diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..7b33e7f
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,6 @@
+__pycache__/
+*.py[cod]
+*$py.class
+.venv/
+.pytest_cache/
+*.metadata.json
diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..7eaf5ba
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2026 NestQuest Contributors / Maniacs Mansion
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/README.md b/README.md
index e69de29..c69832e 100644
--- a/README.md
+++ b/README.md
@@ -0,0 +1,68 @@
+# NestQuest - House Chaos Coordination
+
+Home Assistant custom integration for managing chores, custody schedules, and house coordination.
+
+## Overview
+
+NestQuest helps households coordinate daily life, chore tracking, custody schedules, and shared tasks directly within Home Assistant. Version 0.1.0 is the integration foundation: a configuration scaffold providing the package and manifest, shared constants, a single-instance config flow, setup/unload lifecycle handling with an options-reload listener, an options flow (horizon days, day rollover time, panel idle timeout), SQLite storage-path resolution, and HACS metadata. Sensors, calendar events, and service calls are forthcoming in later releases and are not yet part of the integration.
+
+## Installation
+
+### HACS Installation (Recommended)
+
+1. Ensure [HACS (Home Assistant Community Store)](https://hacs.xyz/) is installed.
+2. In Home Assistant, open **HACS** > **Integrations**.
+3. Select the three-dots menu in the top right and click **Custom repositories**.
+4. Enter the repository URL: `https://github.com/talon2king/NestQuest`
+5. Select category **Integration** and click **Add**.
+6. Search for **NestQuest** and click **Download**.
+7. Restart Home Assistant.
+
+> **Note:** Development happens in the private Gitea repository
+> (`https://code.cubecraftlabs.com/Maniacs_Mansion/NestQuest`). The GitHub
+> repository is a public mirror maintained for HACS distribution.
+
+### Manual Installation
+
+1. Download the latest release from the repository.
+2. Copy the `custom_components/nestquest` directory into your Home Assistant installation's `config/custom_components/` folder:
+   ```bash
+   cp -R custom_components/nestquest <config_dir>/custom_components/
+   ```
+3. Restart Home Assistant.
+
+## Configuration
+
+After installation and restart:
+1. Navigate to **Settings** > **Devices & Services** in Home Assistant.
+2. Click **Add Integration** and search for **NestQuest**.
+3. Follow the on-screen configuration flow.
+
+## Developer Setup and Testing
+
+This project uses [`uv`](https://github.com/astral-sh/uv) for fast Python package and dependency management.
+
+### Prerequisites
+
+- Python 3.11 or newer
+- [uv](https://docs.astral.sh/uv/) installed on your machine
+
+### Setup Environment
+
+To set up the development environment and install dependencies:
+
+```bash
+uv sync
+```
+
+### Running Tests
+
+Run the test suite with `pytest`:
+
+```bash
+uv run pytest
+```
+
+## License
+
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.
diff --git a/RELEASE_NOTES.md b/RELEASE_NOTES.md
new file mode 100644
index 0000000..dd82c4a
--- /dev/null
+++ b/RELEASE_NOTES.md
@@ -0,0 +1,45 @@
+# NestQuest Release Notes
+
+## Version 0.1.0 — 2026-09-13
+
+### Scope
+
+First release of NestQuest, a Home Assistant custom integration for managing chores, custody schedules, and house coordination. This release ships the integration foundation/configuration scaffold only (Feature 01):
+
+- Integration package and manifest, plus HACS metadata (`hacs.json`).
+- Shared constants module.
+- Single-instance config flow for initial setup.
+- Setup/unload lifecycle handling with an options-reload listener.
+- Options flow for configuring `horizon_days`, `day_rollover_time`, and `panel_idle_timeout`.
+- SQLite storage path resolver — path resolution only; the database itself is not created in this release.
+- Test harness (`pytest` via `uv`).
+
+### Requirements
+
+- Minimum Home Assistant version: **2024.6.0**.
+
+### Known Limitations
+
+- No entities, services, or calendar platforms yet — the integration does not expose sensors, calendar events, or service calls in this release.
+- Single-instance only — one NestQuest config entry is permitted per Home Assistant instance.
+- The integration does not yet create its database file; storage is limited to resolved configuration paths.
+
+### Rollback
+
+v0.1.0 is the first release — there is no previous NestQuest version to downgrade to, so rollback means complete removal. This release performs no data or schema migrations.
+
+**HACS installs:**
+
+1. Remove the NestQuest integration via HACS (HACS > Integrations > NestQuest > Remove).
+2. Restart Home Assistant.
+3. Remove the integration in Home Assistant (Settings > Devices & Services > NestQuest > Delete), then restart Home Assistant again.
+
+**Manual installs:**
+
+1. Delete the `custom_components/nestquest/` directory from your Home Assistant configuration directory.
+2. Restart Home Assistant.
+3. Remove the integration in Home Assistant (Settings > Devices & Services > NestQuest > Delete), then restart Home Assistant again.
+
+**Data:** the integration does not yet create its own database file, so there is no application data. However, Home Assistant persists the config entry and its selected options — removing the integration deletes that configuration, and the option values (`horizon_days`, `day_rollover_time`, `panel_idle_timeout`) will be lost on removal.
+
+**Repository operators:** instead of uninstalling, you may git-revert the release merge on `main`, which removes the integration files entirely. End users should use the uninstall path above.
\ No newline at end of file
diff --git a/custom_components/nestquest/__init__.py b/custom_components/nestquest/__init__.py
new file mode 100644
index 0000000..f34c276
--- /dev/null
+++ b/custom_components/nestquest/__init__.py
@@ -0,0 +1,67 @@
+"""The NestQuest integration."""
