fix(agent): file-io path guidance in agent prompts (#2019)

* fix(prompt): guide workspace-relative file io

* Clarify bash agent file IO path guidance

backend/tests/test_lead_agent_prompt.py

@@ -50,6 +50,24 @@ def test_apply_prompt_template_includes_custom_mounts(monkeypatch):
     assert "Custom Mounted Directories" in prompt
 
 
+def test_apply_prompt_template_includes_relative_path_guidance(monkeypatch):
+    config = SimpleNamespace(
+        sandbox=SimpleNamespace(mounts=[]),
+        skills=SimpleNamespace(container_path="/mnt/skills"),
+    )
+    monkeypatch.setattr("deerflow.config.get_app_config", lambda: config)
+    monkeypatch.setattr(prompt_module, "_get_enabled_skills", lambda: [])
+    monkeypatch.setattr(prompt_module, "get_deferred_tools_prompt_section", lambda: "")
+    monkeypatch.setattr(prompt_module, "_build_acp_section", lambda: "")
+    monkeypatch.setattr(prompt_module, "_get_memory_context", lambda agent_name=None: "")
+    monkeypatch.setattr(prompt_module, "get_agent_soul", lambda agent_name=None: "")
+
+    prompt = prompt_module.apply_prompt_template()
+
+    assert "Treat `/mnt/user-data/workspace` as your default current working directory" in prompt
+    assert "`hello.txt`, `../uploads/data.csv`, and `../outputs/report.md`" in prompt
+
+
 def test_refresh_skills_system_prompt_cache_async_reloads_immediately(monkeypatch, tmp_path):
     def make_skill(name: str) -> Skill:
         skill_dir = tmp_path / name

backend/tests/test_subagent_prompt_security.py

@@ -39,3 +39,17 @@ def test_build_subagent_section_includes_bash_when_available(monkeypatch) -> Non
     assert "For command execution (git, build, test, deploy operations)" in section
     assert 'bash("npm test")' in section
     assert "available tools (bash, ls, read_file, web_search, etc.)" in section
+
+
+def test_bash_subagent_prompt_mentions_workspace_relative_paths() -> None:
+    from deerflow.subagents.builtins.bash_agent import BASH_AGENT_CONFIG
+
+    assert "Treat `/mnt/user-data/workspace` as the default working directory for file IO" in BASH_AGENT_CONFIG.system_prompt
+    assert "`hello.txt`, `../uploads/input.csv`, and `../outputs/result.md`" in BASH_AGENT_CONFIG.system_prompt
+
+
+def test_general_purpose_subagent_prompt_mentions_workspace_relative_paths() -> None:
+    from deerflow.subagents.builtins.general_purpose import GENERAL_PURPOSE_CONFIG
+
+    assert "Treat `/mnt/user-data/workspace` as the default working directory for coding and file IO" in GENERAL_PURPOSE_CONFIG.system_prompt
+    assert "`hello.txt`, `../uploads/input.csv`, and `../outputs/result.md`" in GENERAL_PURPOSE_CONFIG.system_prompt