diff --git a/.github/actions/checkout-aws-sdk-swift-composite-action/action.yml b/.github/actions/checkout-aws-sdk-swift-composite-action/action.yml
new file mode 100644
index 000000000..adf8fc72e
--- /dev/null
+++ b/.github/actions/checkout-aws-sdk-swift-composite-action/action.yml
@@ -0,0 +1,51 @@
+name: 'Checkout aws-sdk-swift composite action'
+description: 'A composite action that sets up aws-sdk-swift for the workflow.'
+inputs:
+  AUTOMATION_USER_SSH_PRIVATE_KEY:
+    description: 'SSH private key for the automation user'
+    required: true
+  STAGING_PARTNER_REPO:
+    description: 'The staging partner repository'
+    required: true
+runs:
+  using: 'composite'
+  steps:
+    - name: Set up SSH key
+      if: ${{ github.repository != 'smithy-lang/smithy-swift' }}
+      run: |
+        mkdir -p ~/.ssh
+        echo "${{ inputs.AUTOMATION_USER_SSH_PRIVATE_KEY }}" > ~/.ssh/id_rsa
+        chmod 600 ~/.ssh/id_rsa
+        ssh-keyscan github.com >> ~/.ssh/known_hosts
+      shell: bash
+    - name: Select staging aws-sdk-swift branch
+      if: ${{ github.repository != 'smithy-lang/smithy-swift' }}
+      run: |
+        cd smithy-swift
+        ORIGINAL_REPO_HEAD_REF="$GITHUB_HEAD_REF" \
+        DEPENDENCY_REPO_URL="git@github.com:${{ inputs.STAGING_PARTNER_REPO }}.git" \
+        ./scripts/ci_steps/select_dependency_branch.sh
+      shell: bash
+    - name: Checkout staging aws-sdk-swift
+      if: ${{ github.repository != 'smithy-lang/smithy-swift' }}
+      uses: actions/checkout@v4
+      with:
+        repository: ${{ inputs.STAGING_PARTNER_REPO }}
+        ref: ${{ env.DEPENDENCY_REPO_SHA }}
+        path: aws-sdk-swift
+        ssh-key: ${{ inputs.AUTOMATION_USER_SSH_PRIVATE_KEY }}
+    - name: Select aws-sdk-swift branch
+      if: ${{ github.repository == 'smithy-lang/smithy-swift' }}
+      run: |
+        cd smithy-swift
+        ORIGINAL_REPO_HEAD_REF="$GITHUB_HEAD_REF" \
+        DEPENDENCY_REPO_URL="https://github.com/awslabs/aws-sdk-swift.git" \
+        ./scripts/ci_steps/select_dependency_branch.sh
+      shell: bash
+    - name: Checkout aws-sdk-swift
+      if: ${{ github.repository == 'smithy-lang/smithy-swift' }}
+      uses: actions/checkout@v4
+      with:
+        repository: awslabs/aws-sdk-swift
+        ref: ${{ env.DEPENDENCY_REPO_SHA }}
+        path: aws-sdk-swift
\ No newline at end of file
diff --git a/.github/actions/setup-common-tools-composite-action/action.yml b/.github/actions/setup-common-tools-composite-action/action.yml
new file mode 100644
index 000000000..b5998dc1f
--- /dev/null
+++ b/.github/actions/setup-common-tools-composite-action/action.yml
@@ -0,0 +1,30 @@
+name: 'Setup Common Tools'
+description: 'A composite action that caches Gradle, caches Swift, and sets up Java.'
+runs:
+  using: 'composite'
+  steps:
+    - name: Cache Gradle
+      uses: actions/cache@v4
+      with:
+        path: |
+          ~/.gradle/caches
+          ~/.gradle/wrapper
+        key: 1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
+        restore-keys: |
+          1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
+          1-${{ runner.os }}-gradle-
+    - name: Cache Swift
+      uses: actions/cache@v4
+      with:
+        path: |
+          ~/Library/Caches/org.swift.swiftpm
+          ~/.cache/org.swift.swiftpm
+        key: 1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
+        restore-keys: |
+          1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
+          1-${{ runner.os }}-${{ matrix.xcode }}-spm-
+    - name: Setup Java
+      uses: actions/setup-java@v4
+      with:
+        distribution: corretto
+        java-version: 17
\ No newline at end of file
diff --git a/.github/workflows/codegen.yml b/.github/workflows/codegen.yml
index 578cb3b7d..fe22c5f20 100644
--- a/.github/workflows/codegen.yml
+++ b/.github/workflows/codegen.yml
@@ -8,6 +8,7 @@ on:
 
 jobs:
   codegen:
+    if: github.repository == 'smithy-lang/smithy-swift' || github.event_name == 'pull_request'
     runs-on: ${{ matrix.os }}
     name: Java ${{ matrix.java }} ${{ matrix.os }}
     strategy:
diff --git a/.github/workflows/continuous-integration.yml b/.github/workflows/continuous-integration.yml
index c58b4dbb4..4f9e575e4 100644
--- a/.github/workflows/continuous-integration.yml
+++ b/.github/workflows/continuous-integration.yml
@@ -11,6 +11,7 @@ env:
 
 jobs:
   apple-ci:
+    if: github.repository == 'smithy-lang/smithy-swift' || github.event_name == 'pull_request'
     runs-on: ${{ matrix.runner }}
     strategy:
       fail-fast: false
@@ -65,31 +66,8 @@ jobs:
           sudo xcodebuild -runFirstLaunch
       - name: Checkout smithy-swift
         uses: actions/checkout@v4
-      - name: Cache Gradle
-        uses: actions/cache@v4
-        with:
-          path: |
-            ~/.gradle/caches
-            ~/.gradle/wrapper
-          key: 1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
-          restore-keys: |
-            1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
-            1-${{ runner.os }}-gradle-
-      - name: Cache Swift
-        uses: actions/cache@v4
-        with:
-          path: |
-            ~/Library/Caches/org.swift.swiftpm
-            ~/.cache/org.swift.swiftpm
-          key: 1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
-          restore-keys: |
-            1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
-            1-${{ runner.os }}-${{ matrix.xcode }}-spm-
-      - name: Setup Java
-        uses: actions/setup-java@v4
-        with:
-          distribution: corretto
-          java-version: 17
+      - name: Setup common tools
+        uses: ./.github/actions/setup-common-tools-composite-action
       - name: Build & Run smithy-swift Kotlin Unit Tests
         run: ./gradlew build
       - name: Build & Run smithy-swift Swift Unit Tests
@@ -103,6 +81,7 @@ jobs:
             | xcbeautify
 
