feat(client): NewGame.construct — origin+world+creation -> {canon log, state}

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

client/scripts/newgame/new_game.gd

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+class_name NewGame
+extends RefCounted
+## New-game construction (spec "New-game construction"). Reads three immutable
+## inputs (origin, world, creation) and writes two products (CanonLog, GameState).
+## Nothing flows back up — charter §2 on the client. Validation is front-loaded:
+## a broken origin or illegal class fails here, loudly, not three scenes later.
+
+static func construct(origin: Dictionary, world: ContentDB, creation: Dictionary, rng: RandomNumberGenerator) -> Dictionary:
+	var errors: Array = []
+
+	# 1. content integrity — every referenced id must resolve in world content.
+	for ref in world.unresolved_refs(origin):
+		errors.append("unresolved ref: %s" % ref)
+
+	# 2. build constraints — chosen class must be allowed by the origin.
+	var bc: Dictionary = origin.get("build_constraints", {})
+	var allowed: Array = bc.get("allowed_classes", [])
+	var class_id: String = creation.get("class_id", "")
+	if class_id not in allowed:
+		errors.append("class not allowed by origin: %s" % class_id)
+
+	if not errors.is_empty():
+		return {"ok": false, "errors": errors, "log": null, "state": null}
+
+	# 3. roll Luck (numeric -> state only) and 4. the stat block (data only).
+	var state := GameState.new()
+	state.luck_base = Luck.roll_base(rng, int(bc.get("luck_modifier", 0)))
+	state.luck = state.luck_base
+	state.stats = {
+		"str": _roll_stat(rng), "dex": _roll_stat(rng), "con": _roll_stat(rng),
+		"fth": _roll_stat(rng), "mag": _roll_stat(rng),
+	}
+
+	# 5. assemble the canon log.
+	var log := CanonLog.new()
+	log.player = LogPlayer.new(creation.get("name", ""), class_id, state.luck_descriptor())
+
+	var loc: Dictionary = world.location(origin["start_location_id"])
+	log.set_location(loc.get("id", ""), loc.get("name", ""))
+
+	var overrides: Dictionary = origin.get("disposition_overrides", {})
+	var companion_ids := {}
+	for c in world.companions():
+		companion_ids[c["id"]] = true
+		log.party.append(PartyMember.new(c["id"], c.get("name", ""), int(overrides.get(c["id"], 0))))
+	# non-companion overrides go to game state, never the log (spec §5 / charter §6).
+	for npc_id in overrides:
+		if not companion_ids.has(npc_id):
+			state.set_npc_disposition(npc_id, int(overrides[npc_id]))
+
+	for line in origin.get("situation", []):
+		log.push_event(line)
+	for fact in origin.get("opening_facts", []):
+		log.add_fact(fact)
+
+	var quest_id: Variant = origin.get("start_quest_id", null)
+	if quest_id != null:
+		var qd: Dictionary = world.quest(quest_id)
+		log.active_quests.append(Quest.new(qd.get("id", ""), qd.get("name", ""), "active", qd.get("objective", "")))
+
+	# inventory grants -> game state (NOT the log). Charter §2.
+	for grant in origin.get("inventory_grants", []):
+		state.add_item(grant.get("item_id", ""), int(grant.get("qty", 0)))
+
+	return {"ok": true, "errors": [], "log": log, "state": state}
+
+
+static func _roll_stat(rng: RandomNumberGenerator) -> int:
+	# 3d6 placeholder; the stat block is data-only in this plan. TUNABLE.
+	return rng.randi_range(1, 6) + rng.randi_range(1, 6) + rng.randi_range(1, 6)

client/scripts/newgame/new_game.gd.uid

@@ -0,0 +1 @@
+uid://cju7c1s06onrd