stabilize tests

src/BinaryIndex/__Libraries/StellaOps.BinaryIndex.GoldenSet/Models/GoldenSetDefinition.cs

@@ -249,6 +249,11 @@ public static class GoldenSetConstants
     /// </summary>
     public const string GhsaIdPattern = @"^GHSA-[a-z0-9]{4}-[a-z0-9]{4}-[a-z0-9]{4}$";
 
+    /// <summary>
+    /// Regex pattern for synthetic test fixture IDs.
+    /// </summary>
+    public const string SyntheticIdPattern = @"^SYNTH-\d{4}-[a-z][a-z0-9\-]*$";
+
     /// <summary>
     /// Regex pattern for basic block edge format.
     /// </summary>