diff --git a/.github/workflows/python.yml b/.github/workflows/python.yml
index 982dca875..3d55aaf74 100644
--- a/.github/workflows/python.yml
+++ b/.github/workflows/python.yml
@@ -5,13 +5,13 @@ permissions:
 
 on:
   push:
-    branches: [ 'main' ]
+    branches: ["main"]
     paths:
-      - 'python/**'
+      - "python/**"
   pull_request:
-    branches: [ '*' ]
+    branches: ["*"]
     paths:
-      - 'python/**'
+      - "python/**"
 
 jobs:
   lint:
@@ -21,16 +21,16 @@ jobs:
         working-directory: ./python
 
     steps:
-    - uses: actions/checkout@v4
+      - uses: actions/checkout@v4
 
-    - name: Install Ruff
-      uses: astral-sh/ruff-action@v3
+      - name: Install Ruff
+        uses: astral-sh/ruff-action@v3
 
-    - name: Ruff Format
-      run: ruff format --check --config ./pyproject.toml .
+      - name: Ruff Format
+        run: ruff format --check --config ./pyproject.toml .
 
-    - name: Ruff Lint
-      run: ruff check --config ./pyproject.toml .
+      - name: Ruff Lint
+        run: ruff check --config ./pyproject.toml .
 
   unit_test:
     runs-on: ubuntu-latest
@@ -39,19 +39,24 @@ jobs:
         working-directory: ./python
 
     steps:
-    - uses: actions/checkout@v4
+      - uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
 
-    - name: Set up Python
-      uses: actions/setup-python@v4
-      with:
-        python-version-file: "./python/pyproject.toml"
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version-file: "./python/pyproject.toml"
 
-    - name: Install uv
-      uses: astral-sh/setup-uv@v6
+      - name: Install uv
+        uses: astral-sh/setup-uv@v6
 
-    - name: Install the project
-      run: uv sync --locked --all-extras --dev
+      - name: Install the project
+        run: uv sync --locked --all-extras --dev
 
-    - name: Run tests
-      run: uv run pytest
+      - name: Run tests
+        run: uv run pytest valuecell/core/ --cov=valuecell.core --cov-report=xml --cov-report=term
 
+      - name: Check coverage
+        run: |
+          uv run diff-cover coverage.xml --fail-under=90
diff --git a/python/pyproject.toml b/python/pyproject.toml
index c96f87b94..72213c125 100644
--- a/python/pyproject.toml
+++ b/python/pyproject.toml
@@ -31,6 +31,7 @@ dev = [
     "pytest>=7.4.0",
     "pytest-cov>=4.1.0",
     "pytest-asyncio>=1.0.0",
+    "diff-cover>=9.0.0",
 ]
 
 [dependency-groups]
@@ -45,6 +46,7 @@ test = [
     "pytest>=7.4.0",
     "pytest-cov>=4.1.0",
     "pytest-asyncio>=1.0.0",
+    "diff-cover>=9.0.0",
 ]
 
 [tool.ruff]
diff --git a/python/uv.lock b/python/uv.lock
index 95e6de56f..d7ac00e44 100644
--- a/python/uv.lock
+++ b/python/uv.lock
@@ -297,6 +297,15 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/7c/fc/6a8cb64e5f0324877d503c854da15d76c1e50eb722e320b15345c4d0c6de/cffi-1.17.1-cp313-cp313-win_amd64.whl", hash = "sha256:f6a16c31041f09ead72d69f583767292f750d24913dadacf5756b966aacb3f1a", size = 182009, upload-time = "2024-09-04T20:44:45.309Z" },
 ]
 