   apple-downstream:
+    if: github.repository == 'smithy-lang/smithy-swift' || github.event_name == 'pull_request'
     runs-on: ${{ matrix.runner }}
     strategy:
       fail-fast: false
@@ -157,55 +136,24 @@ jobs:
           sudo xcodebuild -runFirstLaunch
       - name: Checkout smithy-swift
         uses: actions/checkout@v4
-      - name: Select aws-sdk-swift branch
-        run: |
-          ORIGINAL_REPO_HEAD_REF="$GITHUB_HEAD_REF" \
-          DEPENDENCY_REPO_URL="https://github.com/awslabs/aws-sdk-swift.git" \
-          ./scripts/ci_steps/select_dependency_branch.sh
-      - name: Checkout aws-sdk-swift
-        uses: actions/checkout@v4
         with:
-          repository: awslabs/aws-sdk-swift
-          ref: ${{ env.DEPENDENCY_REPO_SHA }}
-          path: aws-sdk-swift
-      - name: Move aws-sdk-swift into place
-        run: mv aws-sdk-swift ..
-      - name: Cache Gradle
-        uses: actions/cache@v4
+          path: smithy-swift
+      - name: Checkout aws-sdk-swift with composite action
+        uses: ./smithy-swift/.github/actions/checkout-aws-sdk-swift-composite-action
         with:
-          path: |
-            ~/.gradle/caches
-            ~/.gradle/wrapper
-          key: 1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
-          restore-keys: |
-            1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
-            1-${{ runner.os }}-gradle-
-      - name: Cache Swift
-        uses: actions/cache@v4
-        with:
-          path: |
-            ~/Library/Caches/org.swift.swiftpm
-            ~/.cache/org.swift.swiftpm
-          key: 1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
-          restore-keys: |
-            1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
-            1-${{ runner.os }}-${{ matrix.xcode }}-spm-
-      - name: Setup Java
-        uses: actions/setup-java@v4
-        with:
-          distribution: corretto
-          java-version: 17
+          AUTOMATION_USER_SSH_PRIVATE_KEY: ${{ secrets.AUTOMATION_USER_SSH_PRIVATE_KEY }}
+          STAGING_PARTNER_REPO: ${{ secrets.STAGING_PARTNER_REPO }}
+      - name: Setup common tools
+        uses: ./smithy-swift/.github/actions/setup-common-tools-composite-action
       - name: Tools Versions
-        run: |
-          cd ../aws-sdk-swift
-          ./scripts/ci_steps/log_tool_versions.sh
+        run: ./aws-sdk-swift/scripts/ci_steps/log_tool_versions.sh
       - name: Prepare aws-sdk-swift Protocol & Unit Tests
         run: |
-          cd ../aws-sdk-swift
+          cd aws-sdk-swift
           ./scripts/ci_steps/prepare_protocol_and_unit_tests.sh
       - name: Build and Run aws-sdk-swift Unit Tests
         run: |
-          cd ../aws-sdk-swift
+          cd aws-sdk-swift
           set -o pipefail && \
           NSUnbufferedIO=YES xcodebuild \
             -scheme aws-sdk-swift-Package \
@@ -214,7 +162,7 @@ jobs:
             | xcbeautify
       - name: Build and Run aws-sdk-swift Protocol Tests
         run: |
-          cd ../aws-sdk-swift/codegen
+          cd aws-sdk-swift/codegen
           set -o pipefail && \
           NSUnbufferedIO=YES xcodebuild \
             -scheme aws-sdk-swift-protocol-tests-Package \
@@ -223,6 +171,7 @@ jobs:
             | xcbeautify
 
   linux-ci:
+    if: github.repository == 'smithy-lang/smithy-swift' || github.event_name == 'pull_request'
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -235,8 +184,8 @@ jobs:
     env:
       ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: true
     steps:
-      - name: Checkout Sources
-        uses: actions/checkout@v3
+      - name: Checkout smithy-swift
+        uses: actions/checkout@v4
       - name: Install openssl
         run: |
           if [ -x "$(command -v apt)" ]; then
@@ -244,37 +193,15 @@ jobs:
           else
             yum install -y openssl-devel which
           fi
-      - name: Cache Gradle
-        uses: actions/cache@v3
-        with:
-          path: |
-            ~/.gradle/caches
-            ~/.gradle/wrapper
-          key: 1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
-          restore-keys: |
-            1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
-            1-${{ runner.os }}-gradle-
-      - name: Cache Swift
-        uses: actions/cache@v3
-        with:
-          path: |
-            ~/Library/Caches/org.swift.swiftpm
-            ~/.cache/org.swift.swiftpm
-          key: 1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
-          restore-keys: |
-            1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
-            1-${{ runner.os }}-${{ matrix.xcode }}-spm-
-      - name: Setup Java
-        uses: actions/setup-java@v3
-        with:
-          distribution: corretto
-          java-version: 17
+      - name: Setup common tools
+        uses: ./.github/actions/setup-common-tools-composite-action
       - name: Build & Run Kotlin Unit Tests
         run: ./gradlew build
       - name: Build & Run Swift Unit Tests
         run: swift test
 
