diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6f7453e3..78069eab 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -23,7 +23,9 @@ jobs:
           - os: macos-latest
             label: macOS
             preflight: false
-          - os: windows-latest
+          # Rust 1.78+ 生成的 Windows 测试运行器会使用 WaitOnAddress。
+          # 固定 Server 2022，减少 windows-latest/Server 2025 的镜像变量。
+          - os: windows-2022
             label: Windows
             preflight: true
           - os: ubuntu-latest
@@ -72,6 +74,21 @@ jobs:
         shell: pwsh
         run: ./scripts/windows-preflight.ps1 -Toolchain msvc
 
+      - name: Check MSVC developer command prompt
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          $vswhere = Join-Path ${env:ProgramFiles(x86)} "Microsoft Visual Studio\Installer\vswhere.exe"
+          $vsInstall = & $vswhere -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath
+          if (-not $vsInstall) {
+            throw "Visual Studio C++ toolchain not found"
+          }
+          $vsDevCmd = Join-Path $vsInstall "Common7\Tools\VsDevCmd.bat"
+          if (-not (Test-Path $vsDevCmd)) {
+            throw "VsDevCmd.bat not found: $vsDevCmd"
+          }
+          Write-Host "[ok] VsDevCmd.bat -> $vsDevCmd"
+
       - name: Check PowerShell scripts
         if: matrix.preflight
         shell: pwsh
@@ -89,18 +106,89 @@ jobs:
         run: npm run build
 
       - name: Check Tauri backend (cargo check)
+        if: runner.os != 'Windows'
         run: cargo check --manifest-path src-tauri/Cargo.toml
 
+      - name: Check Tauri backend (cargo check, Windows MSVC)
+        if: runner.os == 'Windows'
+        shell: pwsh
+        run: |
+          $vswhere = Join-Path ${env:ProgramFiles(x86)} "Microsoft Visual Studio\Installer\vswhere.exe"
+          $vsInstall = & $vswhere -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath
+          $vsDevCmd = Join-Path $vsInstall "Common7\Tools\VsDevCmd.bat"
+          $command = "call `"$vsDevCmd`" -arch=x64 -host_arch=x64 && cargo check --manifest-path src-tauri/Cargo.toml"
+          & cmd.exe /d /s /c $command
+          if ($LASTEXITCODE -ne 0) {
+            exit $LASTEXITCODE
+          }
+
       - name: Run Rust backend unit tests
         if: runner.os != 'Windows'
         run: cargo test --manifest-path src-tauri/Cargo.toml --lib
 
