refactor: Fix code quality issues identified in analysis

1. Rename factory.py's EvoAgent data class to AgentConfig
   - Avoids naming conflict with base/evo_agent.py's EvoAgent

2. Export pipeline_runner functions in backend/core/__init__.py
   - Add create_agents, create_long_term_memory, stop_gateway

3. Consolidate PromptLoader to singleton pattern
   - Add get_prompt_loader() singleton function
   - Update all usages to use singleton

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/agents/factory.py

@@ -1,5 +1,5 @@
 # -*- coding: utf-8 -*-
-"""Agent Factory - Dynamic creation and management of EvoAgents."""
+"""Agent Factory - Dynamic creation and management of AgentConfigs."""
 
 import logging
 import shutil
@@ -37,8 +37,8 @@ class RoleConfig:
             self.constraints = []
 
 
-class EvoAgent:
-    """Represents a configured agent instance."""
+class AgentConfig:
+    """Represents a configured agent instance (data class)."""
 
     def __init__(
         self,
@@ -185,7 +185,7 @@ class AgentFactory:
         model_config: Optional[ModelConfig] = None,
         role_config: Optional[RoleConfig] = None,
         clone_from: Optional[str] = None,
-    ) -> EvoAgent:
+    ) -> AgentConfig:
         """Create a new agent.
 
         Args:
@@ -197,7 +197,7 @@ class AgentFactory:
             clone_from: Path to existing agent to clone from (optional)
 
         Returns:
-            EvoAgent instance
+            AgentConfig instance
 
         Raises:
             ValueError: If agent already exists or workspace doesn't exist
@@ -234,7 +234,7 @@ class AgentFactory:
         config_path = agent_dir / "agent.yaml"
         self._write_agent_yaml(config_path, agent_id, agent_type, model_config)
 
-        return EvoAgent(
+        return AgentConfig(
             agent_id=agent_id,
             agent_type=agent_type,
             workspace_id=workspace_id,
@@ -267,7 +267,7 @@ class AgentFactory:
         new_agent_id: str,
         target_workspace_id: Optional[str] = None,
         model_config: Optional[ModelConfig] = None,
-    ) -> EvoAgent:
+    ) -> AgentConfig:
         """Clone an existing agent.
 
         Args:
@@ -278,7 +278,7 @@ class AgentFactory:
             model_config: Optional new model configuration
 
         Returns:
-            EvoAgent instance for the cloned agent
+            AgentConfig instance for the cloned agent
         """
         target_workspace_id = target_workspace_id or source_workspace_id
         source_dir = self.workspaces_root / source_workspace_id / "agents" / source_agent_id

backend/agents/prompt_factory.py

@@ -6,10 +6,10 @@ from typing import Any, Optional
 
 from .agent_workspace import load_agent_workspace_config
 from backend.config.bootstrap_config import get_bootstrap_config_for_run
-from .prompt_loader import PromptLoader
+from .prompt_loader import get_prompt_loader
 from .skills_manager import SkillsManager
 
-_prompt_loader = PromptLoader()
+_prompt_loader = get_prompt_loader()
 
 
 def _read_file_if_exists(path: Path) -> str:

backend/agents/prompt_loader.py

@@ -10,6 +10,17 @@ from typing import Any, Dict, Optional
 
 import yaml
 
+# Singleton instance
+_prompt_loader_instance: Optional["PromptLoader"] = None
+
+
+def get_prompt_loader() -> "PromptLoader":
+    """Get the singleton PromptLoader instance."""
+    global _prompt_loader_instance
+    if _prompt_loader_instance is None:
+        _prompt_loader_instance = PromptLoader()
+    return _prompt_loader_instance
+
 
 class PromptLoader:
     """Unified Prompt loader"""