   linux-downstream:
+    if: github.repository == 'smithy-lang/smithy-swift' || github.event_name == 'pull_request'
     runs-on: ubuntu-latest
     strategy:
       fail-fast: false
@@ -287,21 +214,6 @@ jobs:
     env:
       ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: true
     steps:
-      - name: Checkout Sources
-        uses: actions/checkout@v3
-      - name: Select aws-sdk-swift branch
-        run: |
-          ORIGINAL_REPO_HEAD_REF="$GITHUB_HEAD_REF" \
-          DEPENDENCY_REPO_URL="https://github.com/awslabs/aws-sdk-swift.git" \
-          ./scripts/ci_steps/select_dependency_branch.sh
-      - name: Checkout aws-sdk-swift
-        uses: actions/checkout@v3
-        with:
-          repository: awslabs/aws-sdk-swift
-          ref: ${{ env.DEPENDENCY_REPO_SHA }}
-          path: aws-sdk-swift
-      - name: Move aws-sdk-swift into place
-        run: mv aws-sdk-swift ..
       - name: Install openssl
         run: |
           if [ -x "$(command -v apt)" ]; then
@@ -309,48 +221,32 @@ jobs:
           else
             yum install -y openssl-devel which
           fi
-      - name: Cache Gradle
-        uses: actions/cache@v3
-        with:
-          path: |
-            ~/.gradle/caches
-            ~/.gradle/wrapper
-          key: 1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
-          restore-keys: |
-            1-${{ runner.os }}-gradle-${{ hashFiles('settings.gradle.kts', 'gradle/wrapper/gradle-wrapper.properties') }}
-            1-${{ runner.os }}-gradle-
-      - name: Cache Swift
-        uses: actions/cache@v3
+      - name: Checkout smithy-swift
+        uses: actions/checkout@v4
         with:
-          path: |
-            ~/Library/Caches/org.swift.swiftpm
-            ~/.cache/org.swift.swiftpm
-          key: 1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
-          restore-keys: |
-            1-${{ runner.os }}-${{ matrix.xcode }}-spm-${{ hashFiles('Package.swift') }}
-            1-${{ runner.os }}-${{ matrix.xcode }}-spm-
-      - name: Setup Java
-        uses: actions/setup-java@v3
+          path: smithy-swift
+      - name: Checkout aws-sdk-swift with composite action
+        uses: ./smithy-swift/.github/actions/checkout-aws-sdk-swift-composite-action
         with:
-          distribution: corretto
-          java-version: 17
+          AUTOMATION_USER_SSH_PRIVATE_KEY: ${{ secrets.AUTOMATION_USER_SSH_PRIVATE_KEY }}
+          STAGING_PARTNER_REPO: ${{ secrets.STAGING_PARTNER_REPO }}
+      - name: Setup common tools
+        uses: ./smithy-swift/.github/actions/setup-common-tools-composite-action
       - name: Tools Versions
-        run: |
-          cd ../aws-sdk-swift
-          ./scripts/ci_steps/log_tool_versions.sh
+        run: ./aws-sdk-swift/scripts/ci_steps/log_tool_versions.sh
       - name: Prepare aws-sdk-swift Protocol & Unit Tests
         run: |
-          cd ../aws-sdk-swift
+          cd aws-sdk-swift
           ./scripts/ci_steps/prepare_protocol_and_unit_tests.sh
       - name: Build and Run aws-sdk-swift Unit Tests
         run: |
-          cd ../aws-sdk-swift
+          cd aws-sdk-swift
           swift test
       - name: Build and Run aws-sdk-swift Protocol Tests
         run: |
           export AWS_REGION=us-west-2
           export AWS_ACCESS_KEY_ID=test-key-id
           export AWS_SECRET_ACCESS_KEY=test-secret-access-key
-          cd ../aws-sdk-swift/codegen
+          cd aws-sdk-swift/codegen
           swift test
 
diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 8aaa6c8b0..14d1049ca 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -8,6 +8,7 @@ on:
 
 jobs:
   ktlint:
+    if: github.repository == 'smithy-lang/smithy-swift' || github.event_name == 'pull_request'
     runs-on: ubuntu-latest
     steps:
       - name: Checkout sources
@@ -16,6 +17,7 @@ jobs:
         run: ./gradlew ktlint
 
   swiftlint:
+    if: github.repository == 'smithy-lang/smithy-swift' || github.event_name == 'pull_request'
     runs-on: ubuntu-latest
     container:
       image: ghcr.io/realm/swiftlint:0.54.0
diff --git a/.github/workflows/repo-sync.yml b/.github/workflows/repo-sync.yml
index 1d2923234..484f7ff57 100644
--- a/.github/workflows/repo-sync.yml
+++ b/.github/workflows/repo-sync.yml
@@ -1,22 +1,21 @@
-name: Sync Staging Repo
+name: Sync Mirror
 
 on:
   push:
-    branches:
-      - main
+    branches: [ main ]
   workflow_dispatch:
 
 jobs:
-  sync:
+  git-sync:
+    if: github.repository == 'smithy-lang/smithy-swift'
     runs-on: ubuntu-latest
+
     steps:
-      - name: Checkout smithy-swift
-        uses: actions/checkout@v4
+      - name: git-sync
+        uses: wei/git-sync@v3
         with:
-          ref: main
-      - name: Add staging repo as remote with token
-        run: |
-          git remote add staging-repo https://${{ secrets.REPO_SYNC_AUTOMATION_USER_TOKEN }}@github.com/awslabs/private-smithy-swift-staging.git
-      - name: Push changes to staging repo
-        run: |
-          git push staging-repo main
+          source_repo: ${{ secrets.GIT_SYNC_SOURCE_REPO }}
+          source_branch: "main"
+          destination_repo: ${{ secrets.GIT_SYNC_DESTINATION_REPO }}
+          destination_branch: "main"
+          destination_ssh_private_key:  ${{ secrets.GIT_SYNC_DESTINATION_SSH_PRIVATE_KEY }}
\ No newline at end of file
diff --git a/Package.version b/Package.version
index fe9209eda..557134bcd 100644
--- a/Package.version
+++ b/Package.version
@@ -1 +1 @@
-0.99.0
\ No newline at end of file
+0.106.0
\ No newline at end of file
diff --git a/Package.version.next b/Package.version.next
index fbd7ac6f8..2500dbc62 100644
--- a/Package.version.next
+++ b/Package.version.next
@@ -1 +1 @@
-0.100.0
\ No newline at end of file
+0.107.0
\ No newline at end of file
diff --git a/Sources/ClientRuntime/Networking/Http/CRT/SDKDefaultIO.swift b/Sources/ClientRuntime/Networking/Http/CRT/SDKDefaultIO.swift
index b6c38dc62..7ba17e9dd 100644
--- a/Sources/ClientRuntime/Networking/Http/CRT/SDKDefaultIO.swift
+++ b/Sources/ClientRuntime/Networking/Http/CRT/SDKDefaultIO.swift
@@ -16,15 +16,11 @@ public final class SDKDefaultIO: @unchecked Sendable {
     /// Provide singleton access since we want to share and re-use the instance properties
     public static let shared = SDKDefaultIO()
 
