feat(subagents): support per-subagent skill loading and custom subagent types (#2253)

* feat(subagents): support per-subagent skill loading and custom subagent types (#2230)

Add per-subagent skill configuration and custom subagent type registration,
aligned with Codex's role-based config layering and per-session skill injection.

Backend:
- SubagentConfig gains `skills` field (None=all, []=none, list=whitelist)
- New CustomSubagentConfig for user-defined subagent types in config.yaml
- SubagentsAppConfig gains `custom_agents` section and `get_skills_for()`
- Registry resolves custom agents with three-layer config precedence
- SubagentExecutor loads skills per-session as conversation items (Codex pattern)
- task_tool no longer appends skills to system_prompt
- Lead agent system prompt dynamically lists all registered subagent types
- setup_agent tool accepts optional skills parameter
- Gateway agents API transparently passes skills in CRUD operations

Frontend:
- Agent/CreateAgentRequest/UpdateAgentRequest types include skills field
- Agent card displays skills as badges alongside tool_groups

Config:
- config.example.yaml documents custom_agents and per-agent skills override

Tests:
- 40 new tests covering all skill config, custom agents, and registry logic
- Existing tests updated for new get_skills_prompt_section signature

Closes #2230

* fix: address review feedback on skills PR

- Remove stale get_skills_prompt_section monkeypatches from test_task_tool_core_logic.py
  (task_tool no longer imports this function after skill injection moved to executor)
- Add key prefixes (tg:/sk:) to agent-card badges to prevent React key collisions
  between tool_groups and skills

* fix(ci): resolve lint and test failures

- Format agent-card.tsx with prettier (lint-frontend)
- Remove stale "Skills Appendix" system_prompt assertion — skills are now
  loaded per-session by SubagentExecutor, not appended to system_prompt

* fix(ci): sort imports in test_subagent_skills_config.py (ruff I001)

* fix(ci): use nullish coalescing in agent-card badge condition (eslint)

* fix: address review feedback on skills PR

- Use model_fields_set in AgentUpdateRequest to distinguish "field omitted"
  from "explicitly set to null" — fixes skills=None ambiguity where None
  means "inherit all" but was treated as "don't change"
- Move lazy import of get_subagent_config outside loop in
  _build_available_subagents_description to avoid repeated import overhead

---------

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

backend/tests/test_subagent_prompt_security.py

@@ -25,7 +25,9 @@ def test_build_subagent_section_hides_bash_examples_when_unavailable(monkeypatch
 
     section = prompt_module._build_subagent_section(3)
 
-    assert "Not available in the current sandbox configuration" in section
+    # When bash is not available, it should not appear at all (aligned with Codex:
+    # unavailable roles are omitted, not listed as disabled)
+    assert "**bash**" not in section
     assert 'bash("npm test")' not in section
     assert 'read_file("/mnt/user-data/workspace/README.md")' in section
     assert "available tools (ls, read_file, web_search, etc.)" in section

