diff --git a/client/tests/unit/test_round_trip.gd b/client/tests/unit/test_round_trip.gd
new file mode 100644
index 0000000..3fb1e3c
--- /dev/null
+++ b/client/tests/unit/test_round_trip.gd
@@ -0,0 +1,39 @@
+extends "res://addons/gut/test.gd"
+
+const NewGame = preload("res://scripts/newgame/new_game.gd")
+const ContentDB = preload("res://scripts/content/content_db.gd")
+const CanonLog = preload("res://scripts/canon_log/canon_log.gd")
+
+
+func _built_log():
+	var world = ContentDB.new()
+	world.load_from(ContentDB.default_content_root())
+	var rng := RandomNumberGenerator.new()
+	rng.seed = 3
+	var origin: Dictionary = ContentDB.load_json(ContentDB.origin_path("deserter"))
+	var res := NewGame.construct(origin, world, {"name": "Aldric", "class_id": "priest"}, rng)
+	assert_true(res["ok"], str(res["errors"]))
+	return res["log"]
+
+
+func test_to_from_dict_is_identity():
+	var log = _built_log()
+	var d1: Dictionary = log.to_dict()
+	var log2 = CanonLog.from_dict(d1)
+	assert_not_null(log2)
+	assert_eq(log2.to_dict(), d1)
+
+
+func test_constructed_log_satisfies_contract_invariants():
+	var d: Dictionary = _built_log().to_dict()
+	assert_eq(d["schema_version"], 1)
+	assert_true(d["recent_events"].size() <= 5)
+	assert_eq(d["player"].keys().size(), 3)          # exactly name/class_id/luck_descriptor
+	assert_false("luck" in d["player"])              # §7: no numeric luck
+	assert_true(d["player"]["class_id"] in ["sellsword", "assassin", "priest"])
+	for m in d["party"]:
+		assert_true(m["disposition"] >= -100 and m["disposition"] <= 100)
+	for q in d["active_quests"]:
+		assert_true(q["status"] in ["active", "complete", "failed"])
+	for h in d["humiliations"]:
+		assert_true(h["weight"] >= 1 and h["weight"] <= 10)