-    /// The setter for changing log level of SDKDefaultIO logger.
-    /// If any log level other than the default log level of `.none` is desired,
-    /// this setter needs to be called as the first thing in the program.
+    /// The public setter for setting log level of CRT logger.
+    ///
+    /// If any log level other than the default log level of `.none` is desired, this setter **MUST** be called before accessing the `SDKDefaultIO.shared` static field.
     public static func setLogLevel(level: LogLevel) {
-        do {
-            try Logger.initialize(target: .standardOutput, level: level)
-        } catch {
-            failOnLogger()
-        }
+        SDKDefaultIO.setupLogger(level: level)
     }
 
     private init() {
diff --git a/Sources/ClientRuntime/Telemetry/Logging/ClientLogMode.swift b/Sources/ClientRuntime/Telemetry/Logging/ClientLogMode.swift
index cc6e19bcd..18f9cf2aa 100644
--- a/Sources/ClientRuntime/Telemetry/Logging/ClientLogMode.swift
+++ b/Sources/ClientRuntime/Telemetry/Logging/ClientLogMode.swift
@@ -5,6 +5,7 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
+/// Additional logging opt-in for request / response flow. For each selected option other than `.none`, the additional info gets logged at `.debug` level by the `LoggingMiddleware`.
 public enum ClientLogMode {
     case none
     case request
diff --git a/Sources/ClientRuntime/Telemetry/Logging/LogLevel+StringExtension.swift b/Sources/ClientRuntime/Telemetry/Logging/LogLevel+StringExtension.swift
index b9760cc61..aeefc9879 100644
--- a/Sources/ClientRuntime/Telemetry/Logging/LogLevel+StringExtension.swift
+++ b/Sources/ClientRuntime/Telemetry/Logging/LogLevel+StringExtension.swift
@@ -5,6 +5,7 @@
 
 import AwsCommonRuntimeKit
 
+/// Extension for CRT's LogLevel enum
 extension LogLevel {
     public var stringValue: String {
         switch self {
diff --git a/Sources/ClientRuntime/Telemetry/Logging/SDKLogHandlerFactory.swift b/Sources/ClientRuntime/Telemetry/Logging/SDKLogHandlerFactory.swift
index 7f5e677d7..3935b1b68 100644
--- a/Sources/ClientRuntime/Telemetry/Logging/SDKLogHandlerFactory.swift
+++ b/Sources/ClientRuntime/Telemetry/Logging/SDKLogHandlerFactory.swift
@@ -7,6 +7,7 @@
 
 import Logging
 
+/// Implement this protocol and add an instance of the implementation to `SDKLoggingSystem` to use custom log handlers.
 public protocol SDKLogHandlerFactory {
     var label: String { get }
     func construct(label: String) -> LogHandler
diff --git a/Sources/ClientRuntime/Telemetry/Logging/SDKLogLevel.swift b/Sources/ClientRuntime/Telemetry/Logging/SDKLogLevel.swift
index 489ef26d1..6c5bf73c4 100644
--- a/Sources/ClientRuntime/Telemetry/Logging/SDKLogLevel.swift
+++ b/Sources/ClientRuntime/Telemetry/Logging/SDKLogLevel.swift
@@ -7,6 +7,7 @@
 
 import Logging
 
+/// Wrapper for Logger.Level; used by SDKLoggingSystem.
 public enum SDKLogLevel: String, Codable, CaseIterable {
     case trace
     case debug
diff --git a/Sources/ClientRuntime/Telemetry/Logging/SDKLoggingSystem.swift b/Sources/ClientRuntime/Telemetry/Logging/SDKLoggingSystem.swift
index fb73a1025..d60e17b5f 100644
--- a/Sources/ClientRuntime/Telemetry/Logging/SDKLoggingSystem.swift
+++ b/Sources/ClientRuntime/Telemetry/Logging/SDKLoggingSystem.swift
@@ -7,22 +7,35 @@
 
 import Logging
 
+/// Use this to turn SDK logging on.
 public actor SDKLoggingSystem {
     private var isInitialized = false
-    private var factories: [String: SDKLogHandlerFactory] = [:]
+    private var logHandlerFactories: [String: SDKLogHandlerFactory] = [:]
 
     public init() {}
 
+    /// Adds custom log handler factory to `this.logHandlerFactories`.
+    ///
+    /// The added log handler factory will be dedicated log handler for any logger with identical label.
     public func add(logHandlerFactory: SDKLogHandlerFactory) {
-        let label = logHandlerFactory.label
-        factories[label] = logHandlerFactory
+        logHandlerFactories[logHandlerFactory.label] = logHandlerFactory
     }
 
+    /// Initializes the logging handler factory for the SDK.
+    /// The default behavior is to log messages at `.error` or more severe levels.
+    ///
+    /// The handler factory closure first checks if there exists a custom handler factory in `this.logHandlerFactories` with the same label as the label given to logger initializer. If it exists, then that factory gets used to create the log handler.
+    ///
+    /// If no custom handler factory is found for the given label, the factory closure creates and returns a `StreamLogHandler` with minimum log level set to `logLevel`.
+    ///
+    /// Loggers output log only if the log level of the message is equal to or more severe than the underlying log handler's log level. E.g., `logger.info(...)` executes only if the underlying log handler's log level is `.info`, `.debug`, or `.trace`. It does not execute if the underlying log handler's minimum log level is any one of the following levels that are more severe than `.info`: `.notice`, `.warning`, `error`, `critical`.
+    ///
+    /// - parameters:
+    ///     - logLevel: The minimum log level to use for the log handler if no custom log handler factory was found. Default is `.error`.
     public func initialize(defaultLogLevel: SDKLogLevel = .error) async {
         if isInitialized { return } else { isInitialized = true }
-        let ptr = factories
-        LoggingSystem.bootstrap { label in
-            if let factory = ptr[label] {
+        LoggingSystem.bootstrap { [logHandlerFactories] label in
+            if let factory = logHandlerFactories[label] {
                 return factory.construct(label: label)
             }
             var handler = StreamLogHandler.standardOutput(label: label)
@@ -32,11 +45,6 @@ public actor SDKLoggingSystem {
     }
 
     public func initialize(logLevel: SDKLogLevel) async {
-        if isInitialized { return } else { isInitialized = true }
-        LoggingSystem.bootstrap { label in
-            var handler = StreamLogHandler.standardOutput(label: label)
-            handler.logLevel = logLevel.toLoggerType()
-            return handler
-        }
+        await self.initialize(defaultLogLevel: logLevel)
     }
 }
diff --git a/Sources/Smithy/Logging/LogAgent.swift b/Sources/Smithy/Logging/LogAgent.swift
index 02486ff7b..696e24ad3 100644
--- a/Sources/Smithy/Logging/LogAgent.swift
+++ b/Sources/Smithy/Logging/LogAgent.swift
@@ -9,9 +9,6 @@ public protocol LogAgent {
     /// name of the struct or class where the logger was instantiated from
     var name: String { get }
 
-    /// Get or set the configured log level.
-    var level: LogAgentLevel { get set }
-
     /// This method is called when a `LogAgent` must emit a log message.
     ///
     /// - parameters:
@@ -31,21 +28,33 @@ public protocol LogAgent {
              line: UInt)
 }
 