backend/tests/test_subagent_skills_config.py

@@ -0,0 +1,596 @@
+"""Tests for subagent per-agent skill configuration and custom subagent types.
+
+Covers:
+- SubagentConfig.skills field
+- SubagentOverrideConfig.skills field
+- CustomSubagentConfig model validation
+- SubagentsAppConfig.custom_agents and get_skills_for()
+- Registry: custom agent lookup, skills override, merged available names
+- Skills filter passthrough in task_tool config assembly
+"""
+
+import pytest
+
+from deerflow.config.subagents_config import (
+    CustomSubagentConfig,
+    SubagentOverrideConfig,
+    SubagentsAppConfig,
+    get_subagents_app_config,
+    load_subagents_config_from_dict,
+)
+from deerflow.subagents.config import SubagentConfig
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def _reset_subagents_config(**kwargs) -> None:
+    """Reset global subagents config to a known state."""
+    load_subagents_config_from_dict(kwargs)
+
+
+# ---------------------------------------------------------------------------
+# SubagentConfig.skills field
+# ---------------------------------------------------------------------------
+
+
+class TestSubagentConfigSkills:
+    def test_default_skills_is_none(self):
+        config = SubagentConfig(name="test", description="test", system_prompt="test")
+        assert config.skills is None
+
+    def test_skills_whitelist(self):
+        config = SubagentConfig(
+            name="test",
+            description="test",
+            system_prompt="test",
+            skills=["data-analysis", "visualization"],
+        )
+        assert config.skills == ["data-analysis", "visualization"]
+
+    def test_skills_empty_list_means_no_skills(self):
+        config = SubagentConfig(
+            name="test",
+            description="test",
+            system_prompt="test",
+            skills=[],
+        )
+        assert config.skills == []
+
+
+# ---------------------------------------------------------------------------
+# SubagentOverrideConfig.skills field
+# ---------------------------------------------------------------------------
+
+
+class TestSubagentOverrideConfigSkills:
+    def test_default_skills_is_none(self):
+        override = SubagentOverrideConfig()
+        assert override.skills is None
+
+    def test_skills_whitelist(self):
+        override = SubagentOverrideConfig(skills=["web-search", "data-analysis"])
+        assert override.skills == ["web-search", "data-analysis"]
+
+    def test_skills_empty_list(self):
+        override = SubagentOverrideConfig(skills=[])
+        assert override.skills == []
+
+    def test_skills_coexists_with_other_fields(self):
+        override = SubagentOverrideConfig(
+            timeout_seconds=300,
+            model="gpt-5",
+            skills=["my-skill"],
+        )
+        assert override.timeout_seconds == 300
+        assert override.model == "gpt-5"
+        assert override.skills == ["my-skill"]
+
+
+# ---------------------------------------------------------------------------
+# CustomSubagentConfig model
+# ---------------------------------------------------------------------------
+
+
+class TestCustomSubagentConfig:
+    def test_minimal_valid(self):
+        config = CustomSubagentConfig(
+            description="A test agent",
+            system_prompt="You are a test agent.",
+        )
+        assert config.description == "A test agent"
+        assert config.system_prompt == "You are a test agent."
+        assert config.tools is None
+        assert config.disallowed_tools == ["task", "ask_clarification", "present_files"]
+        assert config.skills is None
+        assert config.model == "inherit"
+        assert config.max_turns == 50
+        assert config.timeout_seconds == 900
+
+    def test_full_configuration(self):
+        config = CustomSubagentConfig(
+            description="Data analysis specialist",
+            system_prompt="You are a data analysis subagent.",
+            tools=["bash", "read_file", "write_file"],
+            disallowed_tools=["task"],
+            skills=["data-analysis", "visualization"],
+            model="qwen3:32b",
+            max_turns=80,
+            timeout_seconds=600,
+        )
+        assert config.tools == ["bash", "read_file", "write_file"]
+        assert config.skills == ["data-analysis", "visualization"]
+        assert config.model == "qwen3:32b"
+        assert config.max_turns == 80
+        assert config.timeout_seconds == 600
+
+    def test_skills_empty_list_no_skills(self):
+        config = CustomSubagentConfig(
+            description="test",
+            system_prompt="test",
+            skills=[],
+        )
+        assert config.skills == []
+
+    def test_rejects_zero_max_turns(self):
+        with pytest.raises(ValueError):
+            CustomSubagentConfig(
+                description="test",
+                system_prompt="test",
+                max_turns=0,
+            )
+
+    def test_rejects_zero_timeout(self):
+        with pytest.raises(ValueError):
+            CustomSubagentConfig(
+                description="test",
+                system_prompt="test",
+                timeout_seconds=0,
+            )
+
+
+# ---------------------------------------------------------------------------
+# SubagentsAppConfig.custom_agents and get_skills_for()
