diff --git a/.gitattributes b/.gitattributes
index 8cf8104b2a..55bdc47fa2 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -27,7 +27,6 @@ FwHelpAbout.cs -whitespace
 LICENSE -whitespace
 RealSplashScreen.cs -whitespace
 run-app -whitespace
-Bin/ilrepack-assemblies -whitespace
 *.json -whitespace
 *.js -whitespace
 Src/LexText/ParserCore/ParserCoreTests/**/*.txt -whitespace
diff --git a/Bin/ilrepack-assemblies b/Bin/ilrepack-assemblies
deleted file mode 100755
index bc0d30ea84..0000000000
--- a/Bin/ilrepack-assemblies
+++ /dev/null
@@ -1,31 +0,0 @@
-#!/bin/bash
-
-# Repack an assembly.
-# Created 2018-08-13
-#
-# Usage: ./ilrepack-assemblies /path/to/PrimaryAssembly.dll [/path/to/OtherAssemblies.dll ...]
-#
-# Original PrimaryAssembly.dll is left as PrimaryAssembly.dll~.
-#
-# Environment variables:
-#   ILREPACK - path to ILRepack.exe to use.
-
-set -e -o pipefail -u
-
-PRIMARY_ASSEMBLY="$1"
-ILREPACK="${ILREPACK-"$(dirname "$0")/../packages/ILRepack.2.0.15/tools/ILRepack.exe"}"
-TMP_ASSEMBLY=$(mktemp -d)/"$(basename "$PRIMARY_ASSEMBLY")"
-# Set ASSEMBLIES to the remaining arguments.
-shift
-ASSEMBLIES="${@}"
-
-LIBSARGS=/lib:"$(dirname "$PRIMARY_ASSEMBLY")"
-mono "$ILREPACK" /out:"$TMP_ASSEMBLY" "$LIBSARGS" "$PRIMARY_ASSEMBLY" $ASSEMBLIES
-mv "$PRIMARY_ASSEMBLY" "$PRIMARY_ASSEMBLY~"
-mv "$TMP_ASSEMBLY" "$PRIMARY_ASSEMBLY"
-
-for assembly in $ASSEMBLIES; do
-  if [[ -f $assembly.config ]]; then
-	echo >&2 "ilrepack-assemblies($$): WARNING: Not including settings from $assembly.config for $PRIMARY_ASSEMBLY."
-  fi
-done
diff --git a/Directory.Packages.props b/Directory.Packages.props
index fd6974bad6..3c9315077e 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -45,6 +45,9 @@
 		<!-- System.Security.Permissions (LT-22394): ProDotNetZip needs >= 8.0.0,
 			 System.Security.AccessControl needs >= 6.0.0. Pin to 9.0.16. -->
 		<PackageVersion Include="System.Security.Permissions" Version="9.0.16" />
+		<!-- System.Text.Encoding.CodePages: SIL.Machine requires 10.0.x,
+			 other chains resolve to 9.0.9. Pin to 10.0.3 to match the plugin project. -->
+		<PackageVersion Include="System.Text.Encoding.CodePages" Version="10.0.3" />
 	</ItemGroup>
 
 	<!--
@@ -103,6 +106,7 @@
 		=============================================================
 	-->
 	<ItemGroup Label="SIL Tools">
+		<PackageVersion Include="ILRepack" Version="2.0.18" />
 		<PackageVersion Include="SIL.Chorus.App" Version="$(SilChorusVersion)" />
 		<PackageVersion Include="SIL.Chorus.LibChorus" Version="$(SilChorusVersion)" />
 		<PackageVersion Include="SIL.DesktopAnalytics" Version="4.0.0" />
diff --git a/FLExInstaller/PatchableInstallerHeatExclude.xml b/FLExInstaller/PatchableInstallerHeatExclude.xml
index cdf0687f6a..c82c380407 100644
--- a/FLExInstaller/PatchableInstallerHeatExclude.xml
+++ b/FLExInstaller/PatchableInstallerHeatExclude.xml
@@ -5,4 +5,6 @@
 -->
