diff --git a/.github/actions/run-alpine-tests/action.yml b/.github/actions/run-alpine-tests/action.yml
new file mode 100644
index 0000000000..610cdb37a6
--- /dev/null
+++ b/.github/actions/run-alpine-tests/action.yml
@@ -0,0 +1,65 @@
+name: "Run Alpine SDK Tests"
+description: "Run an SDK test command in an ARM64 Alpine container."
+inputs:
+  image:
+    description: "Container image used to run the tests."
+    required: true
+  workdir:
+    description: "Working directory inside the container."
+    required: true
+  transport:
+    description: "SDK transport to test: default or inprocess."
+    required: true
+  command:
+    description: "Language-specific setup and test command."
+    required: true
+runs:
+  using: "composite"
+  steps:
+    - name: Run ${{ inputs.transport }} tests in Alpine
+      shell: bash
+      env:
+        ALPINE_TEST_COMMAND: ${{ inputs.command }}
+        ALPINE_TEST_IMAGE: ${{ inputs.image }}
+        ALPINE_TEST_TRANSPORT: ${{ inputs.transport }}
+        ALPINE_TEST_WORKDIR: ${{ inputs.workdir }}
+      run: |
+        script_path=$(mktemp "$RUNNER_TEMP/copilot-sdk-alpine-test.XXXXXX")
+        trap 'rm -f "$script_path"' EXIT
+        cat > "$script_path" <<'SCRIPT'
+        #!/bin/sh
+        set -eux
+
+        apk add --no-cache bash git
+        git config --global --add safe.directory "$GITHUB_WORKSPACE"
+
+        test "$(uname -m)" = "aarch64"
+        ldd --version 2>&1 | grep -qi musl
+
+        case "$COPILOT_SDK_TEST_TRANSPORT" in
+          inprocess) export COPILOT_SDK_DEFAULT_CONNECTION=inprocess ;;
+          default) unset COPILOT_SDK_DEFAULT_CONNECTION ;;
+          *) echo "Unknown transport: $COPILOT_SDK_TEST_TRANSPORT" >&2; exit 1 ;;
+        esac
+        SCRIPT
+        printf '%s\n' "$ALPINE_TEST_COMMAND" >> "$script_path"
+        chmod +x "$script_path"
+
+        docker run --rm \
+          --platform linux/arm64 \
+          --volume "$GITHUB_WORKSPACE:/workspace" \
+          --volume "$script_path:/tmp/copilot-sdk-alpine-test.sh:ro" \
+          --workdir "$ALPINE_TEST_WORKDIR" \
+          --env CI=true \
+          --env GITHUB_ACTIONS=true \
+          --env GITHUB_WORKSPACE=/workspace \
+          --env COPILOT_HMAC_KEY \
+          --env COPILOT_SDK_E2E_BACKEND \
+          --env BUNDLED_CLI_CACHE_DIR \
+          --env CARGO_TERM_COLOR \
+          --env RUST_BACKTRACE \
+          --env RUSTDOCFLAGS \
+          --env RUSTFLAGS \
+          --env COPILOT_SDK_TEST_TRANSPORT="$ALPINE_TEST_TRANSPORT" \
+          "$ALPINE_TEST_IMAGE" \
+          /bin/sh /tmp/copilot-sdk-alpine-test.sh
diff --git a/.github/workflows/dotnet-sdk-tests.yml b/.github/workflows/dotnet-sdk-tests.yml
index 9b7216ad20..b49c6e33e7 100644
--- a/.github/workflows/dotnet-sdk-tests.yml
+++ b/.github/workflows/dotnet-sdk-tests.yml
@@ -349,3 +349,56 @@ jobs:
           path: dotnet/TestResults/
           if-no-files-found: warn
           retention-days: 7
+
+  # JavaScript actions use a glibc-linked Node runtime, so Alpine runs through Docker.