+# ---------------------------------------------------------------------------
+
+
+class TestSubagentsAppConfigCustomAgents:
+    def test_default_custom_agents_empty(self):
+        config = SubagentsAppConfig()
+        assert config.custom_agents == {}
+
+    def test_custom_agents_loaded(self):
+        config = SubagentsAppConfig(
+            custom_agents={
+                "analysis": CustomSubagentConfig(
+                    description="Analysis agent",
+                    system_prompt="You analyze data.",
+                    skills=["data-analysis"],
+                ),
+            }
+        )
+        assert "analysis" in config.custom_agents
+        assert config.custom_agents["analysis"].skills == ["data-analysis"]
+
+    def test_multiple_custom_agents(self):
+        config = SubagentsAppConfig(
+            custom_agents={
+                "analysis": CustomSubagentConfig(
+                    description="Analysis",
+                    system_prompt="analyze",
+                    skills=["data-analysis"],
+                ),
+                "researcher": CustomSubagentConfig(
+                    description="Research",
+                    system_prompt="research",
+                    skills=["web-search"],
+                ),
+            }
+        )
+        assert len(config.custom_agents) == 2
+
+
+class TestGetSkillsFor:
+    def test_returns_none_when_no_override(self):
+        config = SubagentsAppConfig()
+        assert config.get_skills_for("general-purpose") is None
+        assert config.get_skills_for("unknown") is None
+
+    def test_returns_skills_whitelist(self):
+        config = SubagentsAppConfig(
+            agents={
+                "general-purpose": SubagentOverrideConfig(skills=["web-search", "coding"]),
+            }
+        )
+        assert config.get_skills_for("general-purpose") == ["web-search", "coding"]
+
+    def test_returns_empty_list_for_no_skills(self):
+        config = SubagentsAppConfig(
+            agents={
+                "bash": SubagentOverrideConfig(skills=[]),
+            }
+        )
+        assert config.get_skills_for("bash") == []
+
+    def test_returns_none_for_unrelated_agent(self):
+        config = SubagentsAppConfig(
+            agents={
+                "bash": SubagentOverrideConfig(skills=["web-search"]),
+            }
+        )
+        assert config.get_skills_for("general-purpose") is None
+
+    def test_returns_none_when_skills_not_set(self):
+        config = SubagentsAppConfig(
+            agents={
+                "bash": SubagentOverrideConfig(timeout_seconds=300),
+            }
+        )
+        assert config.get_skills_for("bash") is None
+
+
+# ---------------------------------------------------------------------------
+# load_subagents_config_from_dict with skills and custom_agents
+# ---------------------------------------------------------------------------
+
+
+class TestLoadSubagentsConfigWithSkills:
+    def teardown_method(self):
+        _reset_subagents_config()
+
+    def test_load_with_skills_override(self):
+        load_subagents_config_from_dict(
+            {
+                "timeout_seconds": 900,
+                "agents": {
+                    "general-purpose": {"skills": ["web-search", "data-analysis"]},
+                },
+            }
+        )
+        cfg = get_subagents_app_config()
+        assert cfg.get_skills_for("general-purpose") == ["web-search", "data-analysis"]
+
+    def test_load_with_empty_skills(self):
+        load_subagents_config_from_dict(
+            {
+                "timeout_seconds": 900,
+                "agents": {
+                    "bash": {"skills": []},
+                },
+            }
+        )
+        cfg = get_subagents_app_config()
+        assert cfg.get_skills_for("bash") == []
+
+    def test_load_with_custom_agents(self):
+        load_subagents_config_from_dict(
+            {
+                "timeout_seconds": 900,
+                "custom_agents": {
+                    "analysis": {
+                        "description": "Data analysis specialist",
+                        "system_prompt": "You are a data analysis subagent.",
+                        "skills": ["data-analysis", "visualization"],
+                        "tools": ["bash", "read_file"],
+                        "max_turns": 80,
+                        "timeout_seconds": 600,
+                    },
+                },
+            }
+        )
+        cfg = get_subagents_app_config()
+        assert "analysis" in cfg.custom_agents
+        custom = cfg.custom_agents["analysis"]
+        assert custom.skills == ["data-analysis", "visualization"]
+        assert custom.tools == ["bash", "read_file"]
+        assert custom.max_turns == 80
+        assert custom.timeout_seconds == 600
+
+    def test_load_with_both_overrides_and_custom(self):
+        load_subagents_config_from_dict(
+            {
+                "timeout_seconds": 900,
+                "agents": {
+                    "general-purpose": {"skills": ["web-search"]},
+                },
+                "custom_agents": {
+                    "analysis": {
+                        "description": "Analysis",
+                        "system_prompt": "Analyze.",
+                        "skills": ["data-analysis"],
+                    },
+                },
+            }
+        )
