feat(client): NpcService.speak — post, extract, validate moves (§6)

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

client/scripts/net/npc_service.gd

@@ -0,0 +1,48 @@
+class_name NpcService
+extends RefCounted
+## The client /npc/speak loop (§6). Posts persona-free request (npc_id +
+## disposition + client-computed available_moves + utterance) through an injected
+## transport, degrades to an authored NPC fallback on ANY failure, extracts tags
+## with TagExtractor, validates moves against available_moves (MoveValidator),
+## and returns an NpcResult. It applies NO state — the caller runs MoveApplier,
+## keeping state writes explicit (§2).
+
+const ENDING_MOVES := ["end_conversation", "become_hostile"]
+
+var _transport: DmTransport
+var _fallback: FallbackLibrary
+
+
+func _init(transport: DmTransport, fallback: FallbackLibrary) -> void:
+	_transport = transport
+	_fallback = fallback
+
+
+func speak(npc_id: String, utterance: String, canon_log: CanonLog,
+		disposition: int, available_moves: Array) -> NpcResult:
+	var resp: DmResponse = await _transport.post_json("/npc/speak", {
+		"canon_log": canon_log.to_dict(),
+		"npc_id": npc_id,
+		"disposition": disposition,
+		"available_moves": available_moves,
+		"utterance": utterance,
+	})
+	if not resp.transport_ok or resp.status != 200 \
+			or typeof(resp.body) != TYPE_DICTIONARY or not resp.body.has("prose"):
+		return NpcResult.fallback(_fallback.npc_line())
+
+	var extracted := TagExtractor.extract(str(resp.body["prose"]))
+	var moves: Array = extracted["moves"].duplicate()
+	# Fold the [ADJUST_DISPOSITION:n] alias into the move stream so the validator
+	# sees one uniform shape (§ tag convention).
+	for delta in extracted["dispositions"]:
+		moves.append({"name": "adjust_disposition", "args": [str(delta)]})
+
+	var checked := MoveValidator.validate(moves, available_moves)
+	var ends := false
+	for m in checked["valid"]:
+		if m["name"] in ENDING_MOVES:
+			ends = true
+	return NpcResult.new(
+		extracted["clean_text"], extracted["facts"],
+		checked["valid"], checked["dropped"], ends, false)