feat/per agent skill filter (#1650)

* feat(agent): 为AgentConfig添加skills字段并更新lead_agent系统提示

在AgentConfig中添加skills字段以支持配置agent可用技能
更新lead_agent的系统提示模板以包含可用技能信息

* fix: resolve agent skill configuration edge cases and add tests

* Update backend/packages/harness/deerflow/agents/lead_agent/prompt.py

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

* refactor(agent): address PR review comments for skills configuration

- Add detailed docstring to `skills` field in `AgentConfig` to clarify the semantics of `None` vs `[]`.
- Add unit tests in `test_custom_agent.py` to verify `load_agent_config()` correctly parses omitted skills and explicit empty lists.
- Fix `test_make_lead_agent_empty_skills_passed_correctly` to include `agent_name` in the runtime config, ensuring it exercises the real code path.

* docs: 添加关于按代理过滤技能的配置说明

在配置示例文件和文档中添加说明，解释如何通过代理的config.yaml文件限制加载的技能

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

backend/tests/test_custom_agent.py

@@ -164,6 +164,28 @@ class TestLoadAgentConfig:
 
         assert cfg.tool_groups == ["file:read", "file:write"]
 
+    def test_load_config_with_skills_empty_list(self, tmp_path):
+        config_dict = {"name": "no-skills-agent", "skills": []}
+        _write_agent(tmp_path, "no-skills-agent", config_dict)
+
+        with patch("deerflow.config.agents_config.get_paths", return_value=_make_paths(tmp_path)):
+            from deerflow.config.agents_config import load_agent_config
+
+            cfg = load_agent_config("no-skills-agent")
+
+        assert cfg.skills == []
+
+    def test_load_config_with_skills_omitted(self, tmp_path):
+        config_dict = {"name": "default-skills-agent"}
+        _write_agent(tmp_path, "default-skills-agent", config_dict)
+
+        with patch("deerflow.config.agents_config.get_paths", return_value=_make_paths(tmp_path)):
+            from deerflow.config.agents_config import load_agent_config
+
+            cfg = load_agent_config("default-skills-agent")
+
+        assert cfg.skills is None
+
     def test_legacy_prompt_file_field_ignored(self, tmp_path):
         """Unknown fields like the old prompt_file should be silently ignored."""
         agent_dir = tmp_path / "agents" / "legacy-agent"

backend/tests/test_lead_agent_skills.py

@@ -0,0 +1,96 @@
+from pathlib import Path
+
+from deerflow.agents.lead_agent.prompt import get_skills_prompt_section
+from deerflow.config.agents_config import AgentConfig
+from deerflow.skills.types import Skill
+
+
+def _make_skill(name: str) -> Skill:
+    return Skill(
+        name=name,
+        description=f"Description for {name}",
+        license="MIT",
+        skill_dir=Path(f"/tmp/{name}"),
+        skill_file=Path(f"/tmp/{name}/SKILL.md"),
+        relative_path=Path(name),
+        category="public",
+        enabled=True,
+    )
+
+
+def test_get_skills_prompt_section_returns_empty_when_no_skills_match(monkeypatch):
+    skills = [_make_skill("skill1"), _make_skill("skill2")]
+    monkeypatch.setattr("deerflow.agents.lead_agent.prompt.load_skills", lambda enabled_only: skills)
+
+    result = get_skills_prompt_section(available_skills={"non_existent_skill"})
+    assert result == ""
+
+
+def test_get_skills_prompt_section_returns_empty_when_available_skills_empty(monkeypatch):
+    skills = [_make_skill("skill1"), _make_skill("skill2")]
+    monkeypatch.setattr("deerflow.agents.lead_agent.prompt.load_skills", lambda enabled_only: skills)
+
+    result = get_skills_prompt_section(available_skills=set())
+    assert result == ""
+
+
+def test_get_skills_prompt_section_returns_skills(monkeypatch):
+    skills = [_make_skill("skill1"), _make_skill("skill2")]
+    monkeypatch.setattr("deerflow.agents.lead_agent.prompt.load_skills", lambda enabled_only: skills)
+
+    result = get_skills_prompt_section(available_skills={"skill1"})
+    assert "skill1" in result
+    assert "skill2" not in result
+
+
+def test_get_skills_prompt_section_returns_all_when_available_skills_is_none(monkeypatch):
+    skills = [_make_skill("skill1"), _make_skill("skill2")]
+    monkeypatch.setattr("deerflow.agents.lead_agent.prompt.load_skills", lambda enabled_only: skills)
+
+    result = get_skills_prompt_section(available_skills=None)
+    assert "skill1" in result
+    assert "skill2" in result
+
+
+def test_make_lead_agent_empty_skills_passed_correctly(monkeypatch):
+    from unittest.mock import MagicMock
+
+    from deerflow.agents.lead_agent import agent as lead_agent_module
+
+    # Mock dependencies
+    monkeypatch.setattr(lead_agent_module, "get_app_config", lambda: MagicMock())
+    monkeypatch.setattr(lead_agent_module, "_resolve_model_name", lambda x=None: "default-model")
+    monkeypatch.setattr(lead_agent_module, "create_chat_model", lambda **kwargs: "model")
+    monkeypatch.setattr("deerflow.tools.get_available_tools", lambda **kwargs: [])
+    monkeypatch.setattr(lead_agent_module, "_build_middlewares", lambda *args, **kwargs: [])
+    monkeypatch.setattr(lead_agent_module, "create_agent", lambda **kwargs: kwargs)
+
+    class MockModelConfig:
+        supports_thinking = False
+
+    mock_app_config = MagicMock()
+    mock_app_config.get_model_config.return_value = MockModelConfig()
+    monkeypatch.setattr(lead_agent_module, "get_app_config", lambda: mock_app_config)
+
+    captured_skills = []
+
+    def mock_apply_prompt_template(**kwargs):
+        captured_skills.append(kwargs.get("available_skills"))
+        return "mock_prompt"
+
+    monkeypatch.setattr(lead_agent_module, "apply_prompt_template", mock_apply_prompt_template)
+
+    # Case 1: Empty skills list
+    monkeypatch.setattr(lead_agent_module, "load_agent_config", lambda x: AgentConfig(name="test", skills=[]))
+    lead_agent_module.make_lead_agent({"configurable": {"agent_name": "test"}})
+    assert captured_skills[-1] == set()
+
+    # Case 2: None skills list
+    monkeypatch.setattr(lead_agent_module, "load_agent_config", lambda x: AgentConfig(name="test", skills=None))
+    lead_agent_module.make_lead_agent({"configurable": {"agent_name": "test"}})
+    assert captured_skills[-1] is None
+
+    # Case 3: Some skills list
+    monkeypatch.setattr(lead_agent_module, "load_agent_config", lambda x: AgentConfig(name="test", skills=["skill1"]))
+    lead_agent_module.make_lead_agent({"configurable": {"agent_name": "test"}})
+    assert captured_skills[-1] == {"skill1"}