Track WSL host disk incident and add capacity guard

Assistant: codex
Assistant-Model: gpt-6.1-sol
Assistant-Session: 01a1b4e3-7aa4-75b2-b432-114153ff6879

scripts/workstation_disk_guard.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+"""Read-only WSL host/guest capacity check. Exit 0/1/2/3: OK/warn/critical/unknown."""
+
+import argparse
+from datetime import datetime, timezone
+import json
+import math
+from pathlib import Path
+import shutil
+
+GIB = 1024 ** 3
+LEVELS = {"ok": 0, "warning": 1, "critical": 2, "unknown": 3}
+
+
+def nonnegative_gib(value):
+    number = float(value)
+    if not math.isfinite(number) or number < 0:
+        raise argparse.ArgumentTypeError("reserve must be finite and nonnegative")
+    return number
+
+
+def check_volume(path, warning_gib, critical_gib, reserve_bytes, require_mount=False):
+    result = {"path": str(path), "warning_bytes": warning_gib * GIB,
+              "critical_bytes": critical_gib * GIB, "reserve_bytes": reserve_bytes}
+    try:
+        if require_mount and not Path(path).is_mount():
+            raise OSError("host drive is not mounted")
+        usage = shutil.disk_usage(path)
+        remaining = usage.free - reserve_bytes
+        result.update(total_bytes=usage.total, free_bytes=usage.free,
+                      free_after_reserve_bytes=remaining)
+        result["status"] = ("critical" if remaining < critical_gib * GIB else
+                            "warning" if remaining < warning_gib * GIB else "ok")
+    except OSError:
+        result.update(status="unknown", error="capacity_unavailable_or_drive_unmounted")
+    return result
+
+
+def collect(reserve_bytes=0):
+    volumes = [check_volume("/mnt/c", 60, 30, reserve_bytes, require_mount=True),
+               check_volume("/", 40, 20, reserve_bytes)]
+    status = max((v["status"] for v in volumes), key=LEVELS.get)
+    return {"schema": "platform.workstation-disk-guard.v1",
+            "observed_at": datetime.now(timezone.utc).isoformat(),
+            "status": status, "volumes": volumes}
+
+
+def main():
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("--reserve-gib", type=nonnegative_gib, default=0,
+                        help="expected additional build use; subtract from BOTH host and guest free space")
+    args = parser.parse_args()
+    report = collect(int(args.reserve_gib * GIB))
+    print(json.dumps(report, indent=2, sort_keys=True))
+    return LEVELS[report["status"]]
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())