+from __future__ import annotations
+
+import inspect
+from collections.abc import Callable
+from dataclasses import dataclass
+from typing import Any
+
+from homeassistant.config_entries import ConfigEntry
+from homeassistant.core import HomeAssistant
+
+from .const import DOMAIN, LOGGER
+
+_LOGGER = LOGGER
+
+
+@dataclass
+class NestQuestRuntimeData:
+    """Runtime data stored on a NestQuest config entry."""
+
+    entry_id: str
+    options: dict[str, Any]
+    remove_update_listener: Callable[[], Any]
+
+
+async def async_setup(hass: HomeAssistant, config: dict[str, Any]) -> bool:
+    """Set up the NestQuest integration. YAML configuration is not used, returns True."""
+    return True
+
+
+async def async_setup_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+    """Set up NestQuest from a config entry."""
+    hass.data.setdefault(DOMAIN, {})
+
+    async def _async_update_listener(
+        listener_hass: HomeAssistant, listener_entry: ConfigEntry
+    ) -> None:
+        """Reload the entry when its options change."""
+        await listener_hass.config_entries.async_reload(listener_entry.entry_id)
+
+    runtime_data = NestQuestRuntimeData(
+        entry_id=entry.entry_id,
+        options=dict(entry.options),
+        remove_update_listener=entry.add_update_listener(_async_update_listener),
+    )
+    entry.runtime_data = runtime_data
+    hass.data[DOMAIN][entry.entry_id] = runtime_data
+    return True
+
+
+async def async_unload_entry(hass: HomeAssistant, entry: ConfigEntry) -> bool:
+    """Unload a config entry."""
+    domain_data = hass.data.setdefault(DOMAIN, {})
+    runtime_data = domain_data.pop(entry.entry_id, None)
+    if not domain_data:
+        hass.data.pop(DOMAIN, None)
+    if runtime_data is None:
+        runtime_data = getattr(entry, "runtime_data", None)
+    if runtime_data is not None:
+        remove_update_listener = getattr(runtime_data, "remove_update_listener", None)
+        if remove_update_listener is not None:
+            result = remove_update_listener()
+            if inspect.isawaitable(result):
+                await result
+    if getattr(entry, "runtime_data", None) is not None:
+        entry.runtime_data = None
+    return True
diff --git a/custom_components/nestquest/config_flow.py b/custom_components/nestquest/config_flow.py
new file mode 100644
index 0000000..a8ccbc2
--- /dev/null
+++ b/custom_components/nestquest/config_flow.py
@@ -0,0 +1,39 @@
+"""Config flow for NestQuest."""
+from __future__ import annotations
+
+from typing import Any
+
+from homeassistant import config_entries
+from homeassistant.core import callback
+from homeassistant.data_entry_flow import FlowResult
+
+from .const import DOMAIN
+
+
+class NestQuestConfigFlow(config_entries.ConfigFlow, domain=DOMAIN):
+    """Handle a config flow for NestQuest."""
+
+    VERSION = 1
+
+    @staticmethod
+    @callback
+    def async_get_options_flow(
+        config_entry: config_entries.ConfigEntry,
+    ) -> Any:
+        """Create the options flow handler for NestQuest."""
+        from .options_flow import NestQuestOptionsFlow
+
+        return NestQuestOptionsFlow(config_entry=config_entry)
+
+    async def async_step_user(
+        self, user_input: dict[str, Any] | None = None
+    ) -> FlowResult:
+        """Handle the user step of the config flow."""
+        await self.async_set_unique_id(DOMAIN, raise_on_progress=False)
+        if self._async_in_progress() or self._async_current_entries():
+            return self.async_abort(reason="single_instance_allowed")
+
+        if user_input is None:
+            return self.async_show_form(step_id="user")
+
+        return self.async_create_entry(title="NestQuest", data=user_input)
\ No newline at end of file
diff --git a/custom_components/nestquest/const.py b/custom_components/nestquest/const.py
new file mode 100644
index 0000000..fc45d7c
--- /dev/null
+++ b/custom_components/nestquest/const.py
@@ -0,0 +1,22 @@
+"""Constants for the NestQuest integration."""
+from __future__ import annotations
+
+import logging
+
+DOMAIN = "nestquest"
+LOGGER_NAME = "custom_components.nestquest"
+LOGGER = logging.getLogger(LOGGER_NAME)
+
+PLATFORMS: list[str] = []
+
+SQLITE_DB_FILENAME = "nestquest.db"
+
+# Configuration keys and default values
+CONF_HORIZON_DAYS = "horizon_days"
+DEFAULT_HORIZON_DAYS = 14
+
+CONF_DAY_ROLLOVER_TIME = "day_rollover_time"
+DEFAULT_DAY_ROLLOVER_TIME = "00:00"
+
+CONF_PANEL_IDLE_TIMEOUT = "panel_idle_timeout"
+DEFAULT_PANEL_IDLE_TIMEOUT = 300
diff --git a/custom_components/nestquest/manifest.json b/custom_components/nestquest/manifest.json
new file mode 100644
index 0000000..8e75b31
--- /dev/null
+++ b/custom_components/nestquest/manifest.json
@@ -0,0 +1,12 @@
+{
+  "domain": "nestquest",
+  "name": "NestQuest",
+  "codeowners": ["@overseer"],
+  "config_flow": true,
+  "documentation": "https://github.com/talon2king/NestQuest",
+  "integration_type": "hub",
+  "iot_class": "local_polling",
+  "issue_tracker": "https://github.com/talon2king/NestQuest/issues",
+  "requirements": [],
+  "version": "0.1.0"
+}
diff --git a/custom_components/nestquest/options_flow.py b/custom_components/nestquest/options_flow.py
new file mode 100644
index 0000000..eeacafb
--- /dev/null
+++ b/custom_components/nestquest/options_flow.py
@@ -0,0 +1,120 @@
+"""Options flow for NestQuest post-setup settings."""
