diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..644c3f7
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,34 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["3.10", "3.11", "3.12"]
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install package with dev dependencies
+        run: pip install -e ".[dev]"
+
+      - name: Lint with ruff
+        run: ruff check .
+
+      - name: Test with pytest
+        run: pytest tests/ -v
+        env:
+          MPLBACKEND: Agg  # headless — no display server in CI
diff --git a/.gitignore b/.gitignore
index aa807b4..4265008 100644
--- a/.gitignore
+++ b/.gitignore
@@ -46,3 +46,6 @@ MANIFEST
 
 # Jupyter
 .ipynb_checkpoints/
+
+# ruff
+.ruff_cache/
diff --git a/examples/01_imu_ekf_basic.py b/examples/01_imu_ekf_basic.py
index cb83380..e44ee3e 100644
--- a/examples/01_imu_ekf_basic.py
+++ b/examples/01_imu_ekf_basic.py
@@ -5,15 +5,15 @@
 and runs the 10-state EKF to fuse accel/gyro/mag data.
 """
 
-import numpy as np
 import matplotlib.pyplot as plt
+import numpy as np
 
-from drones_sim.trajectory import generate_hover_accel_cruise
+from drones_sim.estimation import ExtendedKalmanFilter
+from drones_sim.models import load_drone_urdf
 from drones_sim.sensors import IMUSimulator
 from drones_sim.sensors.imu import IMUConfig
-from drones_sim.estimation import ExtendedKalmanFilter
+from drones_sim.trajectory import generate_hover_accel_cruise
 from drones_sim.visualization.plots import plot_ekf_results
-from drones_sim.models import load_drone_urdf
 
 
 def main():
@@ -21,7 +21,7 @@ def main():
     urdf_model = load_drone_urdf()
     print(urdf_model)
     print(f"  Total mass : {urdf_model.total_mass:.3f} kg")
-    print(f"  Links      : {[l.name for l in urdf_model.links]}")
+    print(f"  Links      : {[link.name for link in urdf_model.links]}")
     print(f"  Joints     : {[j.name for j in urdf_model.joints]}")
 
     # 1. Generate trajectory
@@ -56,7 +56,7 @@ def main():
         filt_quat[i] = state["quaternion"]
 
     # 4. Plot
-    fig = plot_ekf_results(
+    plot_ekf_results(
         traj.t,
         traj.position, traj.velocity, traj.orientation_quat,
         filt_pos, filt_vel, filt_quat,
diff --git a/examples/02_ekf_adaptive.py b/examples/02_ekf_adaptive.py
index 9139a48..fdc937f 100644
--- a/examples/02_ekf_adaptive.py
+++ b/examples/02_ekf_adaptive.py
@@ -5,15 +5,15 @@
 sensor models.
 """
 
-import numpy as np
 import matplotlib.pyplot as plt
+import numpy as np
 
-from drones_sim.trajectory import generate_hover_accel_cruise
+from drones_sim.estimation.ekf import AdaptiveEKF
+from drones_sim.models import load_drone_urdf
 from drones_sim.sensors import IMUSimulator
 from drones_sim.sensors.imu import IMUConfig
-from drones_sim.estimation.ekf import AdaptiveEKF
+from drones_sim.trajectory import generate_hover_accel_cruise
 from drones_sim.visualization.plots import plot_ekf_results
-from drones_sim.models import load_drone_urdf
 
 
 def main():
@@ -21,7 +21,7 @@ def main():
     urdf_model = load_drone_urdf()
     print(urdf_model)
     print(f"  Total mass : {urdf_model.total_mass:.3f} kg")
-    print(f"  Links      : {[l.name for l in urdf_model.links]}")
+    print(f"  Links      : {[link.name for link in urdf_model.links]}")
     print(f"  Joints     : {[j.name for j in urdf_model.joints]}")
 