-public enum LogAgentLevel: String, Codable, CaseIterable {
-    case trace
-    case debug
-    case info
-    case warn
-    case error
-    case fatal
-}
-
+/// Convenience wrapper functions that call `self.log()` with corresponding log level.
 public extension LogAgent {
+    /// Use for messages that are typically seen during tracing.
+    func trace(
+        _ message: @autoclosure() -> String,
+        file: String = #fileID,
+        function: String = #function,
+        line: UInt = #line
+    ) {
+        self.log(level: .trace,
+                 message: message(),
+                 metadata: nil,
+                 source: currentModule(fileID: file),
+                 file: file,
+                 function: function,
+                 line: line)
+    }
 
-    /// Log a message passing with the `.info` log level.
-    func info(_ message: String, file: String = #fileID, function: String = #function, line: UInt = #line) {
-        self.log(level: .info,
-                 message: message,
+    /// Use for messages that are typically seen during debugging.
+    func debug(
+        _ message: @autoclosure() -> String,
+        file: String = #fileID,
+        function: String = #function,
+        line: UInt = #line
+    ) {
+        self.log(level: .debug,
+                 message: message(),
                  metadata: nil,
                  source: currentModule(fileID: file),
                  file: file,
@@ -53,10 +62,15 @@ public extension LogAgent {
                  line: line)
     }
 
-    /// Log a message passing with the `LogLevel.warn` log level.
-    func warn(_ message: String, file: String = #fileID, function: String = #function, line: UInt = #line) {
-        self.log(level: .warn,
-                 message: message,
+    /// Use for informational messages.
+    func info(
+        _ message: @autoclosure() -> String,
+        file: String = #fileID,
+        function: String = #function,
+        line: UInt = #line
+    ) {
+        self.log(level: .info,
+                 message: message(),
                  metadata: nil,
                  source: currentModule(fileID: file),
                  file: file,
@@ -64,10 +78,15 @@ public extension LogAgent {
                  line: line)
     }
 
-    /// Log a message passing with the `.debug` log level.
-    func debug(_ message: String, file: String = #fileID, function: String = #function, line: UInt = #line) {
-        self.log(level: .debug,
-                 message: message,
+    /// Use for non-error messages that may need special attention.
+    func notice(
+        _ message: @autoclosure() -> String,
+        file: String = #fileID,
+        function: String = #function,
+        line: UInt = #line
+    ) {
+        self.log(level: .notice,
+                 message: message(),
                  metadata: nil,
                  source: currentModule(fileID: file),
                  file: file,
@@ -75,10 +94,15 @@ public extension LogAgent {
                  line: line)
     }
 
-    /// Log a message passing with the `.error` log level.
-    func error(_ message: String, file: String = #fileID, function: String = #function, line: UInt = #line) {
-        self.log(level: .error,
-                 message: message,
+    /// Use for non-error messages that are more severe than `.notice`.
+    func warn(
+        _ message: @autoclosure() -> String,
+        file: String = #fileID,
+        function: String = #function,
+        line: UInt = #line
+    ) {
+        self.log(level: .warn,
+                 message: message(),
                  metadata: nil,
                  source: currentModule(fileID: file),
                  file: file,
@@ -86,10 +110,15 @@ public extension LogAgent {
                  line: line)
     }
 
-    /// Log a message passing with the `.trace` log level.
-    func trace(_ message: String, file: String = #fileID, function: String = #function, line: UInt = #line) {
-        self.log(level: .trace,
-                 message: message,
+    /// Use for errors.
+    func error(
+        _ message: @autoclosure() -> String,
+        file: String = #fileID,
+        function: String = #function,
+        line: UInt = #line
+    ) {
+        self.log(level: .error,
+                 message: message(),
                  metadata: nil,
                  source: currentModule(fileID: file),
                  file: file,
@@ -97,10 +126,16 @@ public extension LogAgent {
                  line: line)
     }
 
-    /// Log a message passing with the `.fatal` log level.
-    func fatal(_ message: String, file: String = #fileID, function: String = #function, line: UInt = #line) {
+    /// Appropriate for critical error conditions that usually require immediate
+    /// attention.
+    func fatal(
+        _ message: @autoclosure() -> String,
+        file: String = #fileID,
+        function: String = #function,
+        line: UInt = #line
+    ) {
         self.log(level: .fatal,
-                 message: message,
+                 message: message(),
                  metadata: nil,
                  source: currentModule(fileID: file),
                  file: file,
diff --git a/Sources/Smithy/Logging/LogAgentLevel.swift b/Sources/Smithy/Logging/LogAgentLevel.swift
new file mode 100644
index 000000000..85a76e903
--- /dev/null
+++ b/Sources/Smithy/Logging/LogAgentLevel.swift
@@ -0,0 +1,38 @@
+//
+// Copyright Amazon.com Inc. or its affiliates.
+// All Rights Reserved.
+//
+// SPDX-License-Identifier: Apache-2.0
+//
+
+import Logging
+
+/// Wrapper for Logger.Level; used by LogAgent and SwiftLogger.
+public enum LogAgentLevel: String, Codable, CaseIterable {
+    case trace
+    case debug
+    case info
+    case notice
+    case warn
+    case error
+    case fatal
+
+    func toLoggerLevel() -> Logger.Level {
+        switch self {
+        case .trace:
+            return .trace
+        case .debug:
+            return .debug
+        case .info:
+            return .info
+        case .notice:
+            return .notice
+        case .warn:
+            return .warning
+        case .error:
+            return .error
+        case .fatal:
+            return .critical
+        }
+    }
+}
diff --git a/Sources/Smithy/Logging/SwiftLog+LogAgent.swift b/Sources/Smithy/Logging/SwiftLog+LogAgent.swift
index 83cc2ff1c..f99abacba 100644
--- a/Sources/Smithy/Logging/SwiftLog+LogAgent.swift
+++ b/Sources/Smithy/Logging/SwiftLog+LogAgent.swift
@@ -8,27 +8,22 @@
 import Logging
 
 public struct SwiftLogger: LogAgent {
-    public var level: LogAgentLevel
-
     private let logger: Logger
     private let label: String
 
     public init(label: String) {
         self.label = label
         self.logger = Logger(label: label)
-        self.level = LogAgentLevel.info
     }
 
+    @available(*, deprecated, message: "This API is deprecated. Use init(label:) instead.")
     public init(label: String, logLevel: LogAgentLevel) {
-        self.label = label
-        self.logger = Logger(label: label)
-        self.level = logLevel
+        self.init(label: label)
     }
 
