diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsEndpointDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsEndpointDecorator.kt
index 3978332f60118e5d7708b2dcf127d5e4504e7bdf..7690798a3a665367a4fcc571f5be39933aaca4d3 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsEndpointDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsEndpointDecorator.kt
@@ -73,6 +73,9 @@ class AwsEndpointDecorator : RustCodegenDecorator<ClientCodegenContext> {
     ): List<LibRsCustomization> {
         return baseCustomizations + PubUseEndpoint(codegenContext.runtimeConfig)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class EndpointConfigCustomization(private val coreCodegenContext: CoreCodegenContext, private val endpointData: ObjectNode) :
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsFluentClientDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsFluentClientDecorator.kt
index b4bf87eb58c918ce9fdfca46b09b5fc7be3a7078..fe091fdbda0902223a6ae41a5b7d51dee9b221fe 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsFluentClientDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsFluentClientDecorator.kt
@@ -111,6 +111,9 @@ class AwsFluentClientDecorator : RustCodegenDecorator<ClientCodegenContext> {
             }
         }
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 private class AwsFluentClientExtensions(types: Types) {
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsPresigningDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsPresigningDecorator.kt
index d3765fed88ea871f92bc031f0a7f4cd07f962b7f..584f2fac0197e6287196da68d7e09d71a7f72588 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsPresigningDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsPresigningDecorator.kt
@@ -117,6 +117,9 @@ class AwsPresigningDecorator internal constructor(
         return presignableTransforms.fold(intermediate) { m, t -> t.transform(m) }
     }
 
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
+
     private fun addSyntheticOperations(model: Model): Model {
         val presignableOps = model.shapes()
             .filter { shape -> shape is OperationShape && presignableOperations.containsKey(shape.id) }
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsReadmeDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsReadmeDecorator.kt
index 1ef704217327db139f0d19f76560a0ad7aa0e746..3b18640f28c7bf7eea1634faffd589b4ba6327ae 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsReadmeDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/AwsReadmeDecorator.kt
@@ -11,6 +11,7 @@ import org.jsoup.nodes.TextNode
 import software.amazon.smithy.model.traits.DocumentationTrait
 import software.amazon.smithy.rust.codegen.rustlang.raw
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.generators.ManifestCustomizations
@@ -110,6 +111,9 @@ class AwsReadmeDecorator : RustCodegenDecorator<ClientCodegenContext> {
         }
     }
 
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
+
     /**
      * Strips HTML from the description and makes it human-readable Markdown.
      */
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/CrateLicenseDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/CrateLicenseDecorator.kt
index ed152fe83a549ed38b967112fb9a0c8082bb4440..ae8940dd9225610d5926eb9a065507b44c494f5a 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/CrateLicenseDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/CrateLicenseDecorator.kt
@@ -7,6 +7,7 @@ package software.amazon.smithy.rustsdk
 
