diff --git a/Mr. Brick Adventures.csproj b/Mr. Brick Adventures.csproj
index f1a87d0..29aa0d5 100644
--- a/Mr. Brick Adventures.csproj	
+++ b/Mr. Brick Adventures.csproj	
@@ -9,4 +9,15 @@
     <PackageReference Include="Facepunch.Steamworks.Dlls" Version="2.3.2" />
     <PackageReference Include="Facepunch.Steamworks.Library" Version="2.3.3" />
   </ItemGroup>
+
+  <!-- Godot.NET.Sdk globs **/*.cs, which would compile the progression projects into this
+       assembly as well as their own. They are separate projects; exclude them here. -->
+  <ItemGroup>
+    <Compile Remove="progression\**" />
+    <Compile Remove="progression.tests\**" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="progression\Mr.BrickAdventures.Progression.csproj" />
+  </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/Mr. Brick Adventures.sln b/Mr. Brick Adventures.sln
index 7ef00af..02a242d 100644
--- a/Mr. Brick Adventures.sln	
+++ b/Mr. Brick Adventures.sln	
@@ -1,19 +1,110 @@
-Microsoft Visual Studio Solution File, Format Version 12.00
+
+Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio 2012
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Mr. Brick Adventures", "Mr. Brick Adventures.csproj", "{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "progression", "progression", "{73CE8E92-AE0D-34EB-F3CD-A6392CC7A1AA}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Mr.BrickAdventures.Progression", "progression\Mr.BrickAdventures.Progression.csproj", "{4F115C37-24F6-4933-9086-ED5925EE5106}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "progression.tests", "progression.tests", "{B756B2BA-9E41-468E-DBBE-5BA8CC0A1E41}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Mr.BrickAdventures.Progression.Tests", "progression.tests\Mr.BrickAdventures.Progression.Tests.csproj", "{A4660883-E42A-4D04-99A3-770F36E9D861}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
-	Debug|Any CPU = Debug|Any CPU
-	ExportDebug|Any CPU = ExportDebug|Any CPU
-	ExportRelease|Any CPU = ExportRelease|Any CPU
+		Debug|Any CPU = Debug|Any CPU
+		Debug|x64 = Debug|x64
+		Debug|x86 = Debug|x86
+		ExportDebug|Any CPU = ExportDebug|Any CPU
+		ExportDebug|x64 = ExportDebug|x64
+		ExportDebug|x86 = ExportDebug|x86
+		ExportRelease|Any CPU = ExportRelease|Any CPU
+		ExportRelease|x64 = ExportRelease|x64
+		ExportRelease|x86 = ExportRelease|x86
+		Release|Any CPU = Release|Any CPU
+		Release|x64 = Release|x64
+		Release|x86 = Release|x86
 	EndGlobalSection
 	GlobalSection(ProjectConfigurationPlatforms) = postSolution
 		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
 		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Debug|x64.Build.0 = Debug|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Debug|x86.Build.0 = Debug|Any CPU
 		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportDebug|Any CPU.ActiveCfg = ExportDebug|Any CPU
 		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportDebug|Any CPU.Build.0 = ExportDebug|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportDebug|x64.ActiveCfg = ExportDebug|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportDebug|x64.Build.0 = ExportDebug|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportDebug|x86.ActiveCfg = ExportDebug|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportDebug|x86.Build.0 = ExportDebug|Any CPU
 		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportRelease|Any CPU.ActiveCfg = ExportRelease|Any CPU
 		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportRelease|Any CPU.Build.0 = ExportRelease|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportRelease|x64.ActiveCfg = ExportRelease|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportRelease|x64.Build.0 = ExportRelease|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportRelease|x86.ActiveCfg = ExportRelease|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.ExportRelease|x86.Build.0 = ExportRelease|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Release|x64.ActiveCfg = Release|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Release|x64.Build.0 = Release|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Release|x86.ActiveCfg = Release|Any CPU
+		{A1D482B9-207B-4D6C-A0A0-D9E6D1AE2356}.Release|x86.Build.0 = Release|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Debug|x64.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Debug|x86.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportDebug|Any CPU.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportDebug|Any CPU.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportDebug|x64.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportDebug|x64.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportDebug|x86.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportDebug|x86.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportRelease|Any CPU.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportRelease|Any CPU.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportRelease|x64.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportRelease|x64.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportRelease|x86.ActiveCfg = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.ExportRelease|x86.Build.0 = Debug|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Release|Any CPU.Build.0 = Release|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Release|x64.ActiveCfg = Release|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Release|x64.Build.0 = Release|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Release|x86.ActiveCfg = Release|Any CPU
+		{4F115C37-24F6-4933-9086-ED5925EE5106}.Release|x86.Build.0 = Release|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Debug|x64.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Debug|x86.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportDebug|Any CPU.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportDebug|Any CPU.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportDebug|x64.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportDebug|x64.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportDebug|x86.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportDebug|x86.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportRelease|Any CPU.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportRelease|Any CPU.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportRelease|x64.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportRelease|x64.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportRelease|x86.ActiveCfg = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.ExportRelease|x86.Build.0 = Debug|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Release|Any CPU.Build.0 = Release|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Release|x64.ActiveCfg = Release|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Release|x64.Build.0 = Release|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Release|x86.ActiveCfg = Release|Any CPU
+		{A4660883-E42A-4D04-99A3-770F36E9D861}.Release|x86.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(NestedProjects) = preSolution
+		{4F115C37-24F6-4933-9086-ED5925EE5106} = {73CE8E92-AE0D-34EB-F3CD-A6392CC7A1AA}
+		{A4660883-E42A-4D04-99A3-770F36E9D861} = {B756B2BA-9E41-468E-DBBE-5BA8CC0A1E41}
 	EndGlobalSection
 EndGlobal
diff --git a/docs/plans/phase-a-progression-domain.md b/docs/plans/phase-a-progression-domain.md
index cc22b03..641ea98 100644
--- a/docs/plans/phase-a-progression-domain.md
+++ b/docs/plans/phase-a-progression-domain.md
@@ -37,8 +37,14 @@ No tests. Pure setup.
 
