fix: Home Assistant event filtering now closed by default (#1169)

Previously, when no watch_domains or watch_entities were configured,
ALL state_changed events passed through to the agent, causing users
to be flooded with notifications for every HA entity change.

Now events are dropped by default unless the user explicitly configures:
- watch_domains: list of domains to monitor (e.g. climate, light)
- watch_entities: list of specific entity IDs to monitor
- watch_all: true (new option — opt-in to receive all events)

A warning is logged at connect time if no filters are configured,
guiding users to set up their HA platform config.

All 49 gateway HA tests + 52 HA tool tests pass.

gateway/platforms/homeassistant.py

@@ -83,6 +83,7 @@ class HomeAssistantAdapter(BasePlatformAdapter):
         self._watch_domains: Set[str] = set(extra.get("watch_domains", []))
         self._watch_entities: Set[str] = set(extra.get("watch_entities", []))
         self._ignore_entities: Set[str] = set(extra.get("ignore_entities", []))
+        self._watch_all: bool = bool(extra.get("watch_all", False))
         self._cooldown_seconds: int = int(extra.get("cooldown_seconds", 30))
 
         # Cooldown tracking: entity_id -> last_event_timestamp
@@ -115,6 +116,15 @@ class HomeAssistantAdapter(BasePlatformAdapter):
             # Dedicated REST session for send() calls
             self._rest_session = aiohttp.ClientSession()
 
+            # Warn if no event filters are configured
+            if not self._watch_domains and not self._watch_entities and not self._watch_all:
+                logger.warning(
+                    "[%s] No watch_domains, watch_entities, or watch_all configured. "
+                    "All state_changed events will be dropped. Configure filters in "
+                    "your HA platform config to receive events.",
+                    self.name,
+                )
+
             # Start background listener
             self._listen_task = asyncio.create_task(self._listen_loop())
             self._running = True
@@ -257,13 +267,17 @@ class HomeAssistantAdapter(BasePlatformAdapter):
         if entity_id in self._ignore_entities:
             return
 
-        # Apply domain/entity watch filters
+        # Apply domain/entity watch filters (closed by default — require
+        # explicit watch_domains, watch_entities, or watch_all to forward)
         domain = entity_id.split(".")[0] if "." in entity_id else ""
         if self._watch_domains or self._watch_entities:
             domain_match = domain in self._watch_domains if self._watch_domains else False
             entity_match = entity_id in self._watch_entities if self._watch_entities else False
             if not domain_match and not entity_match:
                 return
+        elif not self._watch_all:
+            # No filters configured and watch_all is off — drop the event
+            return
 
         # Apply cooldown
         now = time.time()