 import software.amazon.smithy.rust.codegen.rustlang.raw
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 
@@ -21,4 +22,7 @@ class CrateLicenseDecorator : RustCodegenDecorator<ClientCodegenContext> {
             it.raw(license)
         }
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/CredentialProviders.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/CredentialProviders.kt
index 6853fa2aea2a0a8691cf2bc7fd5d693d412d1caf..4bcaa3d1b7311ee0bc533ceea50fea7acc0d1aaa 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/CredentialProviders.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/CredentialProviders.kt
@@ -12,6 +12,7 @@ import software.amazon.smithy.rust.codegen.rustlang.rust
 import software.amazon.smithy.rust.codegen.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RuntimeConfig
 import software.amazon.smithy.rust.codegen.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.smithy.customize.OperationCustomization
@@ -47,6 +48,9 @@ class CredentialsProviderDecorator : RustCodegenDecorator<ClientCodegenContext>
     ): List<LibRsCustomization> {
         return baseCustomizations + PubUseCredentials(codegenContext.runtimeConfig)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 /**
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/HttpRequestChecksumDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/HttpRequestChecksumDecorator.kt
index d953c23b022bd6ca4ecfa62b0b22684f40cde755..f049ee854692c699914b6007d0d43da178bf0939 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/HttpRequestChecksumDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/HttpRequestChecksumDecorator.kt
@@ -14,6 +14,7 @@ import software.amazon.smithy.rust.codegen.rustlang.asType
 import software.amazon.smithy.rust.codegen.rustlang.rust
 import software.amazon.smithy.rust.codegen.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RuntimeConfig
 import software.amazon.smithy.rust.codegen.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.smithy.customize.OperationCustomization
@@ -51,6 +52,9 @@ class HttpRequestChecksumDecorator : RustCodegenDecorator<ClientCodegenContext>
     ): List<OperationCustomization> {
         return baseCustomizations + HttpRequestChecksumCustomization(codegenContext, operation)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 private fun HttpChecksumTrait.requestAlgorithmMember(
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/HttpResponseChecksumDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/HttpResponseChecksumDecorator.kt
index b253f6fa4dc7964bc7904082837800fa51fde158..0bd4cac382216e42c6ae8e56e8a25ceb4c48a06e 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/HttpResponseChecksumDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/HttpResponseChecksumDecorator.kt
@@ -11,6 +11,7 @@ import software.amazon.smithy.model.shapes.OperationShape
 import software.amazon.smithy.rust.codegen.rustlang.Writable
 import software.amazon.smithy.rust.codegen.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.customize.OperationCustomization
 import software.amazon.smithy.rust.codegen.smithy.customize.OperationSection
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
@@ -38,6 +39,9 @@ class HttpResponseChecksumDecorator : RustCodegenDecorator<ClientCodegenContext>
     ): List<OperationCustomization> {
         return baseCustomizations + HttpResponseChecksumCustomization(codegenContext, operation)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 // This generator was implemented based on this spec:
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/IntegrationTestDependencies.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/IntegrationTestDependencies.kt
index 9189087098e961fc62b7c1415fd6baa7198695a4..f8d67754cdce64c7cdaa725d355499997184d53a 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/IntegrationTestDependencies.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/IntegrationTestDependencies.kt
@@ -13,6 +13,7 @@ import software.amazon.smithy.rust.codegen.rustlang.DependencyScope
 import software.amazon.smithy.rust.codegen.rustlang.Writable
 import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RuntimeConfig
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.generators.LibRsCustomization
@@ -49,6 +50,9 @@ class IntegrationTestDecorator : RustCodegenDecorator<ClientCodegenContext> {
             baseCustomizations
         }
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class IntegrationTestDependencies(
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/RegionDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/RegionDecorator.kt
index e2da2a16b4c79d936e25a4728ab1c1a87741a14d..74fa0c2ea1df94b9e2260453a98a3cd5f55f390b 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/RegionDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/RegionDecorator.kt
@@ -95,6 +95,9 @@ class RegionDecorator : RustCodegenDecorator<ClientCodegenContext> {
     ): List<LibRsCustomization> {
         return baseCustomizations + PubUseRegion(codegenContext.runtimeConfig)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class RegionProviderConfig(coreCodegenContext: CoreCodegenContext) : ConfigCustomization() {
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/RetryPolicyDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/RetryPolicyDecorator.kt
index 76ccbf6561a45ff51a1653d4cffd3e52714fff72..5daee32e56a962eec0f32b272cc8c4cc9cf9cc10 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/RetryPolicyDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/RetryPolicyDecorator.kt
@@ -10,6 +10,7 @@ import software.amazon.smithy.rust.codegen.rustlang.asType
 import software.amazon.smithy.rust.codegen.rustlang.rust
 import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RuntimeConfig
 import software.amazon.smithy.rust.codegen.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.smithy.customize.OperationCustomization
@@ -27,6 +28,9 @@ class RetryPolicyDecorator : RustCodegenDecorator<ClientCodegenContext> {
     ): List<OperationCustomization> {
         return baseCustomizations + RetryPolicyFeature(codegenContext.runtimeConfig)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class RetryPolicyFeature(private val runtimeConfig: RuntimeConfig) : OperationCustomization() {
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/SdkConfigDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/SdkConfigDecorator.kt
index 81118b45976f1b56c7b86f2457cc17a65850c838..5034de6b5d532d3eb1e9c7b83018bf18eb89bb36 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/SdkConfigDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/SdkConfigDecorator.kt
@@ -11,6 +11,7 @@ import software.amazon.smithy.rust.codegen.rustlang.asType
 import software.amazon.smithy.rust.codegen.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RuntimeConfig
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
@@ -66,6 +67,9 @@ class SdkConfigDecorator : RustCodegenDecorator<ClientCodegenContext> {
             )
         }
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class NewFromShared(runtimeConfig: RuntimeConfig) : ConfigCustomization() {
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/ServiceConfigDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/ServiceConfigDecorator.kt
index a5dd575e0393d51a3eaff48a6db3121787fcb70d..75ddac0a1e8a666679a35ce88d1c7ce4ebb49a05 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/ServiceConfigDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/ServiceConfigDecorator.kt
@@ -9,6 +9,7 @@ import software.amazon.smithy.rust.codegen.rustlang.Writable
 import software.amazon.smithy.rust.codegen.rustlang.docs
 import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.generators.config.ConfigCustomization
 import software.amazon.smithy.rust.codegen.smithy.generators.config.ServiceConfig
@@ -21,6 +22,9 @@ class ServiceConfigDecorator : RustCodegenDecorator<ClientCodegenContext> {
         codegenContext: ClientCodegenContext,
         baseCustomizations: List<ConfigCustomization>,
     ): List<ConfigCustomization> = baseCustomizations + SharedConfigDocsCustomization()
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class SharedConfigDocsCustomization : ConfigCustomization() {
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/SigV4SigningDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/SigV4SigningDecorator.kt
index 253af7d5e4eece30dc685caff1394e27622a121f..13f517a43cd8fe3791940cae5272b8d76d04ce3e 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/SigV4SigningDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/SigV4SigningDecorator.kt
@@ -75,6 +75,9 @@ class SigV4SigningDecorator : RustCodegenDecorator<ClientCodegenContext> {
             )
         }
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class SigV4SigningConfig(
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/UserAgentDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/UserAgentDecorator.kt
index d5d93672355e18a85d65ba739d33f098c5719dba..d4f54a6f354f33056ea4b8936a71a35d8eed75af 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/UserAgentDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/UserAgentDecorator.kt
@@ -13,6 +13,7 @@ import software.amazon.smithy.rust.codegen.rustlang.rust
 import software.amazon.smithy.rust.codegen.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RuntimeConfig
 import software.amazon.smithy.rust.codegen.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.smithy.customize.OperationCustomization
@@ -55,6 +56,9 @@ class UserAgentDecorator : RustCodegenDecorator<ClientCodegenContext> {
     ): List<OperationCustomization> {
         return baseCustomizations + UserAgentFeature(codegenContext.runtimeConfig)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 /**
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/apigateway/ApiGatewayDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/apigateway/ApiGatewayDecorator.kt
index 881d5a6acb4c4f285fe333288a6bb02b72c61535..0918208bc627307af1f642c267b932b0df8cc1dc 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/apigateway/ApiGatewayDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/apigateway/ApiGatewayDecorator.kt
@@ -34,6 +34,9 @@ class ApiGatewayDecorator : RustCodegenDecorator<ClientCodegenContext> {
             it + ApiGatewayAddAcceptHeader()
         }
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class ApiGatewayAddAcceptHeader : OperationCustomization() {
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/auth/DisabledAuthDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/auth/DisabledAuthDecorator.kt
index 3d63ccdf29a113d91b637f5b375bad5064aacfca..5e393276e9bc390b5c76f89202b0179cae3ef287 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/auth/DisabledAuthDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/auth/DisabledAuthDecorator.kt
@@ -12,6 +12,7 @@ import software.amazon.smithy.model.shapes.ShapeId
 import software.amazon.smithy.model.traits.AuthTrait
 import software.amazon.smithy.model.transform.ModelTransformer
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 
 private fun String.shapeId() = ShapeId.from(this)
@@ -46,4 +47,7 @@ class DisabledAuthDecorator : RustCodegenDecorator<ClientCodegenContext> {
             }
         }
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/ec2/Ec2Decorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/ec2/Ec2Decorator.kt
index fef52a803d226e66413b93107542d160e3226f5a..d4152dc324d63662134a979693b7df6894a5dfb1 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/ec2/Ec2Decorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/ec2/Ec2Decorator.kt
@@ -9,6 +9,7 @@ import software.amazon.smithy.model.Model
 import software.amazon.smithy.model.shapes.ServiceShape
 import software.amazon.smithy.model.shapes.ShapeId
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.letIf
 