+        cfg = get_subagents_app_config()
+        assert cfg.get_skills_for("general-purpose") == ["web-search"]
+        assert cfg.custom_agents["analysis"].skills == ["data-analysis"]
+
+
+# ---------------------------------------------------------------------------
+# Registry: custom agent lookup
+# ---------------------------------------------------------------------------
+
+
+class TestRegistryCustomAgentLookup:
+    def teardown_method(self):
+        _reset_subagents_config()
+
+    def test_custom_agent_found(self):
+        from deerflow.subagents.registry import get_subagent_config
+
+        load_subagents_config_from_dict(
+            {
+                "custom_agents": {
+                    "analysis": {
+                        "description": "Data analysis specialist",
+                        "system_prompt": "You are a data analysis subagent.",
+                        "skills": ["data-analysis"],
+                        "tools": ["bash", "read_file"],
+                        "max_turns": 80,
+                        "timeout_seconds": 600,
+                    },
+                },
+            }
+        )
+        config = get_subagent_config("analysis")
+        assert config is not None
+        assert config.name == "analysis"
+        assert config.skills == ["data-analysis"]
+        assert config.tools == ["bash", "read_file"]
+        assert config.max_turns == 80
+        assert config.timeout_seconds == 600
+        assert config.model == "inherit"
+
+    def test_custom_agent_not_found(self):
+        from deerflow.subagents.registry import get_subagent_config
+
+        _reset_subagents_config()
+        assert get_subagent_config("nonexistent") is None
+
+    def test_builtin_takes_priority_over_custom(self):
+        """If a custom agent has the same name as a builtin, builtin wins."""
+        from deerflow.subagents.builtins import BUILTIN_SUBAGENTS
+        from deerflow.subagents.registry import get_subagent_config
+
+        load_subagents_config_from_dict(
+            {
+                "custom_agents": {
+                    "general-purpose": {
+                        "description": "Custom override attempt",
+                        "system_prompt": "Should not be used",
+                    },
+                },
+            }
+        )
+        config = get_subagent_config("general-purpose")
+        # Should get the builtin description, not the custom one
+        assert config.description == BUILTIN_SUBAGENTS["general-purpose"].description
+
+    def test_custom_agent_with_override(self):
+        """Per-agent overrides also apply to custom agents."""
+        from deerflow.subagents.registry import get_subagent_config
+
+        load_subagents_config_from_dict(
+            {
+                "custom_agents": {
+                    "analysis": {
+                        "description": "Analysis",
+                        "system_prompt": "Analyze.",
+                        "timeout_seconds": 600,
+                    },
+                },
+                "agents": {
+                    "analysis": {"timeout_seconds": 300, "skills": ["overridden-skill"]},
+                },
+            }
+        )
+        config = get_subagent_config("analysis")
+        assert config is not None
+        assert config.timeout_seconds == 300  # Override applied
+        assert config.skills == ["overridden-skill"]  # Override applied
+
+
+# ---------------------------------------------------------------------------
+# Registry: skills override on builtin agents
+# ---------------------------------------------------------------------------
+
+
+class TestRegistrySkillsOverride:
+    def teardown_method(self):
+        _reset_subagents_config()
+
+    def test_skills_override_applied_to_builtin(self):
+        from deerflow.subagents.registry import get_subagent_config
+
+        load_subagents_config_from_dict(
+            {
+                "agents": {
+                    "general-purpose": {"skills": ["web-search", "data-analysis"]},
+                },
+            }
+        )
+        config = get_subagent_config("general-purpose")
+        assert config.skills == ["web-search", "data-analysis"]
+
+    def test_empty_skills_override(self):
+        from deerflow.subagents.registry import get_subagent_config
+
+        load_subagents_config_from_dict(
+            {
+                "agents": {
+                    "bash": {"skills": []},
+                },
+            }
+        )
+        config = get_subagent_config("bash")
+        assert config.skills == []
+
+    def test_no_skills_override_keeps_default(self):
+        from deerflow.subagents.registry import get_subagent_config
+
+        _reset_subagents_config()
+        config = get_subagent_config("general-purpose")
+        assert config.skills is None  # Default: inherit all
+
+    def test_skills_override_does_not_mutate_builtin(self):
+        from deerflow.subagents.builtins import BUILTIN_SUBAGENTS
+        from deerflow.subagents.registry import get_subagent_config
+
+        load_subagents_config_from_dict(
+            {
+                "agents": {
+                    "general-purpose": {"skills": ["web-search"]},
+                },
+            }
+        )
+        _ = get_subagent_config("general-purpose")
