diff --git a/ErrorOrX.slnx b/ErrorOrX.slnx
index ab55825..fd2875b 100644
--- a/ErrorOrX.slnx
+++ b/ErrorOrX.slnx
@@ -20,11 +20,15 @@
     </Folder>
 
     <!-- Samples -->
-    <!-- ErrorOrX.Samples.Diagnostics is intentionally excluded — it contains deliberately-broken code
-         that triggers EOE001-EOE036 diagnostics. Open it in your IDE for squiggles, or
-         `dotnet build samples/ErrorOrX.Samples.Diagnostics/` to see the errors at the CLI. -->
+    <!-- ErrorOrX.Samples.Diagnostics contains deliberately-broken code that triggers
+         EOE001-EOE036 diagnostics, so it is loaded for IDE squiggles but excluded from
+         the solution build (Build Project="false"). Build it explicitly to see the
+         errors at the CLI: `dotnet build samples/ErrorOrX.Samples.Diagnostics/` -->
     <Folder Name="/samples/">
         <Project Path="samples/ErrorOrX.Samples.Api/ErrorOrX.Samples.Api.csproj" />
+        <Project Path="samples/ErrorOrX.Samples.Diagnostics/ErrorOrX.Samples.Diagnostics.csproj">
+            <Build Solution="*|*" Project="false" />
+        </Project>
     </Folder>
 
     <!-- Tests -->
diff --git a/samples/ErrorOrX.Samples.Diagnostics/README.md b/samples/ErrorOrX.Samples.Diagnostics/README.md
index f6fd252..d858f26 100644
--- a/samples/ErrorOrX.Samples.Diagnostics/README.md
+++ b/samples/ErrorOrX.Samples.Diagnostics/README.md
@@ -1,6 +1,6 @@
 # ErrorOrX.Samples.Diagnostics
 
-Realistic-looking API code that deliberately triggers ErrorOrX diagnostics. This project is **excluded from `ErrorOrX.slnx`** — the source-generator-reported errors halt compilation, which is the entire point. Open the project in your IDE for live squiggles, or build it explicitly:
+Realistic-looking API code that deliberately triggers ErrorOrX diagnostics. This project is **in `ErrorOrX.slnx` but excluded from the solution build** (`<Build Solution="*|*" Project="false" />`) — the source-generator-reported errors halt compilation, which is the entire point. Open the solution in your IDE for live squiggles, or build the project explicitly:
 
 ```bash
 dotnet build samples/ErrorOrX.Samples.Diagnostics/ErrorOrX.Samples.Diagnostics.csproj