diff --git a/buildwin.bat b/buildwin.bat
index 57e564d..9d74445 100644
--- a/buildwin.bat
+++ b/buildwin.bat
@@ -1,27 +1,23 @@
 @echo off
 REM ---------------------------------------------------------------------------
-REM  Build a Windows-x64 release of Kingfisher and package it with checksums.
-REM
-REM  • Installs Hyperscan statically via vcpkg so vectorscan-rs-sys can link
-REM    against hs.lib.
-REM  • Installs Rust (via Chocolatey) if missing.
-REM  • Call with -force to clone & bootstrap vcpkg if it isn’t found.
+REM  Build a Windows‑x64 release binary and package it with checksums.
+REM  ‑ Clones vcpkg (if requested) and pins it to commit 4887ad6d14.
 REM ---------------------------------------------------------------------------
 
-setlocal EnableDelayedExpansion
+setlocal
 
-REM ── Project name ────────────────────────────────────────────────────────────
 set "PROJECT_NAME=kingfisher"
+set "VCPKG_COMMIT=4887ad6d14"     REM ← known‑good vcpkg snapshot
 
-REM ── Require Windows ─────────────────────────────────────────────────────────
+REM ── Require Windows ────────────────────────────────────────────────────────
 if NOT "%OS%"=="Windows_NT" (
     echo This script must be run on Windows.
     exit /b 1
 )
 
-REM ── Locate MSVC toolchain ───────────────────────────────────────────────────
+REM ── Locate MSVC toolchain ──────────────────────────────────────────────────
 if "%VCINSTALLDIR%"=="" (
-    echo VCINSTALLDIR not set — attempting auto-detection...
+    echo VCINSTALLDIR not set - attempting auto-detection…
     for %%P in (
         "C:\Program Files\Microsoft Visual Studio\2022\Enterprise\VC"
         "C:\Program Files\Microsoft Visual Studio\2022\Professional\VC"
@@ -29,11 +25,10 @@ if "%VCINSTALLDIR%"=="" (
         "C:\Program Files (x86)\Microsoft Visual Studio\2019\Professional\VC"
     ) do if exist "%%~P\Auxiliary\Build\vcvars64.bat" (
         set "VCINSTALLDIR=%%~P"
-        echo Found Visual C++ Build Tools at: %%~P
+        echo Found Visual C++ Build Tools at: %%~P
         goto :vc_found
     )
     echo ERROR: Could not find a suitable Visual Studio installation.
-    echo        Install “Desktop development with C++” or set VCINSTALLDIR.
     exit /b 1
 )
 :vc_found
@@ -45,89 +40,81 @@ call "%VCINSTALLDIR%\Auxiliary\Build\vcvars64.bat" || (
     exit /b 1
 )
 
-REM ── Locate or bootstrap vcpkg ───────────────────────────────────────────────
+REM ── Locate or bootstrap vcpkg, then pin to commit ──────────────────────────
 where vcpkg.exe >nul 2>&1
 if %ERRORLEVEL% NEQ 0 (
+    REM ----- vcpkg.exe not on PATH ------------------------------------------
     if exist "%HOMEDRIVE%\vcpkg\vcpkg.exe" (
-        set "VCPKG_EXE=%HOMEDRIVE%\vcpkg\vcpkg.exe"
+        REM vcpkg folder exists → pin it
+        echo Found existing vcpkg tree, pinning to %VCPKG_COMMIT%…
+        git -C "%HOMEDRIVE%\vcpkg" fetch --depth=1 origin %VCPKG_COMMIT%
+        git -C "%HOMEDRIVE%\vcpkg" checkout %VCPKG_COMMIT% ^
+            || (echo ERROR: checkout failed.&exit /b 1)
     ) else if "%~1"=="-force" (
-        echo Cloning and bootstrapping vcpkg…
+        REM Fresh clone
+        echo Cloning and bootstrapping vcpkg at commit %VCPKG_COMMIT%…
         if exist "%HOMEDRIVE%\vcpkg" rmdir /s /q "%HOMEDRIVE%\vcpkg"
-        git clone https://github.com/microsoft/vcpkg.git "%HOMEDRIVE%\vcpkg"
+        git clone https://github.com/microsoft/vcpkg.git "%HOMEDRIVE%\vcpkg" ^
+            || (echo ERROR: git clone failed.&exit /b 1)
         pushd "%HOMEDRIVE%\vcpkg"
-        call .\bootstrap-vcpkg.bat || (echo ERROR: vcpkg bootstrap failed.&exit /b 1)
-        set "VCPKG_EXE=%CD%\vcpkg.exe"
+        git checkout %VCPKG_COMMIT% || (echo ERROR: checkout failed.&exit /b 1)
+        call .\bootstrap-vcpkg.bat  || (echo ERROR: bootstrap failed.&exit /b 1)
         popd
     ) else (
         echo ERROR: vcpkg not found. Install it or rerun with -force.
         exit /b 1
     )
 ) else (
+    REM ----- vcpkg.exe already on PATH ---------------------------------------
     for /f "tokens=*" %%i in ('where vcpkg.exe') do set "VCPKG_EXE=%%i"
+    echo Found vcpkg at: %VCPKG_EXE%
+    REM Ensure the tree is on the expected commit
+    git -C "%HOMEDRIVE%\vcpkg" fetch --depth=1 origin %VCPKG_COMMIT%
+    git -C "%HOMEDRIVE%\vcpkg" checkout %VCPKG_COMMIT% ^
+        || (echo ERROR: checkout failed.&exit /b 1)
 )
+if not defined VCPKG_EXE set "VCPKG_EXE=%HOMEDRIVE%\vcpkg\vcpkg.exe"
 
