nEngine/packages/mcp/test/item-namespace.test.ts

import { mkdtemp, mkdir, readFile, rm, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join, resolve } from "node:path";
import { describe, expect, it } from "vitest";
import { createEngine, type ItemDef } from "@nengine/core";
import { createEngineNamespaces, McpGateway } from "../src/index.js";

const TIME_YAML = [
  "id: default",
  "dayLengthTicks: 480",
  "seasons:",
  "  - { name: spring, dayCount: 28 }",
  "start: { day: 1, season: spring }",
  "",
].join("\n");

const FARM_YAML = [
  "id: farm",
  "width: 2",
  "height: 2",
  'tilesetRef: "tiles"',
  "spawn: { x: 0, y: 0 }",
  "layers:",
  "  - name: ground",
  "    data:",
  "      - [a, b]",
  "      - [b, a]",
  "",
].join("\n");

interface Setup {
  engine: ReturnType<typeof createEngine>;
  gateway: McpGateway;
  tmp: string;
  close: () => Promise<void>;
}

async function setup(): Promise<Setup> {
  const tmp = await mkdtemp(join(tmpdir(), "farm-item-"));
  await mkdir(join(tmp, "maps"), { recursive: true });
  await writeFile(join(tmp, "time.yaml"), TIME_YAML);
  await writeFile(join(tmp, "maps", "farm.yaml"), FARM_YAML);

  const engine = createEngine({ contentDir: tmp });
  const gateway = new McpGateway();
  for (const namespace of createEngineNamespaces(engine, { gateway })) {
    gateway.register(namespace);
  }
  await engine.start();
  return {
    engine,
    gateway,
    tmp,
    close: async () => {
      await engine.stop();
      await rm(tmp, { recursive: true, force: true });
    },
  };
}

async function callText(gateway: McpGateway, name: string, args: Record<string, unknown> = {}): Promise<{
  ok: boolean;
  text: string;
}> {
  const result = await gateway.callTool(name, args);
  return { ok: result.isError !== true, text: result.content[0]?.text ?? "" };
}

const HOE_DEF: ItemDef = { id: "hoe", name: "Hoe", kind: "tool", stackable: false, rarity: "common" };

describe("item namespace", () => {
  it("item.create writes content/items/<id>.yaml, registers live, and persists across restart", async () => {
    const { engine, gateway, tmp, close } = await setup();
    try {
      const created = await callText(gateway, "item.create", { def: HOE_DEF });
      expect(created.ok).toBe(true);
      expect(JSON.parse(created.text) as ItemDef).toEqual(HOE_DEF);

      expect(engine.registry.get<ItemDef>("item", "hoe")).toEqual(HOE_DEF);

      const file = await readFile(join(tmp, "items", "hoe.yaml"), "utf8");
      expect(file).toContain("id: hoe");
      expect(file).toContain("kind: tool");

      await engine.stop();
      const reloaded = createEngine({ contentDir: tmp });
      await reloaded.start();
      try {
        expect(reloaded.registry.get<ItemDef>("item", "hoe")).toEqual(HOE_DEF);
      } finally {
        await reloaded.stop();
      }
    } finally {
      await close();
    }
  });

  it("item.validate accepts a valid def and rejects an invalid one", async () => {
    const { gateway, close } = await setup();
    try {
      const valid = await callText(gateway, "item.validate", { def: HOE_DEF });
      expect(valid.ok).toBe(true);
      expect(JSON.parse(valid.text)).toEqual(HOE_DEF);

      const invalid = await callText(gateway, "item.validate", {
        def: { id: "nope", name: "Nope", kind: "not-a-kind", stackable: false },
      });
      expect(invalid.ok).toBe(false);
      expect(invalid.text).toMatch(/Invalid enum value/);
      expect(invalid.text).toMatch(/kind/);
    } finally {
      await close();
    }
  });

  it("item.create rejects an invalid def and does not write or register", async () => {
    const { engine, gateway, tmp, close } = await setup();
    try {
      const bad = await callText(gateway, "item.create", {
        def: { id: "broken", name: "Broken", kind: "tool", stackable: "yes" },
      });
      expect(bad.ok).toBe(false);
      expect(engine.registry.get("item", "broken")).toBeUndefined();
      await expect(readFile(join(tmp, "items", "broken.yaml"))).rejects.toThrow();
    } finally {
      await close();
    }
  });

  it("duplicate item.create overwrites the existing definition", async () => {
    const { engine, gateway, tmp, close } = await setup();
    try {
      await callText(gateway, "item.create", { def: HOE_DEF });
      const recreated = await callText(gateway, "item.create", {
        def: { id: "hoe", name: "Copper Hoe", kind: "tool", stackable: false, price: 800, rarity: "uncommon" },
      });
      expect(recreated.ok).toBe(true);

      const current = engine.registry.get<ItemDef>("item", "hoe");
      expect(current?.name).toBe("Copper Hoe");
      expect(current?.price).toBe(800);

      const file = await readFile(join(tmp, "items", "hoe.yaml"), "utf8");
      expect(file).toContain("name: Copper Hoe");
    } finally {
      await close();
    }
  });