+from __future__ import annotations
+
+import re
+from typing import Any
+
+import voluptuous as vol
+from homeassistant import config_entries
+from homeassistant.data_entry_flow import FlowResult
+
+from .const import (
+    CONF_DAY_ROLLOVER_TIME,
+    CONF_HORIZON_DAYS,
+    CONF_PANEL_IDLE_TIMEOUT,
+    DEFAULT_DAY_ROLLOVER_TIME,
+    DEFAULT_HORIZON_DAYS,
+    DEFAULT_PANEL_IDLE_TIMEOUT,
+)
+
+MIN_HORIZON_DAYS = 1
+MIN_PANEL_IDLE_TIMEOUT = 30
+
+_TIME_PATTERN = re.compile(r"(?:[01]\d|2[0-3]):[0-5]\d")
+
+
+def _parse_time(value: str) -> bool:
+    """Return True when value is a valid 24-hour HH:MM string."""
+    return _TIME_PATTERN.fullmatch(value) is not None
+
+
+def _async_validate(user_input: dict[str, Any]) -> dict[str, str]:
+    """Validate user input and return field-level errors instead of raising."""
+    errors: dict[str, str] = {}
+
+    horizon_days = user_input.get(CONF_HORIZON_DAYS)
+    if (
+        isinstance(horizon_days, bool)
+        or not isinstance(horizon_days, int)
+        or horizon_days < MIN_HORIZON_DAYS
+    ):
+        errors[CONF_HORIZON_DAYS] = "invalid"
+
+    day_rollover_time = user_input.get(CONF_DAY_ROLLOVER_TIME)
+    if not isinstance(day_rollover_time, str) or not _parse_time(day_rollover_time):
+        errors[CONF_DAY_ROLLOVER_TIME] = "invalid_time"
+
+    panel_idle_timeout = user_input.get(CONF_PANEL_IDLE_TIMEOUT)
+    if (
+        isinstance(panel_idle_timeout, bool)
+        or not isinstance(panel_idle_timeout, int)
+        or panel_idle_timeout < MIN_PANEL_IDLE_TIMEOUT
+    ):
+        errors[CONF_PANEL_IDLE_TIMEOUT] = "invalid"
+
+    return errors
+
+
+def _build_schema(current: dict[str, Any]) -> vol.Schema:
+    """Build the form schema, pre-filled with the current values."""
+    return vol.Schema(
+        {
+            vol.Required(
+                CONF_HORIZON_DAYS, default=current[CONF_HORIZON_DAYS]
+            ): int,
+            vol.Required(
+                CONF_DAY_ROLLOVER_TIME, default=current[CONF_DAY_ROLLOVER_TIME]
+            ): str,
+            vol.Required(
+                CONF_PANEL_IDLE_TIMEOUT, default=current[CONF_PANEL_IDLE_TIMEOUT]
+            ): int,
+        }
+    )
+
+
+class NestQuestOptionsFlow(config_entries.OptionsFlowWithConfigEntry):
+    """Handle the options flow for NestQuest."""
+
+    async def async_step_init(
+        self, user_input: dict[str, Any] | None = None
+    ) -> FlowResult:
+        """Manage the NestQuest options."""
+        if user_input is None:
+            return self.async_show_form(
+                step_id="init", data_schema=_build_schema(self._current_values())
+            )
+
+        errors = _async_validate(user_input)
+        if errors:
+            return self.async_show_form(
+                step_id="init",
+                data_schema=_build_schema(self._current_values()),
+                errors=errors,
+            )
+
+        return self.async_create_entry(
+            title="NestQuest",
+            data={
+                CONF_HORIZON_DAYS: user_input[CONF_HORIZON_DAYS],
+                CONF_DAY_ROLLOVER_TIME: user_input[CONF_DAY_ROLLOVER_TIME],
+                CONF_PANEL_IDLE_TIMEOUT: user_input[CONF_PANEL_IDLE_TIMEOUT],
+            },
+        )
+
+    def _current_values(self) -> dict[str, Any]:
+        """Resolve current values from entry options, then entry data, then defaults."""
+        options = self.options
+        entry_data = getattr(self.config_entry, "data", None) or {}
+        values: dict[str, Any] = {}
+        for key, default in (
+            (CONF_HORIZON_DAYS, DEFAULT_HORIZON_DAYS),
+            (CONF_DAY_ROLLOVER_TIME, DEFAULT_DAY_ROLLOVER_TIME),
+            (CONF_PANEL_IDLE_TIMEOUT, DEFAULT_PANEL_IDLE_TIMEOUT),
+        ):
+            if key in options:
+                values[key] = options[key]
+            elif key in entry_data:
+                values[key] = entry_data[key]
+            else:
+                values[key] = default
+        return values
\ No newline at end of file
diff --git a/custom_components/nestquest/store.py b/custom_components/nestquest/store.py
new file mode 100644
index 0000000..8198d79
--- /dev/null
+++ b/custom_components/nestquest/store.py
@@ -0,0 +1,20 @@
+"""SQLite storage path resolution for the NestQuest integration."""
+from __future__ import annotations
+
+from pathlib import Path
+
+from homeassistant.core import HomeAssistant
+
+from .const import SQLITE_DB_FILENAME
+
+
+def _ensure_dir(path: Path) -> None:
+    """Create the given directory and any missing parents."""