@@ -28,4 +29,7 @@ class Ec2Decorator : RustCodegenDecorator<ClientCodegenContext> {
             BoxPrimitiveShapes::processModel,
         )
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/glacier/GlacierDecorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/glacier/GlacierDecorator.kt
index 1bb6fcbe8605bc66f160b0dfa59bdcc7fe0fd9bd..0de378ca9e6fbee6d0e821075b80b35bc9c1b68c 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/glacier/GlacierDecorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/glacier/GlacierDecorator.kt
@@ -37,4 +37,7 @@ class GlacierDecorator : RustCodegenDecorator<ClientCodegenContext> {
         }
         return baseCustomizations + extras
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/route53/Route53Decorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/route53/Route53Decorator.kt
index ca62e1cd5a61bc381ba084db20319406257ab0a2..ddfab5aac0cd4bd7e1862ae5034a40f4bb467155 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/route53/Route53Decorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/route53/Route53Decorator.kt
@@ -16,6 +16,7 @@ import software.amazon.smithy.rust.codegen.rustlang.Writable
 import software.amazon.smithy.rust.codegen.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.smithy.customize.OperationCustomization
 import software.amazon.smithy.rust.codegen.smithy.customize.OperationSection
@@ -59,6 +60,9 @@ class Route53Decorator : RustCodegenDecorator<ClientCodegenContext> {
         } else baseCustomizations
     }
 