  it("item.update merges a patch, validates, rewrites the file, and re-registers", async () => {
    const { engine, gateway, tmp, close } = await setup();
    try {
      await callText(gateway, "item.create", { def: HOE_DEF });
      const updated = await callText(gateway, "item.update", { id: "hoe", patch: { price: 700 } });
      expect(updated.ok).toBe(true);
      const def = JSON.parse(updated.text) as ItemDef;
      expect(def).toEqual({ id: "hoe", name: "Hoe", kind: "tool", stackable: false, rarity: "common", price: 700 });

      const file = await readFile(join(tmp, "items", "hoe.yaml"), "utf8");
      expect(file).toContain("price: 700");

      const missing = await callText(gateway, "item.update", { id: "nope", patch: { price: 1 } });
      expect(missing.ok).toBe(false);
      expect(missing.text).toMatch(/item not found: nope/);

      const badPatch = await callText(gateway, "item.update", { id: "hoe", patch: { kind: "bogus" } });
      expect(badPatch.ok).toBe(false);
      expect(badPatch.text).toMatch(/Invalid enum value/);
      expect(engine.registry.get<ItemDef>("item", "hoe")?.price).toBe(700);
    } finally {
      await close();
    }
  });

  it("item.list returns one-line summaries", async () => {
    const { gateway, close } = await setup();
    try {
      await callText(gateway, "item.create", { def: HOE_DEF });
      await callText(gateway, "item.create", {
        def: { id: "parsnip-seed", name: "Parsnip Seed", kind: "seed", stackable: true },
      });
      const listed = await callText(gateway, "item.list");
      expect(listed.ok).toBe(true);
      expect(JSON.parse(listed.text)).toEqual({
        items: [
          { id: "hoe", name: "Hoe", kind: "tool" },
          { id: "parsnip-seed", name: "Parsnip Seed", kind: "seed" },
        ],
      });
    } finally {
      await close();
    }
  });

  it("item.get returns the full def; unknown id is an error result", async () => {
    const { gateway, close } = await setup();
    try {
      await callText(gateway, "item.create", { def: HOE_DEF });
      const got = await callText(gateway, "item.get", { itemId: "hoe" });
      expect(got.ok).toBe(true);
      expect(JSON.parse(got.text)).toEqual(HOE_DEF);

      const missing = await callText(gateway, "item.get", { itemId: "nope" });
      expect(missing.ok).toBe(false);
      expect(missing.text).toMatch(/item not found: nope/);
    } finally {
      await close();
    }
  });

  it("item.query_inventory and item.give read and mutate the player inventory", async () => {
    const { engine, gateway, close } = await setup();
    try {
      await callText(gateway, "item.create", { def: HOE_DEF });

      const empty = await callText(gateway, "item.query_inventory");
      expect(JSON.parse(empty.text)).toEqual({ inventory: {} });

      const gave = await callText(gateway, "item.give", { itemId: "hoe", qty: 3 });
      expect(JSON.parse(gave.text)).toEqual({ itemId: "hoe", qty: 3, total: 3 });

      const after = await callText(gateway, "item.query_inventory");
      expect(JSON.parse(after.text)).toEqual({ inventory: { hoe: 3 } });

      const second = await callText(gateway, "item.give", { itemId: "hoe", qty: 2 });
      expect(JSON.parse(second.text)).toEqual({ itemId: "hoe", qty: 2, total: 5 });

      expect(engine.world.get("player")?.inventory).toEqual({ hoe: 5 });

      const unknown = await callText(gateway, "item.give", { itemId: "nope", qty: 1 });
      expect(unknown.ok).toBe(false);
      expect(unknown.text).toMatch(/unknown item: nope/);

      const badQty = await callText(gateway, "item.give", { itemId: "hoe", qty: 0 });
      expect(badQty.ok).toBe(false);
      expect(badQty.text).toMatch(/positive integer/);
    } finally {
      await close();
    }
  });

  it("resources: item://catalog and item://{id}; missing id rejects", async () => {
    const { engine, gateway, close } = await setup();
    try {
      await callText(gateway, "item.create", { def: HOE_DEF });

      const catalog = await gateway.readResource("item://catalog");
      expect(JSON.parse(catalog.contents[0]?.text ?? "{}")).toEqual({ items: [HOE_DEF] });

      const single = await gateway.readResource("item://hoe");
      expect(JSON.parse(single.contents[0]?.text ?? "{}")).toEqual(HOE_DEF);

      await expect(gateway.readResource("item://missing")).rejects.toThrow(/item not found: missing/);
      expect(engine.registry.get("item", "missing")).toBeUndefined();
    } finally {
      await close();
    }
  });

  it("serves the item.create-prompt prompt", async () => {
    const { gateway, close } = await setup();
    try {
      const prompt = await gateway.getPrompt("item.create-prompt", {});
      const text = prompt.messages[0]?.content.text ?? "";
      expect(text).toContain("kind");
      expect(text).toContain("stackable");
      expect(text).toContain("item.validate");
      expect(text).toContain("content/items/<id>.yaml");
    } finally {
      await close();
    }
  });
});