+    path.mkdir(parents=True, exist_ok=True)
+
+
+async def async_get_db_path(hass: HomeAssistant) -> Path:
+    """Return the absolute path to the NestQuest SQLite database file."""
+    db_path = Path(hass.config.path(SQLITE_DB_FILENAME)).absolute()
+    await hass.async_add_executor_job(_ensure_dir, db_path.parent)
+    return db_path
\ No newline at end of file
diff --git a/custom_components/nestquest/strings.json b/custom_components/nestquest/strings.json
new file mode 100644
index 0000000..277492d
--- /dev/null
+++ b/custom_components/nestquest/strings.json
@@ -0,0 +1,34 @@
+{
+  "title": "NestQuest",
+  "config": {
+    "step": {
+      "user": {
+        "title": "Add NestQuest",
+        "description": "Set up NestQuest to start coordinating the household. No additional configuration is required."
+      }
+    },
+    "abort": {
+      "single_instance_allowed": "NestQuest is already configured. Only a single instance is allowed."
+    },
+    "create_entry": {
+      "default": "NestQuest was successfully configured."
+    }
+  },
+  "options": {
+    "step": {
+      "init": {
+        "title": "NestQuest Settings",
+        "description": "Adjust how NestQuest plans, rolls over days, and idles its panel.",
+        "data": {
+          "horizon_days": "Generation horizon (days)",
+          "day_rollover_time": "Day rollover time (HH:MM)",
+          "panel_idle_timeout": "Panel idle timeout (seconds)"
+        }
+      }
+    },
+    "errors": {
+      "invalid": "Invalid value.",
+      "invalid_time": "Time must use 24-hour HH:MM format."
+    }
+  }
+}
\ No newline at end of file
diff --git a/custom_components/nestquest/translations/en.json b/custom_components/nestquest/translations/en.json
new file mode 100644
index 0000000..277492d
--- /dev/null
+++ b/custom_components/nestquest/translations/en.json
@@ -0,0 +1,34 @@
+{
+  "title": "NestQuest",
+  "config": {
+    "step": {
+      "user": {
+        "title": "Add NestQuest",
+        "description": "Set up NestQuest to start coordinating the household. No additional configuration is required."
+      }
+    },
+    "abort": {
+      "single_instance_allowed": "NestQuest is already configured. Only a single instance is allowed."
+    },
+    "create_entry": {
+      "default": "NestQuest was successfully configured."
+    }
+  },
+  "options": {
+    "step": {
+      "init": {
+        "title": "NestQuest Settings",
+        "description": "Adjust how NestQuest plans, rolls over days, and idles its panel.",
+        "data": {
+          "horizon_days": "Generation horizon (days)",
+          "day_rollover_time": "Day rollover time (HH:MM)",
+          "panel_idle_timeout": "Panel idle timeout (seconds)"
+        }
+      }
+    },
+    "errors": {
+      "invalid": "Invalid value.",
+      "invalid_time": "Time must use 24-hour HH:MM format."
+    }
+  }
+}
\ No newline at end of file
diff --git a/hacs.json b/hacs.json
new file mode 100644
index 0000000..722e594
--- /dev/null
+++ b/hacs.json
@@ -0,0 +1,5 @@
+{
+  "name": "NestQuest",
+  "homeassistant": "2024.6.0",
+  "render_readme": true
+}
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..6d77648
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,19 @@
+[project]
+name = "nestquest"
+version = "0.1.0"
+description = "NestQuest Home Assistant Integration"
+readme = "README.md"
+requires-python = ">=3.11"
+dependencies = []
+
+[dependency-groups]
+dev = [
+    "pytest>=8.0.0",
+    "pytest-asyncio>=0.24",
+    "voluptuous>=0.14",
+]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+pythonpath = ["."]
+asyncio_mode = "auto"
diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..e702c10
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,308 @@
+"""Shared pytest fixtures for the NestQuest test suite.
+
+pytest-homeassistant-custom-component could not be adopted: it pins
+``pytest==9.0.3`` and ``voluptuous==0.13.1``, which conflicts with the dev
+group's ``voluptuous>=0.14`` (used directly by the options flow's schema and
+its tests), and its back-releases raise the floor to Python >=3.12 while this
+project supports >=3.11.  The documented fallback is therefore used:
+``pytest-asyncio`` plus a standard-shaped ``hass`` fixture below.
+
+conftest.py is the single place where ``homeassistant`` modules are provided:
+this harness is explicitly MOCK-ONLY.  It unconditionally installs a coherent
+set of MagicMock stand-ins via ``sys.modules`` and wires the parent-package
+attributes.  All of that happens here, before any test module imports the
+integration, so no test module needs its own ``sys.modules`` setup.  It also
+provides the ``hass`` fixture plus shared helpers used by the behavior tests
+(config-entry factory, listener registry).
+
+Run this suite in its own venv *without* homeassistant installed (``uv run
+pytest -q``); it is never meant to run against a real HA install.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import importlib.util
+import inspect
+import sys
+from types import SimpleNamespace
+from unittest.mock import MagicMock
+
+import pytest
+
+# ---------------------------------------------------------------------------
+# Homeassistant module provisioning (explicitly mock-only).
+# ---------------------------------------------------------------------------
+_HA_MODULES = (
+    "homeassistant",
+    "homeassistant.core",
+    "homeassistant.config_entries",
+    "homeassistant.data_entry_flow",
+)
+
+def _find_spec(name: str):
+    """find_spec that returns None when the module (or its parent) is absent."""
