diff --git a/.gitea/workflows/test.yml b/.gitea/workflows/test.yml
new file mode 100644
index 0000000..354dc8d
--- /dev/null
+++ b/.gitea/workflows/test.yml
@@ -0,0 +1,30 @@
+name: CI
+
+on:
+  push:
+    branches: [master]
+  pull_request:
+    branches: [master]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v3
+
+      - name: Set up Python
+        uses: actions/setup-python@v4
+        with:
+          python-version: "3.13"
+
+      - name: Install dependencies
+        run: |
+          pip install ruff
+          pip install -r requirements.txt
+
+      - name: Lint
+        run: ruff check .
+
+      - name: Run tests
+        run: pytest tests/ -v
diff --git a/app.py b/app.py
index 8222165..99894d1 100644
--- a/app.py
+++ b/app.py
@@ -35,7 +35,7 @@ def _safe_next(default_url):
 def _filter_compatible(query, battery_size):
     """Restrict a Battery query to size-compatible batteries (matching size or unsized)."""
     if battery_size:
-        query = query.filter((Battery.size == battery_size) | (Battery.size == None))
+        query = query.filter((Battery.size == battery_size) | (Battery.size == None))  # noqa: E711
     return query
 
 
@@ -130,7 +130,7 @@ def create_app(config_object="config"):
         avail_count = sum(1 for b in batteries if b.status == "available")
         installed_count = sum(1 for b in batteries if b.status == "installed")
         retired_count = sum(1 for b in batteries if b.status == "retired")
-        devices = db.query(Device).filter(Device.parent_id == None).all()
+        devices = db.query(Device).filter(Device.parent_id == None).all()  # noqa: E711
         total_devices = len(devices)
         full_devices = sum(
             1 for d in devices
@@ -283,16 +283,16 @@ def create_app(config_object="config"):
                     .order_by(BatteryPctLog.recorded_at.desc())
                     .all())
         charge_logs_data = [
-            {"id": l.id, "date": l.charged_date, "cycles": l.increment_cycles, "notes": l.notes or ""}
-            for l in charge_logs
+            {"id": log.id, "date": log.charged_date, "cycles": log.increment_cycles, "notes": log.notes or ""}
+            for log in charge_logs
         ]
         capacity_tests_data = [
             {"id": t.id, "date": t.tested_date, "mah": t.tested_capacity_mah, "notes": t.notes or ""}
             for t in sorted(capacity_tests, key=lambda t: (t.tested_date, t.id), reverse=True)
         ]
         pct_logs_data = [
-            {"recorded_at": str(l.recorded_at), "pct": l.percentage, "source": l.source or ""}
-            for l in pct_logs
+            {"recorded_at": str(log.recorded_at), "pct": log.percentage, "source": log.source or ""}
+            for log in pct_logs
         ]
         return render_template("battery_detail.html", battery=battery,
                                storage_locations=storage_locations,
@@ -699,7 +699,7 @@ def create_app(config_object="config"):
 
     @app.route("/device/")
     def device_list():
-        devices = db.query(Device).filter(Device.parent_id == None).order_by(Device.name).all()
+        devices = db.query(Device).filter(Device.parent_id == None).order_by(Device.name).all()  # noqa: E711
         device_types = sorted({d.device_type for d in devices if d.device_type})
         device_locations = sorted({d.location for d in devices if d.location})
         device_battery_sizes = sorted({d.battery_size for d in devices if d.battery_size})
@@ -1237,9 +1237,9 @@ def create_app(config_object="config"):
         buf = io.StringIO()
         w = csv.writer(buf)
         w.writerow(["id", "battery_id", "battery_label", "charged_date", "increment_cycles", "notes"])
-        for l in rows:
-            w.writerow([l.id, l.battery_id, l.battery.label,
-                        l.charged_date, l.increment_cycles, l.notes or ""])
+        for row in rows:
+            w.writerow([row.id, row.battery_id, row.battery.label,
+                        row.charged_date, row.increment_cycles, row.notes or ""])
         return buf.getvalue()
 
