diff --git a/CHANGELOG.md b/CHANGELOG.md
index fca0c89..e2e8631 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -76,6 +76,18 @@ floor.
 - Adopted the canonical `.gitignore` and `.editorconfig`. The `.editorconfig` change
   scopes the private-field naming rule to instance fields — a `const` is a field, so
   the rule previously demanded `_nonceSize` for `private const int NonceSize`.
+- Moved the build properties shared by both projects out of the individual csprojs
+  and into the root `Directory.Build.props`. Both projects previously restated the
+  same fifteen properties, which is fifteen chances for one copy to drift silently.
+  Each csproj now carries only what is specific to it. `Directory.Packages.props`
+  also gains `CentralPackageVersionOverrideEnabled=false`, so a stray inline
+  `Version=` on a `PackageReference` is now an `NU1008` restore failure instead of
+  being silently ignored in favour of the central version. Verified to be a
+  no-op for consumers: packing at the same commit from a clean `obj/` before and
+  after produces a byte-identical `.nuspec`, byte-identical `net8.0` and `net10.0`
+  assemblies and XML docs, and identical `README.md`, icon and package metadata —
+  the only difference anywhere in the package is the `.psmdcp` filename, which NuGet
+  regenerates on every pack.
 
 ### Added
 
diff --git a/Directory.Build.props b/Directory.Build.props
index 08993bb..d216bf1 100644
--- a/Directory.Build.props
+++ b/Directory.Build.props
@@ -1,8 +1,40 @@
 <Project>
-  <PropertyGroup>
-    <Nullable>enable</Nullable>
-    <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
-    <Authors>Stuart Meeks</Authors>
-    <Company>Next Iteration</Company>
-  </PropertyGroup>
+
+	<!--
+		Properties identical across every project in this repo. STANDARD.md 1.2.
+
+		They used to be restated in each csproj. Fifteen copies of a property is
+		fifteen chances for one of them to drift, and the drift is silent — nothing
+		fails when a csproj quietly disagrees with its sibling about DebugType. A
+		csproj below carries only what is genuinely specific to it: PackageId,
+		Version, Description, PackageTags, TargetFrameworks, the package's own URLs,
+		and any real exception (the test project opting out of
+		GenerateDocumentationFile, because sample and fixture code has no XML docs
+		and TreatWarningsAsErrors would fail the build over it).
+
+		EnforceCodeStyleInBuild is deliberately NOT here. STANDARD.md 1.2.1 is
+		blocked: TreatWarningsAsErrors promotes every advisory .editorconfig
+		preference to a hard failure, which produced 490 build errors in a sibling
+		repo. It needs a per-rule gate-versus-advisory decision first.
+	-->
+	<PropertyGroup>
+		<Nullable>enable</Nullable>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<SatelliteResourceLanguages>en</SatelliteResourceLanguages>
+		<AnalysisLevel>latest</AnalysisLevel>
+		<GenerateDocumentationFile>true</GenerateDocumentationFile>
+		<EnablePackageValidation>true</EnablePackageValidation>
+		<IncludeSymbols>true</IncludeSymbols>
+		<SymbolPackageFormat>snupkg</SymbolPackageFormat>
+		<DebugType>portable</DebugType>
+		<PublishRepositoryUrl>true</PublishRepositoryUrl>
+		<EmbedUntrackedSources>true</EmbedUntrackedSources>
+		<ContinuousIntegrationBuild Condition="'$(GITHUB_ACTIONS)' == 'true'">true</ContinuousIntegrationBuild>
+		<PackageLicenseExpression>MIT</PackageLicenseExpression>
+		<Copyright>© Stuart Meeks</Copyright>
+		<TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+		<Authors>Stuart Meeks</Authors>
+		<Company>Next Iteration</Company>
+	</PropertyGroup>
+
 </Project>
diff --git a/Directory.Packages.props b/Directory.Packages.props
index 29313ff..a874583 100644
--- a/Directory.Packages.props
+++ b/Directory.Packages.props
@@ -1,6 +1,13 @@
 <Project>
   <PropertyGroup>
     <ManagePackageVersionsCentrally>true</ManagePackageVersionsCentrally>
+    <!--
+      Hard-fail if a csproj declares <PackageReference Version="…" /> alongside
+      CPM. Without this MSBuild silently ignores the inline version and uses the
+      central one — which is the exact drift this file exists to prevent, and it
+      prevents it without ever saying so. See STANDARD.md 1.3.
+    -->
+    <CentralPackageVersionOverrideEnabled>false</CentralPackageVersionOverrideEnabled>
   </PropertyGroup>
 
