Pin SDK 10.0.401.

docs/topics.md

@@ -34,3 +34,4 @@ No topics recorded yet.
 | Topic | Date noted | Date started | Date completed | Outcome |
 |---|---|---|---|---|
 | Capture the pre-migration BusinessMgr build and test baseline | 2026-09-10 | 2026-09-10 | 2026-09-10 | Using SDK 10.0.401, restore succeeded. Visual Studio 18 MSBuild built the complete Debug solution successfully, including the SSDT-dependent Portal test project. The .NET CLI built all production projects and the Control tests but reports `MSB4278` for the Portal test project's Visual Studio SSDT import, so Visual Studio MSBuild remains required for that project. Common's MailKit 4.13.0 dependency reports `NU1902`; the CLI build otherwise recorded 20 compiler warnings. Control tests passed 8 of 8 and Portal tests passed 13 of 13. |
+| Pin the BusinessMgr .NET 10 SDK | 2026-09-10 | 2026-09-10 | 2026-09-10 | Added `global.json` for SDK 10.0.401 with `latestPatch` roll-forward and prerelease SDKs disabled. Visual Studio MSBuild remains required for the SSDT-dependent Portal test project. |

global.json

@@ -0,0 +1,7 @@
+{
+  "sdk": {
+    "version": "10.0.401",
+    "rollForward": "latestPatch",
+    "allowPrerelease": false
+  }
+}