feat: add auto update support

src/main/runtime/update/update-cli-command.test.ts

@@ -0,0 +1,37 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import type { CliArgs } from '../../../cli/args';
+import { runUpdateCliCommand } from './update-cli-command';
+
+test('runUpdateCliCommand writes launcher response for second-instance update handoff', async () => {
+  const writes: Array<{ path: string; payload: unknown }> = [];
+
+  await runUpdateCliCommand(
+    {
+      update: true,
+      updateLauncherPath: '/home/kyle/.local/bin/subminer',
+      updateResponsePath: '/tmp/subminer-update-response.json',
+    } as CliArgs,
+    'second-instance',
+    {
+      checkForUpdates: async (request) => {
+        assert.deepEqual(request, {
+          source: 'launcher',
+          launcherPath: '/home/kyle/.local/bin/subminer',
+        });
+        return { status: 'up-to-date', version: '0.15.0' };
+      },
+      writeResponse: (responsePath, payload) => {
+        writes.push({ path: responsePath, payload });
+      },
+      logWarn: () => {},
+    },
+  );
+
+  assert.deepEqual(writes, [
+    {
+      path: '/tmp/subminer-update-response.json',
+      payload: { ok: true, status: 'up-to-date', version: '0.15.0' },
+    },
+  ]);
+});