feat: finish the tailscale plugin, including SSH auth (B3)

plugins/tailscale/tests/backend/host-metrics-manager.test.ts

@@ -0,0 +1,55 @@
+import { describe, it, expect } from "vitest";
+import { parseTailscaleData } from "../../src/backend/host-metrics-manager.js";
+
+describe("parseTailscaleData", () => {
+  it("reports not installed when the probe finds no binary", () => {
+    const result = parseTailscaleData("ts_installed=0\n");
+    expect(result.installed).toBe(false);
+    expect(result.running).toBe(false);
+  });
+
+  it("parses a running tailscale status", () => {
+    const status = JSON.stringify({
+      BackendState: "Running",
+      Self: { HostName: "my-server", TailscaleIPs: ["100.1.2.3"] },
+      Peer: {
+        abc: {
+          HostName: "peer-1",
+          TailscaleIPs: ["100.1.2.4"],
+          Online: true,
+          ExitNode: false,
+        },
+      },
+      CurrentExitNode: "",
+    });
+    const result = parseTailscaleData(`ts_installed=1\n${status}`);
+
+    expect(result.installed).toBe(true);
+    expect(result.running).toBe(true);
+    expect(result.hostname).toBe("my-server");
+    expect(result.tailscaleIPs).toEqual(["100.1.2.3"]);
+    expect(result.peers).toHaveLength(1);
+    expect(result.peers[0]).toMatchObject({
+      hostname: "peer-1",
+      online: true,
+    });
+    expect(result.exitNodeInUse).toBe(false);
+  });
+
+  it("reports installed but not running on malformed JSON", () => {
+    const result = parseTailscaleData("ts_installed=1\nnot json");
+    expect(result.installed).toBe(true);
+    expect(result.running).toBe(false);
+  });
+
+  it("detects an active exit node", () => {
+    const status = JSON.stringify({
+      BackendState: "Running",
+      Self: {},
+      Peer: {},
+      CurrentExitNode: "abc123",
+    });
+    const result = parseTailscaleData(`ts_installed=1\n${status}`);
+    expect(result.exitNodeInUse).toBe(true);
+  });
+});