+  alpine-arm64:
+    name: ".NET SDK Tests (Alpine ARM64, ${{ matrix.transport }}, CAPI)"
+    if: github.event.repository.fork == false
+    runs-on: ubuntu-24.04-arm
+    timeout-minutes: 20
+    env:
+      COPILOT_SDK_E2E_BACKEND: capi
+    strategy:
+      fail-fast: false
+      matrix:
+        transport: ["default", "inprocess"]
+    steps:
+      - uses: actions/checkout@v6.0.2
+
+      - name: Run ${{ matrix.transport }} tests on ARM64 Alpine
+        uses: ./.github/actions/run-alpine-tests
+        env:
+          COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
+        with:
+          image: mcr.microsoft.com/dotnet/sdk:10.0-alpine
+          workdir: /workspace
+          transport: ${{ matrix.transport }}
+          command: |
+            dotnet --info | grep -Eq "RID:[[:space:]]+linux-musl-arm64"
+
+            apk add --no-cache nodejs npm
+            (cd nodejs && npm ci --ignore-scripts)
+            (cd test/harness && npm ci --ignore-scripts)
+
+            export DOTNET_ROLL_FORWARD=Major
+            dotnet restore dotnet/test/GitHub.Copilot.SDK.Test.csproj
+
+            dotnet test dotnet/test/GitHub.Copilot.SDK.Test.csproj \
+              --no-restore \
+              --framework net8.0 \
+              -v n \
+              --blame-hang \
+              --blame-hang-timeout 10m \
+              --blame-hang-dump-type none \
+              --logger "trx;LogFilePrefix=test-results" \
+              --results-directory /workspace/dotnet/TestResults \
+              -p:RunAnalyzers=false
+
+      - name: Upload .NET test diagnostics
+        if: failure()
+        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
+        with:
+          name: dotnet-test-diagnostics-alpine-arm64-${{ matrix.transport }}-capi-${{ github.run_attempt }}
+          path: dotnet/TestResults/
+          if-no-files-found: warn
+          retention-days: 7
diff --git a/.github/workflows/go-sdk-tests.yml b/.github/workflows/go-sdk-tests.yml
index 4fb6fd0184..5f06016c3b 100644
--- a/.github/workflows/go-sdk-tests.yml
+++ b/.github/workflows/go-sdk-tests.yml
@@ -8,17 +8,10 @@ permissions:
   contents: read
 
 jobs:
-  test:
-    name: "Go SDK Tests (${{ matrix.os }}, ${{ matrix.transport }})"
+  validate:
+    name: "Go SDK Format and Lint"
     if: github.event.repository.fork == false
-    env:
-      POWERSHELL_UPDATECHECK: Off
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
-        transport: ["default", "inprocess"]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
     timeout-minutes: 20
     defaults:
       run:
@@ -26,15 +19,10 @@ jobs:
         working-directory: ./go
     steps:
       - uses: actions/checkout@v6.0.2
-      - uses: ./.github/actions/setup-copilot
-        id: setup-copilot
       - uses: actions/setup-go@v6
         with:
           go-version: "1.24"
-
       - name: Run go fmt
-        if: runner.os == 'Linux'
-        working-directory: ./go
         run: |
           go fmt ./...
           if [ -n "$(git status --porcelain)" ]; then
@@ -43,15 +31,37 @@ jobs:
             exit 1
           fi
           echo "✅ go fmt produced no changes"
-
       - name: Install golangci-lint
-        if: runner.os == 'Linux'
         uses: golangci/golangci-lint-action@v9
         with:
           working-directory: ./go
           version: latest
           args: --timeout=5m
 
+  test:
+    name: "Go SDK Tests (${{ matrix.os }}, ${{ matrix.transport }})"
+    if: github.event.repository.fork == false
+    env:
+      POWERSHELL_UPDATECHECK: Off
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        transport: ["default", "inprocess"]
+    runs-on: ${{ matrix.os }}
+    timeout-minutes: 20
+    defaults:
+      run:
+        shell: bash
+        working-directory: ./go
+    steps:
+      - uses: actions/checkout@v6.0.2
+      - uses: ./.github/actions/setup-copilot
+        id: setup-copilot
+      - uses: actions/setup-go@v6
+        with:
+          go-version: "1.24"
+
       - name: Install test harness dependencies
         working-directory: ./test/harness
         run: npm ci --ignore-scripts
@@ -71,3 +81,51 @@ jobs:
           COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
           COPILOT_CLI_PATH: ${{ steps.setup-copilot.outputs.cli-path }}
         run: /bin/bash test.sh
+
+  # JavaScript actions use a glibc-linked Node runtime, so Alpine runs through Docker.
+  test-musl-arm64:
+    name: "Go SDK Tests (Alpine ARM64, ${{ matrix.transport }})"
+    if: github.event.repository.fork == false
+    runs-on: ubuntu-24.04-arm
+    timeout-minutes: 20
+    strategy:
+      fail-fast: false
+      matrix:
+        transport: ["default", "inprocess"]
+    steps:
+      - uses: actions/checkout@v6.0.2
+
+      - name: Run Go SDK tests on musl ARM64 (${{ matrix.transport }})
+        uses: ./.github/actions/run-alpine-tests
+        env:
+          COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
+        with:
+          image: golang:1.24-alpine
+          workdir: /workspace
+          transport: ${{ matrix.transport }}
+          command: |
+            apk add --no-cache build-base nodejs npm
+            npm --prefix nodejs ci --ignore-scripts
+            npm --prefix test/harness ci --ignore-scripts
+            runtime_path="$(npm --prefix nodejs run --silent prepare:runtime -- --print-path)"
+            case "$runtime_path" in
+              */prebuilds/linuxmusl-arm64/copilot-runtime) ;;
+              *)
+                echo "Expected the linuxmusl-arm64 runtime bundle, got: $runtime_path" >&2
+                exit 1
+                ;;
+            esac
+            test -x "$runtime_path"
+            test -f "$(dirname "$runtime_path")/runtime.node"