+    try:
+        return importlib.util.find_spec(name)
+    except (ModuleNotFoundError, ValueError):
+        return None
+
+
+def _ensure_mock_only():
+    """Fail fast if real homeassistant is importable: this harness is mock-only."""
+    for _mod in _HA_MODULES:
+        # Anything already in sys.modules at load time is real HA; our mocks
+        # are only installed after this check.
+        if _mod in sys.modules or _find_spec(_mod) is not None:
+            raise pytest.UsageError(
+                "The NestQuest test harness is mock-only: real homeassistant is "
+                f"importable ({_mod!r} found), and mixing real HA modules with the "
+                "shaped mocks is not supported. Run the suite in its own venv "
+                "without homeassistant installed, e.g. `uv run pytest -q`."
+            )
+
+
+_ensure_mock_only()
+
+for _mod in _HA_MODULES:
+    sys.modules.setdefault(_mod, MagicMock())
+
+# Wire parent package attributes so "from homeassistant import
+# config_entries" resolves to the mocked submodule, mirroring real HA's
+# package layout.
+for _parent, _child in (
+    ("homeassistant", "config_entries"),
+    ("homeassistant", "data_entry_flow"),
+    ("homeassistant", "core"),
+):
+    setattr(sys.modules[_parent], _child, sys.modules[f"{_parent}.{_child}"])
+
+
+def _ha_mock(name: str):
+    """Return the shaped mock module object for a homeassistant module."""
+    return sys.modules[name]
+
+
+def options_flow_base():
+    """Return the mocked OptionsFlowWithConfigEntry class."""
+    return getattr(sys.modules["homeassistant.config_entries"], "OptionsFlowWithConfigEntry")
+
+
+class _ConfigFlowBase:
+    """Stand-in for homeassistant.config_entries.ConfigFlow.
+
+    A superset covering both the config-flow and options-flow tests: it must
+    satisfy every consumer of the mocked surface.
+    """
+
+    VERSION = 1
+
+    def __init_subclass__(cls, domain=None, **kwargs):
+        super().__init_subclass__(**kwargs)
+        cls._domain = domain
+
+    def __init__(self):
+        self.context = {}
+
+    def async_show_form(self, *, step_id, **kwargs):
+        return {"type": "form", "step_id": step_id, **kwargs}
+
+    def async_abort(self, *, reason, **kwargs):
+        return {"type": "abort", "reason": reason}
+
+    def async_create_entry(self, *, title, data, **kwargs):
+        """Return the flow result only; the flow manager persists the entry."""
+        return {"type": "create_entry", "title": title, "data": data}
+
+    async def async_set_unique_id(self, unique_id, raise_on_progress=True):
+        self.context["unique_id"] = unique_id
+        return None
+
+    def _async_current_entries(self):
+        return self.hass.config_entries.async_entries(self._domain)
+
+    def _async_in_progress(self):
+        return []
+
+    @staticmethod
+    def async_get_options_flow(config_entry):
+        raise NotImplementedError
+
+
+class _OptionsFlowWithConfigEntryBase:
+    """Stand-in mirroring HA 2024.6 config_entries.OptionsFlowWithConfigEntry."""
+
+    def __init__(self, config_entry=None):
+        self.config_entry = config_entry
+        self.hass = None
+        self.options = dict(config_entry.options) if config_entry is not None else {}
+
+    def async_show_form(self, *, step_id, **kwargs):
+        return {"type": "form", "step_id": step_id, **kwargs}
+
+    def async_create_entry(self, *, title, data, **kwargs):
+        return {"type": "create_entry", "title": title, "data": data}
+
+
+def _callback_decorator(fn):
+    """Mirror homeassistant.core.callback: flags the fn and returns it unchanged."""
+    fn.__ha_callback__ = True
+    return fn
+
+
+# The concrete 2024.6-shaped surface the integration is written against
+# (mirrors the shapes the tests previously installed per module).
+_config_entries_mock = _ha_mock("homeassistant.config_entries")
+_core_mock = _ha_mock("homeassistant.core")
+_data_entry_flow_mock = _ha_mock("homeassistant.data_entry_flow")
+
+_config_entries_mock.ConfigFlow = _ConfigFlowBase
+_config_entries_mock.OptionsFlowWithConfigEntry = _OptionsFlowWithConfigEntryBase
+_core_mock.callback = _callback_decorator
+_data_entry_flow_mock.RESULT_TYPE_FORM = "form"
+_data_entry_flow_mock.RESULT_TYPE_CREATE_ENTRY = "create_entry"
+_data_entry_flow_mock.RESULT_TYPE_ABORT = "abort"
+_data_entry_flow_mock.FlowResult = dict
+
+
+# ---------------------------------------------------------------------------
+# Shared helpers for the behavior tests.
+# ---------------------------------------------------------------------------
+class ListenerRegistry:
+    """Models HA's update-listener bookkeeping: appends to a list per entry, with per-listener removers."""
+
+    def __init__(self, hass=None):
+        self._hass = hass
+        self._listeners: dict[str, list[object]] = {}
+        self.reloaded: list[str] = []
+
+    def add(self, entry_id: str, listener) -> object:
+        def _remove():
+            self._listeners.get(entry_id, []).remove(listener)
+
+        self._listeners.setdefault(entry_id, []).append(listener)
+        return _remove
+
+    async def dispatch_options_update(self, entry) -> None:
+        """Dispatch on the running loop; sync listeners run inline, async ones awaited."""
