diff --git a/src/cliproxy/accounts/registry.ts b/src/cliproxy/accounts/registry.ts
index 06ca3dff..dc65fb01 100644
--- a/src/cliproxy/accounts/registry.ts
+++ b/src/cliproxy/accounts/registry.ts
@@ -5,11 +5,11 @@
 
 import * as fs from 'fs';
 import * as path from 'path';
-import * as lockfile from 'proper-lockfile';
 import { CLIProxyProvider } from '../types';
 import { PROVIDER_CAPABILITIES } from '../provider-capabilities';
 import { PROVIDER_TYPE_VALUES } from '../auth/auth-types';
 import { getAuthDir, getCliproxyDir } from '../config/config-generator';
+import { withSyncLockRetry } from '../../utils/sync-lock-retry';
 import { AccountsRegistry, AccountInfo, PROVIDERS_WITHOUT_EMAIL, DrainOrderConfig } from './types';
 import {
   getAccountsRegistryPath,
@@ -338,24 +338,24 @@ function recoverAccountsRegistryFromCorruption(registryPath: string): AccountsRe
 
 function withAccountsRegistryLock<T>(callback: () => T): T {
   const lockTarget = getCliproxyDir();
-  let release: (() => void) | undefined;
 
   if (!fs.existsSync(lockTarget)) {
     fs.mkdirSync(lockTarget, { recursive: true, mode: 0o700 });
   }
 
-  try {
-    release = lockfile.lockSync(lockTarget, { stale: 10000 }) as () => void;
-    return callback();
-  } finally {
-    if (release) {
-      try {
-        release();
-      } catch {
-        // Best-effort release
-      }
-    }
-  }
+  // proper-lockfile rejects built-in retries in synchronous mode.
+  // Keep this API sync while waiting for short-lived concurrent launches.
+  // Preserve the existing stale-lock window.
+  // Retry only contention failures.
+  // Wait in short intervals so released locks are picked up promptly.
+  // Bound the wait so a genuinely stuck process still produces an error.
+  // The helper adds recovery guidance when that timeout is reached.
+  return withSyncLockRetry(lockTarget, callback, {
+    description: 'CLIProxy account registry lock',
+    staleMs: 10000,
+    retryDelayMs: 200,
+    retryTimeoutMs: 10000,
+  });
 }
 
 function readAccountsRegistryFromDisk(): AccountsRegistry {
diff --git a/src/cliproxy/session-tracker.ts b/src/cliproxy/session-tracker.ts
index ccc59e4c..c211075d 100644
--- a/src/cliproxy/session-tracker.ts
+++ b/src/cliproxy/session-tracker.ts
@@ -17,10 +17,10 @@
 import * as fs from 'fs';
 import * as path from 'path';
 import * as crypto from 'crypto';
-import * as lockfile from 'proper-lockfile';
 import { getCliproxyDir } from './config/config-generator';
 import { getPortProcess, isCLIProxyProcess } from '../utils/port-utils';
 import { CLIPROXY_DEFAULT_PORT } from './config/config-generator';
+import { withSyncLockRetry } from '../utils/sync-lock-retry';
 
 /** Session lock file structure */
 interface SessionLock {
@@ -61,22 +61,9 @@ function ensureCliproxyDir(): string {
 
 function withSessionTrackerLock<T>(fn: () => T): T {
   const dir = ensureCliproxyDir();
-  let release: (() => void) | undefined;
-
-  try {
-    release = lockfile.lockSync(dir, {
-      stale: 10000,
-    }) as () => void;
-    return fn();
-  } finally {
-    if (release) {
-      try {
-        release();
-      } catch {
-        // Best-effort release
-      }
-    }
-  }
+  return withSyncLockRetry(dir, fn, {
+    description: 'CLIProxy session tracker lock',
+  });
 }
 
 /** Get path to session lock file (default port) - kept for future use */
diff --git a/src/utils/sync-lock-retry.ts b/src/utils/sync-lock-retry.ts
new file mode 100644
index 00000000..1e984fc9
--- /dev/null
+++ b/src/utils/sync-lock-retry.ts
@@ -0,0 +1,115 @@
+import * as fs from 'fs';
+import { performance } from 'perf_hooks';
+import * as lockfile from 'proper-lockfile';
+
+const DEFAULT_STALE_MS = 10000;
+const DEFAULT_RETRY_DELAY_MS = 200;
+const DEFAULT_RETRY_TIMEOUT_MS = 10000;
+
+interface SyncLockRetryOptions {
+  description: string;
+  staleMs?: number;
+  retryDelayMs?: number;
+  retryTimeoutMs?: number;
+}
+
+export function withSyncLockRetry<T>(
+  lockTarget: string,
+  callback: () => T,
+  options: SyncLockRetryOptions
+): T {
+  const staleMs = options.staleMs ?? DEFAULT_STALE_MS;
+  const retryDelayMs = options.retryDelayMs ?? DEFAULT_RETRY_DELAY_MS;
+  const retryTimeoutMs = options.retryTimeoutMs ?? DEFAULT_RETRY_TIMEOUT_MS;
+  const startedAt = performance.now();
+  let release: (() => void) | undefined;
+  let contendedLockPath: string | undefined;
+  let lastContentionError: unknown;
+
+  for (;;) {
+    if (contendedLockPath && fs.existsSync(contendedLockPath)) {
+      sleepBeforeRetry(
+        startedAt,
+        retryDelayMs,
+        retryTimeoutMs,
+        options.description,
+        lastContentionError
+      );
+      continue;
+    }
+
+    if (contendedLockPath && performance.now() - startedAt >= retryTimeoutMs) {
+      throw buildLockTimeoutError(options.description, retryTimeoutMs, lastContentionError);
+    }
+
+    try {
+      release = lockfile.lockSync(lockTarget, { stale: staleMs }) as () => void;
+      break;
+    } catch (error) {
+      if (!isLockContentionError(error)) {
+        throw error;
+      }
+      contendedLockPath ??= `${fs.realpathSync(lockTarget)}.lock`;
+      lastContentionError = error;
+      sleepBeforeRetry(startedAt, retryDelayMs, retryTimeoutMs, options.description, error);
+    }
+  }
+
+  try {
+    return callback();
+  } finally {
+    try {
+      release();
+    } catch {
+      // Best-effort release.
+    }
+  }
+}
+
+function isLockContentionError(error: unknown): boolean {
+  const code = (error as NodeJS.ErrnoException | undefined)?.code;
+  return code === 'ELOCKED' || code === 'ENOTACQUIRED';
+}
+
+function sleepSync(ms: number): void {
+  if (ms <= 0) {
+    return;
+  }
+
+  try {
+    Atomics.wait(new Int32Array(new SharedArrayBuffer(4)), 0, 0, ms);
+  } catch {
+    const deadline = performance.now() + ms;
+    while (performance.now() < deadline) {
+      // Fall back for runtimes without Atomics.wait.
+    }
+  }
+}
+
+function sleepBeforeRetry(
+  startedAt: number,
+  retryDelayMs: number,
+  retryTimeoutMs: number,
+  description: string,
+  cause: unknown
+): void {
+  const elapsedMs = performance.now() - startedAt;
+  if (elapsedMs >= retryTimeoutMs) {
+    throw buildLockTimeoutError(description, retryTimeoutMs, cause);
+  }
+  sleepSync(Math.min(retryDelayMs, retryTimeoutMs - elapsedMs));
+}
+
+function buildLockTimeoutError(
+  description: string,
+  timeoutMs: number,
+  cause: unknown
+): NodeJS.ErrnoException {
+  const causeCode = (cause as NodeJS.ErrnoException | undefined)?.code;
+  const error = new Error(
+    `Failed to acquire ${description} after ${timeoutMs}ms; another CCS process may still be updating CLIProxy state. Wait for it to finish, then retry.`
+  ) as NodeJS.ErrnoException & { cause?: unknown };
+  error.code = causeCode === 'ENOTACQUIRED' ? 'ENOTACQUIRED' : 'ELOCKED';
+  error.cause = cause;
+  return error;
+}