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
+
     private fun isResourceId(shape: Shape): Boolean {
         return (shape is MemberShape && resourceShapes.contains(shape.target)) && shape.hasTrait<HttpLabelTrait>()
     }
diff --git a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/s3/S3Decorator.kt b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/s3/S3Decorator.kt
index d31f44ab62a6d3a66ab986ace442932e3db1baba..79ce312dd9f9a26d3cc857700011300faa5c6753 100644
--- a/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/s3/S3Decorator.kt
+++ b/aws/sdk-codegen/src/main/kotlin/software/amazon/smithy/rustsdk/customize/s3/S3Decorator.kt
@@ -56,6 +56,9 @@ class S3Decorator : RustCodegenDecorator<ClientCodegenContext> {
     ): List<LibRsCustomization> = baseCustomizations.letIf(applies(codegenContext.serviceShape.id)) {
         it + S3PubUse()
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class S3(coreCodegenContext: CoreCodegenContext) : RestXml(coreCodegenContext) {
diff --git a/aws/sdk-codegen/src/test/kotlin/software/amazon/smithy/rustsdk/EndpointConfigCustomizationTest.kt b/aws/sdk-codegen/src/test/kotlin/software/amazon/smithy/rustsdk/EndpointConfigCustomizationTest.kt
index fccb2fe4b41c0fb07e16e3fd0fb990ada24d4cd3..528c0a236160fa13e314fb6bf4ae0b06f4bace94 100644
--- a/aws/sdk-codegen/src/test/kotlin/software/amazon/smithy/rustsdk/EndpointConfigCustomizationTest.kt
+++ b/aws/sdk-codegen/src/test/kotlin/software/amazon/smithy/rustsdk/EndpointConfigCustomizationTest.kt
@@ -12,6 +12,7 @@ import software.amazon.smithy.rust.codegen.rustlang.asType
 import software.amazon.smithy.rust.codegen.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.CodegenVisitor
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
 import software.amazon.smithy.rust.codegen.smithy.customizations.AllowLintsGenerator
 import software.amazon.smithy.rust.codegen.smithy.customize.CombinedCodegenDecorator
@@ -147,6 +148,9 @@ internal class EndpointConfigCustomizationTest {
                     test(rustCrate)
                 }
             }
+
+            override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+                clazz.isAssignableFrom(ClientCodegenContext::class.java)
         }
         val customization = CombinedCodegenDecorator(listOf(RequiredCustomizations(), codegenDecorator))
         CodegenVisitor(context, customization).execute()
diff --git a/codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/PythonCodegenServerPlugin.kt b/codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/PythonCodegenServerPlugin.kt
index 5c89e2094b72edf130f42e5ecf6653c8e958a90c..4df3b72fca872fa511c0d5748e441f85da7f01ed 100644
--- a/codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/PythonCodegenServerPlugin.kt
+++ b/codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/PythonCodegenServerPlugin.kt
@@ -11,6 +11,7 @@ import software.amazon.smithy.codegen.core.ReservedWordSymbolProvider
 import software.amazon.smithy.model.Model
 import software.amazon.smithy.model.shapes.ServiceShape
 import software.amazon.smithy.rust.codegen.rustlang.RustReservedWordSymbolProvider
+import software.amazon.smithy.rust.codegen.server.python.smithy.customizations.DECORATORS
 import software.amazon.smithy.rust.codegen.server.python.smithy.generators.PythonServerSymbolProvider
 import software.amazon.smithy.rust.codegen.server.smithy.customizations.ServerRequiredCustomizations
 import software.amazon.smithy.rust.codegen.smithy.BaseSymbolMetadataProvider
@@ -45,7 +46,10 @@ class PythonCodegenServerPlugin : SmithyBuildPlugin {
         // - context (e.g. the of the operation)
         // - writer: The active RustWriter at the given location
         val codegenDecorator: CombinedCodegenDecorator<ServerCodegenContext> =
-            CombinedCodegenDecorator.fromClasspath(context, ServerRequiredCustomizations())
+            CombinedCodegenDecorator.fromClasspath(
+                context,
+                CombinedCodegenDecorator(DECORATORS + ServerRequiredCustomizations()),
+            )
 
         // PythonServerCodegenVisitor is the main driver of code generation that traverses the model and generates code
         logger.info("Loaded plugin to generate Rust/Python bindings for the server SSDK for projection ${context.projectionName}")
diff --git a/codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/customizations/PythonServerCodegenDecorator.kt b/codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/customizations/PythonServerCodegenDecorator.kt
index 734df0b3e0560373af1fac41ea0e481e88ae0bc0..3d033e870b611285d39c0a211e7a727ae453a43e 100644
--- a/codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/customizations/PythonServerCodegenDecorator.kt
+++ b/codegen-server/python/src/main/kotlin/software/amazon/smithy/rust/codegen/server/python/smithy/customizations/PythonServerCodegenDecorator.kt
@@ -14,9 +14,9 @@ import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.server.python.smithy.PythonServerRuntimeType
 import software.amazon.smithy.rust.codegen.server.python.smithy.generators.PythonServerModuleGenerator
 import software.amazon.smithy.rust.codegen.server.smithy.customizations.AddInternalServerErrorToAllOperationsDecorator
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
 import software.amazon.smithy.rust.codegen.smithy.ServerCodegenContext
-import software.amazon.smithy.rust.codegen.smithy.customize.CombinedCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.generators.LibRsCustomization
 import software.amazon.smithy.rust.codegen.smithy.generators.LibRsSection
@@ -44,6 +44,9 @@ class CdylibManifestDecorator : RustCodegenDecorator<ServerCodegenContext> {
                 "crate-type" to listOf("cdylib"),
             ),
         )
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ServerCodegenContext::class.java)
 }
 
 /**
@@ -76,6 +79,9 @@ class PythonExportModuleDecorator : RustCodegenDecorator<ServerCodegenContext> {
         val serviceShapes = Walker(codegenContext.model).walkShapes(service)
         PythonServerModuleGenerator(codegenContext, rustCrate, serviceShapes).render()
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ServerCodegenContext::class.java)
 }
 
