feat: add optional llm-task JSON-only tool (#1498)

* feat(llm-task): add optional JSON-only LLM task tool

* fix(llm-task): fix invalid package.json

* fix(llm-task): fix invalid plugin manifest JSON

* fix(llm-task): fix index.ts import quoting

* fix(llm-task): load embedded runner from src or bundled dist

extensions/llm-task/src/llm-task-tool.test.ts

@@ -0,0 +1,96 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+
+vi.mock("../../../src/agents/pi-embedded-runner.js", () => {
+  return {
+    runEmbeddedPiAgent: vi.fn(async () => ({
+      meta: { startedAt: Date.now() },
+      payloads: [{ text: "{}" }],
+    })),
+  };
+});
+
+import { runEmbeddedPiAgent } from "../../../src/agents/pi-embedded-runner.js";
+import { createLlmTaskTool } from "./llm-task-tool.js";
+
+function fakeApi(overrides: any = {}) {
+  return {
+    id: "llm-task",
+    name: "llm-task",
+    source: "test",
+    config: { agents: { defaults: { workspace: "/tmp", model: { primary: "openai-codex/gpt-5.2" } } } },
+    pluginConfig: {},
+    runtime: { version: "test" },
+    logger: { debug() {}, info() {}, warn() {}, error() {} },
+    registerTool() {},
+    ...overrides,
+  };
+}
+
+describe("llm-task tool (json-only)", () => {
+  beforeEach(() => vi.clearAllMocks());
+
+  it("returns parsed json", async () => {
+    (runEmbeddedPiAgent as any).mockResolvedValueOnce({
+      meta: {},
+      payloads: [{ text: JSON.stringify({ foo: "bar" }) }],
+    });
+    const tool = createLlmTaskTool(fakeApi() as any);
+    const res = await tool.execute("id", { prompt: "return foo" });
+    expect((res as any).details.json).toEqual({ foo: "bar" });
+  });
+
+  it("validates schema", async () => {
+    (runEmbeddedPiAgent as any).mockResolvedValueOnce({
+      meta: {},
+      payloads: [{ text: JSON.stringify({ foo: "bar" }) }],
+    });
+    const tool = createLlmTaskTool(fakeApi() as any);
+    const schema = {
+      type: "object",
+      properties: { foo: { type: "string" } },
+      required: ["foo"],
+      additionalProperties: false,
+    };
+    const res = await tool.execute("id", { prompt: "return foo", schema });
+    expect((res as any).details.json).toEqual({ foo: "bar" });
+  });
+
+  it("throws on invalid json", async () => {
+    (runEmbeddedPiAgent as any).mockResolvedValueOnce({ meta: {}, payloads: [{ text: "not-json" }] });
+    const tool = createLlmTaskTool(fakeApi() as any);
+    await expect(tool.execute("id", { prompt: "x" })).rejects.toThrow(/invalid json/i);
+  });
+
+  it("throws on schema mismatch", async () => {
+    (runEmbeddedPiAgent as any).mockResolvedValueOnce({
+      meta: {},
+      payloads: [{ text: JSON.stringify({ foo: 1 }) }],
+    });
+    const tool = createLlmTaskTool(fakeApi() as any);
+    const schema = { type: "object", properties: { foo: { type: "string" } }, required: ["foo"] };
+    await expect(tool.execute("id", { prompt: "x", schema })).rejects.toThrow(/match schema/i);
+  });
+
+  it("passes provider/model overrides to embedded runner", async () => {
+    (runEmbeddedPiAgent as any).mockResolvedValueOnce({
+      meta: {},
+      payloads: [{ text: JSON.stringify({ ok: true }) }],
+    });
+    const tool = createLlmTaskTool(fakeApi() as any);
+    await tool.execute("id", { prompt: "x", provider: "anthropic", model: "claude-4-sonnet" });
+    const call = (runEmbeddedPiAgent as any).mock.calls[0]?.[0];
+    expect(call.provider).toBe("anthropic");
+    expect(call.model).toBe("claude-4-sonnet");
+  });
+
+  it("enforces allowedModels", async () => {
+    (runEmbeddedPiAgent as any).mockResolvedValueOnce({
+      meta: {},
+      payloads: [{ text: JSON.stringify({ ok: true }) }],
+    });
+    const tool = createLlmTaskTool(fakeApi({ pluginConfig: { allowedModels: ["openai-codex/gpt-5.2"] } }) as any);
+    await expect(tool.execute("id", { prompt: "x", provider: "anthropic", model: "claude-4-sonnet" })).rejects.toThrow(
+      /not allowed/i,
+    );
+  });
+});