Only show tcpdump message when tcpdump is available

- Check for tcpdump availability before printing startup message
- Show 'Note: tcpdump not found, skipping concurrent count' when unavailable
- Prevents confusing message when tcpdump is not installed

Co-authored-by: Cursor <cursoragent@cursor.com>

wifi_monitor.py

@@ -887,9 +887,23 @@ class PacketCapture:
             pcap_file.close()
             print(f"Capturing to file: {pcap_path}")
 
-        # Start tcpdump counter concurrently
-        print("Starting concurrent tcpdump counter for data frames...")
-        tcpdump_task = asyncio.create_task(self._run_tcpdump_counter(interface, duration))
+        # Start tcpdump counter concurrently (only if available)
+        tcpdump_task = None
+        try:
+            # Check if tcpdump is available before starting
+            check_proc = await asyncio.create_subprocess_exec(
+                "which", "tcpdump",
+                stdout=asyncio.subprocess.DEVNULL,
+                stderr=asyncio.subprocess.DEVNULL
+            )
+            await check_proc.wait()
+            if check_proc.returncode == 0:
+                print("Starting concurrent tcpdump counter for data frames...")
+                tcpdump_task = asyncio.create_task(self._run_tcpdump_counter(interface, duration))
+            else:
+                print("Note: tcpdump not found, skipping concurrent count")
+        except Exception:
+            print("Note: tcpdump not found, skipping concurrent count")
 
         capture_error = None
         try:
@@ -928,8 +942,10 @@ class PacketCapture:
             import traceback
             traceback.print_exc()
 
-        # Get tcpdump count
-        tcpdump_data_count = await tcpdump_task
+        # Get tcpdump count (if task was started)
+        tcpdump_data_count = None
+        if tcpdump_task is not None:
+            tcpdump_data_count = await tcpdump_task
 
         self.analyzer.analyze(packets, duration, tcpdump_data_count)