diff --git a/src/hooks-config.ts b/src/hooks-config.ts
index 58edfc33..fda526c7 100644
--- a/src/hooks-config.ts
+++ b/src/hooks-config.ts
@@ -1031,7 +1031,11 @@ export async function ensureStatusLineExporterScript(): Promise<string> {
     // render, and a truncate-then-write (plus a chmod AFTER the write) opened two
     // windows in which Claude Code could run an empty or non-executable file.
     // rename() swaps the complete, already-executable file in atomically.
-    const tmpPath = `${scriptPath}.${process.pid}.${Date.now()}.tmp`;
+    // ⚠️ The temp name must be unique per CALL, not per millisecond: sessions created
+    // concurrently (spawn_workers, a multi-tab Run) refresh this together, a shared
+    // name let the first rename consume the others' temp file, and their ENOENT
+    // dropped those sessions from tmux to the direct-PTY fallback.
+    const tmpPath = `${scriptPath}.${process.pid}.${randomBytes(6).toString('hex')}.tmp`;
     await writeFile(tmpPath, desired);
     await chmod(tmpPath, 0o755);
     await rename(tmpPath, scriptPath);
diff --git a/test/hooks-config.test.ts b/test/hooks-config.test.ts
index 2f65bd9f..502a21b2 100644
--- a/test/hooks-config.test.ts
+++ b/test/hooks-config.test.ts
@@ -5,7 +5,7 @@
  * hook definitions for desktop notifications.
  */
 
-import { describe, it, expect, beforeAll, beforeEach, afterAll, afterEach } from 'vitest';
+import { describe, it, expect, beforeAll, beforeEach, afterAll, afterEach, vi } from 'vitest';
 import {
   chmodSync,
   closeSync,
@@ -26,6 +26,7 @@ import { spawn } from 'node:child_process';
 import {
   applyStatusLineConfig,
   ensureCodemanHooks,
+  ensureStatusLineExporterScript,
   findEffectiveUserStatusLineCommand,
   generateBackgroundWakeScript,
   generateHooksConfig,
@@ -1418,6 +1419,26 @@ describe('resolveStatusLineCliCommand', () => {
     expect(siblings).toEqual([]);
   });
 
+  it('survives concurrent refreshes in the same millisecond (sessions created at once)', async () => {
+    const scriptPath = (await resolveStatusLineCliCommand(testDir, true))!;
+    writeFileSync(scriptPath, '#!/bin/sh\n# CODEMAN_STATUSLINE_EXPORTER_V0\necho stale\n');
+    // A frozen clock makes every writer agree on the timestamp, which is what two
+    // session creates in one millisecond do. A temp name built from pid + Date.now()
+    // is then shared: the first rename consumes it, every later rename fails ENOENT,
+    // and that session's tmux create fell back to a direct PTY.
+    const clock = vi.spyOn(Date, 'now').mockReturnValue(1_700_000_000_000);
+    try {
+      const paths = await Promise.all(Array.from({ length: 8 }, () => ensureStatusLineExporterScript()));
+      expect(new Set(paths)).toEqual(new Set([scriptPath]));
+    } finally {
+      clock.mockRestore();
+    }
+    expect(readFileSync(scriptPath, 'utf-8')).not.toContain('echo stale');
+    expect(statSync(scriptPath).mode & 0o111).not.toBe(0);
+    const siblings = readdirSync(join(scriptPath, '..')).filter((f) => f.startsWith('statusline-exporter.sh.'));
+    expect(siblings).toEqual([]);
+  });
+
   it('never overrides a real, hand-authored statusLine', async () => {
     const claudeDir = join(testDir, '.claude');
     mkdirSync(claudeDir, { recursive: true });