+
+            export COPILOT_CLI_PATH="$runtime_path"
+            if [ "$COPILOT_SDK_TEST_TRANSPORT" = "inprocess" ]; then
+              export GOFLAGS="-tags=copilot_inprocess"
+            else
+              unset GOFLAGS
+            fi
+            export CGO_ENABLED=1
+            test "$(go env GOARCH)" = "arm64"
+            test "$(go env CGO_ENABLED)" = "1"
+            cd go
+            /bin/bash test.sh
diff --git a/.github/workflows/nodejs-sdk-tests.yml b/.github/workflows/nodejs-sdk-tests.yml
index 894f3b5d0d..c7674d5809 100644
--- a/.github/workflows/nodejs-sdk-tests.yml
+++ b/.github/workflows/nodejs-sdk-tests.yml
@@ -11,17 +11,11 @@ permissions:
   contents: read
 
 jobs:
-  test:
-    name: "Node.js SDK Tests (${{ matrix.os }}, ${{ matrix.transport }})"
+  validate:
+    name: "Node.js SDK Build and Validation"
     if: github.event.repository.fork == false
-    env:
-      POWERSHELL_UPDATECHECK: Off
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ubuntu-latest, macos-latest, windows-latest]
-        transport: ["default", "inprocess"]
-    runs-on: ${{ matrix.os }}
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
     defaults:
       run:
         shell: bash
@@ -35,35 +29,57 @@ jobs:
           node-version: 22
       - name: Install dependencies
         run: npm ci --ignore-scripts
-
       - name: Run prettier check
-        if: runner.os == 'Linux'
         run: npm run format:check
-
       - name: Run ESLint
         run: npm run lint
-
       - name: Typecheck SDK
         run: npm run typecheck
-
       - name: Build SDK
         run: npm run build
-
       - name: Build and verify release packages
-        if: runner.os == 'Linux' && matrix.transport == 'default'
         run: |
           npm run pack:release
           npm run verify:release-packages
-
       - name: Install test harness dependencies
         working-directory: ./test/harness
         run: npm ci --ignore-scripts
-
       - name: Run test harness tests
-        if: runner.os == 'Linux' && matrix.transport == 'default'
         working-directory: ./test/harness
         run: npm test
 
+  test:
+    name: "Node.js SDK Tests (${{ matrix.os }}, ${{ matrix.transport }})"
+    if: github.event.repository.fork == false
+    env:
+      POWERSHELL_UPDATECHECK: Off
+    strategy:
+      fail-fast: false
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        transport: ["default", "inprocess"]
+    runs-on: ${{ matrix.os }}
+    defaults:
+      run:
+        shell: bash
+        working-directory: ./nodejs
+    steps:
+      - uses: actions/checkout@v6.0.2
+      - uses: actions/setup-node@v6
+        with:
+          cache: "npm"
+          cache-dependency-path: "./nodejs/package-lock.json"
+          node-version: 22
+      - name: Install dependencies
+        run: npm ci --ignore-scripts
+
+      - name: Build SDK
+        run: npm run build
+
+      - name: Install test harness dependencies
+        working-directory: ./test/harness
+        run: npm ci --ignore-scripts
+
       - name: Prepare Copilot CLI runtime
         run: |
           runtime_path=$(npm run --silent prepare:runtime -- --print-path)
@@ -82,3 +98,40 @@ jobs:
         env:
           COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
         run: npm test
+
+  # JavaScript actions use a glibc-linked Node runtime, so Alpine runs through Docker.
+  test-musl-arm64:
+    name: "Node.js SDK Tests (Alpine ARM64, ${{ matrix.transport }})"
+    if: github.event.repository.fork == false
+    runs-on: ubuntu-24.04-arm
+    strategy:
+      fail-fast: false
+      matrix:
+        transport: ["default", "inprocess"]
+    steps:
+      - uses: actions/checkout@v6.0.2
+      - name: Run Alpine ARM64 tests (${{ matrix.transport }})
+        uses: ./.github/actions/run-alpine-tests
+        env:
+          COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
+        with:
+          image: node:22-alpine
+          workdir: /workspace/nodejs
+          transport: ${{ matrix.transport }}
+          command: |
+            npm ci --ignore-scripts
+            npm run build
+            (cd /workspace/test/harness && npm ci --ignore-scripts)
+
+            runtime_path="$(npm run --silent prepare:runtime -- --print-path)"
+            case "$runtime_path" in
+              */prebuilds/linuxmusl-arm64/copilot-runtime) ;;
+              *)
+                echo "Expected the linuxmusl-arm64 runtime bundle, got: $runtime_path" >&2
+                exit 1
+                ;;
+            esac
+            test -x "$runtime_path"
+            test -f "$(dirname "$runtime_path")/runtime.node"
+            export COPILOT_CLI_PATH="$runtime_path"
+            npm test
diff --git a/.github/workflows/python-sdk-tests.yml b/.github/workflows/python-sdk-tests.yml
index aa6e803372..b4c8b89f10 100644
--- a/.github/workflows/python-sdk-tests.yml
+++ b/.github/workflows/python-sdk-tests.yml
@@ -11,6 +11,33 @@ permissions:
   contents: read
 
 jobs:
+  validate:
+    name: "Python SDK Format and Typecheck"
+    if: github.event.repository.fork == false
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+    defaults:
+      run:
+        shell: bash
+        working-directory: ./python
+    steps:
+      - uses: actions/checkout@v6.0.2
+      - uses: actions/setup-python@v6
+        with:
+          python-version: "3.11"
+      - name: Set up uv
+        uses: astral-sh/setup-uv@37802adc94f370d6bfd71619e3f0bf239e1f3b78 # v7
+        with:
+          enable-cache: true
+      - name: Install Python dev dependencies
+        run: uv sync --all-extras --dev
+      - name: Run ruff format check
+        run: uv run ruff format --check .