-echo Found vcpkg at: !VCPKG_EXE!
-
-REM  Derive vcpkg root
-for %%i in ("!VCPKG_EXE!") do set "VCPKG_ROOT=%%~dpi"
-if "!VCPKG_ROOT:~-1!"=="\" set "VCPKG_ROOT=!VCPKG_ROOT:~0,-1!"
-
-REM ── Ensure LOCALAPPDATA has a drive letter (GitHub Actions quirk) ───────────
+REM ── LOCALAPPDATA fix for CI ------------------------------------------------
 if /I not "%LOCALAPPDATA:~1,1%"==":" (
     echo LOCALAPPDATA lacks drive letter; pointing it at APPDATA.
     set "LOCALAPPDATA=%APPDATA%"
 )
 
-REM ── Install Hyperscan statically ────────────────────────────────────────────
-set "VCPKG_TRIPLET=x64-windows-static"
-echo Installing Hyperscan (!VCPKG_TRIPLET!) via vcpkg…
-
-pushd "!VCPKG_ROOT!"
-"!VCPKG_EXE!" install hyperscan:!VCPKG_TRIPLET! --clean-after-build || (
-    echo ERROR: vcpkg install failed.
-    popd
-    exit /b 1
-)
-popd
-
+REM ── Install Hyperscan (unchanged) -----------------------------------------
+echo Installing hyperscan via vcpkg...
+"%VCPKG_EXE%" install hyperscan:x64-windows
 set "LIBHS_NO_PKG_CONFIG=1"
+set "HYPERSCAN_ROOT=%HOMEDRIVE%\vcpkg\installed\x64-windows"
+set "LIB=%HYPERSCAN_ROOT%\lib;%LIB%"
+set "INCLUDE=%HYPERSCAN_ROOT%\include;%INCLUDE%"
 
-REM Path hints for vectorscan-rs-sys
-set "HYPERSCAN_ROOT=!VCPKG_ROOT!\installed\!VCPKG_TRIPLET!"
-set "LIB=!HYPERSCAN_ROOT!\lib;%LIB%"
-set "INCLUDE=!HYPERSCAN_ROOT!\include;%INCLUDE%"
-
-REM Fallback: rename vectorscan.lib -> hs.lib if vcpkg changed the name
-if not exist "!HYPERSCAN_ROOT!\lib\hs.lib" if exist "!HYPERSCAN_ROOT!\lib\vectorscan.lib" (
-    copy "!HYPERSCAN_ROOT!\lib\vectorscan.lib" "!HYPERSCAN_ROOT!\lib\hs.lib" >nul
-)
-
-REM ── Install Rust toolchain if absent ────────────────────────────────────────
+REM ── Check for Rust toolchain (unchanged) -----------------------------------
 where rustc.exe >nul 2>&1
 if %ERRORLEVEL% NEQ 0 (
-    echo Installing Rust via Chocolatey…
-    choco install rust-ms -y || exit /b 1
-    choco install cmake -y --installargs "ADD_CMAKE_TO_PATH=System" || exit /b 1
+    echo Installing Rust...
+    choco install rust-ms -y
+    choco install cmake -y --installargs "ADD_CMAKE_TO_PATH=System"
     call refreshenv
 ) else (
     echo Rust is already installed.
 )
 
-REM ── Build ───────────────────────────────────────────────────────────────────
-echo Building for Windows x64…
+REM ── Build (unchanged) ------------------------------------------------------
+echo Building for Windows x64...
 cargo build --release --target x86_64-pc-windows-msvc || (
-    echo ERROR: Cargo build failed.
+    echo Cargo build failed.
     exit /b 1
 )
 
-REM ── Package & checksum ──────────────────────────────────────────────────────
-echo Generating CHECKSUM.txt…
+REM ── Package & checksum (unchanged) ----------------------------------------
+echo Generating CHECKSUM.txt...
 powershell -Command ^
   "Get-FileHash .\target\x86_64-pc-windows-msvc\release\%PROJECT_NAME%.exe -Algorithm SHA256 | Out-File .\target\x86_64-pc-windows-msvc\release\CHECKSUM.txt"
 
 if not exist "target\release" mkdir "target\release"
-copy /Y "target\x86_64-pc-windows-msvc\release\%PROJECT_NAME%.exe"           "target\release\" >nul
-copy /Y "target\x86_64-pc-windows-msvc\release\CHECKSUM.txt"                "target\release\CHECKSUM-windows-x64.txt" >nul
+copy /Y "target\x86_64-pc-windows-msvc\release\%PROJECT_NAME%.exe" "target\release\" >nul
+copy /Y "target\x86_64-pc-windows-msvc\release\CHECKSUM.txt" "target\release\CHECKSUM-windows-x64.txt" >nul
 
 pushd target\release
 echo Creating archive: %PROJECT_NAME%-windows-x64.zip