+        for listener in list(self._listeners.get(entry.entry_id, [])):
+            result = listener(self._hass, entry)
+            if inspect.isawaitable(result):
+                await result
+
+    async_dispatch_options_update = dispatch_options_update
+
+    @property
+    def size(self) -> int:
+        return sum(len(listeners) for listeners in self._listeners.values())
+
+
+def make_config_entry(
+    entry_id: str = "test_entry",
+    options: dict | None = None,
+    data: dict | None = None,
+):
+    """Create a stub config entry shaped like HA's ConfigEntry for tests."""
+    entry = SimpleNamespace(
+        entry_id=entry_id,
+        options=dict(options or {}),
+        data=dict(data or {}),
+    )
+    entry.add_update_listener = None
+    return entry
+
+
+def wire_entry_to_registry(entry, registry: ListenerRegistry):
+    """Attach an update-listener registration function to the entry."""
+    entry.add_update_listener = lambda listener: registry.add(entry.entry_id, listener)
+    return entry
+
+
+def make_hass() -> tuple:
+    """Create a hass stub plus its listener registry, mirroring HA's shape."""
+    hass = SimpleNamespace(
+        data={},
+        config=MagicMock(),
+        config_entries=SimpleNamespace(async_reload=None),
+    )
+    registry = ListenerRegistry(hass)
+
+    async def _async_reload(entry_id: str) -> None:
+        registry.reloaded.append(entry_id)
+
+    hass.config_entries.async_reload = MagicMock(side_effect=_async_reload)
+    hass.config_entries._entries = []
+    hass.config_entries.async_add = (
+        lambda entry: hass.config_entries._entries.append(entry)
+    )
+
+    def _async_entries(domain: str):
+        return [e for e in hass.config_entries._entries if e.domain == domain]
+
+    hass.config_entries.async_entries = _async_entries
+    return hass, registry
+
+
+@pytest.fixture
+async def hass():
+    """Provide a standard-shaped hass fixture bound to the running test loop.
+
+    Mirrors the surface of Home Assistant's ``hass`` fixture: a ``config``
+    namespace, a ``config_entries`` manager wired to a listener registry, a
+    ``data`` dict for integration state, and a ``loop`` bound to the
+    pytest-asyncio loop the test itself runs on (HA's running-loop contract),
+    so code scheduling on ``hass.loop`` runs on the actual test loop.
+    """
+    _hass, registry = make_hass()
+    _hass.registry = registry
+    _hass.loop = asyncio.get_running_loop()
+    yield _hass
+
+
+@pytest.fixture
+def make_entry():
+    """Provide the config-entry factory as a fixture."""
+
+    def _factory(entry_id: str = "test_entry", options: dict | None = None, data: dict | None = None):
+        return make_config_entry(entry_id=entry_id, options=options, data=data)
+
+    return _factory
+
+
+@pytest.fixture
+def listener_registry():
+    """Provide a fresh listener registry for manual wiring."""
+
+    def _factory(hass=None):
+        return ListenerRegistry(hass)
+
+    return _factory
+
+
+@pytest.fixture
+def make_flow():
+    """Provide a factory for a stubbed NestQuestConfigFlow bound to hass."""
+
+    def _factory(hass=None, existing_entries=None, in_progress=None):
+        from custom_components.nestquest import config_flow
+
+        flow = config_flow.NestQuestConfigFlow()
+        flow.hass = hass if hass is not None else make_hass()[0]
+        for entry in existing_entries or []:
+            if getattr(entry, "domain", None) == flow._domain:
+                flow.hass.config_entries.async_add(entry)
+        if in_progress:
+            flow._async_in_progress = lambda: in_progress
+        return flow
+
+    return _factory
+
+
+@pytest.fixture
+def make_config_flow_entry():
+    """Provide an entry stub carrying a domain, for current-entries checks."""
+
+    def _factory(domain: str, entry_id: str = "existing"):
+        return SimpleNamespace(domain=domain, entry_id=entry_id)
+
+    return _factory
\ No newline at end of file
diff --git a/tests/test_config_flow.py b/tests/test_config_flow.py
new file mode 100644
index 0000000..b744bf4
--- /dev/null
+++ b/tests/test_config_flow.py
@@ -0,0 +1,157 @@
+"""Tests for the config flow of NestQuest."""
+from __future__ import annotations
+
+import ast
+import json
+from pathlib import Path
+
+import pytest
+
+from custom_components.nestquest import config_flow
+from custom_components.nestquest.const import DOMAIN
+
+PKG_DIR = Path(config_flow.__file__).parent
+STRINGS_PATH = PKG_DIR / "strings.json"
+TRANSLATIONS_EN_PATH = PKG_DIR / "translations" / "en.json"
+
+
+async def test_flow_shows_form_initially(hass, make_flow) -> None:
+    """The initial user step shows a form."""
+    flow = make_flow(hass)
+    result = await flow.async_step_user(None)
+    assert result["type"] == "form"
+    assert result["step_id"] == "user"
+
+
+async def test_flow_creates_entry_on_submit(hass, make_flow) -> None:
+    """Submitting the user step returns a create-entry result with the payload.
+
+    Real HA's ConfigFlow.async_create_entry only returns the flow result; the
+    flow manager persists the entry afterward.  The manager surface therefore
+    stays empty here — persistence is the manager's job, not the flow's.
+    """
+    flow = make_flow(hass)
+    assert hass.config_entries.async_entries(DOMAIN) == []
+    result = await flow.async_step_user({})
+    assert result["type"] == "create_entry"
+    assert result["title"] == "NestQuest"
+    assert result["data"] == {}
+    assert hass.config_entries.async_entries(DOMAIN) == []
+
+
+async def test_second_flow_aborts_single_instance(
+    hass, make_flow, make_config_flow_entry
+) -> None:
+    """A second flow aborts with single_instance_allowed."""
