tools/watch_needs.py: wake the coordinator when a helper appends to the needs file

tools/watch_needs.py

@@ -0,0 +1,29 @@
+"""Block until the helpers' needs file grows (a helper appended something only Claude can do), then print the new
+part and exit, so the coordinator's background task wakes it. Also exits after --minutes as a heartbeat.
+
+    py -3.12 -B tools/watch_needs.py [--file R:/Workspace/Scratch/helpers/needs.md] [--minutes 60]"""
+import argparse
+import time
+from pathlib import Path
+
+ap = argparse.ArgumentParser()
+ap.add_argument("--file", default=r"R:/Workspace/Scratch/helpers/needs.md")
+ap.add_argument("--minutes", type=float, default=60)
+args = ap.parse_args()
+path = Path(args.file)
+path.parent.mkdir(parents=True, exist_ok=True)
+path.touch(exist_ok=True)
+start = path.stat().st_size
+deadline = time.monotonic() + args.minutes * 60
+while time.monotonic() < deadline:
+    size = path.stat().st_size
+    if size > start:
+        time.sleep(3)                      # let the writer finish its entry
+        with path.open(encoding="utf-8", errors="replace") as f:
+            f.seek(start)
+            print(f.read().strip())
+        raise SystemExit(0)
+    if size < start:                       # the file was cleared: follow it from here
+        start = size
+    time.sleep(10)
+print(f"no new needs for {args.minutes:g} minutes")