STRU and exception tasks accepted; G6 cascade fix, exception class mutants, RTTI unit notes

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

tasks_gen/train/G1903/task.json

@@ -0,0 +1,74 @@
+{
+  "id": "G1903",
+  "category": "B",
+  "object_type": "STRU",
+  "difficulty": 2,
+  "release_target": "v816",
+  "expected_outcome": "implement",
+  "budget": {
+    "max_tool_calls": 60,
+    "max_activations": 15
+  },
+  "seed": [
+    {
+      "type": "TABL",
+      "name": "{{P}}STOCK",
+      "file": "seed/stock.tabl.asabap",
+      "description": "Stock positions"
+    }
+  ],
+  "contract": [
+    {
+      "type": "STRU",
+      "name": "{{P}}STOCK_LINE",
+      "fields": [
+        "material",
+        "plant",
+        "net_amount",
+        "currency",
+        "created_by",
+        "created_on"
+      ]
+    },
+    {
+      "type": "STRU",
+      "name": "{{P}}AUDIT_INFO",
+      "fields": [
+        "created_by",
+        "created_on"
+      ]
+    }
+  ],
+  "out_of_scope": [
+    "{{P}}STOCK"
+  ],
+  "hidden_tests": [
+    {
+      "type": "CLAS",
+      "name": "{{P}}T16_HIDDEN",
+      "file": "hidden/t16_hidden.clas.abap",
+      "description": "T16 hidden tests"
+    }
+  ],
+  "reference": [
+    {
+      "type": "STRU",
+      "name": "{{P}}AUDIT_INFO",
+      "file": "reference/audit_info.ddls.asddls",
+      "description": "Audit information structure"
+    },
+    {
+      "type": "STRU",
+      "name": "{{P}}STOCK_LINE",
+      "file": "reference/stock_line.ddls.asddls",
+      "description": "Stock line structure"
+    },
+    {
+      "type": "CLAS",
+      "name": "{{P}}T16_TEST",
+      "file": "reference/t16_test.clas.abap",
+      "description": "T16 own tests"
+    }
+  ],
+  "craft_checks": []
+}