feat: support sub agent mechanism

backend/src/subagents/config.py

@@ -0,0 +1,26 @@
+"""Subagent configuration definitions."""
+
+from dataclasses import dataclass, field
+
+
+@dataclass
+class SubagentConfig:
+    """Configuration for a subagent.
+
+    Attributes:
+        name: Unique identifier for the subagent.
+        description: When Claude should delegate to this subagent.
+        system_prompt: The system prompt that guides the subagent's behavior.
+        tools: Optional list of tool names to allow. If None, inherits all tools.
+        disallowed_tools: Optional list of tool names to deny.
+        model: Model to use - 'inherit' uses parent's model.
+        max_turns: Maximum number of agent turns before stopping.
+    """
+
+    name: str
+    description: str
+    system_prompt: str
+    tools: list[str] | None = None
+    disallowed_tools: list[str] | None = field(default_factory=lambda: ["task"])
+    model: str = "inherit"
+    max_turns: int = 50