     # 1. Trajectory
@@ -62,7 +62,7 @@ def main():
         filt_quat[i] = state["quaternion"]
 
     # 4. Plot
-    fig = plot_ekf_results(
+    plot_ekf_results(
         traj.t,
         traj.position, traj.velocity, traj.orientation_quat,
         filt_pos, filt_vel, filt_quat,
diff --git a/examples/03_waypoint_nav.py b/examples/03_waypoint_nav.py
index 9a2189a..92c05bf 100644
--- a/examples/03_waypoint_nav.py
+++ b/examples/03_waypoint_nav.py
@@ -6,14 +6,14 @@
 acceleration, and jerk) rather than a step-function target jump.
 """
 
-import numpy as np
 import matplotlib.pyplot as plt
+import numpy as np
 
-from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.control import QuadcopterController
+from drones_sim.dynamics import QuadcopterDynamics
+from drones_sim.models import load_drone_urdf
 from drones_sim.trajectory import generate_minimum_snap
 from drones_sim.visualization.plots import plot_quadcopter_results
-from drones_sim.models import load_drone_urdf
 
 
 def main():
@@ -21,7 +21,7 @@ def main():
     urdf_model = load_drone_urdf()
     print(urdf_model)
     print(f"  Total mass : {urdf_model.total_mass:.3f} kg")
-    print(f"  Links      : {[l.name for l in urdf_model.links]}")
+    print(f"  Links      : {[link.name for link in urdf_model.links]}")
     print(f"  Joints     : {[j.name for j in urdf_model.joints]}")
 
     quad = QuadcopterDynamics()
diff --git a/examples/04_viser_viewer.py b/examples/04_viser_viewer.py
index 179f4c1..6a44a7e 100644
--- a/examples/04_viser_viewer.py
+++ b/examples/04_viser_viewer.py
@@ -7,11 +7,11 @@
 
 import numpy as np
 
-from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.control import QuadcopterController
+from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.math_utils import euler_to_rotation_matrix
-from drones_sim.visualization.viewer import DroneViewer
 from drones_sim.models import load_drone_urdf
+from drones_sim.visualization.viewer import DroneViewer
 
 
 def main():
diff --git a/examples/05_full_pipeline.py b/examples/05_full_pipeline.py
index 3402c4d..cd7d5f2 100644
--- a/examples/05_full_pipeline.py
+++ b/examples/05_full_pipeline.py
@@ -10,21 +10,21 @@
 """
 
 import os
-import numpy as np
+
 import matplotlib.pyplot as plt
+import numpy as np
 
-from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.control.pid import PIDController
-from drones_sim.sensors.models import SensorNoiseModel
-from drones_sim.sensors import GPSSimulator, GPSConfig
+from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.estimation import ExtendedKalmanFilter
 from drones_sim.math_utils import (
     euler_to_rotation_matrix,
-    quat_from_euler,
     quat_to_rotation_matrix,
 )
-from drones_sim.visualization.viewer import DroneViewer
 from drones_sim.models import load_drone_urdf
+from drones_sim.sensors import GPSConfig, GPSSimulator
+from drones_sim.sensors.models import SensorNoiseModel
+from drones_sim.visualization.viewer import DroneViewer
 
 
 def main():
@@ -107,7 +107,7 @@ def main():
         # Accelerometer measures specific force = R^T * (a_linear - g_world)
         # which in hover (a_linear ≈ 0) is just R^T * g (the reaction to gravity).
         # We approximate linear accel from the previous dynamics step.
-        lin_accel_world = np.array([0.0, 0.0, quad.g]) - np.array(
+        np.array([0.0, 0.0, quad.g]) - np.array(
             [0.0, 0.0, quad.g]
         )
         # Proper: rotate net force / mass back to body frame as specific force
diff --git a/examples/06_trajectory_following.py b/examples/06_trajectory_following.py
index 33094a1..52cd095 100644
--- a/examples/06_trajectory_following.py
+++ b/examples/06_trajectory_following.py
@@ -29,15 +29,15 @@
 
 import numpy as np
 
-from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.control import QuadcopterController
-from drones_sim.sensors.models import SensorNoiseModel
-from drones_sim.sensors import GPSSimulator, GPSConfig
+from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.estimation import ExtendedKalmanFilter
-from drones_sim.trajectory import generate_circular, generate_minimum_snap
 from drones_sim.math_utils import euler_to_rotation_matrix
-from drones_sim.visualization.viewer import DroneViewer
 from drones_sim.models import load_drone_urdf
+from drones_sim.sensors import GPSConfig, GPSSimulator
+from drones_sim.sensors.models import SensorNoiseModel
+from drones_sim.trajectory import generate_circular, generate_minimum_snap
+from drones_sim.visualization.viewer import DroneViewer
 
