feat: mosaic gateway CLI daemon management + admin token auth (#369)

packages/cli/src/commands/gateway/logs.ts

@@ -0,0 +1,37 @@
+import { existsSync, readFileSync } from 'node:fs';
+import { spawn } from 'node:child_process';
+import { LOG_FILE } from './daemon.js';
+
+interface LogsOpts {
+  follow?: boolean;
+  lines?: number;
+}
+
+export function runLogs(opts: LogsOpts): void {
+  if (!existsSync(LOG_FILE)) {
+    console.log('No log file found. Is the gateway installed?');
+    return;
+  }
+
+  if (opts.follow) {
+    const lines = opts.lines ?? 50;
+    const tail = spawn('tail', ['-n', lines.toString(), '-f', LOG_FILE], {
+      stdio: 'inherit',
+    });
+    tail.on('error', () => {
+      // Fallback for systems without tail
+      console.log(readLastLines(opts.lines ?? 50));
+      console.log('\n(--follow requires `tail` command)');
+    });
+    return;
+  }
+
+  // Just print last N lines
+  console.log(readLastLines(opts.lines ?? 50));
+}
+
+function readLastLines(n: number): string {
+  const content = readFileSync(LOG_FILE, 'utf-8');
+  const lines = content.split('\n');
+  return lines.slice(-n).join('\n');
+}