fix(windows): bundle vulkan-1.dll to fix startup crash

Windows users without the Vulkan runtime installed were experiencing
"vulkan-1.dll not found" errors that prevented the app from starting.
This affected systems without dedicated GPUs, VMs, and clean Windows
installations.

The fix bundles vulkan-1.dll from the Vulkan SDK during CI builds. Since
Tauri places resources in a subdirectory rather than next to the exe,
NSIS installer hooks move the DLL to the correct location after install.
Once the DLL is present, whisper.cpp gracefully falls back to CPU
transcription on systems without GPU/Vulkan drivers.

Fixes #829, fixes #840

Author: braden-w

.github/workflows/pr-preview-builds.yml

@@ -94,6 +94,18 @@ jobs:
           version: 1.4.309.0
           cache: true
 
+      # Bundle Vulkan DLL for Windows users without Vulkan runtime
+      - name: Bundle Vulkan DLL (Windows)
+        if: matrix.platform == 'windows-latest'
+        shell: pwsh
+        run: |
+          $vulkanDll = "$env:VULKAN_SDK\Bin\vulkan-1.dll"
+          $destination = "apps/whispering/src-tauri/vulkan-1.dll"
+          Write-Host "Copying Vulkan DLL from: $vulkanDll"
+          Write-Host "Copying Vulkan DLL to: $destination"
+          Copy-Item $vulkanDll $destination
+          Write-Host "Vulkan DLL bundled successfully"
+
       - name: setup node
         uses: actions/setup-node@v4
         with:

.github/workflows/publish-tauri-releases.yml

@@ -125,6 +125,20 @@ jobs:
           version: 1.4.309.0
           cache: true
 
+      # Bundle Vulkan DLL for Windows users without Vulkan runtime
+      # The DLL is placed in src-tauri where tauri.conf.json resources config picks it up
+      # This fixes the "vulkan-1.dll not found" error on Windows systems without GPU/Vulkan drivers
+      - name: Bundle Vulkan DLL (Windows)
+        if: matrix.platform == 'windows-latest'
+        shell: pwsh
+        run: |
+          $vulkanDll = "$env:VULKAN_SDK\Bin\vulkan-1.dll"
+          $destination = "apps/whispering/src-tauri/vulkan-1.dll"
+          Write-Host "Copying Vulkan DLL from: $vulkanDll"
+          Write-Host "Copying Vulkan DLL to: $destination"
+          Copy-Item $vulkanDll $destination
+          Write-Host "Vulkan DLL bundled successfully"
+
       # Setup Node.js for compatibility
       - name: setup node
         uses: actions/setup-node@v4

apps/whispering/src-tauri/.gitignore

@@ -9,3 +9,6 @@
 # Environment variables
 .env
 .env.local
+
+# Vulkan DLL copied during CI build (not committed, generated from VULKAN_SDK)
+vulkan-1.dll

apps/whispering/src-tauri/nsis/installer-hooks.nsh

@@ -0,0 +1,21 @@
+; Whispering NSIS Installer Hooks
+; This file is included by the Tauri NSIS installer to handle custom installation tasks
+
+; NSIS_HOOK_POSTINSTALL
+; Called after all files are installed to $INSTDIR
+; We need to move vulkan-1.dll from resources/ to the exe directory
+; because Windows needs DLLs next to the executable for load-time linking
+!macro NSIS_HOOK_POSTINSTALL
+  ; Check if the DLL exists in resources and copy it to exe directory
+  ${If} ${FileExists} "$INSTDIR\resources\vulkan-1.dll"
+    CopyFiles /SILENT "$INSTDIR\resources\vulkan-1.dll" "$INSTDIR\vulkan-1.dll"
+    Delete "$INSTDIR\resources\vulkan-1.dll"
+  ${EndIf}
+!macroend
+
+; NSIS_HOOK_POSTUNINSTALL
+; Called after uninstallation to clean up any remaining files
+!macro NSIS_HOOK_POSTUNINSTALL
+  ; Clean up the DLL if it exists
+  Delete "$INSTDIR\vulkan-1.dll"
+!macroend

apps/whispering/src-tauri/tauri.windows.conf.json

@@ -0,0 +1,11 @@
+{
+	"$schema": "https://schema.tauri.app/config/2",
+	"bundle": {
+		"resources": ["vulkan-1.dll"],
+		"windows": {
+			"nsis": {
+				"installerHooks": "nsis/installer-hooks.nsh"
+			}
+		}
+	}
+}