 # ---------------------------------------------------------------------------
 # Module-level constants
diff --git a/pyproject.toml b/pyproject.toml
index b7f56d6..10da453 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -20,5 +20,20 @@ dev = ["pytest>=7.0", "ruff"]
 [tool.setuptools.packages.find]
 where = ["src"]
 
+[tool.ruff]
+line-length = 100
+target-version = "py310"
+src = ["src", "tests", "examples"]
+extend-exclude = [".venv"]
+
+[tool.ruff.lint]
+select = ["E", "F", "W", "I", "UP"]
+ignore = ["E501"]   # long lines — not worth a mass reformat
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+addopts = "-q"
+markers = ["slow: marks tests as slow (deselect with '-m \"not slow\"')"]
+
 [tool.setuptools.package-data]
 "drones_sim.models" = ["*.urdf"]
diff --git a/src/drones_sim/control/__init__.py b/src/drones_sim/control/__init__.py
index ac4dd85..d731a62 100644
--- a/src/drones_sim/control/__init__.py
+++ b/src/drones_sim/control/__init__.py
@@ -1,3 +1,3 @@
-from .pid import PIDController
-from .cascaded import QuadcopterController
-from .lqr import LQRController
+from .cascaded import QuadcopterController  # noqa: F401
+from .lqr import LQRController  # noqa: F401
+from .pid import PIDController  # noqa: F401
diff --git a/src/drones_sim/dynamics/__init__.py b/src/drones_sim/dynamics/__init__.py
index 5dc14cc..67e9607 100644
--- a/src/drones_sim/dynamics/__init__.py
+++ b/src/drones_sim/dynamics/__init__.py
@@ -1 +1 @@
-from .quadcopter import QuadcopterDynamics
+from .quadcopter import QuadcopterDynamics  # noqa: F401
diff --git a/src/drones_sim/dynamics/quadcopter.py b/src/drones_sim/dynamics/quadcopter.py
index 7dc6375..ea861c0 100644
--- a/src/drones_sim/dynamics/quadcopter.py
+++ b/src/drones_sim/dynamics/quadcopter.py
@@ -36,11 +36,11 @@
 from numpy.typing import NDArray
 
 from ..math_utils import (
+    quat_derivative,
     quat_from_euler,
     quat_normalize,
     quat_to_euler,
     quat_to_rotation_matrix,
-    quat_derivative,
 )
 
 
diff --git a/src/drones_sim/estimation/__init__.py b/src/drones_sim/estimation/__init__.py
index 61accf6..9fc3040 100644
--- a/src/drones_sim/estimation/__init__.py
+++ b/src/drones_sim/estimation/__init__.py
@@ -1,2 +1,2 @@
-from .ekf import ExtendedKalmanFilter
-from .ahrs import AHRS
+from .ahrs import AHRS  # noqa: F401
+from .ekf import ExtendedKalmanFilter  # noqa: F401
diff --git a/src/drones_sim/estimation/ahrs.py b/src/drones_sim/estimation/ahrs.py
index 5c1d3fc..24810f7 100644
--- a/src/drones_sim/estimation/ahrs.py
+++ b/src/drones_sim/estimation/ahrs.py
@@ -9,7 +9,7 @@
 import numpy as np
 from numpy.typing import NDArray
 
-from ..math_utils import quat_normalize, quat_multiply, quat_to_rotation_matrix
+from ..math_utils import quat_normalize, quat_to_rotation_matrix
 
 
 class AHRS:
diff --git a/src/drones_sim/estimation/ekf.py b/src/drones_sim/estimation/ekf.py
index 9509789..685567c 100644
--- a/src/drones_sim/estimation/ekf.py
+++ b/src/drones_sim/estimation/ekf.py
@@ -19,14 +19,13 @@
 from numpy.typing import NDArray
 
 from ..math_utils import (
-    quat_derivative,
     quat_angular_velocity_jacobian,
+    quat_derivative,
     quat_normalize,
     quat_to_rotation_matrix,
 )
 from .ahrs import AHRS
 