+      - name: Run ruff lint
+        run: uv run ruff check
+      - name: Run ty type checking
+        run: uv run ty check copilot
+
   test:
     name: "Python SDK Tests (${{ matrix.os }}, ${{ matrix.transport }})"
     if: github.event.repository.fork == false
@@ -41,7 +68,7 @@ jobs:
           cache-dependency-path: "./nodejs/package-lock.json"
 
       - name: Set up uv
-        uses: astral-sh/setup-uv@v7
+        uses: astral-sh/setup-uv@37802adc94f370d6bfd71619e3f0bf239e1f3b78 # v7
         with:
           enable-cache: true
 
@@ -52,15 +79,6 @@ jobs:
         working-directory: ./nodejs
         run: npm ci --ignore-scripts --fetch-retries=4 --fetch-retry-mintimeout=10000 --fetch-retry-maxtimeout=60000
 
-      - name: Run ruff format check
-        run: uv run ruff format --check .
-
-      - name: Run ruff lint
-        run: uv run ruff check
-
-      - name: Run ty type checking
-        run: uv run ty check copilot
-
       - name: Install test harness dependencies
         working-directory: ./test/harness
         run: npm ci --ignore-scripts --fetch-retries=4 --fetch-retry-mintimeout=10000 --fetch-retry-maxtimeout=60000
@@ -80,3 +98,41 @@ jobs:
         # Keep each module's shared E2E client and proxy on one process while
         # running independent modules concurrently in isolated workers.
         run: uv run pytest -v -s -n 2 --dist=loadfile
+
+  # JavaScript actions use a glibc-linked Node runtime, so Alpine runs through Docker.
+  test-musl-arm64:
+    name: "Python SDK Tests (Alpine ARM64, ${{ matrix.transport }})"
+    if: github.event.repository.fork == false
+    strategy:
+      fail-fast: false
+      matrix:
+        transport: ["default", "inprocess"]
+    runs-on: ubuntu-24.04-arm
+    timeout-minutes: 20
+    steps:
+      - uses: actions/checkout@v6.0.2
+
+      - name: Run Python SDK tests on musl
+        uses: ./.github/actions/run-alpine-tests
+        env:
+          COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
+        with:
+          image: python:3.11-alpine
+          workdir: /workspace
+          transport: ${{ matrix.transport }}
+          command: |
+            apk add --no-cache nodejs npm
+            python -m pip install --no-cache-dir uv
+
+            (
+              cd nodejs
+              npm ci --ignore-scripts --fetch-retries=4 --fetch-retry-mintimeout=10000 --fetch-retry-maxtimeout=60000
+            )
+            (
+              cd test/harness
+              npm ci --ignore-scripts --fetch-retries=4 --fetch-retry-mintimeout=10000 --fetch-retry-maxtimeout=60000
+            )
+
+            cd python
+            uv sync --all-extras --dev
+            uv run pytest -v -s -n 2 --dist=loadfile
diff --git a/.github/workflows/required-checks.yml b/.github/workflows/required-checks.yml
index 0fb8acf70b..020ce41969 100644
--- a/.github/workflows/required-checks.yml
+++ b/.github/workflows/required-checks.yml
@@ -36,28 +36,28 @@ jobs:
             orchestrator:
               - '.github/workflows/required-checks.yml'
             nodejs:
-              - '{nodejs/**,test/**,.github/workflows/nodejs-sdk-tests.yml}'
+              - '{nodejs/**,test/**,.github/workflows/nodejs-sdk-tests.yml,.github/actions/run-alpine-tests/**}'
               - '!**/*.md'
               - '!**/LICENSE*'
               - '!**/.gitignore'
               - '!**/.editorconfig'
               - '!**/*.{png,jpg,jpeg,gif,svg}'
             python:
-              - '{python/**,test/**,nodejs/package.json,nodejs/scripts/**,.github/workflows/python-sdk-tests.yml}'
+              - '{python/**,test/**,nodejs/package.json,nodejs/scripts/**,.github/workflows/python-sdk-tests.yml,.github/actions/run-alpine-tests/**}'
               - '!**/*.md'
               - '!**/LICENSE*'
               - '!**/.gitignore'
               - '!**/.editorconfig'
               - '!**/*.{png,jpg,jpeg,gif,svg}'
             go:
-              - '{go/**,test/**,nodejs/package.json,nodejs/scripts/**,.github/workflows/go-sdk-tests.yml,.github/actions/setup-copilot/**}'
+              - '{go/**,test/**,nodejs/package.json,nodejs/scripts/**,.github/workflows/go-sdk-tests.yml,.github/actions/setup-copilot/**,.github/actions/run-alpine-tests/**}'
               - '!**/*.md'
               - '!**/LICENSE*'
               - '!**/.gitignore'
               - '!**/.editorconfig'
               - '!**/*.{png,jpg,jpeg,gif,svg}'
             dotnet:
-              - '{dotnet/**,test/**,nodejs/package.json,nodejs/scripts/**,.github/workflows/dotnet-sdk-tests.yml}'
+              - '{dotnet/**,test/**,nodejs/package.json,nodejs/scripts/**,.github/workflows/dotnet-sdk-tests.yml,.github/actions/run-alpine-tests/**}'
               - '!**/*.md'
               - '!**/LICENSE*'
               - '!**/.gitignore'
@@ -71,7 +71,7 @@ jobs:
               - '!**/.editorconfig'
               - '!**/*.{png,jpg,jpeg,gif,svg}'
             rust:
-              - '{rust/**,test/**,nodejs/package.json,nodejs/scripts/**,.github/workflows/rust-sdk-tests.yml,.github/actions/setup-copilot/**}'
+              - '{rust/**,test/**,nodejs/package.json,nodejs/scripts/**,.github/workflows/rust-sdk-tests.yml,.github/actions/setup-copilot/**,.github/actions/run-alpine-tests/**}'
               - '!**/*.md'
               - '!**/LICENSE*'
               - '!**/.gitignore'
diff --git a/.github/workflows/rust-sdk-tests.yml b/.github/workflows/rust-sdk-tests.yml
index 828459126b..29dec07506 100644
--- a/.github/workflows/rust-sdk-tests.yml
+++ b/.github/workflows/rust-sdk-tests.yml
@@ -331,3 +331,53 @@ jobs:
         run: |
           cargo build
           cargo test --features bundled-in-process --lib embedded_archive_contains_only_expected_files
+
+  # Build natively inside Alpine so Cargo reports target_env="musl". This
+  # exercises selection and extraction of the linuxmusl-arm64 runtime artifact,
+  # then runs the same default and in-process coverage as glibc Linux.
