diff --git a/alphatrion/experiment/base.py b/alphatrion/experiment/base.py
index 0246a98b..75fb69db 100644
--- a/alphatrion/experiment/base.py
+++ b/alphatrion/experiment/base.py
@@ -18,24 +18,30 @@ def __init__(self):
         # All trials in this experiment, key is trial_id, value is Trial instance.
         self._trials = dict()
 
+    @property
+    def id(self):
+        return self._id
+
+    def get_trial(self, id: int) -> trial.Trial | None:
+        return self._trials.get(id)
+
     def _reset(self):
         self._trials = dict()
-        self._exp = None
 
     def __enter__(self):
         if self._id is None:
-            raise RuntimeError("Experiment is not set. Did you call begin()?")
+            raise RuntimeError("Experiment is not set. Did you call run()?")
 
         exp = self._get()
         if exp is None:
             raise RuntimeError(f"Experiment {self._id} not found in the database.")
 
-        self._runtime.current_exp_uuid = exp.uuid
+        self._runtime.current_exp = self
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
         self._reset()
-        self._runtime.current_exp_uuid = None
+        self._runtime.current_exp = None
 
     @classmethod
     @abstractmethod
diff --git a/alphatrion/metadata/sql.py b/alphatrion/metadata/sql.py
index 191c8f27..63880611 100644
--- a/alphatrion/metadata/sql.py
+++ b/alphatrion/metadata/sql.py
@@ -189,12 +189,13 @@ def update_trial(self, trial_id: int, **kwargs):
             session.commit()
         session.close()
 
-    def create_metric(self, trial_id: int, key: str, value: float):
+    def create_metric(self, trial_id: int, key: str, value: float, step: int):
         session = self._session()
         new_metric = Metrics(
             trial_id=trial_id,
             key=key,
             value=value,
+            step=step,
         )
         session.add(new_metric)
         session.commit()
diff --git a/alphatrion/metadata/sql_models.py b/alphatrion/metadata/sql_models.py
index b1934829..f3df8ae4 100644
--- a/alphatrion/metadata/sql_models.py
+++ b/alphatrion/metadata/sql_models.py
@@ -88,4 +88,5 @@ class Metrics(Base):
     key = Column(String, nullable=False)
     value = Column(Float, nullable=False)
     trial_id = Column(Integer, nullable=False)
+    step = Column(Integer, nullable=False, default=0)
     created_at = Column(DateTime(timezone=True), default=datetime.now(UTC))
diff --git a/alphatrion/record/record.py b/alphatrion/record/record.py
index f15811f0..7b09038c 100644
--- a/alphatrion/record/record.py
+++ b/alphatrion/record/record.py
@@ -27,9 +27,16 @@ def log_artifact(
 
     # We use experiment ID as the repo name rather than the experiment name,
     # because experiment name is not unique
-    runtime._artifact.push(
-        repo_name=str(runtime.current_exp_uuid), paths=paths, version=version
-    )
+
+    exp = runtime.current_exp
+    if exp is None:
+        raise RuntimeError("No running experiment found in the current context.")
+
+    exp_obj = runtime._metadb.get_exp(exp.id)
+    if exp_obj is None:
+        raise RuntimeError(f"Experiment {exp.id} not found in the database.")
+
+    runtime._artifact.push(repo_name=str(exp_obj.uuid), paths=paths, version=version)
 