-
 # ---------------------------------------------------------------------------
 # Full-state EKF (10-state) — from imu_ekf_simulation.py
 # ---------------------------------------------------------------------------
@@ -482,8 +481,8 @@ def correct(self, accel: NDArray, adaptive_factor: float = 1.0) -> None:
         self.x += K @ innovation
 
         # Joseph form for numerical stability
-        I = np.eye(self.n)
-        IKH = I - K @ H
+        I_mat = np.eye(self.n)
+        IKH = I_mat - K @ H
         self.P = IKH @ self.P @ IKH.T + K @ self.R_accel @ K.T
 
     # -- state access ------------------------------------------------------
diff --git a/src/drones_sim/math_utils.py b/src/drones_sim/math_utils.py
index 2ce7252..135f5cc 100644
--- a/src/drones_sim/math_utils.py
+++ b/src/drones_sim/math_utils.py
@@ -10,7 +10,6 @@
 import numpy as np
 from numpy.typing import NDArray
 
-
 # ---------------------------------------------------------------------------
 # Quaternion operations
 # ---------------------------------------------------------------------------
diff --git a/src/drones_sim/models/urdf_loader.py b/src/drones_sim/models/urdf_loader.py
index 23f2ace..9a193e4 100644
--- a/src/drones_sim/models/urdf_loader.py
+++ b/src/drones_sim/models/urdf_loader.py
@@ -15,7 +15,6 @@
 import numpy as np
 from numpy.typing import NDArray
 
-
 # ---------------------------------------------------------------------------
 # Data structures
 # ---------------------------------------------------------------------------
@@ -83,7 +82,7 @@ class DroneURDFModel:
     total_inertia: NDArray = field(default_factory=lambda: np.zeros((3, 3)))
 
     def __repr__(self) -> str:
-        link_names = [l.name for l in self.links]
+        link_names = [link.name for link in self.links]
         return (
             f"DroneURDFModel(name={self.name!r}, "
             f"links={link_names}, "
@@ -275,8 +274,8 @@ def load_drone_urdf(urdf_path: str | Path | None = None) -> DroneURDFModel:
         model.joints.append(joint)
 
     # --- aggregates ---
-    model.total_mass = sum(l.mass for l in model.links)
-    model.total_inertia = sum(l.inertia for l in model.links)  # type: ignore[assignment]
+    model.total_mass = sum(link.mass for link in model.links)
+    model.total_inertia = sum(link.inertia for link in model.links)  # type: ignore[assignment]
 
     return model
 
diff --git a/src/drones_sim/sensors/__init__.py b/src/drones_sim/sensors/__init__.py
index 66eab5a..a8ee66d 100644
--- a/src/drones_sim/sensors/__init__.py
+++ b/src/drones_sim/sensors/__init__.py
@@ -1,3 +1,3 @@
-from .imu import IMUSimulator
-from .models import SensorNoiseModel, TemperatureModel
-from .gps import GPSSimulator, GPSConfig, GPSData
+from .gps import GPSConfig, GPSData, GPSSimulator  # noqa: F401
+from .imu import IMUSimulator  # noqa: F401
+from .models import SensorNoiseModel, TemperatureModel  # noqa: F401
diff --git a/src/drones_sim/sensors/gps.py b/src/drones_sim/sensors/gps.py
index ed5d401..10d8a67 100644
--- a/src/drones_sim/sensors/gps.py
+++ b/src/drones_sim/sensors/gps.py
@@ -14,8 +14,7 @@
 
 from __future__ import annotations
 
-from dataclasses import dataclass, field
-from typing import Optional
+from dataclasses import dataclass
 
 import numpy as np
 from numpy.typing import NDArray
diff --git a/src/drones_sim/sensors/imu.py b/src/drones_sim/sensors/imu.py
index c32d3b9..1f287fe 100644
--- a/src/drones_sim/sensors/imu.py
+++ b/src/drones_sim/sensors/imu.py
@@ -7,7 +7,6 @@
 from __future__ import annotations
 
 from dataclasses import dataclass, field
-from typing import Optional
 
 import numpy as np
 from numpy.typing import NDArray
@@ -46,7 +45,7 @@ class IMUData:
     accel: NDArray          # (N, 3)
     gyro: NDArray           # (N, 3)
     mag: NDArray            # (N, 3)
-    temperature: Optional[NDArray] = None  # (N,) if temperature model enabled
+    temperature: NDArray | None = None  # (N,) if temperature model enabled
 