 <HeatHarvestExcludes xmlns="http://fieldworks.sil.org/heat-harvest-excludes/1">
 	<Exclude Name="Newtonsoft.Json.dll" />
+	<!-- Pre-ILRepack copy used only by tests; the packed FwParatextLexiconPlugin.dll is the shipping assembly. -->
+	<Exclude Name="FwParatextLexiconPlugin.PreMerge.dll" />
 </HeatHarvestExcludes>
diff --git a/FLExInstaller/wix6/Shared/Base/heat-exclude.xml b/FLExInstaller/wix6/Shared/Base/heat-exclude.xml
index 7629b0dd49..a70b1d155d 100644
--- a/FLExInstaller/wix6/Shared/Base/heat-exclude.xml
+++ b/FLExInstaller/wix6/Shared/Base/heat-exclude.xml
@@ -6,4 +6,6 @@
 -->
 <HeatHarvestExcludes xmlns="http://fieldworks.sil.org/heat-harvest-excludes/1">
 	<Exclude Name="Newtonsoft.Json.dll" />
+	<!-- Pre-ILRepack copy used only by tests; the packed FwParatextLexiconPlugin.dll is the shipping assembly. -->
+	<Exclude Name="FwParatextLexiconPlugin.PreMerge.dll" />
 </HeatHarvestExcludes>
diff --git a/Src/FwParatextLexiconPlugin/FwParatextLexiconPlugin.csproj b/Src/FwParatextLexiconPlugin/FwParatextLexiconPlugin.csproj
index 4627293a85..07e0ca9cad 100644
--- a/Src/FwParatextLexiconPlugin/FwParatextLexiconPlugin.csproj
+++ b/Src/FwParatextLexiconPlugin/FwParatextLexiconPlugin.csproj
@@ -28,6 +28,7 @@
     <PackageReference Include="SIL.LCModel.Utils" />
     <PackageReference Include="SIL.Machine" />
     <PackageReference Include="SIL.WritingSystems" />
+    <PackageReference Include="ILRepack" GeneratePathProperty="true" ExcludeAssets="all" />
     <PackageReference Include="System.ValueTuple" />
   </ItemGroup>
   <ItemGroup>
@@ -53,4 +54,5 @@
     <EmbeddedResource Include="question.ico" />
     <EmbeddedResource Include="Resources\question.ico" />
   </ItemGroup>
+  <Import Project="ILRepack.targets" />
 </Project>
\ No newline at end of file
diff --git a/Src/FwParatextLexiconPlugin/FwParatextLexiconPluginTests/App.config b/Src/FwParatextLexiconPlugin/FwParatextLexiconPluginTests/App.config
new file mode 100644
index 0000000000..34e4d2f626
--- /dev/null
+++ b/Src/FwParatextLexiconPlugin/FwParatextLexiconPluginTests/App.config
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<configuration>
+<system.diagnostics>
+<trace autoflush="false" indentsize="4">
+<listeners>
+<clear/>
+<add name="FwTraceListener" type="SIL.LCModel.Utils.EnvVarTraceListener, SIL.LCModel.Utils, Version=11.0.0.0, Culture=neutral"
+ initializeData="assertuienabled='false' assertexceptionenabled='true' logfilename='%temp%/asserts.log'"/>
+</listeners>
+</trace>
+</system.diagnostics>
+<runtime>
+<generatePublisherEvidence enabled="false" />
+<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
+<!-- Binding redirects are auto-generated at build time
+ (AutoGenerateBindingRedirects=true in Directory.Build.props).
+ Do NOT add manual redirects here; they will drift from CPM versions. -->
+<!-- Chorus 6.0.0 references L10NSharp 9.0.0; redirect to 10.0.0.
