diff --git a/app/routes/api.agari.ts b/app/routes/api.agari.ts
index cd8c3b2..ab843a8 100644
--- a/app/routes/api.agari.ts
+++ b/app/routes/api.agari.ts
@@ -1,14 +1,11 @@
 import { redirect } from "react-router";
-import { z } from "zod";
 import { getAuth } from "~/lib/auth";
 import { getDB } from "~/lib/db";
 import { getGameState, recordKyoku, restartGame } from "~/lib/game-service";
+import judgeAgari from "~/lib/hai/agari";
+import { sortTehai } from "~/lib/hai/types";
 import type { Route } from "./+types/api.agari";
 
-const agariSchema = z.object({
-	junme: z.coerce.number().optional(),
-});
-
 export async function action({ context, request }: Route.ActionArgs) {
 	const env = context.cloudflare.env;
 	const auth = getAuth(env);
@@ -17,15 +14,6 @@ export async function action({ context, request }: Route.ActionArgs) {
 		return new Response("Unauthorized", { status: 401 });
 	}
 
-	const formData = await request.formData();
-	const junme = formData.get("junme");
-	const parsedData = agariSchema.safeParse({
-		junme: junme === null || junme === "" ? undefined : junme,
-	});
-	if (!parsedData.success) {
-		return new Response("Invalid form data", { status: 400 });
-	}
-
 	const db = getDB(env);
 	const userId = session.user.id;
 	const gameStateRecord = await getGameState(db, userId);
@@ -33,12 +21,21 @@ export async function action({ context, request }: Route.ActionArgs) {
 		return new Response("Game state not found", { status: 404 });
 	}
 
-	const agariJunme = parsedData.data.junme ?? gameStateRecord.junme;
+	const tsumohai = gameStateRecord.tsumohai[0];
+	if (!tsumohai) {
+		return new Response("No tile drawn - cannot declare win", { status: 400 });
+	}
+	const canAgari = judgeAgari(sortTehai([...gameStateRecord.tehai, tsumohai]));
+	if (!canAgari) {
+		return new Response("Hand does not form a valid winning combination", {
+			status: 400,
+		});
+	}
 
 	// Record win with +8000 points
 	await recordKyoku(db, userId, {
 		didAgari: true,
-		agariJunme,
+		agariJunme: gameStateRecord.junme,
 		shanten: 0,
 		scoreDelta: 8000,
 	});
diff --git a/app/routes/api.ryukyoku.ts b/app/routes/api.ryukyoku.ts
index 9cc67da..9e20cef 100644
--- a/app/routes/api.ryukyoku.ts
+++ b/app/routes/api.ryukyoku.ts
@@ -19,6 +19,9 @@ export async function action({ context, request }: Route.ActionArgs) {
 	if (!gameStateRecord) {
 		return new Response("Game state not found", { status: 404 });
 	}
+	if (gameStateRecord.remainTsumo > 0) {
+		return new Response("Ryukyoku is not allowed yet", { status: 400 });
+	}
 
 	// Calculate shanten for current hand
 	const shantenResult = calculateShanten(gameStateRecord.tehai);
diff --git a/app/routes/api.seed.ts b/app/routes/api.seed.ts
index a4b600e..78fbb7d 100644
--- a/app/routes/api.seed.ts
+++ b/app/routes/api.seed.ts
@@ -39,15 +39,11 @@ async function seedAndRespond(env: Env, countInput: unknown) {
 	});
 }
 
-export async function loader({ context, request }: Route.LoaderArgs) {
-	const env = context.cloudflare.env;
-	const session = await ensureSession(request, env);
-	if (!session) {
-		return new Response("Unauthorized", { status: 401 });
-	}
-
-	const count = new URL(request.url).searchParams.get("count") ?? undefined;
-	return seedAndRespond(env, count);
+export async function loader(_: Route.LoaderArgs) {
+	return new Response("Method Not Allowed", {
+		status: 405,
+		headers: { Allow: "POST" },
+	});
 }
 
 export async function action({ context, request }: Route.ActionArgs) {
diff --git a/app/routes/api.tedashi.ts b/app/routes/api.tedashi.ts
index 521ab00..443d8cf 100644
--- a/app/routes/api.tedashi.ts
+++ b/app/routes/api.tedashi.ts
@@ -6,7 +6,7 @@ import { getGameState, tedashi } from "~/lib/game-service";
 import type { Route } from "./+types/api.tedashi";
 
 const tedashiSchema = z.object({
-	index: z.coerce.number(),
+	index: z.coerce.number().int().min(0),
 });
 
 export async function action({ context, request }: Route.ActionArgs) {