diff --git a/api/tests/test_canon_log_schema.py b/api/tests/test_canon_log_schema.py
index 326d289..c5b3908 100644
--- a/api/tests/test_canon_log_schema.py
+++ b/api/tests/test_canon_log_schema.py
@@ -1,4 +1,3 @@
-import copy
 import json
 from pathlib import Path
 
@@ -56,3 +55,16 @@ def test_empty_optional_arrays_are_allowed():
     doc["active_quests"] = []
     doc["humiliations"] = []
     assert validate_canon_log(doc) == []
+
+
+def test_root_level_stray_field_is_rejected():
+    # §2/§7: stats/HP/inventory must never enter the log — additionalProperties:false at root.
+    doc = _valid()
+    doc["hp"] = 10
+    assert validate_canon_log(doc) != []
+
+
+def test_negative_turn_is_rejected():
+    doc = _valid()
+    doc["humiliations"][0]["turn"] = -1
+    assert validate_canon_log(doc) != []
diff --git a/docs/schemas/canon-log.schema.json b/docs/schemas/canon-log.schema.json
index 795a2e9..9853159 100644
--- a/docs/schemas/canon-log.schema.json
+++ b/docs/schemas/canon-log.schema.json
@@ -72,7 +72,7 @@
         "additionalProperties": false,
         "required": ["id", "text", "weight", "turn"],
         "properties": {
-          "id": { "type": "string", "minLength": 1 },
+          "id": { "type": "string", "minLength": 1, "pattern": "^[a-z0-9_]+$" },
           "text": { "type": "string", "minLength": 1 },
           "weight": { "type": "integer", "minimum": 1, "maximum": 10 },
           "turn": { "type": "integer", "minimum": 0 }