Fix duplicate native DLLs in net4x output directory

.github/copilot-instructions.md

@@ -184,3 +184,31 @@ From `namespace OpenCvSharp.Internal`, types in `namespace OpenCvSharp` are dire
 
 See `src/OpenCvSharpExtern/ximgproc_EdgeDrawing.h`, `src/OpenCvSharp/Modules/ximgproc/EdgeDrawing.cs` for a complete example covering: factory, OutputArray methods, std::vector methods, nested Params struct with bool fields, and VectorOfVec6d.
 
+## Repository structure
+
+OpenCvSharp has three layers:
+
+- **`src/OpenCvSharp/`** — managed C# wrapper (P/Invoke, types, extension methods). Target frameworks: `netstandard2.0`, `netstandard2.1`, `net8.0`. Always verify that any change is consistent across all three.
+- **`src/OpenCvSharpExtern/`** — thin C++ bridge called by the C# side via P/Invoke.
+- **`nuget/`** — NuGet packaging projects (runtime packages that bundle the native DLLs).
+
+## Versioning and release process
+
+See `docs/release-process.md` for the full release workflow.
+
+**Key rule: do not edit version numbers in source files for routine releases.** The NuGet package version is passed via `-p:Version=...` at pack time in CI. `AssemblyVersion` and `FileVersion` are hardcoded to `4.0.0.0` in `src/Directory.Build.props` and must not be changed for patch or minor OpenCV upgrades — only bump the major component on a breaking API change or OpenCV major-version upgrade. `InformationalVersion` is set automatically by the SDK to the full NuGet version string.
+
+## Native DLL loading (Windows)
+
+`WindowsLibraryLoader` (`src/OpenCvSharp/Internal/PInvoke/WindowsLibraryLoader.cs`) handles native DLL loading on Windows for .NET Framework targets:
+
+- Uses `AppContext.BaseDirectory` (not `Assembly.Location`) to avoid IL3000 warnings in AoT/single-file apps.
+- For .NET Framework (net4x), looks for DLLs under `dll/x64/` relative to the base directory. The NuGet `.props` file copies DLLs there at build time.
+- For .NET 5+, returns early — the .NET runtime handles native loading via the `runtimes/` folder layout.
+
+The NuGet runtime packages (`nuget/OpenCvSharp4.runtime.win.*`) include a `.targets` file that suppresses the redundant copy NuGet's PackageReference pipeline would otherwise make to the output root for net4x consumers.
+
+## Issue backlog
+
+`docs/issue-backlog.md` tracks actionable issues identified from closed/stale GitHub issues. Update the checkboxes as items are resolved.
+

CLAUDE.md

@@ -0,0 +1 @@
+See `.github/copilot-instructions.md` for development instructions.

docs/issue-backlog.md

@@ -19,7 +19,7 @@ Check off items as they are resolved.
 
 ---
 
-### [ ] #1704 — Assembly version reported as `0.0.0.0`
+### [x] #1704 — Assembly version reported as `0.0.0.0`
 
 - **State**: closed (stale)
 - **URL**: https://github.com/shimat/opencvsharp/issues/1704

