Fix ble_alerter: MAC name filter, Matrix 429 backoff, active scanner

- Reject dash/colon MAC-format device names (e.g. 45-48-39-7F-73-C7)
  from open mode — were slipping past is_generic_name()
- Add exponential backoff (1s, 2s) on Matrix 429/5xx, max 3 attempts —
  startup burst was rate-limiting and dropping alerts
- Commit active scanner flag (scanning_mode=active) that was in working
  tree but not in prior commit 8686eb5 despite the commit message
- Add 3 tests: MAC format filter, 429 retry success, 429 give-up

Fixes DevTrack #518

net_alerter/ble_alerter.py

@@ -11,6 +11,7 @@ import asyncio
 import json
 import logging
 import os
+import re
 import signal
 import sys
 import time
@@ -115,6 +116,9 @@ def load_env():
         logging.error(f"Failed to load .env: {e}")
 
 
+_MAC_RE = re.compile(r'^[0-9A-Fa-f]{2}[:\-][0-9A-Fa-f]{2}[:\-][0-9A-Fa-f]{2}[:\-][0-9A-Fa-f]{2}[:\-][0-9A-Fa-f]{2}[:\-][0-9A-Fa-f]{2}$')
+
+
 def is_generic_name(name):
     """
     Filter out unhelpful device names (generic manufacturer defaults, hex-only, too short).
@@ -122,17 +126,21 @@ def is_generic_name(name):
     """
     if not name or not isinstance(name, str):
         return True
-    
+
     name = name.strip()
-    
+
     # Too short
     if len(name) < 3:
         return True
-    
+
     # All hex characters (looks like MAC address fragment)
     if all(c in "0123456789ABCDEFabcdef" for c in name):
         return True
-    
+
+    # MAC address format with colons or dashes (e.g. 45-48-39-7F-73-C7 or 45:48:39:7F:73:C7)
+    if _MAC_RE.match(name):
+        return True
+
     # Common generic patterns
     generic_patterns = [
         "LE-", "BLE-", "BT-", "BT ", "Bluetooth", "Unknown",
@@ -141,7 +149,7 @@ def is_generic_name(name):
     for pattern in generic_patterns:
         if pattern.lower() in name.lower():
             return True
-    
+
     return False
 
 
@@ -160,34 +168,44 @@ def fmt_duration(secs):
 
 
 def send_alert(msg):
-    """Send alert to Matrix room."""
+    """Send alert to Matrix room. Retries up to 3 times with exponential backoff on 429/5xx."""
     if not MATRIX_ACCESS_TOKEN:
         logging.warning("No MATRIX_ACCESS_TOKEN set, skipping alert")
         return
-    
+
     url = (
         f"{MATRIX_HOMESERVER}/_matrix/client/v3/rooms/"
         f"{urllib.parse.quote(MATRIX_ROOM_ID, safe='')}/send/m.room.message"
     )
     payload = json.dumps({"msgtype": "m.text", "body": msg}).encode()
-    req = urllib.request.Request(
-        url,
-        data=payload,
-        headers={
-            "Authorization": f"Bearer {MATRIX_ACCESS_TOKEN}",
-            "Content-Type": "application/json",
-            "User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36",
-        },
-        method="POST",
-    )
-    try:
-        with urllib.request.urlopen(req, timeout=10) as r:
-            pass
-        logging.debug(f"Alert sent to Matrix")
-    except urllib.error.HTTPError as e:
-        logging.error(f"Matrix send failed with HTTP {e.code}")
-    except Exception as e:
-        logging.error(f"Matrix send exception: {e}")
+
+    for attempt in range(3):
+        req = urllib.request.Request(
+            url,
+            data=payload,
+            headers={
+                "Authorization": f"Bearer {MATRIX_ACCESS_TOKEN}",
+                "Content-Type": "application/json",
+                "User-Agent": "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36",
+            },
+            method="POST",
+        )
+        try:
+            with urllib.request.urlopen(req, timeout=10) as r:
+                pass
+            logging.debug("Alert sent to Matrix")
+            return
+        except urllib.error.HTTPError as e:
+            if e.code in (429, 500, 502, 503, 504) and attempt < 2:
+                wait = 2 ** attempt  # 1s, 2s
+                logging.warning(f"Matrix HTTP {e.code}, retrying in {wait}s")
+                time.sleep(wait)
+            else:
+                logging.error(f"Matrix send failed with HTTP {e.code}")
+                return
+        except Exception as e:
+            logging.error(f"Matrix send exception: {e}")
+            return
 
 
 async def on_arrival(name, mac, rssi):
@@ -256,8 +274,8 @@ async def scan_loop():
         
         await on_arrival(name, mac, rssi)
     
-    # Active scanner — sends SCAN_REQ to get full advertisement data including device names
-    async with BleakScanner(detection_callback=detection_callback) as scanner:
+    # Active scanner — explicitly required; bleak 0.20 BlueZ backend defaults to passive
+    async with BleakScanner(detection_callback=detection_callback, scanning_mode="active") as scanner:
         try:
             while not shutdown_event.is_set():
                 await asyncio.sleep(1)