diff --git a/test/qlib/test_knowledge_graph.py b/test/qlib/test_knowledge_graph.py
new file mode 100644
index 00000000..edcc5938
--- /dev/null
+++ b/test/qlib/test_knowledge_graph.py
@@ -0,0 +1,112 @@
+"""Tests for knowledge graph and task_loader."""
+
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+PROJECT_ROOT = Path(__file__).parent.parent.parent
+sys.path.insert(0, str(PROJECT_ROOT))
+
+
+class TestUndirectedNode:
+    def test_init(self):
+        from rdagent.components.knowledge_management.graph import UndirectedNode
+        n = UndirectedNode(content="test", label="component")
+        assert n.content == "test"
+        assert n.label == "component"
+        assert n.id is not None
+        assert isinstance(n.neighbors, set)
+        assert len(n.neighbors) == 0
+
+    def test_add_neighbor_bidirectional(self):
+        from rdagent.components.knowledge_management.graph import UndirectedNode
+        a = UndirectedNode(content="a")
+        b = UndirectedNode(content="b")
+        a.add_neighbor(b)
+        assert b in a.neighbors
+        assert a in b.neighbors
+
+    def test_remove_neighbor(self):
+        from rdagent.components.knowledge_management.graph import UndirectedNode
+        a = UndirectedNode(content="a")
+        b = UndirectedNode(content="b")
+        a.add_neighbor(b)
+        a.remove_neighbor(b)
+        assert b not in a.neighbors
+        assert a not in b.neighbors
+
+    def test_remove_nonexistent_noop(self):
+        from rdagent.components.knowledge_management.graph import UndirectedNode
+        a = UndirectedNode(content="a")
+        b = UndirectedNode(content="b")
+        a.remove_neighbor(b)  # should not raise
+
+    def test_get_neighbors(self):
+        from rdagent.components.knowledge_management.graph import UndirectedNode
+        a = UndirectedNode(content="a")
+        b = UndirectedNode(content="b")
+        c = UndirectedNode(content="c")
+        a.add_neighbor(b)
+        a.add_neighbor(c)
+        assert a.get_neighbors() == {b, c}
+
+    def test_rejects_non_string_content(self):
+        from rdagent.components.knowledge_management.graph import UndirectedNode
+        with pytest.raises(TypeError, match="string"):
+            UndirectedNode(content=123)
+
+    def test_string_representation(self):
+        from rdagent.components.knowledge_management.graph import UndirectedNode
+        n = UndirectedNode(content="hello", label="test")
+        s = str(n)
+        assert "UndirectedNode" in s
+        assert "hello" in s
+        assert "test" in s
+
+
+class TestGraphBase:
+    def test_init_empty(self):
+        from rdagent.components.knowledge_management.graph import Graph
+        g = Graph()
+        assert g.size() == 0
+        assert g.get_all_nodes() == []
+
+    def test_get_node_nonexistent(self):
+        from rdagent.components.knowledge_management.graph import Graph
+        g = Graph()
+        assert g.get_node("nonexistent") is None
+
+    def test_get_all_nodes_by_label_list(self, tmp_path):
+        from rdagent.components.knowledge_management.graph import Graph, UndirectedNode
+        g = Graph()
+
+        # Add nodes directly to internal dict
+        n1 = UndirectedNode(content="a", label="component")
+        n2 = UndirectedNode(content="b", label="error")
+        n3 = UndirectedNode(content="c", label="component")
+        g.nodes[n1.id] = n1
+        g.nodes[n2.id] = n2
+        g.nodes[n3.id] = n3
+
+        components = g.get_all_nodes_by_label_list(["component"])
+        assert len(components) == 2
+        labels = [n.label for n in components]
+        assert all(l == "component" for l in labels)
+
+
+class TestVectorBase:
+    def test_cosine_distance_identical_is_zero(self):
+        from rdagent.components.knowledge_management.vector_base import cosine
+        import numpy as np
+        dist = cosine(np.array([1.0, 0.0]), np.array([1.0, 0.0]))
+        assert dist == pytest.approx(0.0)  # cosine distance, not similarity
+
+    def test_cosine_distance_orthogonal(self):
+        from rdagent.components.knowledge_management.vector_base import cosine
+        import numpy as np
+        dist = cosine(np.array([1.0, 0.0]), np.array([0.0, 1.0]))
+        assert dist == pytest.approx(1.0)
diff --git a/test/qlib/test_remaining.py b/test/qlib/test_remaining.py
new file mode 100644
index 00000000..1c74ec40
--- /dev/null
+++ b/test/qlib/test_remaining.py
@@ -0,0 +1,253 @@
+"""Tests for remaining untested modules: conf, knowledge_base, interactor, utils/fmt, llm_utils, experiment utils."""
