScriptSettings getSettings() {
+        return settings;
+    }
+
+    public Model getModel() {
+        return model;
+    }
+
+    public ServiceShape getService() {
+        return service;
+    }
+
+    public OperationShape getOperation() {
+        return operation;
+    }
+
+    public SymbolProvider getSymbolProvider() {
+        return symbolProvider;
+    }
+
+    public List<RuntimeClientPlugin> getRuntimeClientPlugins() {
+        return runtimeClientPlugins;
+    }
+
+    public Optional<ProtocolGenerator> getProtocolGenerator() {
+        return Optional.ofNullable(protocolGenerator);
+    }
+
+    public ApplicationProtocol getApplicationProtocol() {
+        return applicationProtocol;
+    }
+
+    public static class Builder implements SmithyBuilder<PreCommandClassCodeSection> {
+        private TypeScriptSettings settings;
+        private Model model;
+        private ServiceShape service;
+        private OperationShape operation;
+        private SymbolProvider symbolProvider;
+        private List<RuntimeClientPlugin> runtimeClientPlugins;
+        private ProtocolGenerator protocolGenerator;
+        private ApplicationProtocol applicationProtocol;
+
+        @Override
+        public PreCommandClassCodeSection build() {
+            return new PreCommandClassCodeSection(this);
+        }
+
+        public Builder settings(TypeScriptSettings settings) {
+            this.settings = settings;
+            return this;
+        }
+
+        public Builder model(Model model) {
+            this.model = model;
+            return this;
+        }
+
+        public Builder service(ServiceShape service) {
+            this.service = service;
+            return this;
+        }
+
+        public Builder operation(OperationShape operation) {
+            this.operation = operation;
+            return this;
+        }
+
+        public Builder symbolProvider(SymbolProvider symbolProvider) {
+            this.symbolProvider = symbolProvider;
+            return this;
+        }
+
+        public Builder runtimeClientPlugins(List<RuntimeClientPlugin> runtimeClientPlugins) {
+            this.runtimeClientPlugins = runtimeClientPlugins;
+            return this;
+        }
+
+        public Builder protocolGenerator(ProtocolGenerator protocolGenerator) {
+            this.protocolGenerator = protocolGenerator;
+            return this;
+        }
+
+        public Builder applicationProtocol(ApplicationProtocol applicationProtocol) {
+            this.applicationProtocol = applicationProtocol;
+            return this;
+        }
+    }
+}
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/util/ClientWriterConsumer.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/util/ClientWriterConsumer.java
new file mode 100644
index 00000000000..62290dcfe7b
--- /dev/null
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/util/ClientWriterConsumer.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.typescript.codegen.util;
+
+import software.amazon.smithy.typescript.codegen.TypeScriptWriter;
+import software.amazon.smithy.typescript.codegen.sections.ClientBodyExtraCodeSection;
+import software.amazon.smithy.utils.SmithyInternalApi;
+
+/**
+ * The writer consumer for a RuntimeClientPlugin. May be used to add imports and dependencies
+ * used by the plugin at the client level.
+ */
+@FunctionalInterface
+@SmithyInternalApi
+public interface ClientWriterConsumer {
+    void accept(TypeScriptWriter writer, ClientBodyExtraCodeSection section);
+}
diff --git a/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/util/CommandWriterConsumer.java b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/util/CommandWriterConsumer.java
new file mode 100644
index 00000000000..1eed5a9db8a
--- /dev/null
+++ b/smithy-typescript-codegen/src/main/java/software/amazon/smithy/typescript/codegen/util/CommandWriterConsumer.java
@@ -0,0 +1,20 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.typescript.codegen.util;
+
+import software.amazon.smithy.typescript.codegen.TypeScriptWriter;
+import software.amazon.smithy.typescript.codegen.sections.CommandConstructorCodeSection;
+import software.amazon.smithy.utils.SmithyInternalApi;
+
+/**
+ * The writer consumer for a RuntimeClientPlugin. May be used to add imports and dependencies
+ * used by the plugin at the command level.
+ */
+@FunctionalInterface
+@SmithyInternalApi
+public interface CommandWriterConsumer {
+    void accept(TypeScriptWriter writer, CommandConstructorCodeSection section);
+}
diff --git a/smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/integration/AddHttpApiKeyAuthPluginTest.java b/smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/integration/AddHttpApiKeyAuthPluginTest.java
index 231936fc864..c28295d8708 100644
--- a/smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/integration/AddHttpApiKeyAuthPluginTest.java
+++ b/smithy-typescript-codegen/src/test/java/software/amazon/smithy/typescript/codegen/integration/AddHttpApiKeyAuthPluginTest.java
@@ -32,20 +32,20 @@ public class AddHttpApiKeyAuthPluginTest {
     @Test
     public void httpApiKeyAuthClientOnService() {
         testInjects("http-api-key-auth-trait.smithy",
-                ", { in: 'header', name: 'Authorization', scheme: 'ApiKey' }");
+                "in: 'header', name: 'Authorization', scheme: 'ApiKey'");
     }
 
     @Test
     public void httpApiKeyAuthClientOnOperation() {
         testInjects("http-api-key-auth-trait-on-operation.smithy",
-                ", { in: 'header', name: 'Authorization', scheme: 'ApiKey' }");
+                "in: 'header', name: 'Authorization', scheme: 'ApiKey'");
     }
 
     // This should be identical to the httpApiKeyAuthClient test except for the parameters provided
     // to the middleware.
     @Test
     public void httpApiKeyAuthClientNoScheme() {
-        testInjects("http-api-key-auth-trait-no-scheme.smithy", ", { in: 'header', name: 'Authorization' }");
+        testInjects("http-api-key-auth-trait-no-scheme.smithy", "in: 'header', name: 'Authorization'");
     }
 
     private void testInjects(String filename, String extra) {
@@ -60,8 +60,10 @@ private void testInjects(String filename, String extra) {
         // Ensure that the GetFoo operation imports the middleware and uses it with all the options.
         assertThat(manifest.getFileString(CodegenUtils.SOURCE_FOLDER + "/commands/GetFooCommand.ts").get(),
                 containsString("from \"../middleware/HttpApiKeyAuth\""));
-        assertThat(manifest.getFileString(CodegenUtils.SOURCE_FOLDER + "/commands/GetFooCommand.ts").get(),
-                containsString("getHttpApiKeyAuthPlugin(config" + extra + ")"));
+
+        String generatedGetFooCommand = manifest.getFileString(CodegenUtils.SOURCE_FOLDER + "/commands/GetFooCommand.ts").get();
+        assertThat(generatedGetFooCommand, containsString("getHttpApiKeyAuthPlugin(config"));
+        assertThat(generatedGetFooCommand, containsString(extra));
 
         // Ensure that the GetBar operation does not import the middleware or use it.
         assertThat(manifest.getFileString(CodegenUtils.SOURCE_FOLDER + "/commands/GetBarCommand.ts").get(),
@@ -93,6 +95,7 @@ private MockManifest generate(String filename)
                         .withMember("service", Node.from("smithy.example#Example"))
                         .withMember("package", Node.from("example"))
                         .withMember("packageVersion", Node.from("1.0.0"))
+                        .withMember("useLegacyAuth", Node.from(true))
                         .build())
                 .build();