     def _capacity_tests_csv():
@@ -1257,9 +1257,9 @@ def create_app(config_object="config"):
         buf = io.StringIO()
         w = csv.writer(buf)
         w.writerow(["id", "battery_id", "battery_label", "percentage", "recorded_at", "source"])
-        for l in rows:
-            w.writerow([l.id, l.battery_id, l.battery.label,
-                        l.percentage, l.recorded_at, l.source or ""])
+        for row in rows:
+            w.writerow([row.id, row.battery_id, row.battery.label,
+                        row.percentage, row.recorded_at, row.source or ""])
         return buf.getvalue()
 
     @app.route("/export")
@@ -1334,10 +1334,10 @@ def create_app(config_object="config"):
                 for d in devices
             ],
             "charge_logs": [
-                {"id": l.id, "battery_id": l.battery_id, "battery_label": l.battery.label,
-                 "charged_date": l.charged_date, "increment_cycles": l.increment_cycles,
-                 "notes": l.notes}
-                for l in charge_logs
+                {"id": log.id, "battery_id": log.battery_id, "battery_label": log.battery.label,
+                 "charged_date": log.charged_date, "increment_cycles": log.increment_cycles,
+                 "notes": log.notes}
+                for log in charge_logs
             ],
             "capacity_tests": [
                 {"id": t.id, "battery_id": t.battery_id, "battery_label": t.battery.label,
@@ -1346,9 +1346,9 @@ def create_app(config_object="config"):
                 for t in capacity_tests
             ],
             "pct_logs": [
-                {"id": l.id, "battery_id": l.battery_id, "battery_label": l.battery.label,
-                 "percentage": l.percentage, "recorded_at": l.recorded_at, "source": l.source}
-                for l in pct_logs
+                {"id": log.id, "battery_id": log.battery_id, "battery_label": log.battery.label,
+                 "percentage": log.percentage, "recorded_at": log.recorded_at, "source": log.source}
+                for log in pct_logs
             ],
         }
         return Response(json.dumps(payload, indent=2), mimetype="application/json",
diff --git a/ha_poller.py b/ha_poller.py
index abed3f9..066a6eb 100644
--- a/ha_poller.py
+++ b/ha_poller.py
@@ -37,7 +37,7 @@ class HaPoller:
             self._poll_once()
 
     def _poll_once(self):
-        from models import Battery, BatteryPctLog, Device  # local import avoids circular-import risk
+        from models import BatteryPctLog, Device  # local import avoids circular-import risk
 
         session = self._Session()
         try:
diff --git a/models.py b/models.py
index 462ebb6..5ec1eb3 100644
--- a/models.py
+++ b/models.py
@@ -1,4 +1,3 @@
-from datetime import datetime
 
 from sqlalchemy import Column, Integer, String, Text, ForeignKey, Table, UniqueConstraint
 from sqlalchemy.orm import declarative_base, relationship
diff --git a/sbin/gen_icons.py b/sbin/gen_icons.py
index 7ca41e3..0c1e748 100644
--- a/sbin/gen_icons.py
+++ b/sbin/gen_icons.py
@@ -1,5 +1,7 @@
 """Generate solid-color PNG icons for PWA manifest using stdlib only (no Pillow)."""
-import zlib, struct, os
+import zlib
+import struct
+import os
 
 def make_png(size, rgb=(0x25, 0x63, 0xEB)):
     """Create a minimal valid RGB PNG of the given size filled with one color."""
diff --git a/sbin/migrate_parent_key.py b/sbin/migrate_parent_key.py
index d32c1d8..bb96b96 100644
--- a/sbin/migrate_parent_key.py
+++ b/sbin/migrate_parent_key.py
@@ -16,7 +16,6 @@ Usage:
 
 import os
 import shutil
-import sys
 from datetime import date
 from pathlib import Path
 
diff --git a/sbin/setup_mariadb.py b/sbin/setup_mariadb.py
index 5b087a6..7c3291a 100755
--- a/sbin/setup_mariadb.py
+++ b/sbin/setup_mariadb.py
@@ -31,11 +31,11 @@ from pathlib import Path
 REPO_ROOT = Path(__file__).resolve().parent.parent
 sys.path.insert(0, str(REPO_ROOT))
 
