fix: surface configured sandbox mounts to agents (#1638)

* fix: surface configured sandbox mounts to agents

* fix: address PR review feedback

---------

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

backend/tests/test_lead_agent_prompt.py

@@ -0,0 +1,46 @@
+from types import SimpleNamespace
+
+from deerflow.agents.lead_agent import prompt as prompt_module
+
+
+def test_build_custom_mounts_section_returns_empty_when_no_mounts(monkeypatch):
+    config = SimpleNamespace(sandbox=SimpleNamespace(mounts=[]))
+    monkeypatch.setattr("deerflow.config.get_app_config", lambda: config)
+
+    assert prompt_module._build_custom_mounts_section() == ""
+
+
+def test_build_custom_mounts_section_lists_configured_mounts(monkeypatch):
+    mounts = [
+        SimpleNamespace(container_path="/home/user/shared", read_only=False),
+        SimpleNamespace(container_path="/mnt/reference", read_only=True),
+    ]
+    config = SimpleNamespace(sandbox=SimpleNamespace(mounts=mounts))
+    monkeypatch.setattr("deerflow.config.get_app_config", lambda: config)
+
+    section = prompt_module._build_custom_mounts_section()
+
+    assert "**Custom Mounted Directories:**" in section
+    assert "`/home/user/shared`" in section
+    assert "read-write" in section
+    assert "`/mnt/reference`" in section
+    assert "read-only" in section
+
+
+def test_apply_prompt_template_includes_custom_mounts(monkeypatch):
+    mounts = [SimpleNamespace(container_path="/home/user/shared", read_only=False)]
+    config = SimpleNamespace(
+        sandbox=SimpleNamespace(mounts=mounts),
+        skills=SimpleNamespace(container_path="/mnt/skills"),
+    )
+    monkeypatch.setattr("deerflow.config.get_app_config", lambda: config)
+    monkeypatch.setattr(prompt_module, "load_skills", lambda enabled_only=True: [])
+    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 "`/home/user/shared`" in prompt
+    assert "Custom Mounted Directories" in prompt

backend/tests/test_run_manager.py

@@ -86,6 +86,18 @@ async def test_list_by_thread(manager: RunManager):
     assert runs[1].run_id == r1.run_id
 
 
+@pytest.mark.anyio
+async def test_list_by_thread_is_stable_when_timestamps_tie(manager: RunManager, monkeypatch: pytest.MonkeyPatch):
+    """Newest-first ordering should not depend on timestamp precision."""
+    monkeypatch.setattr("deerflow.runtime.runs.manager._now_iso", lambda: "2026-01-01T00:00:00+00:00")
+
+    r1 = await manager.create("thread-1")
+    r2 = await manager.create("thread-1")
+
+    runs = await manager.list_by_thread("thread-1")
+    assert [run.run_id for run in runs] == [r2.run_id, r1.run_id]
+
+
 @pytest.mark.anyio
 async def test_has_inflight(manager: RunManager):
     """has_inflight should be True when a run is pending or running."""