 /**
@@ -91,6 +97,9 @@ class PubUsePythonTypesDecorator : RustCodegenDecorator<ServerCodegenContext> {
     ): List<LibRsCustomization> {
         return baseCustomizations + PubUsePythonTypes(codegenContext)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ServerCodegenContext::class.java)
 }
 
 val DECORATORS = listOf(
@@ -106,9 +115,3 @@ val DECORATORS = listOf(
     // Render the Python shared library export.
     PythonExportModuleDecorator(),
 )
-
-// Combined codegen decorator for Python services.
-class PythonServerCodegenDecorator : CombinedCodegenDecorator<ServerCodegenContext>(DECORATORS) {
-    override val name: String = "PythonServerCodegenDecorator"
-    override val order: Byte = -1
-}
diff --git a/codegen-server/python/src/main/resources/META-INF/services/software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator b/codegen-server/python/src/main/resources/META-INF/services/software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
deleted file mode 100644
index 13a1fd23750a07674e326fc691799e22d87c2dd3..0000000000000000000000000000000000000000
--- a/codegen-server/python/src/main/resources/META-INF/services/software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
+++ /dev/null
@@ -1,6 +0,0 @@
-#
-# Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
-# SPDX-License-Identifier: Apache-2.0
-#
-
-software.amazon.smithy.rust.codegen.server.python.smithy.customizations.PythonServerCodegenDecorator
diff --git a/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/AdditionalErrorsDecorator.kt b/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/AdditionalErrorsDecorator.kt
index 628d7a2843d9c2059efd57ed18448fd0e7b5c994..402e791129c8f81e2c5a739cb199f65d8652ed2c 100644
--- a/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/AdditionalErrorsDecorator.kt
+++ b/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/AdditionalErrorsDecorator.kt
@@ -13,6 +13,7 @@ import software.amazon.smithy.model.shapes.StructureShape
 import software.amazon.smithy.model.traits.ErrorTrait
 import software.amazon.smithy.model.traits.RequiredTrait
 import software.amazon.smithy.model.transform.ModelTransformer
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.ServerCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.transformers.allErrors
@@ -37,6 +38,9 @@ class AddInternalServerErrorToInfallibleOperationsDecorator : RustCodegenDecorat
 
     override fun transformModel(service: ServiceShape, model: Model): Model =
         addErrorShapeToModelOperations(service, model) { shape -> shape.allErrors(model).isEmpty() }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ServerCodegenContext::class.java)
 }
 
 /**
@@ -63,6 +67,9 @@ class AddInternalServerErrorToAllOperationsDecorator : RustCodegenDecorator<Serv
 
     override fun transformModel(service: ServiceShape, model: Model): Model =
         addErrorShapeToModelOperations(service, model) { true }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ServerCodegenContext::class.java)
 }
 
 fun addErrorShapeToModelOperations(service: ServiceShape, model: Model, opSelector: (OperationShape) -> Boolean): Model {
diff --git a/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/ServerRequiredCustomizations.kt b/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/ServerRequiredCustomizations.kt
index c3925d0fc1232e7d236397077826d346e9ce81ad..e3ae4f23c4e0ffe5a707ce993f048b2bd7ea043b 100644
--- a/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/ServerRequiredCustomizations.kt
+++ b/codegen-server/src/main/kotlin/software/amazon/smithy/rust/codegen/server/smithy/customizations/ServerRequiredCustomizations.kt
@@ -6,6 +6,7 @@
 package software.amazon.smithy.rust.codegen.server.smithy.customizations
 
 import software.amazon.smithy.rust.codegen.rustlang.Feature
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
 import software.amazon.smithy.rust.codegen.smithy.ServerCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.customizations.AllowLintsGenerator
@@ -35,4 +36,7 @@ class ServerRequiredCustomizations : RustCodegenDecorator<ServerCodegenContext>
         // Add rt-tokio feature for `ByteStream::from_path`
         rustCrate.mergeFeature(Feature("rt-tokio", true, listOf("aws-smithy-http/rt-tokio")))
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ServerCodegenContext::class.java)
 }
diff --git a/codegen-server/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/CombinedCodegenDecoratorTest.kt b/codegen-server/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/CombinedCodegenDecoratorTest.kt
new file mode 100644
index 0000000000000000000000000000000000000000..285e00ab6c2e5244388af87e5e9cfa950a0fadd6
--- /dev/null
+++ b/codegen-server/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/CombinedCodegenDecoratorTest.kt
@@ -0,0 +1,35 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.rust.codegen.smithy.customize
+
+import io.kotest.matchers.collections.shouldContainExactly
+import org.junit.jupiter.api.Test
+import software.amazon.smithy.rust.codegen.server.smithy.customizations.ServerRequiredCustomizations
+import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.ServerCodegenContext
+
+internal class CombinedCodegenDecoratorTest {
+    private val clientDecorator: RustCodegenDecorator<ClientCodegenContext> = RequiredCustomizations()
+    private val serverDecorator: RustCodegenDecorator<ServerCodegenContext> = ServerRequiredCustomizations()
+
+    @Test
+    fun filterClientDecorators() {
+        val filteredDecorators = CombinedCodegenDecorator.filterDecorators<ClientCodegenContext>(
+            listOf(clientDecorator, serverDecorator),
+        ).toList()
+
+        filteredDecorators.shouldContainExactly(clientDecorator)
+    }
+
+    @Test
+    fun filterServerDecorators() {
+        val filteredDecorators = CombinedCodegenDecorator.filterDecorators<ServerCodegenContext>(
+            listOf(clientDecorator, serverDecorator),
+        ).toList()
+
+        filteredDecorators.shouldContainExactly(serverDecorator)
+    }
+}
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/ClientCustomizations.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/ClientCustomizations.kt
index 168bb506f5ce54d93f728888e9903071789673a8..029587ea80c06691b0b0d6ddee87310dc3654d94 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/ClientCustomizations.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/ClientCustomizations.kt
@@ -6,6 +6,7 @@
 package software.amazon.smithy.rust.codegen.smithy.customizations
 