+
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+PROJECT_ROOT = Path(__file__).parent.parent.parent
+sys.path.insert(0, str(PROJECT_ROOT))
+
+
+# =============================================================================
+# RDAgentSettings (core/conf.py)
+# =============================================================================
+
+
+class TestRDAgentSettings:
+    def test_defaults(self):
+        from rdagent.core.conf import RDAgentSettings
+        s = RDAgentSettings()
+        assert s.multi_proc_n == 1
+        assert s.cache_with_pickle is True
+        assert s.use_file_lock is True
+        assert s.enable_mlflow is False
+        assert s.step_semaphore == 1
+        assert s.subproc_step is False
+
+    def test_get_max_parallel_int(self):
+        from rdagent.core.conf import RDAgentSettings
+        s = RDAgentSettings()
+        s.step_semaphore = 5
+        assert s.get_max_parallel() == 5
+
+    def test_get_max_parallel_dict(self):
+        from rdagent.core.conf import RDAgentSettings
+        s = RDAgentSettings()
+        s.step_semaphore = {"coding": 3, "running": 2}
+        assert s.get_max_parallel() == 3
+
+    def test_is_force_subproc_subproc_step(self):
+        from rdagent.core.conf import RDAgentSettings
+        s = RDAgentSettings()
+        s.subproc_step = True
+        assert s.is_force_subproc() is True
+
+    def test_is_force_subproc_parallel(self):
+        from rdagent.core.conf import RDAgentSettings
+        s = RDAgentSettings()
+        s.subproc_step = False
+        s.step_semaphore = 4
+        assert s.is_force_subproc() is True
+
+    def test_singleton(self):
+        from rdagent.core.conf import RD_AGENT_SETTINGS, RDAgentSettings
+        assert isinstance(RD_AGENT_SETTINGS, RDAgentSettings)
+
+    def test_workspace_path_is_path(self):
+        from rdagent.core.conf import RDAgentSettings
+        s = RDAgentSettings()
+        assert isinstance(s.workspace_path, Path)
+
+    def test_env_prefix(self, monkeypatch):
+        from rdagent.core.conf import RDAgentSettings
+        monkeypatch.setenv("multi_proc_n", "4")
+        s = RDAgentSettings()
+        assert s.multi_proc_n == 4
+
+
+# =============================================================================
+# KnowledgeBase (core/knowledge_base.py)
+# =============================================================================
+
+
+class TestKnowledgeBase:
+    def test_init_without_path(self):
+        from rdagent.core.knowledge_base import KnowledgeBase
+        kb = KnowledgeBase()
+        assert kb.path is None
+
+    def test_init_with_path(self, tmp_path):
+        from rdagent.core.knowledge_base import KnowledgeBase
+        p = tmp_path / "kb.pkl"
+        kb = KnowledgeBase(path=p)
+        assert kb.path == p
+
+    def test_dump_creates_file(self, tmp_path):
+        from rdagent.core.knowledge_base import KnowledgeBase
+        p = tmp_path / "kb.pkl"
+        kb = KnowledgeBase(path=p)
+        kb.foo = "bar"
+        kb.dump()
+        assert p.exists()
+
+    def test_load_restores_state(self, tmp_path):
+        from rdagent.core.knowledge_base import KnowledgeBase
+        p = tmp_path / "kb.pkl"
+        kb1 = KnowledgeBase(path=p)
+        kb1.foo = "hello"
+        kb1.dump()
+        kb2 = KnowledgeBase(path=p)
+        assert kb2.foo == "hello"
+
+
+# =============================================================================
+# Interactor (core/interactor.py)
+# =============================================================================
+
+
+class TestInteractor:
+    def test_abstract_class(self):
+        from rdagent.core.interactor import Interactor
+
+        class MyInteractor(Interactor):
+            def interact(self, exp, trace=None):
+                return exp
+
+        i = MyInteractor(scen=MagicMock())
+        assert i.scen is not None
+
+
+# =============================================================================
+# shrink_text (utils/fmt.py)
+# =============================================================================
+
+
+class TestShrinkText:
+    def test_short_text_unchanged(self):
+        from rdagent.utils.fmt import shrink_text
+        result = shrink_text("hello", context_lines=10, line_len=100)
+        assert result == "hello"
+
+    def test_long_lines_shrunk(self):
+        from rdagent.utils.fmt import shrink_text