     # Ground-truth biases for validation
     accel_bias: NDArray = field(default_factory=lambda: np.zeros(3))
diff --git a/src/drones_sim/trajectory.py b/src/drones_sim/trajectory.py
index a07e9c2..d48ecdf 100644
--- a/src/drones_sim/trajectory.py
+++ b/src/drones_sim/trajectory.py
@@ -6,13 +6,13 @@
 
 from __future__ import annotations
 
-from dataclasses import dataclass, field
+from dataclasses import dataclass
 from math import factorial
-from typing import Literal
 
 import numpy as np
+from numpy.polynomial.polynomial import polyder
+from numpy.polynomial.polynomial import polyval as polyval1d
 from numpy.typing import NDArray
-from numpy.polynomial.polynomial import polyval as polyval1d, polyder
 from scipy.linalg import lstsq
 from scipy.spatial.transform import Rotation as R
 
diff --git a/src/drones_sim/visualization/__init__.py b/src/drones_sim/visualization/__init__.py
index 4ba01df..330e5bd 100644
--- a/src/drones_sim/visualization/__init__.py
+++ b/src/drones_sim/visualization/__init__.py
@@ -1,2 +1,2 @@
-from .plots import plot_ekf_results, plot_quadcopter_results
-from .viewer import DroneViewer
+from .plots import plot_ekf_results, plot_quadcopter_results  # noqa: F401
+from .viewer import DroneViewer  # noqa: F401
diff --git a/src/drones_sim/visualization/plots.py b/src/drones_sim/visualization/plots.py
index 15a6ab7..392bffd 100644
--- a/src/drones_sim/visualization/plots.py
+++ b/src/drones_sim/visualization/plots.py
@@ -2,9 +2,9 @@
 
 from __future__ import annotations
 
+import matplotlib.pyplot as plt
 import numpy as np
 from numpy.typing import NDArray
-import matplotlib.pyplot as plt
 
 
 def plot_ekf_results(
@@ -32,8 +32,6 @@ def plot_ekf_results(
 
     labels = ["X", "Y", "Z"]
     colors = ["blue", "green", "red"]
-    styles_true = ["-", "-", "-"]
-    styles_filt = ["--", "--", "--"]
 
     # Position
     ax = axes[0, 0]
@@ -133,8 +131,8 @@ def plot_quadcopter_results(
 
     # Position vs time
     ax2 = fig.add_subplot(2, 3, 2)
-    for j, (c, l) in enumerate(zip(["r", "g", "b"], ["X", "Y", "Z"])):
-        ax2.plot(t, position[:, j], f"{c}-", label=l)
+    for j, (c, label) in enumerate(zip(["r", "g", "b"], ["X", "Y", "Z"])):
+        ax2.plot(t, position[:, j], f"{c}-", label=label)
         ax2.plot(t, target_position[:, j], f"{c}--", alpha=0.5)
     ax2.set_xlabel("Time (s)")
     ax2.set_ylabel("Position (m)")
@@ -144,8 +142,8 @@ def plot_quadcopter_results(
 