   <ItemGroup>
diff --git a/src/NextIteration.SpectreConsole.Settings/NextIteration.SpectreConsole.Settings.csproj b/src/NextIteration.SpectreConsole.Settings/NextIteration.SpectreConsole.Settings.csproj
index fe0e712..f3070e7 100644
--- a/src/NextIteration.SpectreConsole.Settings/NextIteration.SpectreConsole.Settings.csproj
+++ b/src/NextIteration.SpectreConsole.Settings/NextIteration.SpectreConsole.Settings.csproj
@@ -1,37 +1,26 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
+	<!--
+		Only what is specific to this project. Everything shared with the test
+		project lives in the root Directory.Build.props (STANDARD.md 1.2).
+	-->
 	<PropertyGroup>
 		<TargetFrameworks>net8.0;net10.0</TargetFrameworks>
-		<ImplicitUsings>enable</ImplicitUsings>
-		<Nullable>enable</Nullable>
-		<SatelliteResourceLanguages>en</SatelliteResourceLanguages>
-		<GenerateDocumentationFile>true</GenerateDocumentationFile>
-		<AnalysisLevel>latest</AnalysisLevel>
 	</PropertyGroup>
 
 	<PropertyGroup>
 		<PackageId>NextIteration.SpectreConsole.Settings</PackageId>
 		<Version>0.3.0</Version>
-		<Authors>Stuart Meeks</Authors>
 		<Description>Strongly-typed, JSON-persisted settings for CLI tools, with automatic or explicit persistence and ready-made Spectre.Console settings commands.</Description>
 		<GeneratePackageOnBuild Condition="'$(Configuration)' == 'Release'">true</GeneratePackageOnBuild>
 		<PackageOutputPath>$(MSBuildThisFileDirectory)..\..\artifacts\packages</PackageOutputPath>
 		<IncludeBuildOutput>true</IncludeBuildOutput>
-		<PackageLicenseExpression>MIT</PackageLicenseExpression>
 		<PackageReadmeFile>README.md</PackageReadmeFile>
 		<PackageProjectUrl>https://github.com/StuartMeeks/NextIteration.SpectreConsole.Settings</PackageProjectUrl>
 		<RepositoryUrl>https://github.com/StuartMeeks/NextIteration.SpectreConsole.Settings.git</RepositoryUrl>
 		<RepositoryType>git</RepositoryType>
 		<PackageTags>spectre;cli;settings;configuration;json</PackageTags>
 		<PackageIcon>icon.png</PackageIcon>
-		<Copyright>© Stuart Meeks</Copyright>
-		<EnablePackageValidation>true</EnablePackageValidation>
-		<PublishRepositoryUrl>true</PublishRepositoryUrl>
-		<EmbedUntrackedSources>true</EmbedUntrackedSources>
-		<IncludeSymbols>true</IncludeSymbols>
-		<SymbolPackageFormat>snupkg</SymbolPackageFormat>
-		<DebugType>portable</DebugType>
-		<ContinuousIntegrationBuild Condition="'$(GITHUB_ACTIONS)' == 'true'">true</ContinuousIntegrationBuild>
 	</PropertyGroup>
 
 	<ItemGroup>
diff --git a/tests/NextIteration.SpectreConsole.Settings.Tests/NextIteration.SpectreConsole.Settings.Tests.csproj b/tests/NextIteration.SpectreConsole.Settings.Tests/NextIteration.SpectreConsole.Settings.Tests.csproj
index 62fd542..d3429cd 100644
--- a/tests/NextIteration.SpectreConsole.Settings.Tests/NextIteration.SpectreConsole.Settings.Tests.csproj
+++ b/tests/NextIteration.SpectreConsole.Settings.Tests/NextIteration.SpectreConsole.Settings.Tests.csproj
@@ -10,10 +10,11 @@
 		<!-- xUnit.net v3 test projects are self-hosting executables, not
 		     libraries loaded by an external runner. -->
 		<OutputType>Exe</OutputType>
-		<ImplicitUsings>enable</ImplicitUsings>
-		<Nullable>enable</Nullable>
 		<IsPackable>false</IsPackable>
 		<IsTestProject>true</IsTestProject>
+		<!-- Opts out of the Directory.Build.props default. Test and fixture code
+		     carries no XML docs, and TreatWarningsAsErrors would fail the build
+		     over every missing one. -->
 		<GenerateDocumentationFile>false</GenerateDocumentationFile>
 		<!--
 			CA1707 (no underscores in member names) is the xUnit-naming