+  test-musl-arm64:
+    name: "Rust SDK Tests (Alpine ARM64, ${{ matrix.transport }})"
+    if: github.event.repository.fork == false
+    runs-on: ubuntu-24.04-arm
+    timeout-minutes: 60
+    strategy:
+      fail-fast: false
+      matrix:
+        transport: [default, inprocess]
+    steps:
+      - uses: actions/checkout@v6.0.2
+
+      - name: Test ${{ matrix.transport }} transport in Alpine
+        uses: ./.github/actions/run-alpine-tests
+        env:
+          COPILOT_HMAC_KEY: ${{ secrets.COPILOT_DEVELOPER_CLI_INTEGRATION_HMAC_KEY }}
+          CARGO_TERM_COLOR: always
+          RUST_BACKTRACE: 1
+          BUNDLED_CLI_CACHE_DIR: /workspace/rust/.bundled-cli-cache
+          # Rust's musl target defaults to a static CRT, which cannot load the in-process runtime.
+          RUSTFLAGS: "-C target-feature=-crt-static"
+          RUSTDOCFLAGS: "-C target-feature=-crt-static"
+        with:
+          image: rust:1.94.0-alpine
+          workdir: /workspace/rust
+          transport: ${{ matrix.transport }}
+          command: |
+            rustc --print cfg | grep -Fqx "target_arch=\"aarch64\""
+            rustc --print cfg | grep -Fqx "target_env=\"musl\""
+            apk add --no-cache build-base pkgconf openssl-dev nodejs npm
+            npm --prefix /workspace/nodejs ci --ignore-scripts
+            export COPILOT_CLI_PATH="$(npm --prefix /workspace/nodejs run --silent prepare:runtime -- --print-path)"
+            test -f "$COPILOT_CLI_PATH"
+            cd /workspace/test/harness
+            npm ci --ignore-scripts
+            cd /workspace/rust
+            # Keep native musl artifacts out of the mounted workspace so they cannot
+            # collide with glibc or another architecture's host-build artifacts.
+            export CARGO_TARGET_DIR=/tmp/copilot-sdk-rust-target
+            if [ "$COPILOT_SDK_TEST_TRANSPORT" = "inprocess" ]; then
+              unset RUST_E2E_CONCURRENCY
+              cargo test --no-default-features --features test-support,bundled-in-process --test e2e -- --test-threads=1 --nocapture
+            else
+              export RUST_E2E_CONCURRENCY=4
+              cargo test --no-default-features --features test-support -- --test-threads=4 --nocapture
+            fi
diff --git a/dotnet/test/Unit/MSBuildTargetsTests.cs b/dotnet/test/Unit/MSBuildTargetsTests.cs
index a6e3bb5660..fd6ffa6ac8 100644
--- a/dotnet/test/Unit/MSBuildTargetsTests.cs
+++ b/dotnet/test/Unit/MSBuildTargetsTests.cs
@@ -289,7 +289,19 @@ private static string GetReleasePlatform()
                 : "x64";
         if (OperatingSystem.IsWindows()) return $"win32-{arch}";
         if (OperatingSystem.IsMacOS()) return $"darwin-{arch}";
-        return $"linux-{arch}";
+        var platform = IsMusl() ? "linuxmusl" : "linux";
+        return $"{platform}-{arch}";
+    }
+
+    private static bool IsMusl()
+    {
+#if NETFRAMEWORK
+        return false;
+#else
+        return System.Runtime.InteropServices.RuntimeInformation.RuntimeIdentifier.StartsWith(
+            "linux-musl-",
+            StringComparison.Ordinal);
+#endif
     }
 
     private static string ComputeSha256(byte[] contents)
@@ -505,11 +517,13 @@ private static string GetPortableRid()
                     _ => "osx-x64",
                 };
             }
-            return System.Runtime.InteropServices.RuntimeInformation.OSArchitecture switch
+            var os = IsMusl() ? "linux-musl" : "linux";
+            var architecture = System.Runtime.InteropServices.RuntimeInformation.OSArchitecture switch
             {
-                System.Runtime.InteropServices.Architecture.Arm64 => "linux-arm64",
-                _ => "linux-x64",
+                System.Runtime.InteropServices.Architecture.Arm64 => "arm64",
+                _ => "x64",
             };
+            return $"{os}-{architecture}";
         }
     }
 
diff --git a/dotnet/test/Unit/RuntimeWrapperTests.cs b/dotnet/test/Unit/RuntimeWrapperTests.cs
index 9a9dacb7d3..e7c77ab92d 100644
--- a/dotnet/test/Unit/RuntimeWrapperTests.cs
