Reimplement duplicated run detection as a file lock

utils.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import io
 import os
 import sys
 import json
@@ -77,6 +78,29 @@ def format_traceback(exc: BaseException, **kwargs: Any) -> str:
     return ''.join(traceback.format_exception(type(exc), exc, **kwargs))
 
 
+def lock_file(path: Path) -> tuple[bool, io.TextIOWrapper]:
+    file = path.open('w', encoding="utf8")
+    file.write('ツ')
+    file.flush()
+    if sys.platform == "win32":
+        import msvcrt
+        try:
+            # we need to lock at least one byte for this to work
+            msvcrt.locking(file.fileno(), msvcrt.LK_NBLCK, max(path.stat().st_size, 1))
+        except Exception:
+            return False, file
+        return True, file
+    if sys.platform == "linux":
+        import fcntl
+        try:
+            fcntl.lockf(file, fcntl.LOCK_EX | fcntl.LOCK_NB)
+        except Exception:
+            return False, file
+        return True, file
+    # for unsupported systems, just always return True
+    return True, file
+
+
 def json_minify(data: JsonType | list[JsonType]) -> str:
     """
     Returns minified JSON for payload usage.