     // This initializer is currently only used in tests, to inject a mock LogHandler.
-    init(label: String, logLevel: LogAgentLevel, factory: (String) -> any LogHandler) {
+    init(label: String, factory: (String) -> any LogHandler) {
         self.label = label
-        self.level = logLevel
         self.logger = Logger(label: label, factory: factory)
     }
 
@@ -56,23 +51,3 @@ public struct SwiftLogger: LogAgent {
         )
     }
 }
-
-extension LogAgentLevel {
-
-    func toLoggerLevel() -> Logger.Level {
-        switch self {
-        case .trace:
-            return .trace
-        case .debug:
-            return .debug
-        case .info:
-            return .info
-        case .warn:
-            return .warning
-        case .error:
-            return .error
-        case .fatal:
-            return .critical
-        }
-    }
-}
diff --git a/Sources/SmithyHTTPAPI/HTTPResponse.swift b/Sources/SmithyHTTPAPI/HTTPResponse.swift
index 0840d9990..20e430c1e 100644
--- a/Sources/SmithyHTTPAPI/HTTPResponse.swift
+++ b/Sources/SmithyHTTPAPI/HTTPResponse.swift
@@ -8,43 +8,48 @@
 import protocol Smithy.ResponseMessage
 import protocol Smithy.Stream
 import enum Smithy.ByteStream
-import class Foundation.DispatchQueue
+import class Foundation.NSRecursiveLock
 
-public class HTTPResponse: HTTPURLResponse, ResponseMessage {
+public final class HTTPResponse: ResponseMessage, @unchecked Sendable {
+    private var lock = NSRecursiveLock()
 
-    public var headers: Headers
-    public var body: ByteStream
-    public var reason: String?
+    private var _headers: Headers
+    public var headers: Headers {
+        get { lock.lock(); defer { lock.unlock() }; return _headers }
+        set { lock.lock(); defer { lock.unlock() }; self._headers = newValue }
+    }
+
+    private var _body: ByteStream
+    public var body: ByteStream {
+        get { lock.lock(); defer { lock.unlock() }; return _body }
+        set { lock.lock(); defer { lock.unlock() }; self._body = newValue }
+    }
 
     private var _statusCode: HTTPStatusCode
-    private let statusCodeQueue = DispatchQueue(label: "statusCodeSerialQueue")
     public var statusCode: HTTPStatusCode {
-        get {
-            statusCodeQueue.sync {
-                return _statusCode
-            }
-        }
-        set {
-            statusCodeQueue.sync {
-                self._statusCode = newValue
-            }
-        }
+        get { lock.lock(); defer { lock.unlock() }; return _statusCode }
+        set { lock.lock(); defer { lock.unlock() }; self._statusCode = newValue }
     }
 
+    public let reason: String?
+
     public init(
         headers: Headers = .init(),
         statusCode: HTTPStatusCode = .processing,
         body: ByteStream = .noStream,
-        reason: String? = nil) {
-        self.headers = headers
+        reason: String? = nil
+    ) {
+        self._headers = headers
         self._statusCode = statusCode
-        self.body = body
+        self._body = body
+        self.reason = reason
     }
 
     public init(headers: Headers = .init(), body: ByteStream, statusCode: HTTPStatusCode, reason: String? = nil) {
-        self.body = body
+        self._body = body
         self._statusCode = statusCode
-        self.headers = headers
+        self._headers = headers
+        self.reason = reason
     }
 
     /**
diff --git a/Sources/SmithyHTTPAPI/HTTPURLResponse.swift b/Sources/SmithyHTTPAPI/HTTPURLResponse.swift
deleted file mode 100644
index 3498db019..000000000
--- a/Sources/SmithyHTTPAPI/HTTPURLResponse.swift
+++ /dev/null
@@ -1,15 +0,0 @@
-//
-// Copyright Amazon.com Inc. or its affiliates.
-// All Rights Reserved.
-//
-// SPDX-License-Identifier: Apache-2.0
-//
-
-import enum Smithy.ByteStream
-
-protocol HTTPURLResponse {
-    var headers: Headers { get set }
-    var body: ByteStream { get set }
-    var statusCode: HTTPStatusCode { get set }
-    var reason: String? { get set }
-}
diff --git a/Sources/SmithyHTTPAPI/Headers.swift b/Sources/SmithyHTTPAPI/Headers.swift
index 6358ecc6f..bf9100359 100644
--- a/Sources/SmithyHTTPAPI/Headers.swift
+++ b/Sources/SmithyHTTPAPI/Headers.swift
@@ -5,8 +5,28 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
-public struct Headers: Sendable {
-    public var headers: [Header] = []
+import class Foundation.NSRecursiveLock
+
+public struct Headers: @unchecked Sendable {
+    private let lock = NSRecursiveLock()
+
+    private var _headers: [Header] = []
+    public var headers: [Header] {
+        get { access { $0 } }
+        set { mutate { $0 = newValue } }
+    }
+
+    private mutating func mutate(_ block: (inout [Header]) -> Void) {
+        lock.lock()
+        defer { lock.unlock() }
+        block(&_headers)
+    }
+
+    private func access<T>(_ block: ([Header]) throws -> T) rethrows -> T {
+        lock.lock()
+        defer { lock.unlock() }
+        return try block(_headers)
+    }
 
     /// Creates an empty instance.
     public init() {}
@@ -53,11 +73,13 @@ public struct Headers: Sendable {
     /// - Parameters:
     ///   - header:  The `Header` to be added or updated.
     public mutating func add(_ header: Header) {
-        guard let index = headers.index(of: header.name) else {
-            headers.append(header)
-            return
+        mutate { headers in
+            guard let index = headers.index(of: header.name) else {
+                headers.append(header)
+                return
+            }
+            headers[index].value.append(contentsOf: header.value)
         }
-        headers[index].value.append(contentsOf: header.value)
     }
 
     /// Case-insensitively updates the value of a `Header` by replacing the values of it or appends a `Header`
@@ -66,11 +88,13 @@ public struct Headers: Sendable {
     /// - Parameters:
     ///   - header:  The `Header` to be added or updated.
     public mutating func update(_ header: Header) {
-        guard let index = headers.index(of: header.name) else {
-            headers.append(header)
-            return
+        mutate { headers in
+            guard let index = headers.index(of: header.name) else {
+                headers.append(header)
+                return
+            }
+            headers.replaceSubrange(index...index, with: [header])
         }
-        headers.replaceSubrange(index...index, with: [header])
     }
 
