fix: resolve critical architectural issues from reviewer feedback

- Fix IndexRegistry singleton broken in knowledge/index.py (P0)
- Fix sync/async unified dispatch default inconsistency
- Fix message slicing logic that drops first user message
- Add thread safety to all singleton patterns with double-checked locking
- Enhance Ollama adapter to handle both dict and list-shaped tool payloads

Addresses feedback from Greptile, Gemini, CodeRabbit, and Copilot reviewers.
Fixes remaining critical issues in architectural gap PR.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Mervin Praison <MervinPraison@users.noreply.github.com>

Author: praisonai-triage-agent[bot]

src/praisonai-agents/praisonaiagents/agent/agent.py

@@ -182,7 +182,11 @@ def __init__(self):
     def get_default_instance():
         """Get default global registry for backward compatibility."""
         if not hasattr(ServerRegistry, '_default_instance'):
-            ServerRegistry._default_instance = ServerRegistry()
+            import threading
+            # Double-checked locking pattern for thread safety
+            with threading.Lock():
+                if not hasattr(ServerRegistry, '_default_instance'):
+                    ServerRegistry._default_instance = ServerRegistry()
         return ServerRegistry._default_instance
 
     def is_server_started(self, port: int) -> bool:

src/praisonai-agents/praisonaiagents/agent/chat_mixin.py

@@ -580,9 +580,10 @@ def _chat_completion(self, messages, temperature=1.0, tools=None, stream=True, r
                     )
                 else:
                     # Non-streaming with custom LLM - direct execution
+                    has_system = bool(messages and messages[0].get('role') == 'system')
                     final_response = self.llm_instance.get_response(
-                        prompt=messages[1:],
-                        system_prompt=messages[0]['content'] if messages and messages[0]['role'] == 'system' else None,
+                        prompt=messages[1:] if has_system else messages,
+                        system_prompt=messages[0]['content'] if has_system else None,
                         temperature=temperature,
                         tools=formatted_tools if formatted_tools else None,
                         verbose=self.verbose,
@@ -1834,8 +1835,8 @@ async def _achat_impl(self, prompt, temperature, tools, output_json, output_pyda
                     formatted_tools = self._format_tools_for_completion(tools)
 
                     # NEW: Unified protocol dispatch path (Issue #1304) - Async version
-                    # Check if unified dispatch is enabled (opt-in for backward compatibility)
-                    if getattr(self, '_use_unified_llm_dispatch', False):
+                    # Enable unified dispatch by default for DRY and feature parity (sync/async consistent)
+                    if getattr(self, '_use_unified_llm_dispatch', True):
                         # Use composition instead of runtime class mutation for safety
                         response = await self._execute_unified_achat_completion(
                             messages=messages,

src/praisonai-agents/praisonaiagents/knowledge/index.py

@@ -109,7 +109,13 @@ def __init__(self):
     def default(cls) -> "IndexRegistry":
         """Get a default global registry instance for convenience."""
         if not hasattr(cls, '_default_instance'):
-            cls._default_instance = cls()
+            import threading
+            # Use lock for thread safety 
+            if not hasattr(cls, '_init_lock'):
+                cls._init_lock = threading.Lock()
+            with cls._init_lock:
+                if not hasattr(cls, '_default_instance'):
+                    cls._default_instance = cls()
         return cls._default_instance
 
     def register(self, name: str, factory: Callable[..., IndexProtocol]) -> None:
@@ -136,7 +142,7 @@ def clear(self) -> None:
 
 def get_index_registry() -> IndexRegistry:
     """Get the global index registry instance."""
-    return IndexRegistry()
+    return IndexRegistry.default()
 
 class KeywordIndex:
     """

src/praisonai-agents/praisonaiagents/llm/adapters/__init__.py

@@ -126,16 +126,24 @@ def recover_tool_calls_from_text(self, response_text: str, tools: List[Dict[str,
         try:
             import json
             response_json = json.loads(response_text.strip())
-            if isinstance(response_json, dict) and "name" in response_json:
-                # Convert Ollama format to standard tool_calls format
-                return [{
-                    "id": f"call_{response_json['name']}_{hash(response_text) % 10000}",
-                    "type": "function",
-                    "function": {
-                        "name": response_json["name"],
-                        "arguments": json.dumps(response_json.get("arguments", {}))
-                    }
-                }]
+            
+            # Normalize to list so both single and multi-tool payloads are supported
+            if isinstance(response_json, dict):
+                response_json = [response_json]
+
+            if isinstance(response_json, list):
+                tool_calls: List[Dict[str, Any]] = []
+                for idx, tool_json in enumerate(response_json):
+                    if isinstance(tool_json, dict) and "name" in tool_json:
+                        tool_calls.append({
+                            "id": f"call_{tool_json['name']}_{idx}_{hash(response_text) % 10000}",
+                            "type": "function",
+                            "function": {
+                                "name": tool_json["name"],
+                                "arguments": json.dumps(tool_json.get("arguments", {}))
+                            }
+                        })
+                return tool_calls if tool_calls else None
         except (json.JSONDecodeError, TypeError, KeyError):
             pass
 

src/praisonai-agents/praisonaiagents/memory/adapters/registry.py

@@ -37,7 +37,13 @@ def __init__(self):
 def get_default_memory_registry() -> MemoryAdapterRegistry:
     """Get the default global registry instance for convenience."""
     if not hasattr(get_default_memory_registry, '_default_instance'):
-        get_default_memory_registry._default_instance = MemoryAdapterRegistry()
+        import threading
+        # Use lock for thread safety
+        if not hasattr(get_default_memory_registry, '_init_lock'):
+            get_default_memory_registry._init_lock = threading.Lock()
+        with get_default_memory_registry._init_lock:
+            if not hasattr(get_default_memory_registry, '_default_instance'):
+                get_default_memory_registry._default_instance = MemoryAdapterRegistry()
     return get_default_memory_registry._default_instance