+     Remove when Chorus is updated to reference L10NSharp 10. -->
+<dependentAssembly>
+<assemblyIdentity name="L10NSharp" publicKeyToken="fd0b3e309a5b7c28" culture="neutral" />
+<bindingRedirect oldVersion="0.0.0.0-10.0.0.0" newVersion="10.0.0.0" />
+</dependentAssembly>
+<!-- Load the pre-ILRepack copy of the plugin so that tests run against
+     the un-merged assembly. The packed (ILRepack'd) assembly internalizes
+     SIL.LCModel / SIL.Core / etc., which causes type-identity mismatches
+     at runtime when the test project also references those NuGet packages. -->
+<dependentAssembly>
+<assemblyIdentity name="FwParatextLexiconPlugin" culture="neutral" />
+<codeBase version="9.3.9.0" href="FwParatextLexiconPlugin.PreMerge.dll" />
+</dependentAssembly>
+</assemblyBinding>
+</runtime>
+</configuration>
diff --git a/Src/FwParatextLexiconPlugin/FwParatextLexiconPluginTests/FwParatextLexiconPluginTests.csproj b/Src/FwParatextLexiconPlugin/FwParatextLexiconPluginTests/FwParatextLexiconPluginTests.csproj
index 3b03e2b20a..277ad554d1 100644
--- a/Src/FwParatextLexiconPlugin/FwParatextLexiconPluginTests/FwParatextLexiconPluginTests.csproj
+++ b/Src/FwParatextLexiconPlugin/FwParatextLexiconPluginTests/FwParatextLexiconPluginTests.csproj
@@ -29,13 +29,20 @@
   </ItemGroup>
   <ItemGroup>
     <Reference Include="netstandard" />
+    <!-- Reference the pre-ILRepack copy of the plugin assembly. The codeBase redirect
+         in App.config ensures the runtime also loads this copy instead of the packed one. -->
+    <Reference Include="FwParatextLexiconPlugin">
+      <HintPath>$(OutputPath)FwParatextLexiconPlugin.PreMerge.dll</HintPath>
+    </Reference>
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="../../Common/FwUtils/FwUtilsTests/FwUtilsTests.csproj" />
-    <ProjectReference Include="../FwParatextLexiconPlugin.csproj" />
+    <!-- Build the plugin first but don't reference its output (which is the ILRepack'd DLL).
+         Instead, reference the pre-merge copy below so tests compile against the un-merged assembly. -->
+    <ProjectReference Include="../FwParatextLexiconPlugin.csproj" ReferenceOutputAssembly="false" />
   </ItemGroup>
   <ItemGroup>
-    <None Include="../../AppForTests.config" Link="App.config">
+    <None Include="App.config">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
     </None>
   </ItemGroup>
diff --git a/Src/FwParatextLexiconPlugin/ILRepack.targets b/Src/FwParatextLexiconPlugin/ILRepack.targets
index bdc0217354..18bd584edc 100644
--- a/Src/FwParatextLexiconPlugin/ILRepack.targets
+++ b/Src/FwParatextLexiconPlugin/ILRepack.targets
@@ -6,10 +6,12 @@ This software is licensed under the LGPL, version 2.1 or later
 -->
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003" ToolsVersion="Current">
 	<PropertyGroup>
-		<FwrtPath>../..</FwrtPath>
-		<ILRepackBin Condition="('$(OS)' == 'Windows_NT')">&quot;$(FwrtPath)\packages\ILRepack.2.0.16\tools\ILRepack.exe&quot;</ILRepackBin>
-		<ILRepackBin Condition="('$(OS)' != 'Windows_NT')">mono &quot;$(FwrtPath)\packages\ILRepack.2.0.16\tools\ILRepack.exe&quot;</ILRepackBin>
+		<ILRepackBin>&quot;$(PkgILRepack)\tools\ILRepack.exe&quot;</ILRepackBin>