docs/release-process.md

@@ -0,0 +1,51 @@
+# Release Process
+
+This document describes the steps required to publish a new version of OpenCvSharp.
+
+---
+
+## Version numbering
+
+NuGet package versions follow the pattern `{opencv_version}.{YYYYMMDD}`, e.g. `4.13.0.20260530`. The `-beta` suffix is stripped by `OpenCvSharp.NupkgBetaRemover` at publish time.
+
+The version is passed at pack time via `-p:Version=...` in CI. **No source file needs to be edited to change the version number.**
+
+### Assembly versioning policy
+
+Managed assembly attributes are set as follows (see `src/Directory.Build.props`):
+
+| Attribute | Value | Rationale |
+|---|---|---|
+| `AssemblyVersion` | `4.0.0.0` (major-pinned, hardcoded) | Changing this on every release is a breaking change for .NET Framework consumers of the strong-named assembly — they would need binding redirects in `app.config`. Only bump the major component when there is a breaking API change. |
+| `FileVersion` | `4.0.0.0` (hardcoded) | The date-based 4th component (e.g. `20260530`) exceeds the 65535 per-component limit of the Windows FILEVERSION PE resource. |
+| `InformationalVersion` | Set automatically by the .NET SDK to `$(Version)` | This is the human-readable version visible in Windows file properties ("Product version") and most tooling. It tracks the NuGet version correctly with no manual action needed. |
+
+### When to bump `AssemblyVersion`
+
+- **Patch / minor OpenCV update** (e.g. 4.13.0 → 4.13.1, or 4.13 → 4.14): **do nothing**. The assembly version stays at `4.0.0.0`.
+- **OpenCV major version bump** (e.g. 4.x → 5.x): update `AssemblyVersion` and `FileVersion` in `src/Directory.Build.props` to `5.0.0.0`. Be aware this is a breaking change for .NET Framework consumers.
+- **Breaking API change in the C# wrapper** (rare): same as above — bump the major component.
+
+---
+
+## CI workflow
+
+Releases are produced by running the following workflows in order:
+
+1. **`windows.yml`** — builds `OpenCvSharpExtern.dll` (full and slim), runs tests, packs NuGet packages with a `-beta` version suffix.
+2. **`linux-arm64.yml`** — builds the Linux ARM64 native library.
+3. **`manylinux.yml`** — builds the Linux x64 native library.
+4. **`wasm.yml`** — builds the WASM native library.
+5. **`publish_nuget.yml`** — collects all artifacts, strips the `-beta` suffix via `OpenCvSharp.NupkgBetaRemover`, validates the package set, and pushes to NuGet.org.
+
+The `OPENCV_VERSION` environment variable in `windows.yml` controls the OpenCV version embedded in the package version string. Update it there when upgrading OpenCV.
+
+---
+
+## Upgrading OpenCV
+
+1. Update the `opencv` and `opencv_contrib` submodules to the new tag.
+2. Update `OPENCV_VERSION` in `.github/workflows/windows.yml`.
+3. Update the ffmpeg DLL filename references in `nuget/OpenCvSharp4.runtime.win.props` and `nuget/OpenCvSharp4.runtime.win.csproj` if the ffmpeg DLL name changed (e.g. `opencv_videoio_ffmpeg4130_64.dll` → `opencv_videoio_ffmpeg4140_64.dll`).
+4. Run the full CI pipeline and verify all tests pass.
+5. `AssemblyVersion` does **not** need to be changed for a minor/patch OpenCV upgrade.

nuget/OpenCvSharp4.runtime.win.csproj

@@ -27,6 +27,9 @@
     <None Include="OpenCvSharp4.runtime.win.props" Pack="true" PackagePath="build/netstandard" />
     <None Include="OpenCvSharp4.runtime.win.props" Pack="true" PackagePath="build/netcoreapp" />
     <None Include="OpenCvSharp4.runtime.win.props" Pack="true" PackagePath="build/net8.0" />
+    <None Include="OpenCvSharp4.runtime.win.targets" Pack="true" PackagePath="build/netstandard" />
+    <None Include="OpenCvSharp4.runtime.win.targets" Pack="true" PackagePath="build/netcoreapp" />
+    <None Include="OpenCvSharp4.runtime.win.targets" Pack="true" PackagePath="build/net8.0" />
     <None Include="icon/opencvsharp.png" Pack="true" PackagePath="" />
     <None Include="README.runtime.md" Pack="true" PackagePath="" />
   </ItemGroup>

