diff --git a/.gitignore b/.gitignore
index 0808c4a..6381ead 100644
--- a/.gitignore
+++ b/.gitignore
@@ -480,3 +480,4 @@
 
 # Vim temporary swap files
 *.swp
+.codex
diff --git a/Program.cs b/Program.cs
index 1bc95b9..a258a89 100644
--- a/Program.cs
+++ b/Program.cs
@@ -42,6 +42,7 @@
                 return 0;
             }
 
+            WritePayloadToVarLog(reading);
             Console.Error.WriteLine($"http {statusCode}: {body}");
             return 2;
         }
@@ -80,6 +81,27 @@
     }
 
     /// <summary>
+    /// 将失败的上报 payload 写入 /var/log，便于后续排查与补发。
+    /// </summary>
+    /// <param name="payload">失败时的传感器读数。</param>
+    private static void WritePayloadToVarLog(Jciebu2 payload)
+    {
+        try
+        {
+            var directory = "/var/log/sensorreadings";
+            Directory.CreateDirectory(directory);
+            var fileName = $"{DateTimeOffset.UtcNow:yyyyMMddHHmmssfff}.json";
+            var path = Path.Combine(directory, fileName);
+            var json = JsonSerializer.Serialize(payload, SensorReadingsJsonContext.Default.Jciebu2);
+            File.WriteAllText(path, json, Encoding.UTF8);
+        }
+        catch (Exception ex)
+        {
+            Console.Error.WriteLine($"error: failed to write payload log: {ex.Message}");
+        }
+    }
+
+    /// <summary>
     /// 从串口设备读取最新数据，并统一时间戳与位置字段。
     /// </summary>
     /// <param name="port">串口设备路径。</param>
@@ -215,7 +237,8 @@
     {
         if (data.Length < 56)
         {
-            throw new InvalidOperationException($"response too short: {data.Length} bytes (need >= 56)");
+            Console.Error.WriteLine($"error: response too short: {data.Length} bytes (need >= 56)");
+            Environment.Exit(2);
         }
 
         return new Jciebu2
diff --git a/ReadSensors.py b/ReadSensors.py
deleted file mode 100644
index ff2bec3..0000000
--- a/ReadSensors.py
+++ /dev/null
@@ -1,117 +0,0 @@
-#!/usr/bin/env python3
-"""Read 2JCIE-BU once and POST to OData.
-
-Endpoint (given): http://10.16.1.100:8016/odata/SensorReadings
-
-No pip deps: uses Python stdlib only.
-
-Env vars:
-  SENSOR_PORT      default /dev/ttyUSB0
-  SENSOR_LOCATION  default home_2f
-  ODATA_URL        default http://10.16.1.100:8016/odata/SensorReadings
-  ODATA_TOKEN      optional bearer token
-  ODATA_TIMEOUT_S  default 10
-"""
-
-import json
-import os
-import sys
-import urllib.request
-import urllib.error
-
-import importlib.util
-from pathlib import Path
-
-PORT = os.getenv("SENSOR_PORT", "/dev/ttyUSB0")
-LOCATION = os.getenv("SENSOR_LOCATION", "home_2f")
-ODATA_URL = os.getenv("ODATA_URL", "http://10.16.1.100:8016/odata/SensorReadings")
-ODATA_TOKEN = os.getenv("ODATA_TOKEN", "").strip()
-TIMEOUT_S = float(os.getenv("ODATA_TIMEOUT_S", "10"))
-
-# Load local sensor module (filename starts with digit)
-_2JCIE_PATH = Path(__file__).with_name("2jciebu.py")
-_spec = importlib.util.spec_from_file_location("_2jciebu", _2JCIE_PATH)
-_mod = importlib.util.module_from_spec(_spec)
-assert _spec and _spec.loader
-_spec.loader.exec_module(_mod)
-get_latest_reading = _mod.get_latest_reading
-
-
-def _to_odata_payload(r: dict) -> dict:
-    """Map our snake_case reading dict to the OData entity property names.
-
-    The OData service appears to use PascalCase keys (e.g. Ts, Location, TemperatureC...).
-    """
-    ts = r.get("ts")
-    if ts is None:
-        raise ValueError("missing ts")
-
-    # datetimeoffset(0) -> ISO8601 without fractional seconds, with Z
-    ts_str = ts.isoformat().replace("+00:00", "Z")
-
-    payload = {
-        "Ts": ts_str,
-        "Location": r.get("location") or LOCATION,
-        "TemperatureC": r.get("temperature_c"),
-        "HumidityRh": r.get("humidity_rh"),
-        "AmbientLight": r.get("ambient_light"),
-        "PressureHpa": r.get("pressure_hpa"),
-        "NoiseDb": r.get("noise_db"),
-        "EtvocPpb": r.get("etvoc_ppb"),
-        "Eco2Ppm": r.get("eco2_ppm"),
-        "DiscomfortIndex": r.get("discomfort_index"),
-        "HeatstrokeIndex": r.get("heatstroke_index"),
-        "VibrationInfo": r.get("vibration_info"),
-        "SiValue": r.get("si_value"),
-        "PgaGal": r.get("pga_gal"),
-        "SeismicIntensity": r.get("seismic_intensity"),
-        "TemperatureFlag": r.get("temperature_flag"),
-        "HumidityFlag": r.get("humidity_flag"),
-        "AmbientLightFlag": r.get("ambient_light_flag"),
-        "PressureFlag": r.get("pressure_flag"),
-        "NoiseFlag": r.get("noise_flag"),
-        "EtvocFlag": r.get("etvoc_flag"),
-        "Eco2Flag": r.get("eco2_flag"),
-        "DiscomfortFlag": r.get("discomfort_flag"),
-        "HeatstrokeFlag": r.get("heatstroke_flag"),
-        "SiFlag": r.get("si_flag"),
-        "PgaFlag": r.get("pga_flag"),
-        "SeismicIntensityFlag": r.get("seismic_intensity_flag"),
-    }
-
-    # Drop None values to avoid type issues on some OData backends
-    return {k: v for k, v in payload.items() if v is not None}
-
-
-def post_odata(payload: dict) -> tuple[int, str]:
-    body = json.dumps(payload, ensure_ascii=False).encode("utf-8")
-    headers = {
-        "Content-Type": "application/json",
-        "Accept": "application/json",
-    }
-    if ODATA_TOKEN:
-        headers["Authorization"] = f"Bearer {ODATA_TOKEN}"
-
-    req = urllib.request.Request(ODATA_URL, data=body, headers=headers, method="POST")
-    try:
-        with urllib.request.urlopen(req, timeout=TIMEOUT_S) as resp:
-            resp_body = resp.read().decode("utf-8", errors="replace")
-            return resp.status, resp_body
-    except urllib.error.HTTPError as e:
-        err_body = e.read().decode("utf-8", errors="replace")
-        return e.code, err_body
-
-
-def main():
-    r = get_latest_reading(port=PORT, location=LOCATION)
-    payload = _to_odata_payload(r)
-    code, body = post_odata(payload)
-    if 200 <= code < 300:
-        print("ok")
-        return
-    print(f"http {code}: {body}", file=sys.stderr)
-    sys.exit(2)
-
-
-if __name__ == "__main__":
-    main()