 		<PrimaryAssembly>$(OutputPath)/FwParatextLexiconPlugin.dll</PrimaryAssembly>
+		<!-- Pre-merge copy: used as ILRepack input AND referenced by the test project
+		     so tests compile and run against the un-merged assembly (avoiding type
+		     ambiguity between ILRepack-internalized types and NuGet originals). -->
+		<PreMergeAssembly>$(OutputPath)/FwParatextLexiconPlugin.PreMerge.dll</PreMergeAssembly>
 	</PropertyGroup>
 	<ItemGroup>
 		<RepackAssemblies Include="$(OutputPath)/SIL.Core.dll"/>
@@ -27,16 +29,17 @@ This software is licensed under the LGPL, version 2.1 or later
 	<ItemGroup>
 		<LibDirs Include="$(OutputPath)"/>
 	</ItemGroup>
-	<Target Name="AfterBuild" DependsOnTargets="ILRepack">
-		<!-- Insert tasks to run after build here -->
-	</Target>
-	<Target Name="ILRepack" DependsOnTargets="">
-		<!-- ILRepack some dependencies into primary assembly, first renaming
-			primary assembly so the original filename can be used as the
-			output of ILRepack. -->
-		<Copy SourceFiles="$(PrimaryAssembly)" DestinationFiles="$(PrimaryAssembly)~" />
-		<Exec Command="$(ILRepackBin) /internalize /repackDrop:NoLinuxRepack /out:$(PrimaryAssembly) @(LibDirs -> '/lib:%(Identity)', ' ') $(PrimaryAssembly)~ @(RepackAssemblies -> '%(Identity)', ' ')" />
-		<!-- Any dependency .config files may contain dllmaps that we will need in the repacked assembly. -->
-		<Copy SourceFiles="$(OutputPath)/SIL.LCModel.Core.dll.config" DestinationFiles="$(PrimaryAssembly).config"/>
+	<Target Name="ILRepack" AfterTargets="Build">
+		<!-- Save the un-merged assembly before ILRepack overwrites it.
+		     This copy serves double duty: ILRepack input, and the assembly
+		     that the test project compiles/runs against (via codeBase redirect). -->
+		<Copy SourceFiles="$(PrimaryAssembly)" DestinationFiles="$(PreMergeAssembly)" />
+		<!-- Remove auto-generated binding-redirect configs for merged assemblies
+			 to prevent ILRepack config-merge failures (DataSet schema conflicts). -->
+		<Delete Files="@(RepackAssemblies -> '%(Identity).config')" />
+		<Exec Command="$(ILRepackBin) /internalize /out:$(PrimaryAssembly) @(LibDirs -> '/lib:%(Identity)', ' ') $(PreMergeAssembly) @(RepackAssemblies -> '%(Identity)', ' ')" />
+		<!-- SIL.LCModel.Core.dll.config contains dllmaps needed for the repacked assembly.
+			 It was deleted above, so restore it from the NuGet package and copy as the plugin config. -->
+		<Copy SourceFiles="$(PkgSIL_LCModel_Core)/contentFiles/any/any/SIL.LCModel.Core.dll.config" DestinationFiles="$(PrimaryAssembly).config"/>
 	</Target>
 </Project>
diff --git a/Src/FwParatextLexiconPlugin/Properties/AssemblyInfo.cs b/Src/FwParatextLexiconPlugin/Properties/AssemblyInfo.cs
index 79acdfa859..0013a147eb 100644
--- a/Src/FwParatextLexiconPlugin/Properties/AssemblyInfo.cs
+++ b/Src/FwParatextLexiconPlugin/Properties/AssemblyInfo.cs
@@ -20,4 +20,4 @@
 // The following GUID is for the ID of the typelib if this project is exposed to COM
 [assembly: Guid("a787fc88-0ff6-4982-9305-8da92ef8fc7f")]
 
-[assembly: InternalsVisibleTo("FwParatextLexiconPluginTests")]
\ No newline at end of file
+[assembly: InternalsVisibleTo("FwParatextLexiconPluginTests")]