diff --git a/browse/src/browser-manager.ts b/browse/src/browser-manager.ts
index 2bc1c597d..c96530faa 100644
--- a/browse/src/browser-manager.ts
+++ b/browse/src/browser-manager.ts
@@ -254,6 +254,14 @@ export class BrowserManager {
 
   getConnectionMode(): 'launched' | 'headed' { return this.connectionMode; }
 
+  /**
+   * The live browser context, or null before launch / after close. Exposed for
+   * the auto-cookie-persist layer (server.ts) to snapshot cookies on a
+   * checkpoint without reaching into private state. Callers must null-check —
+   * a checkpoint can fire between close() and the next launch().
+   */
+  getContext(): import('playwright').BrowserContext | null { return this.context; }
+
   // ─── Watch Mode Methods ─────────────────────────────────
   isWatching(): boolean { return this.watching; }
 
@@ -401,6 +409,27 @@ export class BrowserManager {
     if (this.customUserAgent) {
       contextOptions.userAgent = this.customUserAgent;
     }
+
+    // Auto-cookie persistence (opt-in): seed the fresh context with previously
+    // persisted cookies so a device-trust cookie survives a daemon restart.
+    // Read-only + best-effort — the writer path (server.ts) owns the lock; a
+    // concurrent read of an atomically-written file is always a complete file.
+    // recreateContext() does NOT go through here (it restores in-memory state
+    // itself), so there's no double-restore.
+    try {
+      const { resolveConfig } = await import('./config');
+      const { loadAutoCookieState, warnPlaintextOnce } = await import('./auto-cookie-persist');
+      const cfg = resolveConfig();
+      warnPlaintextOnce(cfg);
+      const restored = loadAutoCookieState(cfg);
+      if (restored && restored.cookies.length > 0) {
+        contextOptions.storageState = restored;
+        console.log(`[browse] Restored ${restored.cookies.length} persisted cookie(s) from auto-state`);
+      }
+    } catch {
+      // Never block launch on the persistence layer.
+    }
+
     this.context = await this.browser.newContext(contextOptions);
 
     if (Object.keys(this.extraHeaders).length > 0) {
diff --git a/browse/src/server.ts b/browse/src/server.ts
index 301781acc..a1c6ea765 100644
--- a/browse/src/server.ts
+++ b/browse/src/server.ts
@@ -37,6 +37,13 @@ import {
 } from './token-registry';
 import { validateTempPath } from './path-security';
 import { resolveConfig, ensureStateDir, readVersionHash, resolveChromiumProfile, cleanSingletonLocks } from './config';
+import {
+  isAutoCookiePersistEnabled,
+  acquireLock as acquireAutoCookieLock,
+  releaseLock as releaseAutoCookieLock,
+  saveAutoCookieState,
+  cleanStaleTempFiles as cleanAutoCookieTempFiles,
+} from './auto-cookie-persist';
 import { emitActivity, subscribe, getActivityAfter, getActivityHistory, getSubscriberCount } from './activity';
 import { createSseEndpoint } from './sse-helpers';
 import { initAuditLog, writeAuditEntry } from './audit';
@@ -648,6 +655,47 @@ function idleCheckTick() {
 }
 const idleCheckInterval = setInterval(idleCheckTick, 60_000);
 
