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

tests/test_filesystem_tools.py

@@ -251,3 +251,114 @@ class TestListDirTool:
         result = await tool.execute(path=str(tmp_path / "nope"))
         assert "Error" in result
         assert "not found" in result
+
+
+# ---------------------------------------------------------------------------
+# Workspace restriction + extra_allowed_dirs
+# ---------------------------------------------------------------------------
+
+class TestWorkspaceRestriction:
+
+    @pytest.mark.asyncio
+    async def test_read_blocked_outside_workspace(self, tmp_path):
+        workspace = tmp_path / "ws"
+        workspace.mkdir()
+        outside = tmp_path / "outside"
+        outside.mkdir()
+        secret = outside / "secret.txt"
+        secret.write_text("top secret")
+
+        tool = ReadFileTool(workspace=workspace, allowed_dir=workspace)
+        result = await tool.execute(path=str(secret))
+        assert "Error" in result
+        assert "outside" in result.lower()
+
+    @pytest.mark.asyncio
+    async def test_read_allowed_with_extra_dir(self, tmp_path):
+        workspace = tmp_path / "ws"
+        workspace.mkdir()
+        skills_dir = tmp_path / "skills"
+        skills_dir.mkdir()
+        skill_file = skills_dir / "test_skill" / "SKILL.md"
+        skill_file.parent.mkdir()
+        skill_file.write_text("# Test Skill\nDo something.")
+
+        tool = ReadFileTool(
+            workspace=workspace, allowed_dir=workspace,
+            extra_allowed_dirs=[skills_dir],
+        )
+        result = await tool.execute(path=str(skill_file))
+        assert "Test Skill" in result
+        assert "Error" not in result
+
+    @pytest.mark.asyncio
+    async def test_extra_dirs_does_not_widen_write(self, tmp_path):
+        from nanobot.agent.tools.filesystem import WriteFileTool
+
+        workspace = tmp_path / "ws"
+        workspace.mkdir()
+        outside = tmp_path / "outside"
+        outside.mkdir()
+
+        tool = WriteFileTool(workspace=workspace, allowed_dir=workspace)
+        result = await tool.execute(path=str(outside / "hack.txt"), content="pwned")
+        assert "Error" in result
+        assert "outside" in result.lower()
+
+    @pytest.mark.asyncio
+    async def test_read_still_blocked_for_unrelated_dir(self, tmp_path):
+        workspace = tmp_path / "ws"
+        workspace.mkdir()
+        skills_dir = tmp_path / "skills"
+        skills_dir.mkdir()
+        unrelated = tmp_path / "other"
+        unrelated.mkdir()
+        secret = unrelated / "secret.txt"
+        secret.write_text("nope")
+
+        tool = ReadFileTool(
+            workspace=workspace, allowed_dir=workspace,
+            extra_allowed_dirs=[skills_dir],
+        )
+        result = await tool.execute(path=str(secret))
+        assert "Error" in result
+        assert "outside" in result.lower()
+
+    @pytest.mark.asyncio
+    async def test_workspace_file_still_readable_with_extra_dirs(self, tmp_path):
+        """Adding extra_allowed_dirs must not break normal workspace reads."""
+        workspace = tmp_path / "ws"
+        workspace.mkdir()
+        ws_file = workspace / "README.md"
+        ws_file.write_text("hello from workspace")
+        skills_dir = tmp_path / "skills"
+        skills_dir.mkdir()
+
+        tool = ReadFileTool(
+            workspace=workspace, allowed_dir=workspace,
+            extra_allowed_dirs=[skills_dir],
+        )
+        result = await tool.execute(path=str(ws_file))
+        assert "hello from workspace" in result
+        assert "Error" not in result
+
+    @pytest.mark.asyncio
+    async def test_edit_blocked_in_extra_dir(self, tmp_path):
+        """edit_file must not be able to modify files in extra_allowed_dirs."""
+        workspace = tmp_path / "ws"
+        workspace.mkdir()
+        skills_dir = tmp_path / "skills"
+        skills_dir.mkdir()
+        skill_file = skills_dir / "weather" / "SKILL.md"
+        skill_file.parent.mkdir()
+        skill_file.write_text("# Weather\nOriginal content.")
+
+        tool = EditFileTool(workspace=workspace, allowed_dir=workspace)
+        result = await tool.execute(
+            path=str(skill_file),
+            old_text="Original content.",
+            new_text="Hacked content.",
+        )
+        assert "Error" in result
+        assert "outside" in result.lower()
+        assert skill_file.read_text() == "# Weather\nOriginal content."