-from sqlalchemy import create_engine, text
-from sqlalchemy.orm import sessionmaker
+from sqlalchemy import create_engine, text  # noqa: E402
+from sqlalchemy.orm import sessionmaker  # noqa: E402
 
-import config
-from models import Base, Battery, BatteryPctLog, CapacityTest, ChargeLog, Device
+import config  # noqa: E402
+from models import Base, Battery, BatteryPctLog, CapacityTest, ChargeLog, Device  # noqa: E402
 
 
 # ---------------------------------------------------------------------------
@@ -62,7 +62,7 @@ def collect_credentials() -> str:
     """Return a MariaDB SQLAlchemy URL, prompting for any missing pieces."""
     url = os.environ.get("MARIADB_URL", "").strip()
     if url:
-        print(f"  Using MARIADB_URL from environment.")
+        print("  Using MARIADB_URL from environment.")
         return url
 
     print("Enter MariaDB connection details (press Enter to accept defaults):\n")
diff --git a/tests/test_acceptance.py b/tests/test_acceptance.py
index 4a57623..4d08cf4 100644
--- a/tests/test_acceptance.py
+++ b/tests/test_acceptance.py
@@ -8,7 +8,8 @@ The `seeded_client` fixture pre-populates:
              BrandX 002 (id=3, retired)
 """
 
-import pytest
+import io
+import json as _json
 
 
 # ------------------------------------------------------------------ #
@@ -169,7 +170,7 @@ def test_edit_details_percentage_valid(seeded_client):
     data = _json.loads(seeded_client.get("/export/all.json").data)
     bat = next(b for b in data["batteries"] if b["id"] == 1)
     assert bat["battery_percentage"] == 100
-    assert any(l["battery_id"] == 1 and l["source"] == "manual" for l in data["pct_logs"])
+    assert any(entry["battery_id"] == 1 and entry["source"] == "manual" for entry in data["pct_logs"])
 
 
 def test_assign_battery(seeded_client):
@@ -699,9 +700,6 @@ def test_bulk_install_filters_by_size(client):
 # Import
 # ------------------------------------------------------------------ #
 
-import io
-import json as _json
-
 
 def _make_import_payload(devices=None, batteries=None,
                          charge_logs=None, capacity_tests=None, pct_logs=None):
diff --git a/tests/test_coverage.py b/tests/test_coverage.py
index c394b86..ae3f8d5 100644
--- a/tests/test_coverage.py
+++ b/tests/test_coverage.py
@@ -6,7 +6,6 @@ ha_client/ha_poller branches, export/import edge cases, bulk actions.
 
 import io
 import json
-import pytest
 from unittest.mock import patch, MagicMock
 
 
diff --git a/tests/test_ha_integration.py b/tests/test_ha_integration.py
index 7bd321b..91685dc 100644
--- a/tests/test_ha_integration.py
+++ b/tests/test_ha_integration.py
@@ -484,7 +484,8 @@ def test_poll_skips_update_when_percentage_unchanged(ha_app, ha_client_f):
     engine = create_engine(ha_app.config["SQLALCHEMY_DATABASE_URI"])
     s = sessionmaker(bind=engine)()
     s.get(Battery, 1).battery_percentage = 50
-    s.commit(); s.close()
+    s.commit()
+    s.close()
 
     from ha_client import HomeAssistantClient
     from ha_poller import HaPoller