Replace load_skill tool with read_file extra_allowed_dirs for builtin skills access

Instead of adding a separate load_skill tool to bypass workspace restrictions,
extend ReadFileTool with extra_allowed_dirs so it can read builtin skill paths
while keeping write/edit tools locked to the workspace. Fixes the original issue
for both main agent and subagents.

Made-with: Cursor

nanobot/agent/subagent.py

@@ -8,6 +8,7 @@ from typing import Any
 
 from loguru import logger
 
+from nanobot.agent.skills import BUILTIN_SKILLS_DIR
 from nanobot.agent.tools.filesystem import EditFileTool, ListDirTool, ReadFileTool, WriteFileTool
 from nanobot.agent.tools.registry import ToolRegistry
 from nanobot.agent.tools.shell import ExecTool
@@ -92,7 +93,8 @@ class SubagentManager:
             # Build subagent tools (no message tool, no spawn tool)
             tools = ToolRegistry()
             allowed_dir = self.workspace if self.restrict_to_workspace else None
-            tools.register(ReadFileTool(workspace=self.workspace, allowed_dir=allowed_dir))
+            extra_read = [BUILTIN_SKILLS_DIR] if allowed_dir else None
+            tools.register(ReadFileTool(workspace=self.workspace, allowed_dir=allowed_dir, extra_allowed_dirs=extra_read))
             tools.register(WriteFileTool(workspace=self.workspace, allowed_dir=allowed_dir))
             tools.register(EditFileTool(workspace=self.workspace, allowed_dir=allowed_dir))
             tools.register(ListDirTool(workspace=self.workspace, allowed_dir=allowed_dir))
@@ -213,7 +215,7 @@ Stay focused on the assigned task. Your final response will be reported back to
 
         skills_summary = SkillsLoader(self.workspace).build_skills_summary()
         if skills_summary:
-            parts.append(f"## Skills\n\nUse load_skill tool to load a skill by name.\n\n{skills_summary}")
+            parts.append(f"## Skills\n\nRead SKILL.md with read_file to use a skill.\n\n{skills_summary}")
 
         return "\n\n".join(parts)