feat(protocol): negotiate display and native input

tools/validate.py

@@ -36,6 +36,24 @@ def main() -> int:
             maximum = entry.get("max_frame_bytes", entry.get("max_payload_bytes"))
             assert isinstance(maximum, int) and 1 <= maximum <= maximum_bound
 
+    feature_registry = json.loads((ROOT / "registries/features.json").read_text(encoding="utf-8"))
+    registered_features = {entry["id"] for entry in feature_registry["features"]}
+    assert {"display.request.v1", "input.absolute.v1", "input.scroll.v1"}.issubset(registered_features)
+
+    display_mode = defs["DisplayMode"]
+    assert display_mode["required"] == ["resolution_width", "resolution_height", "fps"]
+    assert display_mode["properties"]["resolution_width"] == {"type": "integer", "minimum": 320, "maximum": 16384}
+    assert display_mode["properties"]["resolution_height"] == {"type": "integer", "minimum": 200, "maximum": 8640}
+    assert display_mode["properties"]["fps"] == {"type": "integer", "minimum": 1, "maximum": 240}
+    for owner, field in (
+        ("SessionRequest", "requested_display_mode"),
+        ("BrokerSession", "requested_display_mode"),
+        ("BrokerSession", "effective_display_mode"),
+        ("ManifestProfile", "display_mode"),
+    ):
+        assert field not in defs[owner]["required"]
+        assert defs[owner]["properties"][field] == {"$ref": "#/$defs/DisplayMode"}
+
     manifest = json.loads((ROOT / "fixtures/valid/manifest.json").read_text(encoding="utf-8"))
     assert set(manifest).issubset(set(defs["ConnectionManifest"]["properties"]))
     forbidden = json.loads((ROOT / "fixtures/invalid/manifest-provider-field.json").read_text(encoding="utf-8"))