+        assert BUILTIN_SUBAGENTS["general-purpose"].skills is None
+
+
+# ---------------------------------------------------------------------------
+# Registry: get_available_subagent_names merges custom types
+# ---------------------------------------------------------------------------
+
+
+class TestRegistryAvailableNames:
+    def teardown_method(self):
+        _reset_subagents_config()
+
+    def test_includes_builtin_names(self):
+        from deerflow.subagents.registry import get_subagent_names
+
+        _reset_subagents_config()
+        names = get_subagent_names()
+        assert "general-purpose" in names
+        assert "bash" in names
+
+    def test_includes_custom_names(self):
+        from deerflow.subagents.registry import get_subagent_names
+
+        load_subagents_config_from_dict(
+            {
+                "custom_agents": {
+                    "analysis": {
+                        "description": "Analysis",
+                        "system_prompt": "Analyze.",
+                    },
+                    "researcher": {
+                        "description": "Research",
+                        "system_prompt": "Research.",
+                    },
+                },
+            }
+        )
+        names = get_subagent_names()
+        assert "general-purpose" in names
+        assert "bash" in names
+        assert "analysis" in names
+        assert "researcher" in names
+
+    def test_no_duplicates_when_custom_name_matches_builtin(self):
+        from deerflow.subagents.registry import get_subagent_names
+
+        load_subagents_config_from_dict(
+            {
+                "custom_agents": {
+                    "general-purpose": {
+                        "description": "Duplicate name",
+                        "system_prompt": "test",
+                    },
+                },
+            }
+        )
+        names = get_subagent_names()
+        assert names.count("general-purpose") == 1
+
+
+# ---------------------------------------------------------------------------
+# Registry: list_subagents includes custom agents
+# ---------------------------------------------------------------------------
+
+
+class TestRegistryListSubagentsWithCustom:
+    def teardown_method(self):
+        _reset_subagents_config()
+
+    def test_list_includes_custom_agents(self):
+        from deerflow.subagents.registry import list_subagents
+
+        load_subagents_config_from_dict(
+            {
+                "custom_agents": {
+                    "analysis": {
+                        "description": "Analysis",
+                        "system_prompt": "Analyze.",
+                        "skills": ["data-analysis"],
+                    },
+                },
+            }
+        )
+        configs = list_subagents()
+        names = {c.name for c in configs}
+        assert "general-purpose" in names
+        assert "bash" in names
+        assert "analysis" in names
+
+    def test_list_custom_agent_has_correct_skills(self):
+        from deerflow.subagents.registry import list_subagents
+
+        load_subagents_config_from_dict(
+            {
+                "custom_agents": {
+                    "analysis": {
+                        "description": "Analysis",
+                        "system_prompt": "Analyze.",
+                        "skills": ["data-analysis", "visualization"],
+                    },
+                },
+            }
+        )
+        by_name = {c.name: c for c in list_subagents()}
+        assert by_name["analysis"].skills == ["data-analysis", "visualization"]
+
+
+# ---------------------------------------------------------------------------
+# Skills filter passthrough: verify config.skills is used in task_tool assembly
+# ---------------------------------------------------------------------------
+
+
+class TestSkillsFilterPassthrough:
+    """Test that SubagentConfig.skills is correctly passed to get_skills_prompt_section."""
+
+    def test_none_skills_passes_none_to_prompt(self):
+        """When config.skills is None, available_skills=None should be passed (inherit all)."""
+        config = SubagentConfig(
+            name="test",
+            description="test",
+            system_prompt="test",
+            skills=None,
+        )
+        # Verify: set(None) would raise, so the code must check for None first
+        available = set(config.skills) if config.skills is not None else None
+        assert available is None
+
+    def test_empty_skills_passes_empty_set(self):
+        """When config.skills is [], available_skills=set() should be passed (no skills)."""
+        config = SubagentConfig(
+            name="test",
+            description="test",
+            system_prompt="test",
+            skills=[],
+        )
+        available = set(config.skills) if config.skills is not None else None
+        assert available == set()
+
+    def test_skills_whitelist_passes_correct_set(self):
+        """When config.skills has values, those should be passed as available_skills."""
+        config = SubagentConfig(
+            name="test",
+            description="test",
+            system_prompt="test",
+            skills=["data-analysis", "web-search"],
+        )
+        available = set(config.skills) if config.skills is not None else None
+        assert available == {"data-analysis", "web-search"}

