Adding the new rewrite

app/apc_cli.py

@@ -1,22 +1,24 @@
 from __future__ import annotations
+
 import asyncio
-import shutil
 import logging
-from typing import Dict, Any
+import shutil
+from typing import Any
 
 logger = logging.getLogger(__name__)
 
 APCACCESS_BIN = shutil.which('apcaccess') or 'apcaccess'
+APCACCESS_TIMEOUT_SECONDS = 10.0
 
 
 class APCStatusError(Exception):
     pass
 
 
-async def fetch_status(host: str, port: int) -> Dict[str, Any]:
+async def fetch_status(host: str, port: int) -> dict[str, Any]:
     """Invoke apcaccess CLI and parse key:value lines into a dict.
 
-    Raises APCStatusError if binary fails or returns no data.
+    Raises APCStatusError if binary fails, times out, or returns no data.
     """
     proc = await asyncio.create_subprocess_exec(
         APCACCESS_BIN,
@@ -25,14 +27,26 @@ async def fetch_status(host: str, port: int) -> Dict[str, Any]:
         stdout=asyncio.subprocess.PIPE,
         stderr=asyncio.subprocess.PIPE,
     )
-    stdout, stderr = await proc.communicate()
+    try:
+        stdout, stderr = await asyncio.wait_for(
+            proc.communicate(), timeout=APCACCESS_TIMEOUT_SECONDS
+        )
+    except TimeoutError:
+        try:
+            proc.kill()
+            await proc.wait()
+        except ProcessLookupError:
+            pass
+        raise APCStatusError(
+            f"apcaccess timed out after {APCACCESS_TIMEOUT_SECONDS}s for {host}:{port}"
+        )
     if proc.returncode != 0:
         err_txt = stderr.decode(errors="replace").strip()
         raise APCStatusError(
             f'apcaccess exit {proc.returncode}: {err_txt}'
         )
     text = stdout.decode(errors='replace')
-    data: Dict[str, Any] = {}
+    data: dict[str, Any] = {}
     for line in text.splitlines():
         if ':' not in line:
             continue
@@ -40,7 +54,8 @@ async def fetch_status(host: str, port: int) -> Dict[str, Any]:
         key = k.strip()
         val = v.strip()
         data[key] = val
-    # Normalize expected fields/aliases
+    if not data:
+        raise APCStatusError("apcaccess returned no data")
     if 'UPSNAME' not in data and 'NAME' in data:
         data['UPSNAME'] = data['NAME']
     if 'MODEL' in data: