diff --git a/lib/src/pty/pty_log.dart b/lib/src/pty/pty_log.dart
index 2e50781c..7c61f9bc 100644
--- a/lib/src/pty/pty_log.dart
+++ b/lib/src/pty/pty_log.dart
@@ -65,7 +65,12 @@ class IsolateCrumbFile {
   IsolateCrumbFile(String? path, this.source, {int capBytes = 256 * 1024}) : _capBytes = capBytes {
     if (path == null) return;
     try {
-      final raf = File(path).openSync(mode: FileMode.append);
+      final f = File(path);
+      // Create the parent dir ourselves — a standalone caller (the soak probe)
+      // may point us at a dir nothing else has made yet. In the app the
+      // FileLogSink already created logDirectory(), so this is a no-op there.
+      f.parent.createSync(recursive: true);
+      final raf = f.openSync(mode: FileMode.append);
       _raf = raf;
       _size = raf.lengthSync();
     } catch (_) {
diff --git a/test/pty/pty_log_test.dart b/test/pty/pty_log_test.dart
index 6673bee6..d0eaa94b 100644
--- a/test/pty/pty_log_test.dart
+++ b/test/pty/pty_log_test.dart
@@ -44,6 +44,14 @@ void main() {
       c.close();
     });
 
+    test('creates a missing parent directory (standalone soak probe case)', () {
+      final nested = '${dir.path}${Platform.pathSeparator}a${Platform.pathSeparator}b${Platform.pathSeparator}crumbs.log';
+      final c = IsolateCrumbFile(nested, 'conpty.reader')..crumb('ReadFile enter');
+      c.close();
+      expect(File(nested).existsSync(), isTrue);
+      expect(File(nested).readAsStringSync(), contains('ReadFile enter'));
+    });
+
     test('writes one tagged, timestamped line per crumb', () {
       final c = IsolateCrumbFile(path(), 'pty.reader');
       expect(c.enabled, isTrue);