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.generators.LibRsCustomization
 
@@ -20,4 +21,7 @@ class ClientCustomizations : RustCodegenDecorator<ClientCodegenContext> {
         codegenContext: ClientCodegenContext,
         baseCustomizations: List<LibRsCustomization>,
     ): List<LibRsCustomization> = baseCustomizations + ClientDocsGenerator()
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/DocsRsMetadataDecorator.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/DocsRsMetadataDecorator.kt
index d7aed5c18d3385e8253ec1b1bcb05744c4371400..212f4de72fbdecd5a689df25bad59076f3e16cfc 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/DocsRsMetadataDecorator.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/DocsRsMetadataDecorator.kt
@@ -6,6 +6,7 @@
 package software.amazon.smithy.rust.codegen.smithy.customizations
 
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.customize.RustCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.generators.ManifestCustomizations
 
@@ -56,4 +57,7 @@ class DocsRsMetadataDecorator(private val docsRsMetadataSettings: DocsRsMetadata
     override fun crateManifestCustomizations(codegenContext: ClientCodegenContext): ManifestCustomizations {
         return docsRsMetadataSettings.asMap()
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/RetryConfigDecorator.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/RetryConfigDecorator.kt
index e7ff953b7d04ac99e32992f726fa5c75ebdd673d..9d83a80e60e954f2392fdc08815671fe68dfdf77 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/RetryConfigDecorator.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/RetryConfigDecorator.kt
@@ -84,6 +84,9 @@ class RetryConfigDecorator : RustCodegenDecorator<ClientCodegenContext> {
     ): List<LibRsCustomization> {
         return baseCustomizations + PubUseRetryConfig(codegenContext.runtimeConfig)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class RetryConfigProviderConfig(coreCodegenContext: CoreCodegenContext) : ConfigCustomization() {
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/SleepImplDecorator.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/SleepImplDecorator.kt
index cb3ad3cd621eb54642f59fd218bdb7fb18cd9ea0..126e264b397ccf635d5d648e62d61bdc1c719f0f 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/SleepImplDecorator.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/SleepImplDecorator.kt
@@ -126,6 +126,9 @@ class SleepImplDecorator : RustCodegenDecorator<ClientCodegenContext> {
     ): List<ConfigCustomization> {
         return baseCustomizations + SleepImplProviderConfig(codegenContext)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class SleepImplProviderConfig(coreCodegenContext: CoreCodegenContext) : ConfigCustomization() {
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/TimeoutConfigDecorator.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/TimeoutConfigDecorator.kt
index f82aa69b7df8ca3fc761e2ea96315e0713e748cf..8425e1963725897391e739bb48e2a934f1dd12d2 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/TimeoutConfigDecorator.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customizations/TimeoutConfigDecorator.kt
@@ -113,6 +113,9 @@ class TimeoutConfigDecorator : RustCodegenDecorator<ClientCodegenContext> {
     ): List<ConfigCustomization> {
         return baseCustomizations + TimeoutConfigProviderConfig(codegenContext)
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 class TimeoutConfigProviderConfig(coreCodegenContext: CoreCodegenContext) : ConfigCustomization() {
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/NoOpEventStreamSigningDecorator.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/NoOpEventStreamSigningDecorator.kt
index 534368c6bf10a474f1ce582587953debc5ec1669..35bfdf9704bc038377bfc667bf2330084aae4c24 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/NoOpEventStreamSigningDecorator.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/NoOpEventStreamSigningDecorator.kt
@@ -40,6 +40,8 @@ open class NoOpEventStreamSigningDecorator<C : CoreCodegenContext> : RustCodegen
             codegenContext.runtimeConfig,
         )
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>) = true
 }
 
