tests fixes and sprints work

src/Policy/__Libraries/StellaOps.Policy/Licensing/LicenseCompatibilityChecker.cs

@@ -0,0 +1,69 @@
+namespace StellaOps.Policy.Licensing;
+
+public sealed record LicenseCompatibilityResult(bool IsCompatible, string? Reason);
+
+public sealed class LicenseCompatibilityChecker
+{
+    public LicenseCompatibilityResult Check(
+        LicenseDescriptor first,
+        LicenseDescriptor second,
+        ProjectContext context)
+    {
+        if (first is null)
+        {
+            throw new ArgumentNullException(nameof(first));
+        }
+
+        if (second is null)
+        {
+            throw new ArgumentNullException(nameof(second));
+        }
+
+        if (IsApacheGpl2Conflict(first.Id, second.Id))
+        {
+            return new LicenseCompatibilityResult(
+                false,
+                "Apache-2.0 is incompatible with GPL-2.0-only due to patent clauses.");
+        }
+
+        if (first.Category == LicenseCategory.Proprietary
+            && second.Category == LicenseCategory.StrongCopyleft)
+        {
+            return new LicenseCompatibilityResult(
+                false,
+                "Strong copyleft is incompatible with proprietary licensing.");
+        }
+
+        if (second.Category == LicenseCategory.Proprietary
+            && first.Category == LicenseCategory.StrongCopyleft)
+        {
+            return new LicenseCompatibilityResult(
+                false,
+                "Strong copyleft is incompatible with proprietary licensing.");
+        }
+
+        if (context.DistributionModel == DistributionModel.Commercial
+            && first.Category == LicenseCategory.StrongCopyleft
+            && second.Category == LicenseCategory.StrongCopyleft)
+        {
+            return new LicenseCompatibilityResult(
+                true,
+                "Strong copyleft pairing detected; ensure redistribution obligations are met.");
+        }
+
+        return new LicenseCompatibilityResult(true, null);
+    }
+
+    private static bool IsApacheGpl2Conflict(string first, string second)
+    {
+        return (IsApache(first) && IsGpl2Only(second))
+            || (IsApache(second) && IsGpl2Only(first));
+    }
+
+    private static bool IsApache(string licenseId)
+        => licenseId.Equals("Apache-2.0", StringComparison.OrdinalIgnoreCase);
+
+    private static bool IsGpl2Only(string licenseId)
+        => licenseId.Equals("GPL-2.0-only", StringComparison.OrdinalIgnoreCase)
+           || licenseId.Equals("GPL-2.0+", StringComparison.OrdinalIgnoreCase);
+}