-      - name: Compile Rust backend unit tests (Windows)
-        # Windows runner 能链接 lib test binary，但干净镜像缺少可选 native runtime
-        # DLL entrypoint 时，进程会在 test harness 启动前退出。这里保留 cfg/link
-        # 覆盖；共享单测在 macOS / Linux 上实际执行。
+      - name: Run Rust backend unit tests (Windows)
         if: runner.os == 'Windows'
-        run: cargo test --manifest-path src-tauri/Cargo.toml --lib --no-run
+        shell: pwsh
+        run: |
+          # 产品默认构建仍通过 cargo check 覆盖 Foundry 链接形态，单测门禁
+          # 用无 Foundry native 链接的构建来真正执行 Windows 后端测试。
+          # stable test harness 在 runner 上会直接导入
+          # api-ms-win-core-synch-l1-2-0.dll/WaitOnAddress 并在单测开始前
+          # loader 失败。先 no-run 生成测试 exe，把该 import 指向更常规
+          # 的 Kernel32.dll，再直接运行已修补的 harness，避免 cargo 重新链接。
+          $env:CARGO_TARGET_DIR = Join-Path (Get-Location) "src-tauri\target\windows-unit-tests"
+          $vswhere = Join-Path ${env:ProgramFiles(x86)} "Microsoft Visual Studio\Installer\vswhere.exe"
+          $vsInstall = & $vswhere -latest -products * -requires Microsoft.VisualStudio.Component.VC.Tools.x86.x64 -property installationPath
+          $vsDevCmd = Join-Path $vsInstall "Common7\Tools\VsDevCmd.bat"
+          $targetDir = $env:CARGO_TARGET_DIR
+          $buildCommand = "call `"$vsDevCmd`" -arch=x64 -host_arch=x64 && set `"CARGO_TARGET_DIR=$targetDir`" && cargo test --manifest-path src-tauri/Cargo.toml --lib --no-default-features --features custom-protocol --no-run"
+          & cmd.exe /d /s /c $buildCommand
+          if ($LASTEXITCODE -ne 0) {
+            exit $LASTEXITCODE
+          }
+
+          $depsDir = Join-Path $env:CARGO_TARGET_DIR "debug\deps"
+          $needleText = "api-ms-win-core-synch-l1-2-0.dll" + [char]0
+          $replacementText = "kernel32.dll" + [char]0
+          $encoding = [System.Text.Encoding]::GetEncoding("iso-8859-1")
+          $needle = $encoding.GetBytes($needleText)
+          $replacement = New-Object byte[] $needle.Length
+          $replacementBytes = $encoding.GetBytes($replacementText)
+          [Array]::Copy($replacementBytes, $replacement, $replacementBytes.Length)
+          $patchedExes = @()
+          Get-ChildItem -Path $depsDir -Filter "openless_lib-*.exe" | ForEach-Object {
+            $bytes = [System.IO.File]::ReadAllBytes($_.FullName)
+            $text = $encoding.GetString($bytes)
+            $offset = $text.IndexOf($needleText, [System.StringComparison]::Ordinal)
+            $patchedThis = $false
+            while ($offset -ge 0) {
+              [Array]::Copy($replacement, 0, $bytes, $offset, $replacement.Length)
+              $patchedThis = $true
+              $offset = $text.IndexOf($needleText, $offset + $needle.Length, [System.StringComparison]::Ordinal)
+            }
+            if ($patchedThis) {
+              [System.IO.File]::WriteAllBytes($_.FullName, $bytes)
+              $patchedExes += $_.FullName
+              Write-Host "[ci] Patched Windows Rust test import to Kernel32.dll: $($_.FullName)"
+            }
+          }
+          if ($patchedExes.Count -eq 0) {
+            throw "api-ms-win-core-synch-l1-2-0.dll import not found in Windows Rust test executable."
+          }
+
+          foreach ($testExe in $patchedExes) {
+            $patchedText = $encoding.GetString([System.IO.File]::ReadAllBytes($testExe))
+            if ($patchedText.Contains($needleText)) {
+              throw "Windows Rust test executable still imports api-ms-win-core-synch-l1-2-0.dll: $testExe"
+            }
+            Write-Host "[ci] Running patched Windows Rust test executable: $testExe"
+            & $testExe
+            if ($LASTEXITCODE -ne 0) {
+              $unsignedExit = $LASTEXITCODE -band 0xffffffff
+              Write-Host ("[ci] Patched Windows Rust test executable failed with exit 0x{0:X8}" -f $unsignedExit)
+              exit $LASTEXITCODE
+            }
+          }
 
       - name: Verify version sync across all 5 files
         # 两个平台都跑这个校验：Windows runner 自带 git-bash，跨 shell 表现一致。
diff --git a/openless-all/app/src-tauri/Cargo.toml b/openless-all/app/src-tauri/Cargo.toml
index eead6568..132ddecb 100644
--- a/openless-all/app/src-tauri/Cargo.toml
+++ b/openless-all/app/src-tauri/Cargo.toml
@@ -78,7 +78,7 @@ objc2-app-kit = "0.2"
 libc = "0.2"
 
 [target.'cfg(target_os = "windows")'.dependencies]
-foundry-local-sdk = { version = "1.1.0", features = ["winml"] }
+foundry-local-sdk = { version = "1.1.0", features = ["winml"], optional = true }
 raw-window-handle = "0.6"
 windows = { version = "0.58", features = [
   "Win32_Foundation",
@@ -103,5 +103,6 @@ winreg = "0.52"
 window-vibrancy = "0.7"
 