 **Done when:** `dotnet test` runs and reports zero tests; Godot still builds; the game still launches and plays.
 
-**Guard rail for the whole phase:** `grep -r "using Godot" progression/` must stay empty. That single check is
-what ADR-0004 buys you.
+**Guard rail for the whole phase:**
+
+```sh
+grep -rn "using Godot" progression progression.tests --include=*.cs   # must print nothing
+```
+
+That single check is what ADR-0004 buys you. Scope it to `--include=*.cs` — an unscoped `grep -r` also matches
+prose in the `.csproj` comments and reports a false violation.
 
 ---
 
diff --git a/progression.tests/.gdignore b/progression.tests/.gdignore
new file mode 100644
index 0000000..e69de29
diff --git a/progression.tests/GlobalUsings.cs b/progression.tests/GlobalUsings.cs
new file mode 100644
index 0000000..8c927eb
--- /dev/null
+++ b/progression.tests/GlobalUsings.cs
@@ -0,0 +1 @@
+global using Xunit;
\ No newline at end of file
diff --git a/progression.tests/Mr.BrickAdventures.Progression.Tests.csproj b/progression.tests/Mr.BrickAdventures.Progression.Tests.csproj
new file mode 100644
index 0000000..e6bbf02
--- /dev/null
+++ b/progression.tests/Mr.BrickAdventures.Progression.Tests.csproj
@@ -0,0 +1,30 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+
+    <IsPackable>false</IsPackable>
+    <IsTestProject>true</IsTestProject>
+    <RootNamespace>Mr.BrickAdventures.Progression.Tests</RootNamespace>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\progression\Mr.BrickAdventures.Progression.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.0" />
+    <PackageReference Include="xunit" Version="2.4.2" />
+    <PackageReference Include="xunit.runner.visualstudio" Version="2.4.5">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="coverlet.collector" Version="6.0.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+  </ItemGroup>
+
+</Project>
diff --git a/progression/.gdignore b/progression/.gdignore
new file mode 100644
index 0000000..e69de29
diff --git a/progression/Mr.BrickAdventures.Progression.csproj b/progression/Mr.BrickAdventures.Progression.csproj
new file mode 100644
index 0000000..5362823
--- /dev/null
+++ b/progression/Mr.BrickAdventures.Progression.csproj
@@ -0,0 +1,17 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <RootNamespace>Mr.BrickAdventures.Progression</RootNamespace>
+
+    <!-- Required on assemblies referenced by a Godot project, or Godot fails to load them
+         on hot reload. See docs/adr/0004-domain-does-not-reference-godot.md -->
+    <EnableDynamicLoading>true</EnableDynamicLoading>
+  </PropertyGroup>
+
+  <!-- ADR-0004: this project must never reference the engine. Verified by the guard rail
+       documented in docs/plans/phase-a-progression-domain.md, slice 0. -->
+
+</Project>