backend/tests/test_task_tool_core_logic.py

@@ -143,7 +143,7 @@ def test_task_tool_emits_running_and_completed_events(monkeypatch):
     monkeypatch.setattr(task_tool_module, "SubagentStatus", FakeSubagentStatus)
     monkeypatch.setattr(task_tool_module, "SubagentExecutor", DummyExecutor)
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "Skills Appendix")
+
     monkeypatch.setattr(task_tool_module, "get_background_task_result", lambda _: next(responses))
     monkeypatch.setattr(task_tool_module, "get_stream_writer", lambda: events.append)
     monkeypatch.setattr(task_tool_module.asyncio, "sleep", _no_sleep)
@@ -165,7 +165,9 @@ def test_task_tool_emits_running_and_completed_events(monkeypatch):
     assert captured["executor_kwargs"]["thread_id"] == "thread-1"
     assert captured["executor_kwargs"]["parent_model"] == "ark-model"
     assert captured["executor_kwargs"]["config"].max_turns == 7
-    assert "Skills Appendix" in captured["executor_kwargs"]["config"].system_prompt
+    # Skills are no longer appended to system_prompt; they are loaded per-session
+    # by SubagentExecutor and injected as conversation items (Codex pattern).
+    assert captured["executor_kwargs"]["config"].system_prompt == "Base system prompt"
 
     get_available_tools.assert_called_once_with(model_name="ark-model", groups=None, subagent_enabled=False)
 
@@ -311,7 +313,7 @@ def test_task_tool_runtime_none_passes_groups_none(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -345,7 +347,7 @@ def test_task_tool_returns_timed_out_message(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -381,7 +383,7 @@ def test_task_tool_polling_safety_timeout(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -417,7 +419,7 @@ def test_cleanup_called_on_completed(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -457,7 +459,7 @@ def test_cleanup_called_on_failed(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -497,7 +499,7 @@ def test_cleanup_called_on_timed_out(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -544,7 +546,7 @@ def test_cleanup_not_called_on_polling_safety_timeout(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -597,7 +599,7 @@ def test_cleanup_scheduled_on_cancellation(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(task_tool_module, "get_background_task_result", get_result)
     monkeypatch.setattr(task_tool_module, "get_stream_writer", lambda: events.append)
     monkeypatch.setattr(task_tool_module.asyncio, "sleep", cancel_on_first_sleep)
@@ -648,7 +650,7 @@ def test_cancelled_cleanup_stops_after_timeout(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -703,7 +705,7 @@ def test_cancellation_calls_request_cancel(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(
         task_tool_module,
         "get_background_task_result",
@@ -761,7 +763,7 @@ def test_task_tool_returns_cancelled_message(monkeypatch):
         type("DummyExecutor", (), {"__init__": lambda self, **kwargs: None, "execute_async": lambda self, prompt, task_id=None: task_id}),
     )
     monkeypatch.setattr(task_tool_module, "get_subagent_config", lambda _: config)
-    monkeypatch.setattr(task_tool_module, "get_skills_prompt_section", lambda: "")
+
     monkeypatch.setattr(task_tool_module, "get_background_task_result", lambda _: next(responses))
     monkeypatch.setattr(task_tool_module, "get_stream_writer", lambda: events.append)
     monkeypatch.setattr(task_tool_module.asyncio, "sleep", _no_sleep)