     # Attitude
     ax3 = fig.add_subplot(2, 3, 3)
-    for j, (c, l) in enumerate(zip(["r", "g", "b"], ["Roll", "Pitch", "Yaw"])):
-        ax3.plot(t, np.rad2deg(attitude[:, j]), f"{c}-", label=l)
+    for j, (c, label) in enumerate(zip(["r", "g", "b"], ["Roll", "Pitch", "Yaw"])):
+        ax3.plot(t, np.rad2deg(attitude[:, j]), f"{c}-", label=label)
     ax3.set_xlabel("Time (s)")
     ax3.set_ylabel("Angle (deg)")
     ax3.set_title("Attitude vs Time")
@@ -165,8 +163,8 @@ def plot_quadcopter_results(
     # Position error
     ax5 = fig.add_subplot(2, 3, 5)
     err = target_position - position
-    for j, (c, l) in enumerate(zip(["r", "g", "b"], ["X", "Y", "Z"])):
-        ax5.plot(t, err[:, j], f"{c}-", label=f"{l} Error")
+    for j, (c, label) in enumerate(zip(["r", "g", "b"], ["X", "Y", "Z"])):
+        ax5.plot(t, err[:, j], f"{c}-", label=f"{label} Error")
     ax5.set_xlabel("Time (s)")
     ax5.set_ylabel("Error (m)")
     ax5.set_title("Position Error vs Time")
diff --git a/src/drones_sim/visualization/viewer.py b/src/drones_sim/visualization/viewer.py
index 83c0b16..32875ed 100644
--- a/src/drones_sim/visualization/viewer.py
+++ b/src/drones_sim/visualization/viewer.py
@@ -295,8 +295,9 @@ def playback(
         if reference_positions is not None:
             _errors = np.linalg.norm(positions - reference_positions, axis=1)
             import io
-            import matplotlib.figure
+
             import matplotlib.backends.backend_agg as _agg
+            import matplotlib.figure
 
             def _render_error_plot(idx: int) -> NDArray:
                 fig = matplotlib.figure.Figure(figsize=(4, 1.9))
diff --git a/tests/test_cascaded.py b/tests/test_cascaded.py
index f0d9aa0..6674287 100644
--- a/tests/test_cascaded.py
+++ b/tests/test_cascaded.py
@@ -6,8 +6,8 @@
 from drones_sim.control import QuadcopterController
 from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.estimation import ExtendedKalmanFilter
-from drones_sim.sensors.models import SensorNoiseModel
 from drones_sim.math_utils import euler_to_rotation_matrix
+from drones_sim.sensors.models import SensorNoiseModel
 
 
 def _simulate_targets(
@@ -83,7 +83,7 @@ def test_ekf_position_error_bounded(seed):
     With GPS σ=0.5 m the theoretical floor is well below 2 m; a regression that
     re-introduces any of the six historical bugs will exceed this threshold.
     """
-    rng = np.random.default_rng(seed)
+    np.random.default_rng(seed)
     quad = QuadcopterDynamics()
     dt   = 0.01
     gravity = np.array([0.0, 0.0, 9.81])
diff --git a/tests/test_dynamics.py b/tests/test_dynamics.py
index 3aaf52d..2dbecdf 100644
--- a/tests/test_dynamics.py
+++ b/tests/test_dynamics.py
@@ -1,7 +1,6 @@
 """Tests for quadcopter dynamics."""
 
 import numpy as np
-import pytest
 
 from drones_sim.dynamics import QuadcopterDynamics
 
diff --git a/tests/test_dynamics_quaternion.py b/tests/test_dynamics_quaternion.py
index 07d5bfe..5fe2ce0 100644
--- a/tests/test_dynamics_quaternion.py
+++ b/tests/test_dynamics_quaternion.py
@@ -6,17 +6,14 @@
 """
 
 import numpy as np
-import pytest
 
 from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.math_utils import (
     quat_from_euler,
     quat_normalize,
-    quat_to_euler,
     quat_to_rotation_matrix,
 )
 
-
 # ---------------------------------------------------------------------------
 # Numerical stability
 # ---------------------------------------------------------------------------
diff --git a/tests/test_ekf.py b/tests/test_ekf.py
index d7c07f4..942eaf1 100644
--- a/tests/test_ekf.py
+++ b/tests/test_ekf.py
@@ -4,8 +4,7 @@
 import pytest
 
 from drones_sim.estimation.ekf import ExtendedKalmanFilter
-from drones_sim.math_utils import quat_to_rotation_matrix, quat_normalize
-
+from drones_sim.math_utils import quat_normalize, quat_to_rotation_matrix
 
