Claude Code: add system status logging module with /admin/system endpoint

- Add .openclaw/core/system_logger.py for startup/heartbeat logging
- Integrate logging into FastAPI lifespan manager
- Add heartbeat loop (30s intervals) with current status
- Add /admin/system endpoint to read last 50 lines of logs/system.log

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.openclaw/core/system_logger.py

@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+"""
+System status logging module for HuggingClaw.
+Logs FastAPI startup events and heartbeat signals to logs/system.log
+"""
+import os
+import threading
+from datetime import datetime
+from pathlib import Path
+
+# Paths
+OPENCLAW_DIR = "/app/.openclaw"
+LOG_DIR = f"{OPENCLAW_DIR}/logs"
+SYSTEM_LOG = f"{LOG_DIR}/system.log"
+
+# Ensure log directory exists
+Path(LOG_DIR).mkdir(parents=True, exist_ok=True)
+
+# Thread lock for safe concurrent writes
+_lock = threading.Lock()
+
+
+def _write_log(message: str):
+    """Internal: write a log entry with timestamp."""
+    with _lock:
+        timestamp = datetime.utcnow().isoformat() + "+00:00"
+        with open(SYSTEM_LOG, "a") as f:
+            f.write(f"[{timestamp}] {message}\n")
+
+
+def log_startup(app_name: str = "Cain", version: str = "1.0.0"):
+    """Log FastAPI application startup."""
+    _write_log(f"STARTUP {app_name} v{version} - FastAPI server starting")
+
+
+def log_heartbeat(status: str = "RUNNING"):
+    """Log a heartbeat signal with current status."""
+    _write_log(f"HEARTBEAT status={status}")
+
+
+def log_event(event_type: str, message: str):
+    """Log a custom event."""
+    _write_log(f"EVENT {event_type} - {message}")
+
+
+def get_last_lines(n: int = 50) -> list[str]:
+    """Read the last n lines from the system log."""
+    try:
+        with open(SYSTEM_LOG, "r") as f:
+            lines = f.readlines()
+        return [line.strip() for line in lines[-n:]]
+    except FileNotFoundError:
+        return []

app.py

@@ -14,11 +14,40 @@ import os
 import sys
 from datetime import datetime
 import asyncio
+from contextlib import asynccontextmanager
 
 # Add /app to sys.path for proper package imports
 sys.path.insert(0, "/app")
 
-app = FastAPI(title="HuggingClaw - Cain", version="1.0.0")
+# Import system logger
+from openclaw.core.system_logger import log_startup, log_heartbeat, get_last_lines
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """Lifespan context manager for startup/shutdown events."""
+    # Startup: log system startup
+    log_startup("Cain", "1.0.0")
+
+    # Start heartbeat task
+    heartbeat_task = asyncio.create_task(heartbeat_loop())
+
+    yield
+
+    # Shutdown: cancel heartbeat
+    heartbeat_task.cancel()
+
+
+# Background heartbeat loop
+async def heartbeat_loop():
+    """Write heartbeat signal every 30 seconds."""
+    while True:
+        await asyncio.sleep(30)
+        status = get_cain_status().get("current_state", "unknown")
+        log_heartbeat(status)
+
+
+app = FastAPI(title="HuggingClaw - Cain", version="1.0.0", lifespan=lifespan)
 
 # Mount static files directory
 static_dir = "/app/static"
@@ -161,6 +190,18 @@ async def websocket_endpoint(websocket: WebSocket):
         await websocket.close()
 
 
+@app.get("/admin/system")
+async def admin_system():
+    """Admin endpoint - read last 50 lines of system log."""
+    lines = get_last_lines(50)
+    return {
+        "log_file": "logs/system.log",
+        "line_count": len(lines),
+        "lines": lines,
+        "timestamp": datetime.utcnow().isoformat() + "+00:00"
+    }
+
+
 if __name__ == "__main__":
     import uvicorn
     uvicorn.run(app, host="0.0.0.0", port=7860)