fix(gateway): Pass session_db to AIAgent, fixing session_search error

When running via the gateway (e.g. Telegram), the session_search tool
returned: {"error": "session_search must be handled by the agent loop"}

Root cause:
- gateway/run.py creates AIAgent without passing session_db=
- self._session_db is None in the agent instance
- The dispatch condition "elif function_name == 'session_search' and self._session_db"
  skips when _session_db is None, falling through to the generic error

This fix:
1. Initializes self._session_db in GatewayRunner.__init__()
2. Passes session_db to all AIAgent instantiations in gateway/run.py
3. Adds defensive fallback in run_agent.py to return a clear error when
   session_db is unavailable, instead of falling through

Fixes #105

gateway/run.py

@@ -149,6 +149,14 @@ class GatewayRunner:
         # Key: session_key, Value: {"command": str, "pattern_key": str}
         self._pending_approvals: Dict[str, Dict[str, str]] = {}
         
+        # Initialize session database for session_search tool support
+        self._session_db = None
+        try:
+            from hermes_state import SessionDB
+            self._session_db = SessionDB()
+        except Exception as e:
+            logger.debug("SQLite session store not available: %s", e)
+        
     def _flush_memories_before_reset(self, old_entry):
         """Prompt the agent to save memories/skills before an auto-reset.
         
@@ -177,6 +185,7 @@ class GatewayRunner:
                 quiet_mode=True,
                 enabled_toolsets=["memory", "skills"],
                 session_id=old_entry.session_id,
+                session_db=self._session_db,
             )
 
             # Build conversation history from transcript
@@ -862,6 +871,7 @@ class GatewayRunner:
                     _flush_api_key = os.getenv("OPENAI_API_KEY") or os.getenv("OPENROUTER_API_KEY", "")
                     _flush_base_url = os.getenv("OPENAI_BASE_URL") or os.getenv("OPENROUTER_BASE_URL", "https://openrouter.ai/api/v1")
                     _flush_model = os.getenv("HERMES_MODEL") or os.getenv("LLM_MODEL", "anthropic/claude-opus-4.6")
+                    _flush_session_db = self._session_db
                     def _do_flush():
                         tmp_agent = AIAgent(
                             model=_flush_model,
@@ -871,6 +881,7 @@ class GatewayRunner:
                             quiet_mode=True,
                             enabled_toolsets=["memory"],
                             session_id=old_entry.session_id,
+                            session_db=_flush_session_db,
                         )
                         # Build simple message list from transcript
                         msgs = []
@@ -1530,6 +1541,7 @@ class GatewayRunner:
                 session_id=session_id,
                 tool_progress_callback=progress_callback if tool_progress_enabled else None,
                 platform=platform_key,
+                session_db=self._session_db,
             )
             
             # Store agent reference for interrupt support

run_agent.py

@@ -1467,14 +1467,17 @@ class AIAgent:
                 tool_duration = time.time() - tool_start_time
                 if self.quiet_mode:
                     print(f"  {_get_cute_tool_message_impl('todo', function_args, tool_duration, result=function_result)}")
-            elif function_name == "session_search" and self._session_db:
-                from tools.session_search_tool import session_search as _session_search
-                function_result = _session_search(
-                    query=function_args.get("query", ""),
-                    role_filter=function_args.get("role_filter"),
-                    limit=function_args.get("limit", 3),
-                    db=self._session_db,
-                )
+            elif function_name == "session_search":
+                if not self._session_db:
+                    function_result = json.dumps({"success": False, "error": "Session database not available."})
+                else:
+                    from tools.session_search_tool import session_search as _session_search
+                    function_result = _session_search(
+                        query=function_args.get("query", ""),
+                        role_filter=function_args.get("role_filter"),
+                        limit=function_args.get("limit", 3),
+                        db=self._session_db,
+                    )
                 tool_duration = time.time() - tool_start_time
                 if self.quiet_mode:
                     print(f"  {_get_cute_tool_message_impl('session_search', function_args, tool_duration, result=function_result)}")