     /// Case-insensitively updates the value of a `Header` by replacing the values of it or appends a `Header`
@@ -97,17 +121,20 @@ public struct Headers: Sendable {
     ///
     /// - Parameters:
     ///   - headers:  The `Headers` object.
-    public mutating func addAll(headers: Headers) {
-        self.headers.append(contentsOf: headers.headers)
+    public mutating func addAll(headers otherHeaders: Headers) {
+        mutate { headers in
+            headers.append(contentsOf: otherHeaders.headers)
+        }
     }
 
     /// Case-insensitively removes a `Header`, if it exists, from the instance.
     ///
     /// - Parameter name: The name of the `HTTPHeader` to remove.
     public mutating func remove(name: String) {
-        guard let index = headers.index(of: name) else { return }
-
-        headers.remove(at: index)
+        mutate { headers in
+            guard let index = headers.index(of: name) else { return }
+            headers.remove(at: index)
+        }
     }
 
     /// Case-insensitively find a header's values by name.
@@ -116,13 +143,14 @@ public struct Headers: Sendable {
     ///
     /// - Returns: The values of the header, if they exist.
     public func values(for name: String) -> [String]? {
-        guard let indices = headers.indices(of: name), !indices.isEmpty else { return nil }
-        var values = [String]()
-        for index in indices {
-            values.append(contentsOf: headers[index].value)
+        access { headers in
+            guard let indices = headers.indices(of: name), !indices.isEmpty else { return nil }
+            var values = [String]()
+            for index in indices {
+                values.append(contentsOf: headers[index].value)
+            }
+            return values
         }
-
-        return values
     }
 
     /// Case-insensitively find a header's value by name.
@@ -131,29 +159,28 @@ public struct Headers: Sendable {
     ///
     /// - Returns: The value of header as a comma delimited string, if it exists.
     public func value(for name: String) -> String? {
-        guard let values = values(for: name) else {
-            return nil
-        }
+        guard let values = values(for: name) else { return nil }
         return values.joined(separator: ",")
     }
 
     public func exists(name: String) -> Bool {
-        headers.index(of: name) != nil
+        access { $0.index(of: name) != nil }
     }
 
     /// The dictionary representation of all headers.
     ///
     /// This representation does not preserve the current order of the instance.
     public var dictionary: [String: [String]] {
-        let namesAndValues = headers.map { ($0.name, $0.value) }
-
-        return Dictionary(namesAndValues) { (first, last) -> [String] in
-            return first + last
+        access { headers in
+            let namesAndValues = headers.map { ($0.name, $0.value) }
+            return Dictionary(namesAndValues) { (first, last) -> [String] in
+                first + last
+            }
         }
     }
 
     public var isEmpty: Bool {
-        return self.headers.isEmpty
+        access { $0.isEmpty }
     }
 }
 
@@ -164,14 +191,18 @@ extension Headers: Equatable {
     ///   - rhs: The second `Headers` to compare.
     /// - Returns: `true` if the two values are equal irrespective of order, otherwise `false`.
     public static func == (lhs: Headers, rhs: Headers) -> Bool {
-        return lhs.headers.sorted() == rhs.headers.sorted()
+        lhs.access { lhsHeaders in
+            rhs.access { rhsHeaders in
+                lhsHeaders.sorted() == rhsHeaders.sorted()
+            }
+        }
     }
 }
 
 extension Headers: Hashable {
 
     public func hash(into hasher: inout Hasher) {
-        hasher.combine(headers.sorted())
+        access { hasher.combine($0.sorted()) }
     }
 }
 
diff --git a/Tests/ClientRuntimeTests/LoggingTests/SwiftLoggerTests.swift b/Tests/ClientRuntimeTests/LoggingTests/SwiftLoggerTests.swift
index 02b167d88..a9b3ae478 100644
--- a/Tests/ClientRuntimeTests/LoggingTests/SwiftLoggerTests.swift
+++ b/Tests/ClientRuntimeTests/LoggingTests/SwiftLoggerTests.swift
@@ -38,7 +38,7 @@ final class SwiftLoggerTests: XCTestCase {
 
     private func logsLeveledMessage(
         logLevel: Logger.Level,
-        loggerBlock: (SwiftLogger) -> (String, String, String, UInt) -> Void,
+        loggerBlock: (SwiftLogger) -> (@autoclosure() -> String, String, String, UInt) -> Void,
         testFile: StaticString = #filePath,
         testLine: UInt = #line
     ) throws {
@@ -53,7 +53,7 @@ final class SwiftLoggerTests: XCTestCase {
         // Create a TestLogHandler, then create a SwiftLogger (the test subject)
         // with it.
         var logHandler: TestLogHandler!
-        let subject = SwiftLogger(label: "Test", logLevel: .trace, factory: { label in
+        let subject = SwiftLogger(label: "Test", factory: { label in
             logHandler = TestLogHandler(label: label)
             return logHandler
         })
diff --git a/Tests/ClientRuntimeTests/NetworkingTests/URLSession/FoundationStreamBridgeTests.swift b/Tests/ClientRuntimeTests/NetworkingTests/URLSession/FoundationStreamBridgeTests.swift
index 7bf46b480..d86f84bf3 100644
--- a/Tests/ClientRuntimeTests/NetworkingTests/URLSession/FoundationStreamBridgeTests.swift
+++ b/Tests/ClientRuntimeTests/NetworkingTests/URLSession/FoundationStreamBridgeTests.swift
@@ -109,12 +109,9 @@ private class TestLogger: LogAgent {
 
     var messages: [(level: LogAgentLevel, message: String)] = []
 
-    var level: LogAgentLevel
-
     init(name: String = "Test", messages: [(level: LogAgentLevel, message: String)] = [], level: LogAgentLevel = .info) {
         self.name = name
         self.messages = messages
-        self.level = level
     }
 
     func log(level: LogAgentLevel = .info, message: @autoclosure () -> String, metadata: @autoclosure () -> [String : String]? = nil, source: @autoclosure () -> String = "ChecksumUnitTests", file: String = #file, function: String = #function, line: UInt = #line) {
diff --git a/gradle.properties b/gradle.properties
index 0fddf21da..d6f7479d7 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -3,7 +3,7 @@ kotlin.code.style=official
 # config
 
