feat: make each plugin an npm workspace built by a termix-plugin CLI

plugins/host-metrics/tests/backend/widgets/cpu-collector.test.ts

@@ -0,0 +1,45 @@
+import { describe, it, expect } from "vitest";
+import {
+  parseCpuLine,
+  parseDarwinCpuUsageLine,
+} from "../../../src/backend/widgets/cpu-collector.js";
+
+describe("parseCpuLine", () => {
+  it("parses a standard /proc/stat cpu line", () => {
+    // user nice system idle iowait irq softirq
+    const result = parseCpuLine("cpu  100 0 50 800 30 0 20");
+    expect(result).toBeDefined();
+    // idle = idle(800) + iowait(30)
+    expect(result?.idle).toBe(830);
+    // total = sum of all fields
+    expect(result?.total).toBe(100 + 0 + 50 + 800 + 30 + 0 + 20);
+  });
+
+  it("tolerates leading/trailing whitespace", () => {
+    const result = parseCpuLine("  cpu 1 2 3 4  ");
+    expect(result?.total).toBe(10);
+    expect(result?.idle).toBe(4);
+  });
+
+  it("returns undefined for non-cpu lines", () => {
+    expect(parseCpuLine("cpu0 1 2 3 4")).toBeUndefined();
+    expect(parseCpuLine("intr 12345")).toBeUndefined();
+  });
+
+  it("returns undefined when there are fewer than 4 numeric fields", () => {
+    expect(parseCpuLine("cpu 1 2 3")).toBeUndefined();
+  });
+});
+
+describe("parseDarwinCpuUsageLine", () => {
+  it("parses macOS `top -l 1` CPU usage line", () => {
+    const result = parseDarwinCpuUsageLine(
+      "CPU usage: 12.34% user, 5.66% sys, 82.00% idle",
+    );
+    expect(result?.percent).toBeCloseTo(18.0, 5);
+  });
+
+  it("returns undefined for unrelated lines", () => {
+    expect(parseDarwinCpuUsageLine("Processes: 400 total")).toBeUndefined();
+  });
+});