nuget/OpenCvSharp4.runtime.win.slim.csproj

@@ -25,6 +25,9 @@
     <None Include="OpenCvSharp4.runtime.win.slim.props" Pack="true" PackagePath="build/netstandard" />
     <None Include="OpenCvSharp4.runtime.win.slim.props" Pack="true" PackagePath="build/netcoreapp" />
     <None Include="OpenCvSharp4.runtime.win.slim.props" Pack="true" PackagePath="build/net8.0" />
+    <None Include="OpenCvSharp4.runtime.win.slim.targets" Pack="true" PackagePath="build/netstandard" />
+    <None Include="OpenCvSharp4.runtime.win.slim.targets" Pack="true" PackagePath="build/netcoreapp" />
+    <None Include="OpenCvSharp4.runtime.win.slim.targets" Pack="true" PackagePath="build/net8.0" />
     <None Include="icon/opencvsharp.png" Pack="true" PackagePath="" />
     <None Include="README.runtime.md" Pack="true" PackagePath="" />
   </ItemGroup>

nuget/OpenCvSharp4.runtime.win.slim.targets

@@ -0,0 +1,24 @@
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <!--
+    For .NET Framework (net4x) targets using PackageReference, NuGet's build pipeline automatically
+    copies runtimes/win-x64/native/ assets to the output root directory. However, the companion
+    .props file already places these DLLs under dll/x64/, which is where WindowsLibraryLoader looks
+    at runtime. The root copies are therefore redundant and bloat the output directory.
+
+    This target removes the package's native assets from RuntimeCopyLocalItems — the item group
+    populated by ResolvePackageAssets — so NuGet does not copy them to the output root.
+    The dll/x64/ placement from the .props file is unaffected.
+
+    Note: RuntimeCopyLocalItems is only present in SDK-style projects using PackageReference.
+    Old-style (packages.config) projects do not process runtimes/ assets at all, so this target
+    has no effect there (which is fine — no duplicate exists in that case either).
+  -->
+  <Target Name="OpenCvSharp4RuntimeWinSlim_RemoveRootNativeAssets"
+          AfterTargets="ResolvePackageAssets"
+          Condition="$(TargetFramework.StartsWith('net4')) Or $(TargetFrameworkVersion.StartsWith('v4'))">
+    <ItemGroup>
+      <RuntimeCopyLocalItems Remove="@(RuntimeCopyLocalItems)"
+          Condition="'%(NuGetPackageId)' == 'OpenCvSharp4.runtime.win.slim'" />
+    </ItemGroup>
+  </Target>
+</Project>

nuget/OpenCvSharp4.runtime.win.targets

@@ -0,0 +1,24 @@
+<Project ToolsVersion="4.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <!--
+    For .NET Framework (net4x) targets using PackageReference, NuGet's build pipeline automatically
+    copies runtimes/win-x64/native/ assets to the output root directory. However, the companion
+    .props file already places these DLLs under dll/x64/, which is where WindowsLibraryLoader looks
+    at runtime. The root copies are therefore redundant and bloat the output directory.
+
+    This target removes the package's native assets from RuntimeCopyLocalItems — the item group
+    populated by ResolvePackageAssets — so NuGet does not copy them to the output root.
+    The dll/x64/ placement from the .props file is unaffected.
+
+    Note: RuntimeCopyLocalItems is only present in SDK-style projects using PackageReference.
+    Old-style (packages.config) projects do not process runtimes/ assets at all, so this target
+    has no effect there (which is fine — no duplicate exists in that case either).
+  -->
+  <Target Name="OpenCvSharp4RuntimeWin_RemoveRootNativeAssets"
+          AfterTargets="ResolvePackageAssets"
+          Condition="$(TargetFramework.StartsWith('net4')) Or $(TargetFrameworkVersion.StartsWith('v4'))">
+    <ItemGroup>
+      <RuntimeCopyLocalItems Remove="@(RuntimeCopyLocalItems)"
+          Condition="'%(NuGetPackageId)' == 'OpenCvSharp4.runtime.win'" />
+    </ItemGroup>
+  </Target>
+</Project>