 # ---------------------------------------------------------------------------
 # Helpers
diff --git a/tests/test_gps.py b/tests/test_gps.py
index 9cf4543..53877a6 100644
--- a/tests/test_gps.py
+++ b/tests/test_gps.py
@@ -3,9 +3,9 @@
 import numpy as np
 import pytest
 
-from drones_sim.sensors.gps import GPSSimulator, GPSConfig, GPSData
-from drones_sim.trajectory import generate_hover_accel_cruise
 from drones_sim.estimation import ExtendedKalmanFilter
+from drones_sim.sensors.gps import GPSConfig, GPSSimulator
+from drones_sim.trajectory import generate_hover_accel_cruise
 
 
 @pytest.fixture
@@ -85,7 +85,7 @@ def test_ekf_gps_fusion_reduces_position_error(traj):
 
     dt = float(np.mean(np.diff(traj.t)))
     gps_dt = 1.0 / 5.0
-    gps_steps = max(1, int(round(gps_dt / dt)))
+    max(1, int(round(gps_dt / dt)))
 
     # EKF without GPS
     ekf_no_gps = ExtendedKalmanFilter(dt=dt)
diff --git a/tests/test_lqr.py b/tests/test_lqr.py
index 3aac90f..a08867d 100644
--- a/tests/test_lqr.py
+++ b/tests/test_lqr.py
@@ -1,7 +1,6 @@
 """Tests for the LQR controller."""
 
 import numpy as np
-import pytest
 
 from drones_sim.control import LQRController
 from drones_sim.dynamics import QuadcopterDynamics
diff --git a/tests/test_math_utils.py b/tests/test_math_utils.py
index 63c28ca..6b897b0 100644
--- a/tests/test_math_utils.py
+++ b/tests/test_math_utils.py
@@ -1,17 +1,16 @@
 """Tests for math_utils quaternion operations."""
 
 import numpy as np
-import pytest
 
 from drones_sim.math_utils import (
-    quat_normalize,
-    quat_multiply,
+    euler_to_rotation_matrix,
     quat_conjugate,
-    quat_to_rotation_matrix,
+    quat_derivative,
     quat_from_euler,
+    quat_multiply,
+    quat_normalize,
     quat_to_euler,
-    quat_derivative,
-    euler_to_rotation_matrix,
+    quat_to_rotation_matrix,
 )
 
 
diff --git a/tests/test_pid.py b/tests/test_pid.py
index 957b4f4..8f23f46 100644
--- a/tests/test_pid.py
+++ b/tests/test_pid.py
@@ -1,7 +1,6 @@
 """Tests for PID controller."""
 
 import numpy as np
-import pytest
 
 from drones_sim.control.pid import PIDController
 
diff --git a/tests/test_sensor_models.py b/tests/test_sensor_models.py
index b81b0f9..03ddddb 100644
--- a/tests/test_sensor_models.py
+++ b/tests/test_sensor_models.py
@@ -9,6 +9,7 @@
 
 from drones_sim.dynamics import QuadcopterDynamics
 from drones_sim.math_utils import euler_to_rotation_matrix
+from drones_sim.sensors.models import SensorNoiseModel
 
 
 def test_hover_specific_force_magnitude_equals_g():
@@ -62,8 +63,6 @@ def test_accel_simulation_includes_dynamics():
 # Gauss-Markov bias random walk tests
 # ---------------------------------------------------------------------------
 
-from drones_sim.sensors.models import SensorNoiseModel
-
 
 def test_bias_constant_when_gauss_markov_disabled():
     """Default infinite time constant means the bias never changes."""
diff --git a/tests/test_trajectory.py b/tests/test_trajectory.py
index 94c8293..a007019 100644
--- a/tests/test_trajectory.py
+++ b/tests/test_trajectory.py
@@ -4,11 +4,10 @@
 import pytest
 
 from drones_sim.trajectory import (
-    generate_minimum_snap,
     TrajectoryData,
+    generate_minimum_snap,
 )
 
-
 # ---------------------------------------------------------------------------
 # Minimum-snap tests
 # ---------------------------------------------------------------------------