feat(client): GameState move targets — remove_item, reveal/gift tracking

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

client/scripts/state/game_state.gd

@@ -9,6 +9,8 @@ var luck_base: int = 0
 var stats: Dictionary = {}            # {str, dex, con, fth, mag}
 var npc_dispositions: Dictionary = {} # world-npc id -> int (−100..100)
 var inventory: Dictionary = {}        # item_id -> qty
+var revealed_topics: Dictionary = {}  # topic_id -> true
+var gifts_given: Dictionary = {}      # item_id -> true (idempotency for give_item)
 
 
 func set_luck(v: int) -> void:
@@ -29,3 +31,27 @@ func set_npc_disposition(id: String, v: int) -> void:
 
 func add_item(item_id: String, qty: int) -> void:
 	inventory[item_id] = int(inventory.get(item_id, 0)) + qty
+
+
+func remove_item(item_id: String, qty: int) -> void:
+	var left := int(inventory.get(item_id, 0)) - qty
+	if left > 0:
+		inventory[item_id] = left
+	else:
+		inventory.erase(item_id)
+
+
+func mark_revealed(topic_id: String) -> void:
+	revealed_topics[topic_id] = true
+
+
+func is_revealed(topic_id: String) -> bool:
+	return revealed_topics.has(topic_id)
+
+
+func mark_gift_given(item_id: String) -> void:
+	gifts_given[item_id] = true
+
+
+func is_gift_given(item_id: String) -> bool:
+	return gifts_given.has(item_id)

client/tests/unit/test_game_state.gd

@@ -28,3 +28,26 @@ func test_luck_descriptor_delegates():
 	var s = GameState.new()
 	s.luck = 4
 	assert_eq(s.luck_descriptor(), "Fortune spits on you")
+
+
+func test_remove_item_decrements_and_floors_at_zero():
+	var gs = GameState.new()
+	gs.add_item("coin", 3)
+	gs.remove_item("coin", 2)
+	assert_eq(gs.inventory.get("coin", 0), 1)
+	gs.remove_item("coin", 5)
+	assert_eq(gs.inventory.get("coin", 0), 0)
+
+
+func test_revealed_topics_tracked():
+	var gs = GameState.new()
+	assert_false(gs.is_revealed("varrell_twins"))
+	gs.mark_revealed("varrell_twins")
+	assert_true(gs.is_revealed("varrell_twins"))
+
+
+func test_gifts_given_tracked():
+	var gs = GameState.new()
+	assert_false(gs.is_gift_given("amulet"))
+	gs.mark_gift_given("amulet")
+	assert_true(gs.is_gift_given("amulet"))