+    existing = make_config_flow_entry(DOMAIN)
+    flow = make_flow(hass, existing_entries=[existing])
+    assert hass.config_entries.async_entries(DOMAIN) == [existing]
+    result = await flow.async_step_user(None)
+    assert result["type"] == "abort"
+    assert result["reason"] == "single_instance_allowed"
+    assert hass.config_entries.async_entries(DOMAIN) == [existing]
+
+
+async def test_flow_aborts_when_in_progress(hass, make_flow) -> None:
+    """A concurrent flow in progress aborts with single_instance_allowed."""
+    flow = make_flow(hass, in_progress=[{"flow_id": "other"}])
+    result = await flow.async_step_user(None)
+    assert result["type"] == "abort"
+    assert result["reason"] == "single_instance_allowed"
+
+
+async def test_flow_sets_stable_unique_id(hass, make_flow) -> None:
+    """The flow assigns a stable unique id equal to the domain."""
+    flow = make_flow(hass)
+    assert flow.context.get("unique_id") is None
+    await flow.async_step_user(None)
+    assert flow.context["unique_id"] == DOMAIN
+
+
+async def test_flow_ignores_other_domain_entries(hass, make_flow, make_config_flow_entry) -> None:
+    """Entries of other domains do not trigger the abort."""
+    flow = make_flow(hass, existing_entries=[make_config_flow_entry("other_domain")])
+    result = await flow.async_step_user(None)
+    assert result["type"] == "form"
+    assert result["step_id"] == "user"
+
+
+@pytest.fixture
+def strings() -> dict:
+    """Load and parse strings.json."""
+    assert STRINGS_PATH.exists(), f"strings.json does not exist at {STRINGS_PATH}"
+    with open(STRINGS_PATH, encoding="utf-8") as f:
+        return json.load(f)
+
+
+@pytest.fixture
+def translations_en() -> dict:
+    """Load and parse translations/en.json."""
+    assert TRANSLATIONS_EN_PATH.exists(), (
+        f"translations/en.json does not exist at {TRANSLATIONS_EN_PATH}"
+    )
+    with open(TRANSLATIONS_EN_PATH, encoding="utf-8") as f:
+        return json.load(f)
+
+
+@pytest.mark.parametrize("fixture_name", ["strings", "translations_en"])
+def test_flow_strings_valid_json(fixture_name: str, request: pytest.FixtureRequest) -> None:
+    """strings.json and translations/en.json are valid JSON objects."""
+    content = request.getfixturevalue(fixture_name)
+    assert isinstance(content, dict)
+
+
+@pytest.mark.parametrize("fixture_name", ["strings", "translations_en"])
+def test_flow_strings_structure(fixture_name: str, request: pytest.FixtureRequest) -> None:
+    """Config flow strings contain title, user step, and abort reasons."""
+    content = request.getfixturevalue(fixture_name)
+    assert content.get("title")
+    config = content.get("config", {})
+    assert config.get("step", {}).get("user", {}).get("title")
+    assert config.get("step", {}).get("user", {}).get("description")
+    abort = config.get("abort", {})
+    assert "single_instance_allowed" in abort
+    assert abort["single_instance_allowed"]
+
+
+@pytest.mark.parametrize("fixture_name", ["strings", "translations_en"])
+def test_flow_strings_no_raw_keys(fixture_name: str, request: pytest.FixtureRequest) -> None:
+    """No placeholder/raw keys appear in the flow strings."""
+    content = request.getfixturevalue(fixture_name)
+
+    def check(value) -> None:
+        if isinstance(value, dict):
+            for key, val in value.items():
+                assert val, f"Empty string value for key '{key}'"
+                check(val)
+        elif isinstance(value, str):
+            assert value.strip() != ""
+
+    check(content)
+
+
+def test_flow_strings_match_translations(
+    strings: dict, translations_en: dict
+) -> None:
+    """strings.json and translations/en.json carry identical flow strings."""
+    assert strings == translations_en
+
+
+def test_no_hardcoded_domain_or_db_filename_in_new_modules() -> None:
+    """Ensure no module other than const.py hardcodes the domain or db filename."""
+    pkg_dir = Path(config_flow.__file__).parent
+    py_files = [f for f in pkg_dir.glob("*.py") if f.name not in ("const.py",)]
+
+    assert len(py_files) > 0, "No python modules found in package to check"
+
+    for py_file in py_files:
+        tree = ast.parse(py_file.read_text(encoding="utf-8"), filename=str(py_file))
+        for node in ast.walk(tree):
+            if isinstance(node, ast.Constant) and isinstance(node.value, str):
+                if node.value == "nestquest":
+                    raise AssertionError(
+                        f"Found hard-coded domain string in {py_file.name}:{node.lineno}"
+                    )
+                assert node.value != "nestquest.db", (
+                    f"Found hard-coded database filename in {py_file.name}:{node.lineno}"
+                )
\ No newline at end of file
diff --git a/tests/test_const.py b/tests/test_const.py
new file mode 100644
index 0000000..aea1bd9
--- /dev/null
+++ b/tests/test_const.py
@@ -0,0 +1,95 @@
+"""Tests for const.py of NestQuest."""
+from __future__ import annotations
+
+import ast
+from datetime import datetime
+import logging
+from pathlib import Path
+
+from custom_components.nestquest import const
+
+
+def test_domain() -> None:
+    """Verify DOMAIN is defined and equals 'nestquest'."""
+    assert hasattr(const, "DOMAIN")
+    assert const.DOMAIN == "nestquest"
+    assert isinstance(const.DOMAIN, str)
+
+
+def test_logger() -> None:
+    """Verify LOGGER_NAME and LOGGER are defined with correct types and values."""
