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

import { mkdtemp, mkdir, readFile, rm, writeFile } from "node:fs/promises";
import { tmpdir } from "node:os";
import { join } from "node:path";
import { describe, expect, it } from "vitest";
import { createEngine, type ShaderDef } 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-shader-"));
  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 RAIN_TINT_DEF: ShaderDef = {
  id: "rain-tint",
  filter: "grayscale",
  params: { factor: 0.7 },
};

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

      expect(engine.registry.get<ShaderDef>("shader", "rain-tint")).toEqual(RAIN_TINT_DEF);

      const file = await readFile(join(tmp, "shaders", "rain-tint.yaml"), "utf8");
      expect(file).toContain("id: rain-tint");
      expect(file).toContain("filter: grayscale");

      await engine.stop();
      const reloaded = createEngine({ contentDir: tmp });
      await reloaded.start();
      try {
        expect(reloaded.registry.get<ShaderDef>("shader", "rain-tint")).toEqual(RAIN_TINT_DEF);
      } finally {
        await reloaded.stop();
      }
    } finally {
      await close();
    }
  });

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

      const invalid = await callText(gateway, "shader.validate", {
        def: { id: "nope", filter: "vignette" },
      });
      expect(invalid.ok).toBe(false);
      expect(invalid.text).toMatch(/filter/);

      const strictInvalid = await callText(gateway, "shader.validate", {
        def: { id: "nope", filter: "blur", extra: 1 },
      });
      expect(strictInvalid.ok).toBe(false);
      expect(strictInvalid.text).toMatch(/Unrecognized key/);
    } finally {
      await close();
    }
  });

  it("shader.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, "shader.create", {
        def: { id: "broken", filter: "nope" },
      });
      expect(bad.ok).toBe(false);
      expect(engine.registry.get("shader", "broken")).toBeUndefined();
      await expect(readFile(join(tmp, "shaders", "broken.yaml"))).rejects.toThrow();
    } finally {
      await close();
    }
  });

  it("shader.update merges a patch, validates, rewrites the file, and re-registers", async () => {
    const { engine, gateway, tmp, close } = await setup();
    try {
      await callText(gateway, "shader.create", { def: RAIN_TINT_DEF });
      const updated = await callText(gateway, "shader.update", {
        id: "rain-tint",
        patch: { params: { factor: 0.5 } },
      });
      expect(updated.ok).toBe(true);
      const def = JSON.parse(updated.text) as ShaderDef;
      expect(def.params).toEqual({ factor: 0.5 });

      const file = await readFile(join(tmp, "shaders", "rain-tint.yaml"), "utf8");
      expect(file).toContain("factor: 0.5");

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

  it("shader.list and shader.get return summaries and defs; unknown id errors", async () => {
    const { gateway, close } = await setup();
    try {
      await callText(gateway, "shader.create", { def: RAIN_TINT_DEF });
      await callText(gateway, "shader.create", { def: { id: "sparkle-glow", filter: "brightness", params: { factor: 1.2 } } });

      const listed = await callText(gateway, "shader.list");
      expect(JSON.parse(listed.text)).toEqual({
        shaders: [
          { id: "rain-tint", filter: "grayscale" },
          { id: "sparkle-glow", filter: "brightness" },
        ],
      });

      const got = await callText(gateway, "shader.get", { shaderId: "rain-tint" });
      expect(JSON.parse(got.text)).toEqual(RAIN_TINT_DEF);

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

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

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

      const single = await gateway.readResource("shader://rain-tint");
      expect(JSON.parse(single.contents[0]?.text ?? "{}")).toEqual(RAIN_TINT_DEF);

      await expect(gateway.readResource("shader://missing")).rejects.toThrow(/shader not found: missing/);
    } finally {
      await close();
    }
  });

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