feat: finish the ai plugin (B18)

plugins/ai/tests/backend/command-history-service.test.ts

@@ -1,39 +1,60 @@
-import { afterEach, describe, expect, it, vi } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import {
-  listCommandHistory,
-  setPluginServices,
+  readService,
+  requireService,
+  serviceAvailable,
+  SERVICE,
 } from "../../src/backend/services.js";
 
-afterEach(() => setPluginServices(null));
+function services(provided: Record<string, object>) {
+  return {
+    providers: (service: string) => (service in provided ? [""] : []),
+    get: vi.fn((service: string) => provided[service]),
+  } as never;
+}
 
-describe("listCommandHistory", () => {
+describe("optional services", () => {
   it("reads the user's history through terminal.history", async () => {
     const list = vi.fn(async () => [
       { command: "ls", executedAt: "2026-01-01T00:00:00.000Z" },
     ]);
-    const get = vi.fn(() => ({ list }));
-    setPluginServices({ get, provide: vi.fn() } as never);
+    const history = await readService(
+      services({ [SERVICE.history]: { list } }),
+      SERVICE.history,
+      (terminal) => terminal.list(4, 25),
+    );
 
-    const history = await listCommandHistory("user-1", 4, 25);
-
-    expect(get).toHaveBeenCalledWith("terminal.history", { userId: "user-1" });
     expect(list).toHaveBeenCalledWith(4, 25);
     expect(history).toEqual([
       { command: "ls", executedAt: "2026-01-01T00:00:00.000Z" },
     ]);
   });
 
-  it("answers null while the terminal is off or refuses the user", async () => {
-    expect(await listCommandHistory("user-1", 4, 25)).toBeNull();
+  it("answers null while the provider is off or refuses the user", async () => {
+    expect(
+      await readService(services({}), SERVICE.history, (terminal) =>
+        terminal.list(4, 25),
+      ),
+    ).toBeNull();
 
-    setPluginServices({
-      get: () => ({
-        list: async () => {
-          throw new Error("unavailable");
-        },
-      }),
-      provide: vi.fn(),
-    } as never);
-    expect(await listCommandHistory("user-1", 4, 25)).toBeNull();
+    const refusing = {
+      list: async () => {
+        throw new Error("Missing permission");
+      },
+    };
+    expect(
+      await readService(
+        services({ [SERVICE.history]: refusing }),
+        SERVICE.history,
+        (terminal) => terminal.list(4, 25),
+      ),
+    ).toBeNull();
+  });
+
+  it("says which plugin is missing when a write needs it", () => {
+    expect(serviceAvailable(services({}), SERVICE.fleets)).toBe(false);
+    expect(() => requireService(services({}), SERVICE.fleets)).toThrow(
+      "The fleets plugin is not available",
+    );
   });
 });