+[[package]]
+name = "chardet"
+version = "5.2.0"
+source = { registry = "https://pypi.org/simple" }
+sdist = { url = "https://files.pythonhosted.org/packages/f3/0d/f7b6ab21ec75897ed80c17d79b15951a719226b9fababf1e40ea74d69079/chardet-5.2.0.tar.gz", hash = "sha256:1b3b6ff479a8c414bc3fa2c0852995695c4a026dcd6d0633b2dd092ca39c1cf7", size = 2069618, upload-time = "2023-08-01T19:23:02.662Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/38/6f/f5fbc992a329ee4e0f288c1fe0e2ad9485ed064cac731ed2fe47dcc38cbf/chardet-5.2.0-py3-none-any.whl", hash = "sha256:e1cf59446890a00105fe7b7912492ea04b6e6f06d4b742b2c788469e34c82970", size = 199385, upload-time = "2023-08-01T19:23:00.661Z" },
+]
+
 [[package]]
 name = "charset-normalizer"
 version = "3.4.3"
@@ -454,6 +463,21 @@ wheels = [
     { url = "https://files.pythonhosted.org/packages/4e/8c/f3147f5c4b73e7550fe5f9352eaa956ae838d5c51eb58e7a25b9f3e2643b/decorator-5.2.1-py3-none-any.whl", hash = "sha256:d316bb415a2d9e2d2b3abcc4084c6502fc09240e292cd76a76afc106a1c8e04a", size = 9190, upload-time = "2025-02-24T04:41:32.565Z" },
 ]
 
+[[package]]
+name = "diff-cover"
+version = "9.7.1"
+source = { registry = "https://pypi.org/simple" }
+dependencies = [
+    { name = "chardet" },
+    { name = "jinja2" },
+    { name = "pluggy" },
+    { name = "pygments" },
+]
+sdist = { url = "https://files.pythonhosted.org/packages/eb/b7/3124f2038eb9d2842665c109d4516110e3e5570615243ee1065fdc65ac7d/diff_cover-9.7.1.tar.gz", hash = "sha256:a03b78bc64b7dc27dda7f11c46bc6d44f4e121c8fb9a5068d41f20a05d463548", size = 100366, upload-time = "2025-09-26T01:02:43.81Z" }
+wheels = [
+    { url = "https://files.pythonhosted.org/packages/1d/c2/36d747a14dd3834af7e2f4f86daf8d6e21762ffbdb2b177a5bb3be8f0e8f/diff_cover-9.7.1-py3-none-any.whl", hash = "sha256:a662f3cacf57ba494dcb0235349c4912ae7f44345b162894ce5949745501c9c7", size = 56008, upload-time = "2025-09-26T01:02:42.399Z" },
+]
+
 [[package]]
 name = "distro"
 version = "1.9.0"
@@ -2122,6 +2146,7 @@ dependencies = [
 
 [package.optional-dependencies]
 dev = [
+    { name = "diff-cover" },
     { name = "pytest" },
     { name = "pytest-asyncio" },
     { name = "pytest-cov" },
@@ -2130,6 +2155,7 @@ dev = [
 
 [package.dev-dependencies]
 dev = [
+    { name = "diff-cover" },
     { name = "pytest" },
     { name = "pytest-asyncio" },
     { name = "pytest-cov" },
@@ -2139,6 +2165,7 @@ lint = [
     { name = "ruff" },
 ]
 test = [
+    { name = "diff-cover" },
     { name = "pytest" },
     { name = "pytest-asyncio" },
     { name = "pytest-cov" },
@@ -2150,6 +2177,7 @@ requires-dist = [
     { name = "agno", extras = ["openai"], specifier = ">=1.8.2,<2.0" },
     { name = "aiosqlite", specifier = ">=0.19.0" },
     { name = "akshare", specifier = ">=1.17.44" },
+    { name = "diff-cover", marker = "extra == 'dev'", specifier = ">=9.0.0" },
     { name = "edgartools", specifier = ">=4.12.2" },
     { name = "fastapi", specifier = ">=0.104.0" },
     { name = "pydantic", specifier = ">=2.0.0" },
@@ -2169,6 +2197,7 @@ provides-extras = ["dev"]
 
 [package.metadata.requires-dev]
 dev = [
+    { name = "diff-cover", specifier = ">=9.0.0" },
     { name = "pytest", specifier = ">=7.4.0" },
     { name = "pytest-asyncio", specifier = ">=1.0.0" },
     { name = "pytest-cov", specifier = ">=4.1.0" },
@@ -2176,6 +2205,7 @@ dev = [
 ]
 lint = [{ name = "ruff" }]
 test = [
+    { name = "diff-cover", specifier = ">=9.0.0" },
     { name = "pytest", specifier = ">=7.4.0" },
     { name = "pytest-asyncio", specifier = ">=1.0.0" },
     { name = "pytest-cov", specifier = ">=4.1.0" },