 class NoOpEventStreamSigningConfig(
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/RequiredCustomizations.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/RequiredCustomizations.kt
index c34c4301a262e54f8d90bfb2d72ecdab2d202709..659f00230ca20ef5c55bbe4f0a43dbb66a186386 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/RequiredCustomizations.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/RequiredCustomizations.kt
@@ -8,6 +8,7 @@ package software.amazon.smithy.rust.codegen.smithy.customize
 import software.amazon.smithy.model.shapes.OperationShape
 import software.amazon.smithy.rust.codegen.rustlang.Feature
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
 import software.amazon.smithy.rust.codegen.smithy.customizations.AllowLintsGenerator
 import software.amazon.smithy.rust.codegen.smithy.customizations.CrateVersionGenerator
@@ -48,4 +49,7 @@ class RequiredCustomizations : RustCodegenDecorator<ClientCodegenContext> {
         // Add rt-tokio feature for `ByteStream::from_path`
         rustCrate.mergeFeature(Feature("rt-tokio", true, listOf("aws-smithy-http/rt-tokio")))
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/RustCodegenDecorator.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/RustCodegenDecorator.kt
index 1981285e8b6b6f134894aa66126070e32a80dfcc..d3c4e92e8296d7a918fed1142422bcb6447ce7c1 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/RustCodegenDecorator.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/customize/RustCodegenDecorator.kt
@@ -68,6 +68,8 @@ interface RustCodegenDecorator<C : CoreCodegenContext> {
         currentProtocols
 
     fun transformModel(service: ServiceShape, model: Model): Model = model
+
+    fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean
 }
 
 /**
@@ -75,7 +77,8 @@ interface RustCodegenDecorator<C : CoreCodegenContext> {
  *
  * This makes the actual concrete codegen simpler by not needing to deal with multiple separate decorators.
  */
-open class CombinedCodegenDecorator<C : CoreCodegenContext>(decorators: List<RustCodegenDecorator<C>>) : RustCodegenDecorator<C> {
+open class CombinedCodegenDecorator<C : CoreCodegenContext>(decorators: List<RustCodegenDecorator<C>>) :
+    RustCodegenDecorator<C> {
     private val orderedDecorators = decorators.sortedBy { it.order }
     override val name: String
         get() = "MetaDecorator"
@@ -137,6 +140,10 @@ open class CombinedCodegenDecorator<C : CoreCodegenContext>(decorators: List<Rus
         }
     }
 
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        // `CombinedCodegenDecorator` can work with all types of codegen context.
+        CoreCodegenContext::class.java.isAssignableFrom(clazz)
+
     companion object {
         inline fun <reified T : CoreCodegenContext> fromClasspath(
             context: PluginContext,
@@ -147,31 +154,46 @@ open class CombinedCodegenDecorator<C : CoreCodegenContext>(decorators: List<Rus
                 RustCodegenDecorator::class.java,
                 context.pluginClassLoader.orElse(RustCodegenDecorator::class.java.classLoader),
             )
+
+            val filteredDecorators = filterDecorators<T>(decorators, logger).toList()
+            return CombinedCodegenDecorator(filteredDecorators + extras)
+        }
+
+        /*
+         * This function has been extracted solely for the purposes of easily unit testing the important filtering logic.
+         * Unfortunately, it must be part of the public API because public API inline functions are not allowed to use
+         * non-public-API declarations.
+         * See https://kotlinlang.org/docs/inline-functions.html#restrictions-for-public-api-inline-functions.
+         */
+        inline fun <reified T : CoreCodegenContext> filterDecorators(
+            decorators: Iterable<RustCodegenDecorator<*>>,
+            logger: Logger = Logger.getLogger("RustCodegenSPILoader"),
+        ): Sequence<RustCodegenDecorator<T>> =
+            decorators.asSequence()
+                .onEach {
+                    logger.info("Discovered Codegen Decorator: ${it.javaClass.name}")
+                }
                 // The JVM's `ServiceLoader` is woefully underpowered in that it can not load classes with generic
                 // parameters with _fixed_ parameters (like what we're trying to do here; we only want `RustCodegenDecorator`
                 // classes with code-generation context matching the input `T`).
                 // There are various workarounds: https://stackoverflow.com/questions/5451734/loading-generic-service-implementations-via-java-util-serviceloader
                 // All involve loading _all_ classes from the classpath (i.e. all `RustCodegenDecorator<*>`), and then
-                // filtering them. The most elegant way to filter is arguably by checking if we can cast the loaded
-                // class to what we want.
+                // filtering them.
+                // Note that attempting to downcast a generic class `C<T>` to `C<U>` where `U: T` is not possible to do
+                // in Kotlin (and presumably all JVM-based languages) _at runtime_. Not even when using reified type
+                // parameters of inline functions. See https://kotlinlang.org/docs/generics.html#type-erasure for details.
                 .filter {
-                    try {
-                        it as RustCodegenDecorator<T>
-                        true
-                    } catch (e: ClassCastException) {
-                        false
-                    }
+                    val clazz = T::class.java
+                    it.supportsCodegenContext(clazz)
                 }
                 .onEach {
                     logger.info("Adding Codegen Decorator: ${it.javaClass.name}")
                 }
                 .map {
                     // Cast is safe because of the filter above.
+                    // Not that it really has an effect at runtime, since its unchecked.
                     @Suppress("UNCHECKED_CAST")
                     it as RustCodegenDecorator<T>
                 }
-                .toList()
-            return CombinedCodegenDecorator(decorators + extras)
-        }
     }
 }
diff --git a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/client/FluentClientDecorator.kt b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/client/FluentClientDecorator.kt
index eaf3c066cd416879f6c457b7ce4bca427546eb20..99fbfb71e4bfa71cbc5dbfeb3fc64b5e09dc8e4c 100644
--- a/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/client/FluentClientDecorator.kt
+++ b/codegen/src/main/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/client/FluentClientDecorator.kt
@@ -99,6 +99,9 @@ class FluentClientDecorator : RustCodegenDecorator<ClientCodegenContext> {
             }
         }
     }
+
+    override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+        clazz.isAssignableFrom(ClientCodegenContext::class.java)
 }
 
