stabilize tests

docs/technical/testing/SPRINT_EXECUTION_PLAYBOOK.md

@@ -422,6 +422,17 @@ If a sprint is BLOCKED:
 3. Avoid hard-coded timeouts; use configurable timeouts
 4. Run tests 10× locally to verify determinism
 
+
+### Pattern 7: MSBuild OutOfMemory During Restore
+
+**Symptom:** `dotnet test` fails with MSBuild `OutOfMemoryException` during restore.
+
+**Root Cause:** Parallel restore spawns too many MSBuild nodes under constrained memory.
+
+**Fix:**
+1. Ensure `RestoreDisableParallel=true` is set for test projects (see `src/Directory.Build.props`).
+2. Re-run `dotnet test` to restore sequentially and reduce memory pressure.
+
 ---
 
 ## Troubleshooting Guide