+// ─── Auto-cookie persistence (opt-in) ──────────────────────────
+// Checkpoints the live context's persistent cookies to a per-workspace state
+// file so a device-trust cookie survives a daemon restart. Three triggers:
+// (1) a periodic checkpoint below, (2) a debounced checkpoint after mutating
+// commands (scheduleAutoCookieCheckpoint, called from handleCommandInternalImpl),
+// and (3) a final flush in shutdown() before the browser closes. The crash
+// path (emergencyCleanup) deliberately does NOT save — serializing a dying
+// context risks a corrupt write; we rely on the most recent good checkpoint.
+let autoCookieLockHeld = false;
+let autoCookieLastHash: string | null = null;
+let autoCookieDebounce: ReturnType<typeof setTimeout> | null = null;
+
+async function autoCookieCheckpoint(): Promise<void> {
+  if (!autoCookieLockHeld) return; // never write without owning the lock
+  const res = await saveAutoCookieState(config, activeBrowserManager.getContext(), autoCookieLastHash);
+  autoCookieLastHash = res.hash;
+}
+
+// Debounced checkpoint: coalesces bursts of mutating commands into one write a
+// short while after the last one. unref'd so it never keeps the process alive.
+function scheduleAutoCookieCheckpoint(): void {
+  if (!autoCookieLockHeld) return;
+  if (autoCookieDebounce) clearTimeout(autoCookieDebounce);
+  autoCookieDebounce = setTimeout(() => {
+    autoCookieDebounce = null;
+    void autoCookieCheckpoint();
+  }, 1500);
+  if (typeof autoCookieDebounce.unref === 'function') autoCookieDebounce.unref();
+}
+
+// Periodic safety-net checkpoint (covers crash-before-shutdown where the
+// debounce/flush never runs). unref'd — must not hold the daemon open.
+const autoCookieInterval = setInterval(() => { void autoCookieCheckpoint(); }, 60_000);
+if (typeof autoCookieInterval.unref === 'function') autoCookieInterval.unref();
+
+// Commands that can mutate cookies/browser state and thus warrant a checkpoint.
+const AUTO_COOKIE_MUTATING_COMMANDS = new Set([
+  'goto', 'click', 'fill', 'type', 'press', 'select', 'reload', 'back', 'forward',
+  'chain', 'state', 'cookie-picker', 'set-cookie',
+]);
+
 // Test-only surface for server-factory.test.ts. Lets the dual-instance
 // idle-timer behavior be exercised deterministically without mutating
 // Date.now (which would interact with the leaked module-level setInterval).
@@ -959,6 +1007,14 @@ async function handleCommandInternalImpl(
   const command = canonicalizeCommand(rawCommand);
   const isAliased = command !== rawCommand;
 
+  // Auto-cookie checkpoint (opt-in): a mutating command may have changed
+  // cookies. Schedule a debounced checkpoint — the 1.5s debounce means the
+  // capture runs after the command has actually applied. No-op unless the lock
+  // is held. Skip nested chain subcommands: the outer chain already scheduled.
+  if ((opts?.chainDepth ?? 0) === 0 && AUTO_COOKIE_MUTATING_COMMANDS.has(command)) {
+    scheduleAutoCookieCheckpoint();
+  }
+
   // ─── Recursion guard: reject nested chains ──────────────────
   if (command === 'chain' && (opts?.chainDepth ?? 0) > 0) {
     return { status: 400, result: JSON.stringify({ error: 'Nested chain commands are not allowed' }), json: true };
@@ -1607,9 +1663,17 @@ export function buildFetchHandler(cfg: ServerConfig): ServerHandle {
     if (cfgBrowserManager.isWatching()) cfgBrowserManager.stopWatch();
     clearInterval(flushInterval);
     clearInterval(idleCheckInterval);
+    clearInterval(autoCookieInterval);
+    if (autoCookieDebounce) { clearTimeout(autoCookieDebounce); autoCookieDebounce = null; }
     if (agentWatchdogInterval) clearInterval(agentWatchdogInterval);
     await flushBuffers();
 
+    // Final cookie checkpoint BEFORE the context closes — this is the graceful
+    // path all intentional shutdowns funnel through (idle timeout, SIGINT,
+    // /stop). Must run while the context still exists. Then release the lock.
+    await autoCookieCheckpoint();
+    if (autoCookieLockHeld) { releaseAutoCookieLock(config); autoCookieLockHeld = false; }
+
     await cfgBrowserManager.close();
 
     cleanSingletonLocks(resolveChromiumProfile());
@@ -1640,6 +1704,20 @@ export function buildFetchHandler(cfg: ServerConfig): ServerHandle {
   // reports connectionMode === 'launched'.
   activeBrowserManager = cfgBrowserManager;
 
+  // Acquire the per-workspace auto-cookie lock once, at daemon start. Holding
+  // it for the daemon's lifetime is what serializes concurrent daemons (e.g.
+  // separate git worktrees) — only the lock holder writes the shared slot.
+  // If a live peer owns it, disable auto-persistence for this daemon (loud) so
+  // two daemons never last-writer-wins each other's cookies. Reads still work
+  // without the lock (atomic writes make a concurrent read safe).
+  if (isAutoCookiePersistEnabled()) {
+    cleanAutoCookieTempFiles(config);
+    autoCookieLockHeld = acquireAutoCookieLock(config);
+    if (!autoCookieLockHeld) {
+      console.warn('[browse] Auto-cookie persistence disabled for this daemon: another instance holds the workspace lock.');
+    }
+  }
+
   // Wire the cfg-instance's onDisconnect to run shutdown when the user
   // closes the headed browser window. CHAIN any caller-provided handler
   // instead of overwriting it: gbrowser may have set its own onDisconnect