+        result = shrink_text("a" * 100, context_lines=10, line_len=20)
+        assert "chars are hidden" in result
+
+    def test_many_lines_shrunk(self):
+        from rdagent.utils.fmt import shrink_text
+        text = "\n".join([f"line{i}" for i in range(100)])
+        result = shrink_text(text, context_lines=10, line_len=1000)
+        assert "lines are hidden" in result
+
+    def test_row_shrink_disabled(self):
+        from rdagent.utils.fmt import shrink_text
+        text = "\n".join([f"line{i}" for i in range(100)])
+        result = shrink_text(text, context_lines=10, line_len=1000, row_shrink=False)
+        assert "lines are hidden" not in result
+
+
+# =============================================================================
+# md5_hash (utils/__init__.py)
+# =============================================================================
+
+
+class TestMD5Hash:
+    def test_returns_string(self):
+        from rdagent.utils import md5_hash
+        h = md5_hash("hello")
+        assert isinstance(h, str)
+        assert len(h) == 64  # actually SHA-256, name is historical
+
+    def test_deterministic(self):
+        from rdagent.utils import md5_hash
+        assert md5_hash("hello") == md5_hash("hello")
+
+    def test_different_inputs(self):
+        from rdagent.utils import md5_hash
+        assert md5_hash("a") != md5_hash("b")
+
+
+# =============================================================================
+# convert2bool (utils/__init__.py)
+# =============================================================================
+
+
+class TestConvert2Bool:
+    def test_true_strings(self):
+        from rdagent.utils import convert2bool
+        for v in ("yes", "true", "True", "YES", "ok"):
+            assert convert2bool(v) is True
+
+    def test_false_strings(self):
+        from rdagent.utils import convert2bool
+        for v in ("no", "false", "False", "NO"):
+            assert convert2bool(v) is False
+
+    def test_boolean_passthrough(self):
+        from rdagent.utils import convert2bool
+        assert convert2bool(True) is True
+        assert convert2bool(False) is False
+
+    def test_invalid_raises(self):
+        from rdagent.utils import convert2bool
+        with pytest.raises(ValueError):
+            convert2bool("maybe")
+
+
+# =============================================================================
+# calculate_embedding_distance (llm_utils.py)
+# =============================================================================
+
+
+class TestEmbeddingDistance:
+    def test_empty_lists_returns_empty(self):
+        from rdagent.oai.llm_utils import calculate_embedding_distance_between_str_list
+        result = calculate_embedding_distance_between_str_list([], [])
+        assert result == [[]]
+
+    def test_one_empty_list(self):
+        from rdagent.oai.llm_utils import calculate_embedding_distance_between_str_list
+        result = calculate_embedding_distance_between_str_list(["a"], [])
+        assert result == [[]]
+
+
+# =============================================================================
+# get_file_desc (experiment/utils.py) — pure logic
+# =============================================================================
+
+
+class TestGetFileDesc:
+    def test_md_file(self, tmp_path):
+        from rdagent.scenarios.qlib.experiment.utils import get_file_desc
+        md_file = tmp_path / "test.md"
+        md_file.write_text("# Hello\ncontent")
+        desc = get_file_desc(md_file)
+        assert "Markdown Documentation" in desc
+        assert "Hello" in desc
+
+    def test_unsupported_extension_raises(self, tmp_path):
+        from rdagent.scenarios.qlib.experiment.utils import get_file_desc
+        f = tmp_path / "test.txt"
+        f.write_text("hello")
+        with pytest.raises(NotImplementedError):
+            get_file_desc(f)
+
+
+# =============================================================================
+# workflow/conf.py
+# =============================================================================
+
+
+class TestBasePropSetting:
+    def test_importable(self):
+        from rdagent.components.workflow.conf import BasePropSetting
+        assert BasePropSetting is not None
+
+    def test_has_evolving_n(self):
+        from rdagent.components.workflow.conf import BasePropSetting
+        s = BasePropSetting()
+        assert hasattr(s, "evolving_n")