 sealed class FluentClientSection(name: String) : Section(name) {
diff --git a/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/customizations/HttpVersionListGeneratorTest.kt b/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/customizations/HttpVersionListGeneratorTest.kt
index 4dff1e5c4f512dfdbafb9a88a3a37d8784032786..45c5bae1ac4daf7a73bbed417bce17849f03e9d9 100644
--- a/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/customizations/HttpVersionListGeneratorTest.kt
+++ b/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/customizations/HttpVersionListGeneratorTest.kt
@@ -13,6 +13,7 @@ import software.amazon.smithy.rust.codegen.rustlang.rustTemplate
 import software.amazon.smithy.rust.codegen.rustlang.writable
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.CodegenVisitor
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RuntimeConfig
 import software.amazon.smithy.rust.codegen.smithy.RuntimeType
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
@@ -84,6 +85,9 @@ internal class HttpVersionListGeneratorTest {
                     )
                 }
             }
+
+            override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+                clazz.isAssignableFrom(ClientCodegenContext::class.java)
         }
         val combinedCodegenDecorator: CombinedCodegenDecorator<ClientCodegenContext> =
             CombinedCodegenDecorator.fromClasspath(ctx, RequiredCustomizations()).withDecorator(testWriter)
@@ -146,6 +150,9 @@ internal class HttpVersionListGeneratorTest {
                     )
                 }
             }
+
+            override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+                clazz.isAssignableFrom(ClientCodegenContext::class.java)
         }
 
         val combinedCodegenDecorator: CombinedCodegenDecorator<ClientCodegenContext> =
@@ -228,6 +235,9 @@ internal class HttpVersionListGeneratorTest {
                     )
                 }
             }
+
+            override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+                clazz.isAssignableFrom(ClientCodegenContext::class.java)
         }
 
         val combinedCodegenDecorator: CombinedCodegenDecorator<ClientCodegenContext> =
diff --git a/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/EndpointTraitBindingsTest.kt b/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/EndpointTraitBindingsTest.kt
index e141f64b54547e0fc7dfa04974a355ba3d8c3109..ad845b9cc8c465c89d31e324e982e513f8eac4e8 100644
--- a/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/EndpointTraitBindingsTest.kt
+++ b/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/EndpointTraitBindingsTest.kt
@@ -15,6 +15,7 @@ import software.amazon.smithy.rust.codegen.rustlang.rust
 import software.amazon.smithy.rust.codegen.rustlang.rustBlock
 import software.amazon.smithy.rust.codegen.smithy.ClientCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.CodegenVisitor
+import software.amazon.smithy.rust.codegen.smithy.CoreCodegenContext
 import software.amazon.smithy.rust.codegen.smithy.RustCrate
 import software.amazon.smithy.rust.codegen.smithy.customize.CombinedCodegenDecorator
 import software.amazon.smithy.rust.codegen.smithy.customize.RequiredCustomizations
@@ -171,6 +172,9 @@ internal class EndpointTraitBindingsTest {
                     )
                 }
             }
+
+            override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+                clazz.isAssignableFrom(ClientCodegenContext::class.java)
         }
         val combinedCodegenDecorator: CombinedCodegenDecorator<ClientCodegenContext> =
             CombinedCodegenDecorator.fromClasspath(ctx, RequiredCustomizations()).withDecorator(codegenDecorator)
diff --git a/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGeneratorTest.kt b/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGeneratorTest.kt
index ea39c74804cf194e9e52ca8841b6a8608feabf5a..e65c558dc4df62ecd2ba4635b96c1c212003735e 100644
--- a/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGeneratorTest.kt
+++ b/codegen/src/test/kotlin/software/amazon/smithy/rust/codegen/smithy/generators/protocol/ProtocolTestGeneratorTest.kt
@@ -231,6 +231,9 @@ class ProtocolTestGeneratorTest {
                 ): ProtocolMap<ClientCodegenContext> =
                     // Intentionally replace the builtin implementation of RestJson1 with our fake protocol
                     mapOf(RestJson1Trait.ID to TestProtocolFactory(httpRequestBuilder, body, correctResponse))
+
+                override fun supportsCodegenContext(clazz: Class<out CoreCodegenContext>): Boolean =
+                    clazz.isAssignableFrom(ClientCodegenContext::class.java)
             },
         )
         visitor.execute()