diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index ba0cd0c..983ada7 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -2,37 +2,23 @@ name: CI
 
 on:
   push:
-    branches: [ main, master ]
+    branches: [main, master]
   pull_request:
-    branches: [ main, master ]
+    branches: [main, master]
 
 jobs:
-  test:
+  python:
+    name: pytest and flake8 (Python 3.11)
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
       - name: Set up Python
-        uses: actions/setup-python@v4
+        uses: actions/setup-python@v5
         with:
-          python-version: '3.9'
-      - name: Install deps
-        run: |
-          python -m pip install --upgrade pip
-          pip install -r requirements.txt
-      - name: Run tests
-        run: pytest -q
-  lint:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - name: Set up Python
-        uses: actions/setup-python@v4
-        with:
-          python-version: '3.9'
-      - name: Install flake8
-        run: |
-          python -m pip install --upgrade pip
-          pip install flake8
-      - name: Run flake8
-        run: |
-          flake8 --max-line-length=120 || true
+          python-version: '3.11'
+      - name: Install test tools
+        run: python -m pip install pytest flake8
+      - name: Test database model
+        run: python -m pytest -q tests
+      - name: Check Python syntax and critical lint errors
+        run: python -m flake8 . --select=E9,F63,F7,F82 --show-source
diff --git a/tests/README.md b/tests/README.md
new file mode 100644
index 0000000..80bf2df
--- /dev/null
+++ b/tests/README.md
@@ -0,0 +1,16 @@
+# Isolated Python model tests
+
+Run from the repository root with Python 3.11+:
+
+    python -m pip install pytest flake8
+    python -m pytest -q tests
+    python -m flake8 . --select=E9,F63,F7,F82 --show-source
+
+The tests use a temporary SQLite database. They do not need actual Raspberry Pi
+hardware, a Docker daemon, FastAPI, network access, or production credentials.
+
+The CI intentionally runs a critical-error lint subset across the existing
+Python files: syntax errors and high-impact Pyflakes checks. This is not
+equivalent to full-project flake8 compliance. The previous lint step ignored
+failures, and the previous dependency-install step targeted requirements.txt,
+which does not exist in this repository.
diff --git a/tests/test_models.py b/tests/test_models.py
new file mode 100644
index 0000000..e8f8554
--- /dev/null
+++ b/tests/test_models.py
@@ -0,0 +1,74 @@
+"""Isolated SQLite model regression tests; no Raspberry Pi/network required."""
+import sqlite3
+
+import pytest
+
+from app.models import Database
+
+
+@pytest.fixture
+def database(tmp_path):
+    db = Database(str(tmp_path / "devices.db"))
+    db.init_db()
+    return db
+
+
+def test_initial_database_is_empty(database):
+    assert database.list_devices() == []
+
+
+def test_upsert_creates_device_with_boolean_liveness(database):
+    database.upsert_device("192.0.2.1", "Primary Pi", True)
+    devices = database.list_devices()
+    assert len(devices) == 1
+    assert devices[0]["ip"] == "192.0.2.1"
+    assert devices[0]["name"] == "Primary Pi"
+    assert devices[0]["alive"] is True
+
+
+def test_upsert_same_ip_updates_without_creating_duplicate(database):
+    database.upsert_device("192.0.2.2", "Old name", True)
+    existing = database.list_devices()[0]["id"]
+    database.upsert_device("192.0.2.2", "Updated name", False)
+    devices = database.list_devices()
+    assert len(devices) == 1
+    assert devices[0]["id"] == existing
+    assert devices[0]["name"] == "Updated name"
+    assert devices[0]["alive"] is False
+
+
+def test_get_device_returns_one_device_by_id(database):
+    database.upsert_device("192.0.2.3", "Living room", False)
+    id_ = database.list_devices()[0]["id"]
+    assert database.get_device(id_) == {
+        "id": id_,
+        "ip": "192.0.2.3",
+        "name": "Living room",
+        "alive": False,
+    }
+
+
+def test_get_device_missing_returns_none(database):
+    assert database.get_device(999) is None
+
+
+def test_unique_ip_constraint_and_other_rows_are_unchanged(database):
+    database.upsert_device("192.0.2.4", "Sensor", True)
+    with pytest.raises(sqlite3.IntegrityError):
+        with database.conn() as conn:
+            conn.execute(
+                "INSERT INTO devices(ip, name) VALUES (?, ?)",
+                ("192.0.2.4", "Duplicate"),
+            )
+    assert len(database.list_devices()) == 1
+
+
+def test_upsert_allows_null_name(database):
+    database.upsert_device("192.0.2.5", None, True)
+    assert database.list_devices()[0]["name"] is None
+
+
+def test_schema_init_is_repeatable(database):
+    database.upsert_device("192.0.2.6", "Retained", True)
+    database.init_db()
+    assert database.list_devices()[0]["name"] == "Retained"