+++ b/dotnet/test/Unit/RuntimeWrapperTests.cs
@@ -122,7 +122,9 @@ private static string GetPortableRid()
     {
         var os = OperatingSystem.IsWindows() ? "win"
             : OperatingSystem.IsMacOS() ? "osx"
-            : "linux";
+            : IsMusl()
+                ? "linux-musl"
+                : "linux";
         var architecture = System.Runtime.InteropServices.RuntimeInformation.OSArchitecture switch
         {
             System.Runtime.InteropServices.Architecture.X64 => "x64",
@@ -131,4 +133,15 @@ private static string GetPortableRid()
         };
         return $"{os}-{architecture}";
     }
+
+    private static bool IsMusl()
+    {
+#if NETFRAMEWORK
+        return false;
+#else
+        return System.Runtime.InteropServices.RuntimeInformation.RuntimeIdentifier.StartsWith(
+            "linux-musl-",
+            StringComparison.Ordinal);
+#endif
+    }
 }
diff --git a/nodejs/package-lock.json b/nodejs/package-lock.json
index a10153a1d3..0de83bc883 100644
--- a/nodejs/package-lock.json
+++ b/nodejs/package-lock.json
@@ -9,7 +9,7 @@
             "version": "0.0.0-dev",
             "license": "MIT",
             "dependencies": {
-                "koffi": "^3.1.0",
+                "koffi": "^3.2.1",
                 "vscode-jsonrpc": "^8.2.1",
                 "zod": "^4.3.6"
             },
@@ -735,9 +735,39 @@
             "dev": true,
             "license": "MIT"
         },
+        "node_modules/@koromix/koffi-android-arm64": {
+            "version": "3.2.1",
+            "integrity": "sha512-1pJQ4jnZlUJduK9u9DC5CGy3aOgDUPvIXpNb6syV3+Dh5Q/ugezAIGCqvY+w+1mgXsve0pd0NVvJRjdZNHQ6MA==",
+            "cpu": [
+                "arm64"
+            ],
+            "license": "MIT",
+            "optional": true,
+            "os": [
+                "android"
+            ],
+            "funding": {
+                "url": "https://liberapay.com/Koromix"
+            }
+        },
+        "node_modules/@koromix/koffi-android-x64": {
+            "version": "3.2.1",
+            "integrity": "sha512-HH40xGh3gVQifjOBnhwT2tECC0lL1lYe+nxHvWNSzxDIyQNcVPXg38ta7vuONRFpD+uIrw7fqGYLzbZIagkVcg==",
+            "cpu": [
+                "x64"
+            ],
+            "license": "MIT",
+            "optional": true,
+            "os": [
+                "android"
+            ],
+            "funding": {
+                "url": "https://liberapay.com/Koromix"
+            }
+        },
         "node_modules/@koromix/koffi-darwin-arm64": {
-            "version": "3.1.0",
-            "integrity": "sha512-VEt5r3fXTfbejr83PnuOP0H7s9Zmazcs+lofu96DOcRkistlMsn59wYyWiKpyAjs9PCgm0Ykh62ChZ3CGMmIOg==",
+            "version": "3.2.1",
+            "integrity": "sha512-Vj4h+xcjc5+Cn0DhPHjgRX4omKAv96Kehtcd+1YgYuY2W7FvQn9vS+3SmzVwhC5Qmg9bIwUZObYQ8T/4hBqQqA==",
             "cpu": [
                 "arm64"
             ],
@@ -751,8 +781,8 @@
             }
         },
         "node_modules/@koromix/koffi-darwin-x64": {
-            "version": "3.1.0",
-            "integrity": "sha1-r1z9mNiPAynDUcq8q6sPqKFY+xs=",
+            "version": "3.2.1",
+            "integrity": "sha512-gFCWxNBTZIvxo1p+PURWfsy2Ctj5FGnVVs1f03lTLhBvmxEto70pdIiFztdFLDFkAJ1pmtQmruRKapeK+E8YPA==",
             "cpu": [
                 "x64"
             ],
@@ -766,8 +796,8 @@
             }
         },
         "node_modules/@koromix/koffi-freebsd-arm64": {
-            "version": "3.1.0",
-            "integrity": "sha1-rOu888/eXKu5jj4KgZb0gCzt+xE=",
+            "version": "3.2.1",
+            "integrity": "sha512-qj+f1s2e6vULaUG1cdlTcCXmunCq2t+rjxku1+esaMIqVnHpOwj0QzPuInG0AFdXjwBNQhyVR/HpDj8daEwwsQ==",
             "cpu": [
                 "arm64"
             ],
@@ -781,8 +811,8 @@
             }
         },
         "node_modules/@koromix/koffi-freebsd-ia32": {
-            "version": "3.1.0",
-            "integrity": "sha1-0mky/r//V0JaXd+q9IRmdsZrkPI=",
+            "version": "3.2.1",
+            "integrity": "sha512-6olHb1Qfgai0jjs6ddlDDD0ZfsCxy7SPi8rMRpuYQWH0qhgtyQu82hw5b1p7z+TJ0zZP3ZeQQ6l+U/MlM1ICHQ==",
             "cpu": [