 [features]
-default = ["custom-protocol"]
+default = ["custom-protocol", "foundry-local-runtime"]
 custom-protocol = ["tauri/custom-protocol"]
+foundry-local-runtime = ["dep:foundry-local-sdk"]
diff --git a/openless-all/app/src-tauri/src/asr/local/foundry_runtime.rs b/openless-all/app/src-tauri/src/asr/local/foundry_runtime.rs
index 7a762fcb..3f8676fb 100644
--- a/openless-all/app/src-tauri/src/asr/local/foundry_runtime.rs
+++ b/openless-all/app/src-tauri/src/asr/local/foundry_runtime.rs
@@ -1,4 +1,4 @@
-#[cfg(target_os = "windows")]
+#[cfg(all(target_os = "windows", feature = "foundry-local-runtime"))]
 #[allow(dead_code)]
 mod imp {
     use std::path::{Path, PathBuf};
@@ -579,23 +579,27 @@ mod imp {
     }
 }
 
-#[cfg(target_os = "windows")]
+#[cfg(all(target_os = "windows", feature = "foundry-local-runtime"))]
 pub use imp::FoundryLocalRuntime;
 
-#[cfg(not(target_os = "windows"))]
-pub struct FoundryLocalRuntime;
+#[cfg(any(not(target_os = "windows"), all(target_os = "windows", not(feature = "foundry-local-runtime"))))]
+pub struct FoundryLocalRuntime {
+    cancel_prepare: std::sync::atomic::AtomicBool,
+}
 
-#[cfg(not(target_os = "windows"))]
+#[cfg(any(not(target_os = "windows"), all(target_os = "windows", not(feature = "foundry-local-runtime"))))]
 impl Default for FoundryLocalRuntime {
     fn default() -> Self {
         Self::new()
     }
 }
 
-#[cfg(not(target_os = "windows"))]
+#[cfg(any(not(target_os = "windows"), all(target_os = "windows", not(feature = "foundry-local-runtime"))))]
 impl FoundryLocalRuntime {
     pub fn new() -> Self {
-        Self
+        Self {
+            cancel_prepare: std::sync::atomic::AtomicBool::new(false),
+        }
     }
 
     pub async fn status_snapshot(
@@ -605,7 +609,7 @@ impl FoundryLocalRuntime {
     ) -> super::foundry::FoundryRuntimeStatus {
         let mut status = super::foundry::FoundryRuntimeStatus::unavailable(
             active_model.to_string(),
-            "Foundry Local Whisper is only available on Windows",
+            "Foundry Local Whisper is unavailable in this build",
         );
         status.runtime_source = super::foundry_native::normalize_runtime_source_str(runtime_source);
         status
@@ -616,7 +620,7 @@ impl FoundryLocalRuntime {
         alias: &str,
         _runtime_source: &str,
     ) -> anyhow::Result<String> {
-        anyhow::bail!("Foundry Local Whisper is only available on Windows: {alias}");
+        anyhow::bail!("Foundry Local Whisper is unavailable in this build: {alias}");
     }
 
     pub async fn ensure_loaded_with_progress<F>(
@@ -628,10 +632,19 @@ impl FoundryLocalRuntime {
     where
         F: Fn(super::foundry::FoundryPrepareProgressPayload) + Send + Sync + 'static,
     {
-        anyhow::bail!("Foundry Local Whisper is only available on Windows: {alias}");
+        anyhow::bail!("Foundry Local Whisper is unavailable in this build: {alias}");
+    }
+
+    pub fn request_cancel_prepare(&self) {
+        self.cancel_prepare
+            .store(true, std::sync::atomic::Ordering::SeqCst);
     }
 
-    pub fn request_cancel_prepare(&self) {}
+    #[cfg(test)]
+    pub(crate) fn cancel_prepare_requested_for_tests(&self) -> bool {
+        self.cancel_prepare
+            .load(std::sync::atomic::Ordering::SeqCst)
+    }
 
     pub async fn catalog_snapshot(
         &self,
@@ -647,7 +660,7 @@ impl FoundryLocalRuntime {
         _audio_path: &std::path::Path,
         _audio_timeout: std::time::Duration,
     ) -> anyhow::Result<String> {
-        anyhow::bail!("Foundry Local Whisper is only available on Windows: {alias}");
+        anyhow::bail!("Foundry Local Whisper is unavailable in this build: {alias}");
     }
 
     pub async fn release_now(&self) -> anyhow::Result<()> {