feat: non-blocking version check on CLI startup (Phase 1)

packages/squad-cli/src/cli-entry.ts

@@ -211,6 +211,8 @@ async function main(): Promise<void> {
   // No args → launch interactive shell; whitespace-only arg → show help
   if (rawCmd === undefined) {
     await checkNodeSqlite();
+    // Fire-and-forget update check — non-blocking, never delays shell startup
+    import('./cli/self-update.js').then(m => m.notifyIfUpdateAvailable(VERSION)).catch(() => {});
     const { runShell } = await lazyRunShell();
     await runShell();
     return;

packages/squad-cli/src/cli/self-update.ts

@@ -0,0 +1,122 @@
+/**
+ * Self-update check — Phase 1: background version check with notification.
+ *
+ * Non-blocking startup check that queries the npm registry for the latest
+ * version of @bradygaster/squad-cli and displays a passive banner when
+ * an update is available. Results are cached for 24 hours.
+ *
+ * Disable with: SQUAD_NO_UPDATE_CHECK=1
+ *
+ * @module cli/self-update
+ */
+
+import fs from 'node:fs';
+import path from 'node:path';
+import os from 'node:os';
+import { compareVersions } from './upgrade.js';
+import { BOLD, RESET, DIM, YELLOW } from './core/output.js';
+
+const PACKAGE_NAME = '@bradygaster/squad-cli';
+const REGISTRY_URL = `https://registry.npmjs.org/${PACKAGE_NAME}`;
+const CACHE_TTL_MS = 24 * 60 * 60 * 1000; // 24 hours
+const FETCH_TIMEOUT_MS = 3000; // 3 seconds
+
+interface CacheData {
+  latestVersion: string;
+  checkedAt: number;
+}
+
+/** Directory for squad CLI cache files. */
+function getCacheDir(): string {
+  const base = process.env.APPDATA
+    ?? (process.platform === 'darwin'
+      ? path.join(os.homedir(), 'Library', 'Application Support')
+      : path.join(os.homedir(), '.config'));
+  return path.join(base, 'squad-cli');
+}
+
+function getCachePath(): string {
+  return path.join(getCacheDir(), 'update-check.json');
+}
+
+/** Read cached version check result, if still valid. */
+function readCache(): CacheData | null {
+  try {
+    const raw = fs.readFileSync(getCachePath(), 'utf8');
+    const data: CacheData = JSON.parse(raw);
+    if (Date.now() - data.checkedAt < CACHE_TTL_MS) {
+      return data;
+    }
+  } catch {
+    // Cache missing, corrupt, or expired — ignore
+  }
+  return null;
+}
+
+/** Write version check result to cache. */
+function writeCache(data: CacheData): void {
+  try {
+    const dir = getCacheDir();
+    fs.mkdirSync(dir, { recursive: true });
+    fs.writeFileSync(getCachePath(), JSON.stringify(data), 'utf8');
+  } catch {
+    // Non-critical — silently ignore write failures
+  }
+}
+
+/** Fetch latest version from npm registry with timeout. */
+async function fetchLatestVersion(): Promise<string | null> {
+  try {
+    const controller = new AbortController();
+    const timer = setTimeout(() => controller.abort(), FETCH_TIMEOUT_MS);
+    const res = await fetch(REGISTRY_URL, {
+      headers: { Accept: 'application/vnd.npm.install-v1+json' },
+      signal: controller.signal,
+    });
+    clearTimeout(timer);
+    if (!res.ok) return null;
+    const data = await res.json() as { 'dist-tags'?: { latest?: string } };
+    return data['dist-tags']?.latest ?? null;
+  } catch {
+    // Network failure, timeout, or parse error — silently ignore
+    return null;
+  }
+}
+
+/**
+ * Check for updates and print a banner if a newer version is available.
+ *
+ * This function is designed to be fire-and-forget: it never throws,
+ * never blocks the shell, and silently no-ops on any failure.
+ *
+ * @param currentVersion - The currently running CLI version
+ */
+export async function notifyIfUpdateAvailable(currentVersion: string): Promise<void> {
+  try {
+    // Respect opt-out
+    if (process.env.SQUAD_NO_UPDATE_CHECK === '1') return;
+
+    // Check cache first
+    const cached = readCache();
+    let latest: string;
+
+    if (cached) {
+      latest = cached.latestVersion;
+    } else {
+      const fetched = await fetchLatestVersion();
+      if (!fetched) return;
+      latest = fetched;
+      writeCache({ latestVersion: latest, checkedAt: Date.now() });
+    }
+
+    // Only notify if strictly newer
+    if (compareVersions(latest, currentVersion) > 0) {
+      console.log(
+        `\n${YELLOW}⚡${RESET} ${BOLD}Squad v${latest}${RESET} available ${DIM}(you have v${currentVersion})${RESET}` +
+        `\n   Run: ${BOLD}npm install -g @bradygaster/squad-cli@latest${RESET}\n`,
+      );
+    }
+  } catch {
+    // Absolute safety net — never crash the CLI for an update check
+  }
+}