                 "ia32"
             ],
@@ -796,8 +826,8 @@
             }
         },
         "node_modules/@koromix/koffi-freebsd-x64": {
-            "version": "3.1.0",
-            "integrity": "sha1-2INR65Jz3bqyIPXHyqZ+PRGVkCs=",
+            "version": "3.2.1",
+            "integrity": "sha512-Dikhw1ySYNVMkmeFvFVjnU5Wdk6mffNoOjJxm9bTG96vg7OlemylxqdEven47R1YJ3yzNVJn/MlQ207ORWfi2w==",
             "cpu": [
                 "x64"
             ],
@@ -810,9 +840,24 @@
                 "url": "https://liberapay.com/Koromix"
             }
         },
+        "node_modules/@koromix/koffi-linux-arm": {
+            "version": "3.2.1",
+            "integrity": "sha512-OfwUwZylidq95wQKp6ClInULrfB2giu7dqM6Rhe0zAe6lES5I2SXNw15T9+GnRHk3/9hKT2XZ37OZLaKSyWNLA==",
+            "cpu": [
+                "arm"
+            ],
+            "license": "MIT",
+            "optional": true,
+            "os": [
+                "linux"
+            ],
+            "funding": {
+                "url": "https://liberapay.com/Koromix"
+            }
+        },
         "node_modules/@koromix/koffi-linux-arm64": {
-            "version": "3.1.0",
-            "integrity": "sha1-9h8pjdDbtKufG4JXoxDFRNzAbnI=",
+            "version": "3.2.1",
+            "integrity": "sha512-K+cGUL5iBcDqxmsocrjmlASqDf24gc7artbVW3PewG2c9AqwC63lezgwvB85Nx4lZAQjB6zIFHh9A7t1yGbwhw==",
             "cpu": [
                 "arm64"
             ],
@@ -826,8 +871,8 @@
             }
         },
         "node_modules/@koromix/koffi-linux-ia32": {
-            "version": "3.1.0",
-            "integrity": "sha1-8AbgHpYQoyx0uSoDgGpHwc1sGvM=",
+            "version": "3.2.1",
+            "integrity": "sha512-rxj6UYjU1qd98gxNQOSCdLpc5cPRi5Giq9rNd3jnGuSNIyMkwa6Dxw4cUjmhIBCYESMJtmNt5NWnJp5u9wTfYQ==",
             "cpu": [
                 "ia32"
             ],
@@ -841,8 +886,8 @@
             }
         },
         "node_modules/@koromix/koffi-linux-loong64": {
-            "version": "3.1.0",
-            "integrity": "sha1-bQvI/dvGGdARiMeDkZg0R+POkPI=",
+            "version": "3.2.1",
+            "integrity": "sha512-aHhnHzkPRmT/IHDlGvESJ/Bs32m8N6UE6Ab6kMeJzgk74IN8af2m/81/wZJtybR1M2UxCV4NmlVNUYQQvSAO3Q==",
             "cpu": [
                 "loong64"
             ],
@@ -856,8 +901,8 @@
             }
         },
         "node_modules/@koromix/koffi-linux-riscv64": {
-            "version": "3.1.0",
-            "integrity": "sha1-V5aXxWe4DH2j2r1dnJcMH9w44co=",
+            "version": "3.2.1",
+            "integrity": "sha512-qtQBsjbm3LiirLJvajWmKkNb7ARk7fvJVXdftJ7NtAnF3Xw8EbDvrtvmvtNI1yLPlYcBmlzCCD71hwhWYk0SIA==",
             "cpu": [
                 "riscv64"
             ],
@@ -871,8 +916,8 @@
             }
         },
         "node_modules/@koromix/koffi-linux-x64": {
-            "version": "3.1.0",
-            "integrity": "sha1-eJX/wAVe0HJASLRTgubjJrHppuo=",
+            "version": "3.2.1",
+            "integrity": "sha512-c7hw7Qs/r5gnFRTQLcbifBwRU7wiocj+2pVuDQ5Ahb3r36SZmupmgYbTWcLvTW+hul1jd7SKRV0d14ZJq/tvSw==",
             "cpu": [
                 "x64"
             ],
@@ -886,8 +931,8 @@
             }
         },
         "node_modules/@koromix/koffi-openbsd-ia32": {
-            "version": "3.1.0",
-            "integrity": "sha1-LwhKcVohSKoVCgY945O/4/gyoSk=",
+            "version": "3.2.1",
+            "integrity": "sha512-mmY8fY8LQ/CB52+h3yrMYmVyoxzW3x08S0yI6VNfHWdfU6yJtZkKCbhjmQCYMrWbYKC4gMvwZwCywIGPAkLyeA==",
             "cpu": [
                 "ia32"
             ],
@@ -901,8 +946,8 @@
             }
         },
         "node_modules/@koromix/koffi-openbsd-x64": {
-            "version": "3.1.0",
-            "integrity": "sha1-wWm472ijVY45okrdH/8EIAVtzAo=",
+            "version": "3.2.1",
+            "integrity": "sha512-k4ig6aAPbFSRATOIIOfdf/KtlOGH4SVls6L9fy0QnTxRJYvY2oSltTsQtBDANgEQldlq8Kl5WnpRa1VSibP4Lw==",
             "cpu": [
                 "x64"
             ],
@@ -915,9 +960,24 @@
                 "url": "https://liberapay.com/Koromix"
             }
         },
+        "node_modules/@koromix/koffi-win32-arm64": {