 
 # log_params is used to save a set of parameters, which is a dict of key-value pairs.
@@ -48,9 +55,18 @@ def log_params(params: dict):
 # metric key must be string, value must be float
 def log_metrics(metrics: dict[str, float]):
     runtime = global_runtime()
+    exp = runtime.current_exp
+
+    trial_id = current_trial_id.get()
+    trial = exp.get_trial(id=trial_id)
+    if trial is None:
+        raise RuntimeError(f"Trial {trial_id} not found in the database.")
+
+    step = trial.increment_step()
     for key, value in metrics.items():
         runtime._metadb.create_metric(
             key=key,
             value=value,
-            trial_id=current_trial_id.get(),
+            trial_id=trial.id,
+            step=step,
         )
diff --git a/alphatrion/runtime/runtime.py b/alphatrion/runtime/runtime.py
index 9ccf315a..19fd501d 100644
--- a/alphatrion/runtime/runtime.py
+++ b/alphatrion/runtime/runtime.py
@@ -29,6 +29,8 @@ def global_runtime():
 # Runtime contains all kinds of clients, e.g., metadb client, artifact client, etc.
 # Stateful information will also be stored here, e.g., current running experiment ID.
 class Runtime:
+    __slots__ = ("_project_id", "_metadb", "_artifact", "__current_exp")
+
     def __init__(self, project_id: str, artifact_insecure: bool = False):
         self._project_id = project_id
         self._metadb = SQLStore(os.getenv(consts.METADATA_DB_URL), init_tables=True)
@@ -36,15 +38,11 @@ def __init__(self, project_id: str, artifact_insecure: bool = False):
             project_id=self._project_id, insecure=artifact_insecure
         )
 
-        # Current running Experiment UUID. One experiment at a time.
-        # Set in Experiment.__enter__ and cleared in __exit__.
-        # This is for global access, e.g., log_metrics/artifacts/params
-        self.__current_exp_uuid = None
-
+    # current_exp is the current running experiment.
     @property
-    def current_exp_uuid(self):
-        return self.__current_exp_uuid
+    def current_exp(self):
+        return self.__current_exp
 
-    @current_exp_uuid.setter
-    def current_exp_uuid(self, value):
-        self.__current_exp_uuid = value
+    @current_exp.setter
+    def current_exp(self, value):
+        self.__current_exp = value
diff --git a/alphatrion/trial/trial.py b/alphatrion/trial/trial.py
index 2738e758..988048f7 100644
--- a/alphatrion/trial/trial.py
+++ b/alphatrion/trial/trial.py
@@ -79,12 +79,15 @@ class Trial:
         "_config",
         "_runtime",
         "_token",
+        "_step",
     )
 
     def __init__(self, exp_id: int, config: TrialConfig | None = None):
         self._exp_id = exp_id
         self._config = config or TrialConfig()
         self._runtime = global_runtime()
+        # step is used to track the round, e.g. the step in metric logging.
+        self._step = 0
 
     def _start(
         self,
@@ -103,6 +106,10 @@ def _start(
         self._token = current_trial_id.set(self._id)
         return self._id
 
+    @property
+    def id(self):
+        return self._id
+
     # finish function should be called manually as a pair of start
     def finish(self, status: TrialStatus = TrialStatus.FINISHED):
         trial = self._runtime._metadb.get_trial(trial_id=self._id)
@@ -119,3 +126,7 @@ def finish(self, status: TrialStatus = TrialStatus.FINISHED):
 
     def _get(self):
         return self._runtime._metadb.get_trial(trial_id=self._id)
+
+    def increment_step(self) -> int:
+        self._step += 1
+        return self._step
diff --git a/poetry.lock b/poetry.lock
index 75e12abd..c1f9000d 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -409,14 +409,14 @@ files = [
 
 [[package]]
 name = "pydantic"
-version = "2.11.8"
+version = "2.11.9"
 description = "Data validation using Python type hints"
 optional = false
 python-versions = ">=3.9"
 groups = ["main"]
 files = [
-    {file = "pydantic-2.11.8-py3-none-any.whl", hash = "sha256:830ec4cccc3cf21be1ef5aec1d3348a179c92a61a7dab0e59837f9cc9fa93351"},
-    {file = "pydantic-2.11.8.tar.gz", hash = "sha256:3d080f4a3ac6bde98e959ba552124d46be9f565b7be67769e49fcb286bae1bfb"},
+    {file = "pydantic-2.11.9-py3-none-any.whl", hash = "sha256:c42dd626f5cfc1c6950ce6205ea58c93efa406da65f479dcb4029d5934857da2"},
+    {file = "pydantic-2.11.9.tar.gz", hash = "sha256:6b8ffda597a14812a7975c90b82a8a2e777d9257aba3453f973acd3c032a18e2"},
 ]
 
