diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..1b1efef
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,29 @@
+name: CI
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  checks:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: astral-sh/setup-uv@v5
+        with:
+          cache-dependency-glob: "requirements_dev.txt"
+      - run: uv venv --python 3.14 .venv && uv pip install --python .venv/bin/python -r requirements_dev.txt
+      - run: .venv/bin/ruff check . && .venv/bin/ruff format --check .
+      - run: .venv/bin/pytest -q --cov --cov-report=term-missing
+  hassfest:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: home-assistant/actions/hassfest@master
+  hacs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+      - uses: hacs/action@main
+        with:
+          category: integration
diff --git a/custom_components/ninlight/__init__.py b/custom_components/ninlight/__init__.py
new file mode 100644
index 0000000..96636a5
--- /dev/null
+++ b/custom_components/ninlight/__init__.py
@@ -0,0 +1 @@
+"""The ninlight integration."""
diff --git a/custom_components/ninlight/const.py b/custom_components/ninlight/const.py
new file mode 100644
index 0000000..9a181a6
--- /dev/null
+++ b/custom_components/ninlight/const.py
@@ -0,0 +1,34 @@
+"""Constants for the ninlight integration. Deliberately free of Home Assistant imports."""
+
+from __future__ import annotations
+
+from datetime import timedelta
+from typing import Final
+
+DOMAIN: Final = "ninlight"
+
+# Public default token of the ninlight firmware (CMakeLists.txt of the firmware repo).
+DEFAULT_TOKEN: Final = "aabbccddeeff0011223344"
+
+CONF_SCAN_INTERVAL: Final = "scan_interval"
+CONF_LAMP_BASE_URL: Final = "lamp_base_url"
+
+DEFAULT_SCAN_INTERVAL: Final = 30
+MIN_SCAN_INTERVAL: Final = 10
+MAX_SCAN_INTERVAL: Final = 300
+
+MAX_TRANSITION_MS: Final = 60_000
+
+FIRMWARE_DIR_NAME: Final = "ninlight_firmware"
+CATALOG_SCAN_INTERVAL: Final = timedelta(minutes=5)
+SIGNAL_CATALOG_UPDATED: Final = f"{DOMAIN}_catalog_updated"
+
+FIRMWARE_URL_PREFIX: Final = "/api/ninlight/firmware/"
+# len(secrets.token_urlsafe(32))
+FIRMWARE_KEY_LENGTH: Final = 43
+# The lamp rejects fw_update URLs longer than this (nl_api.c: get_string(cmd, "url", 8, 255)).
+MAX_LAMP_URL_LENGTH: Final = 255
+
+OTA_POLL_INTERVAL_S: Final = 5.0
+# The firmware aborts a stalled download after 10 min; a dead peer can hang ~7 min in TCP.
+OTA_TIMEOUT_S: Final = 12 * 60.0
diff --git a/custom_components/ninlight/manifest.json b/custom_components/ninlight/manifest.json
new file mode 100644
index 0000000..75207e4
--- /dev/null
+++ b/custom_components/ninlight/manifest.json
@@ -0,0 +1,14 @@
+{
+  "domain": "ninlight",
+  "name": "ninlight",
+  "codeowners": ["@ninharp"],
+  "config_flow": true,
+  "dependencies": ["http"],
+  "documentation": "https://github.com/ninharp/ha-ninlight",
+  "integration_type": "device",
+  "iot_class": "local_polling",
+  "issue_tracker": "https://github.com/ninharp/ha-ninlight/issues",
+  "requirements": [],
+  "version": "0.1.0",
+  "zeroconf": [{ "type": "_ninlight._tcp.local." }]
+}
diff --git a/hacs.json b/hacs.json
new file mode 100644
index 0000000..4d80464
--- /dev/null
+++ b/hacs.json
@@ -0,0 +1,5 @@
+{
+  "name": "ninlight",
+  "render_readme": true,
+  "homeassistant": "2026.9.0"
+}
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..7491918
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,27 @@
+[tool.pytest.ini_options]
+testpaths = ["tests_unit", "tests"]
+asyncio_mode = "auto"
+addopts = "-p no:cacheprovider"
+
+[tool.coverage.run]
+source = ["custom_components/ninlight"]
+branch = true
+
+[tool.coverage.report]
+fail_under = 95
+show_missing = true
+
+[tool.ruff]
+target-version = "py314"
+line-length = 100
+exclude = ["docs/"]
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "UP", "B", "SIM", "RUF", "ASYNC"]
+# E501: line length is the formatter's job; long literals in test tables stay on one line.
+# RUF012: HA entities declare _attr_* lists as plain class attributes by convention.
+ignore = ["E501", "RUF012"]
+
+[tool.ruff.lint.isort]
+known-first-party = ["custom_components.ninlight", "tests", "tests_unit"]
+force-sort-within-sections = true
diff --git a/requirements_dev.txt b/requirements_dev.txt
new file mode 100644
index 0000000..549572b
--- /dev/null
+++ b/requirements_dev.txt
@@ -0,0 +1,4 @@
+homeassistant==2026.9.0
+pytest-homeassistant-custom-component==0.13.363
+pytest-cov
+ruff>=0.9
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..d6651e5
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,13 @@
+"""Fixtures for tests that run against a Home Assistant instance."""
+
+from __future__ import annotations
+
+from collections.abc import Generator
+
+import pytest
+
+
+@pytest.fixture(autouse=True)
+def auto_enable_custom_integrations(enable_custom_integrations: None) -> Generator[None]:
+    """Load custom_components/ in every Home Assistant test."""
+    yield
diff --git a/tests_unit/__init__.py b/tests_unit/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/tests_unit/test_manifest.py b/tests_unit/test_manifest.py
new file mode 100644
index 0000000..5a169a1
--- /dev/null
+++ b/tests_unit/test_manifest.py
@@ -0,0 +1,20 @@
+"""The manifest must agree with the constants the code relies on."""
+
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+from custom_components.ninlight.const import DOMAIN
+
+MANIFEST = Path(__file__).parents[1] / "custom_components" / "ninlight" / "manifest.json"
+
+
+def test_manifest_matches_constants() -> None:
+    manifest = json.loads(MANIFEST.read_text(encoding="utf-8"))
+    assert manifest["domain"] == DOMAIN
+    assert manifest["zeroconf"] == [{"type": "_ninlight._tcp.local."}]
+    assert manifest["iot_class"] == "local_polling"
+    assert manifest["config_flow"] is True
+    assert manifest["requirements"] == []
+    assert manifest["dependencies"] == ["http"]