+            "version": "3.2.1",
+            "integrity": "sha512-cTWBJGK//pDMeKQJE/79Aq9MiOAF4H8QyLZHSQ9IWm8czOfwjG4J1AhsQ9DjI9KFOykH77hhnpmQTGVMIubGig==",
+            "cpu": [
+                "arm64"
+            ],
+            "license": "MIT",
+            "optional": true,
+            "os": [
+                "win32"
+            ],
+            "funding": {
+                "url": "https://liberapay.com/Koromix"
+            }
+        },
         "node_modules/@koromix/koffi-win32-ia32": {
-            "version": "3.1.0",
-            "integrity": "sha1-nDF+wS4sK934tD6A6e4I036PANM=",
+            "version": "3.2.1",
+            "integrity": "sha512-Z50EM6TAZ7CFyMmyX6thv8eNpJchqe9eenhibSIy2Eq/FQYF76gU2VK/LEoaF46L8hfC7TpTp9b10MvReHEyFA==",
             "cpu": [
                 "ia32"
             ],
@@ -931,8 +991,8 @@
             }
         },
         "node_modules/@koromix/koffi-win32-x64": {
-            "version": "3.1.0",
-            "integrity": "sha1-FyJ7F9SaNAIYddhe6gJ533eKOI4=",
+            "version": "3.2.1",
+            "integrity": "sha512-ZmZNiBO6bkOSh3QNzgfvb1cMY0yMobn6ZQrSMqbAce21qyYL8niIbyipz9N/PIRDciGhsV0wUxnZsxIO+yWsHQ==",
             "cpu": [
                 "x64"
             ],
@@ -2511,28 +2571,32 @@
             }
         },
         "node_modules/koffi": {
-            "version": "3.1.0",
-            "integrity": "sha512-0mCvdjTJBXioiaKNz0vajAEdWtfM5qyhVXSq+wQrrU3odzNvl/J7Cqna79QpNo9mfoKpQgGsyFFDRtDACCwGrQ==",
+            "version": "3.2.1",
+            "integrity": "sha512-0qE3lZ8jllRqPN4Ob6Ajl7c2bJSJDhQWuKLGP5hIEpHLllJWv1ydHFMhHmHc5p/W9GticKVDbYzZd7TBoQ4CZg==",
             "hasInstallScript": true,
             "license": "MIT",
             "funding": {
                 "url": "https://liberapay.com/Koromix"
             },
             "optionalDependencies": {
-                "@koromix/koffi-darwin-arm64": "3.1.0",
-                "@koromix/koffi-darwin-x64": "3.1.0",
-                "@koromix/koffi-freebsd-arm64": "3.1.0",
-                "@koromix/koffi-freebsd-ia32": "3.1.0",
-                "@koromix/koffi-freebsd-x64": "3.1.0",
-                "@koromix/koffi-linux-arm64": "3.1.0",
-                "@koromix/koffi-linux-ia32": "3.1.0",
-                "@koromix/koffi-linux-loong64": "3.1.0",
-                "@koromix/koffi-linux-riscv64": "3.1.0",
-                "@koromix/koffi-linux-x64": "3.1.0",
-                "@koromix/koffi-openbsd-ia32": "3.1.0",
-                "@koromix/koffi-openbsd-x64": "3.1.0",
-                "@koromix/koffi-win32-ia32": "3.1.0",
-                "@koromix/koffi-win32-x64": "3.1.0"
+                "@koromix/koffi-android-arm64": "3.2.1",
+                "@koromix/koffi-android-x64": "3.2.1",
+                "@koromix/koffi-darwin-arm64": "3.2.1",
+                "@koromix/koffi-darwin-x64": "3.2.1",
+                "@koromix/koffi-freebsd-arm64": "3.2.1",
+                "@koromix/koffi-freebsd-ia32": "3.2.1",
+                "@koromix/koffi-freebsd-x64": "3.2.1",
+                "@koromix/koffi-linux-arm": "3.2.1",
+                "@koromix/koffi-linux-arm64": "3.2.1",
+                "@koromix/koffi-linux-ia32": "3.2.1",
+                "@koromix/koffi-linux-loong64": "3.2.1",
+                "@koromix/koffi-linux-riscv64": "3.2.1",
+                "@koromix/koffi-linux-x64": "3.2.1",
+                "@koromix/koffi-openbsd-ia32": "3.2.1",
+                "@koromix/koffi-openbsd-x64": "3.2.1",
+                "@koromix/koffi-win32-arm64": "3.2.1",
+                "@koromix/koffi-win32-ia32": "3.2.1",
+                "@koromix/koffi-win32-x64": "3.2.1"
             }
         },
         "node_modules/levn": {
diff --git a/nodejs/package.json b/nodejs/package.json
index 783c4d5390..ee02f32fb6 100644
--- a/nodejs/package.json
+++ b/nodejs/package.json
@@ -61,7 +61,7 @@
     "author": "GitHub",
     "license": "MIT",
     "dependencies": {
-        "koffi": "^3.1.0",
+        "koffi": "^3.2.1",
         "vscode-jsonrpc": "^8.2.1",
         "zod": "^4.3.6"
     },