 [package.dependencies]
diff --git a/tests/integration/test_log_functions.py b/tests/integration/test_log_functions.py
index 34367dd6..2abc53af 100644
--- a/tests/integration/test_log_functions.py
+++ b/tests/integration/test_log_functions.py
@@ -16,6 +16,9 @@ def test_log_artifact():
     ) as exp:
         trial = exp.start_trial(description="First trial")
 
+        exp_obj = exp._runtime._metadb.get_exp(exp_id=exp._id)
+        assert exp_obj is not None
+
         with tempfile.TemporaryDirectory() as tmpdir:
             os.chdir(tmpdir)
 
@@ -25,7 +28,7 @@ def test_log_artifact():
 
             alpha.log_artifact(paths="file1.txt", version="v1")
             versions = exp._runtime._artifact.list_versions(
-                exp._runtime.current_exp_uuid
+                exp_obj.uuid
             )
             assert "v1" in versions
 
@@ -35,15 +38,15 @@ def test_log_artifact():
             # push folder instead
             alpha.log_artifact(paths=["file1.txt"], version="v2")
             versions = exp._runtime._artifact.list_versions(
-                exp._runtime.current_exp_uuid
+                exp_obj.uuid
             )
             assert "v2" in versions
 
         exp._runtime._artifact.delete(
-            repo_name=exp._runtime.current_exp_uuid,
+            repo_name=exp_obj.uuid,
             versions=["v1", "v2"],
         )
-        versions = exp._runtime._artifact.list_versions(exp._runtime.current_exp_uuid)
+        versions = exp._runtime._artifact.list_versions(exp_obj.uuid)
         assert len(versions) == 0
 
         trial.finish()
@@ -94,13 +97,26 @@ def test_log_metrics():
         assert new_trial is not None
         assert new_trial.params == {"param1": 0.1}
 
+        metrics = exp._runtime._metadb.list_metrics(trial_id=trial._id)
+        assert len(metrics) == 0
+
         alpha.log_metrics({"accuracy": 0.95, "loss": 0.1})
 
         metrics = exp._runtime._metadb.list_metrics(trial_id=trial._id)
         assert len(metrics) == 2
         assert metrics[0].key == "accuracy"
         assert metrics[0].value == 0.95
+        assert metrics[0].step == 1
         assert metrics[1].key == "loss"
         assert metrics[1].value == 0.1
+        assert metrics[1].step == 1
+
+        alpha.log_metrics({"accuracy": 0.96})
+
+        metrics = exp._runtime._metadb.list_metrics(trial_id=trial._id)
+        assert len(metrics) == 3
+        assert metrics[2].key == "accuracy"
+        assert metrics[2].value == 0.96
+        assert metrics[2].step == 2
 
         trial.finish()
diff --git a/tests/unit/metadata/test_sql.py b/tests/unit/metadata/test_sql.py
index 296b912e..9977c76a 100644
--- a/tests/unit/metadata/test_sql.py
+++ b/tests/unit/metadata/test_sql.py
@@ -77,8 +77,8 @@ def test_update_trial(db):
 
 def test_create_metric(db):
     trial_id = db.create_trial(1, "test description", None)
-    db.create_metric(trial_id, "accuracy", 0.95)
-    db.create_metric(trial_id, "accuracy", 0.85)
+    db.create_metric(trial_id, "accuracy", 0.95, 1)
+    db.create_metric(trial_id, "accuracy", 0.85, 2)
 
     metrics = db.list_metrics(trial_id)
     assert len(metrics) == 2