fix(docs): derive grammar field count on main

docs/CONTENT_GRAMMAR_CONTRACTS.md

@@ -39,7 +39,7 @@ The active server is authoritative for the accepted legacy grammar:
 - `atrinik/server:src/loaders/object.l#get_ob_diff` defines object serialization.
 - `atrinik/server:src/server/map.c#new_save_map` defines map serialization.
 
-`grammar-inventory.json` captures those source locations, 282 known object
+`grammar-inventory.json` captures those source locations, 285 known object
 fields, the map-header fields and tiled-map key pattern, object and header
 delimiters, all four object scanner entry modes, both map-header scanner entry
 modes, the three observable load flags, byte/line-ending behavior, and the

tools/tests/test_content_contracts.py

@@ -7,6 +7,7 @@
 import io
 import json
 from pathlib import Path
+import re
 import shutil
 import tempfile
 import unittest
@@ -81,6 +82,19 @@ def test_grammar_inventory_is_complete_and_canonical(self):
             {entry["name"] for entry in self.grammar["load_modes"]},
         )
 
+    def test_grammar_documentation_reports_authoritative_field_count(self):
+        documentation = (ROOT / "docs" / "CONTENT_GRAMMAR_CONTRACTS.md").read_text()
+        match = re.search(
+            r"captures those source locations, ([0-9]+) known object\s+fields,",
+            documentation,
+        )
+
+        self.assertIsNotNone(match)
+        self.assertEqual(
+            len(self.grammar["object_grammar"]["known_fields"]),
+            int(match.group(1)),
+        )
+
     def test_consumer_inventory_covers_every_legacy_role_and_repository(self):
         inventory = load_json(CONTRACT_ROOT / "consumer-inventory.json")
         entries = inventory["consumers"]