 # codegen
-smithyVersion=1.52.1
+smithyVersion=1.53.0
 smithyGradleVersion=0.6.0
 
 # kotlin
diff --git a/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/ShapeValueGenerator.kt b/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/ShapeValueGenerator.kt
index 673da8e55..e5b7ec7ed 100644
--- a/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/ShapeValueGenerator.kt
+++ b/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/ShapeValueGenerator.kt
@@ -28,6 +28,7 @@ import software.amazon.smithy.model.traits.EnumTrait
 import software.amazon.smithy.model.traits.StreamingTrait
 import software.amazon.smithy.swift.codegen.model.hasTrait
 import software.amazon.smithy.swift.codegen.model.toMemberNames
+import software.amazon.smithy.swift.codegen.swiftmodules.FoundationTypes
 import software.amazon.smithy.swift.codegen.swiftmodules.SmithyStreamsTypes
 import software.amazon.smithy.swift.codegen.swiftmodules.SmithyTimestampsTypes
 import software.amazon.smithy.swift.codegen.swiftmodules.SmithyTypes
@@ -160,11 +161,12 @@ class ShapeValueGenerator(
             }
             ShapeType.BLOB -> {
                 if (shape.hasTrait<StreamingTrait>()) {
-                    writer.writeInline(".stream(\$N(data: ", SmithyStreamsTypes.Core.BufferedStream)
-                    ".data(using: .utf8)!, isClosed: true))"
+                    writer.writeInline(".stream(\$N(data: \$N(", SmithyStreamsTypes.Core.BufferedStream, FoundationTypes.Data)
+                    ".utf8), isClosed: true))"
                 } else {
                     // TODO: properly handle this optional with an unwrapped statement before it's passed as a value to a shape.
-                    ".data(using: .utf8)!"
+                    writer.writeInline("\$N(", FoundationTypes.Data)
+                    ".utf8)"
                 }
             }
             else -> { "" }
diff --git a/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/StructureGenerator.kt b/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/StructureGenerator.kt
index d11d00fd2..88dcd287b 100644
--- a/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/StructureGenerator.kt
+++ b/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/StructureGenerator.kt
@@ -215,10 +215,11 @@ class StructureGenerator(
 
         writer.writeAvailableAttribute(model, shape)
         writer.openBlock(
-            "public struct \$struct.name:L: \$N, \$error.protocol:N, \$N, \$N {",
+            "public struct \$struct.name:L: \$N, \$error.protocol:N, \$N, \$N, \$N {",
             ClientRuntimeTypes.Core.ModeledError,
             ClientRuntimeTypes.Http.HttpError,
-            SwiftTypes.Error
+            SwiftTypes.Error,
+            SwiftTypes.Protocols.Sendable,
         )
             .call { generateErrorStructMembers() }
             .write("")
@@ -234,7 +235,7 @@ class StructureGenerator(
     private fun generateErrorStructMembers() {
         if (membersSortedByName.isNotEmpty()) {
             writer.write("")
-            writer.openBlock("public struct Properties {", "}") {
+            writer.openBlock("public struct Properties: \$N {", "}", SwiftTypes.Protocols.Sendable) {
                 membersSortedByName.forEach {
                     val (memberName, memberSymbol) = memberShapeDataContainer.getOrElse(it) { return@forEach }
                     writer.writeMemberDocs(model, it)
diff --git a/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/SwiftSymbolProvider.kt b/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/SwiftSymbolProvider.kt
index a1234bd82..4942e639b 100644
--- a/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/SwiftSymbolProvider.kt
+++ b/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/SwiftSymbolProvider.kt
@@ -380,14 +380,14 @@ class SwiftSymbolProvider(private val model: Model, val swiftSettings: SwiftSett
             if (shape.hasTrait<StreamingTrait>()) {
                 { writer ->
                     writer.format(
-                        "\$N.data(\$N(\"$literal\".utf8))",
+                        "\$N.data(\$N(base64Encoded: \"$literal\"))",
                         SmithyTypes.ByteStream,
                         FoundationTypes.Data
                     )
                 }
             } else {
                 { writer ->
-                    writer.format("\$N(\"$literal\".utf8)", FoundationTypes.Data)
+                    writer.format("\$N(base64Encoded: \"$literal\")", FoundationTypes.Data)
                 }
             }
         )
diff --git a/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/integration/serde/member/MemberShapeDecodeGenerator.kt b/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/integration/serde/member/MemberShapeDecodeGenerator.kt
index 510c1cd6b..e0bbde818 100644
--- a/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/integration/serde/member/MemberShapeDecodeGenerator.kt
+++ b/smithy-swift-codegen/src/main/kotlin/software/amazon/smithy/swift/codegen/integration/serde/member/MemberShapeDecodeGenerator.kt
@@ -243,14 +243,16 @@ open class MemberShapeDecodeGenerator(
         writer.addImport(FoundationTypes.Data)
         return if (targetShape.hasTrait<StreamingTrait>()) {
             writer.format(
-                " ?? \$N.data(\$N(\"$value\".utf8))",
+                " ?? \$N.data(\$N(base64Encoded: \$S))",
                 SmithyTypes.ByteStream,
-                FoundationTypes.Data
+                FoundationTypes.Data,
+                value,
             )
         } else {
             writer.format(
-                " ?? \$N(\"$value\".utf8)",
-                FoundationTypes.Data
+                " ?? \$N(base64Encoded: \$S)",
+                FoundationTypes.Data,
+                value,
             )
         }
     }
diff --git a/smithy-swift-codegen/src/test/kotlin/software/amazon/smithy/swift/codegen/basicshapes/StructureGeneratorTests.kt b/smithy-swift-codegen/src/test/kotlin/software/amazon/smithy/swift/codegen/basicshapes/StructureGeneratorTests.kt
index 536949b6b..8a21ba2f7 100644
--- a/smithy-swift-codegen/src/test/kotlin/software/amazon/smithy/swift/codegen/basicshapes/StructureGeneratorTests.kt
+++ b/smithy-swift-codegen/src/test/kotlin/software/amazon/smithy/swift/codegen/basicshapes/StructureGeneratorTests.kt
@@ -262,9 +262,9 @@ public struct RecursiveShapesInputOutputLists: Swift.Sendable {
 
         contents.shouldContain(swiftSettings.copyrightNotice)
         val expectedGeneratedStructure = """
-public struct MyError: ClientRuntime.ModeledError, ClientRuntime.ServiceError, ClientRuntime.HTTPError, Swift.Error {
+public struct MyError: ClientRuntime.ModeledError, ClientRuntime.ServiceError, ClientRuntime.HTTPError, Swift.Error, Swift.Sendable {
 
-    public struct Properties {
+    public struct Properties: Swift.Sendable {
         /// This is documentation about the member.
         public internal(set) var baz: Swift.Int? = nil
         public internal(set) var message: Swift.String? = nil