+    assert hasattr(const, "LOGGER_NAME")
+    assert const.LOGGER_NAME == "custom_components.nestquest"
+    assert isinstance(const.LOGGER_NAME, str)
+
+    assert hasattr(const, "LOGGER")
+    assert isinstance(const.LOGGER, logging.Logger)
+    assert const.LOGGER.name == "custom_components.nestquest"
+
+
+def test_platforms() -> None:
+    """Verify PLATFORMS is defined as an empty list."""
+    assert hasattr(const, "PLATFORMS")
+    assert isinstance(const.PLATFORMS, list)
+    assert const.PLATFORMS == []
+
+
+def test_sqlite_db_filename() -> None:
+    """Verify SQLITE_DB_FILENAME is defined and equals 'nestquest.db'."""
+    assert hasattr(const, "SQLITE_DB_FILENAME")
+    assert const.SQLITE_DB_FILENAME == "nestquest.db"
+    assert isinstance(const.SQLITE_DB_FILENAME, str)
+
+
+def test_horizon_days_config() -> None:
+    """Verify CONF_HORIZON_DAYS and DEFAULT_HORIZON_DAYS are valid."""
+    assert hasattr(const, "CONF_HORIZON_DAYS")
+    assert const.CONF_HORIZON_DAYS == "horizon_days"
+    assert hasattr(const, "DEFAULT_HORIZON_DAYS")
+    assert isinstance(const.DEFAULT_HORIZON_DAYS, int)
+    assert const.DEFAULT_HORIZON_DAYS == 14
+    assert const.DEFAULT_HORIZON_DAYS > 0
+
+
+def test_day_rollover_time_config() -> None:
+    """Verify CONF_DAY_ROLLOVER_TIME and DEFAULT_DAY_ROLLOVER_TIME are valid."""
+    assert hasattr(const, "CONF_DAY_ROLLOVER_TIME")
+    assert const.CONF_DAY_ROLLOVER_TIME == "day_rollover_time"
+    assert hasattr(const, "DEFAULT_DAY_ROLLOVER_TIME")
+    assert isinstance(const.DEFAULT_DAY_ROLLOVER_TIME, str)
+    assert const.DEFAULT_DAY_ROLLOVER_TIME == "00:00"
+    # Validate time format HH:MM
+    parsed = datetime.strptime(const.DEFAULT_DAY_ROLLOVER_TIME, "%H:%M")
+    assert parsed.hour == 0 and parsed.minute == 0
+
+
+def test_panel_idle_timeout_config() -> None:
+    """Verify CONF_PANEL_IDLE_TIMEOUT and DEFAULT_PANEL_IDLE_TIMEOUT are valid."""
+    assert hasattr(const, "CONF_PANEL_IDLE_TIMEOUT")
+    assert const.CONF_PANEL_IDLE_TIMEOUT == "panel_idle_timeout"
+    assert hasattr(const, "DEFAULT_PANEL_IDLE_TIMEOUT")
+    assert isinstance(const.DEFAULT_PANEL_IDLE_TIMEOUT, int)
+    assert const.DEFAULT_PANEL_IDLE_TIMEOUT == 300
+    assert const.DEFAULT_PANEL_IDLE_TIMEOUT > 0
+
+
+def test_no_hardcoded_domain_or_db_filename_in_modules() -> None:
+    """Ensure no module other than const.py hardcodes DOMAIN string or SQLITE_DB_FILENAME."""
+    pkg_dir = Path(const.__file__).parent
+    py_files = [f for f in pkg_dir.glob("*.py") if f.name != "const.py"]
+
+    assert len(py_files) > 0, "No python modules found in package to check"
+
+    for py_file in py_files:
+        content = py_file.read_text(encoding="utf-8")
+        tree = ast.parse(content, filename=str(py_file))
+
+        for node in ast.walk(tree):
+            if isinstance(node, ast.Constant) and isinstance(node.value, str):
+                assert node.value != "nestquest.db", (
+                    f"Found hard-coded database filename '{node.value}' in {py_file.name}:{node.lineno}"
+                )
+                if node.value == "nestquest":
+                    raise AssertionError(
+                        f"Found hard-coded domain string '{node.value}' in {py_file.name}:{node.lineno}"
+                    )
diff --git a/tests/test_hacs.py b/tests/test_hacs.py
new file mode 100644
index 0000000..275d7ee
--- /dev/null
+++ b/tests/test_hacs.py
@@ -0,0 +1,82 @@
+"""Tests verifying HACS repository metadata, documentation, and licensing."""
+from __future__ import annotations
+
+import json
+from pathlib import Path
+import pytest
+
+REPO_ROOT = Path(__file__).parent.parent
+HACS_JSON_PATH = REPO_ROOT / "hacs.json"
+LICENSE_PATH = REPO_ROOT / "LICENSE"
+README_PATH = REPO_ROOT / "README.md"
+MANIFEST_PATH = REPO_ROOT / "custom_components" / "nestquest" / "manifest.json"
+
+
+@pytest.fixture
+def hacs_config() -> dict:
+    """Load and parse hacs.json."""
+    assert HACS_JSON_PATH.exists(), f"hacs.json does not exist at {HACS_JSON_PATH}"
+    with open(HACS_JSON_PATH, encoding="utf-8") as f:
+        data = json.load(f)
+    return data
+
+
+def test_hacs_json_exists_and_is_valid(hacs_config: dict) -> None:
+    """Verify hacs.json exists and is valid JSON."""
+    assert isinstance(hacs_config, dict)
+    assert hacs_config.get("name") == "NestQuest"
+    assert hacs_config.get("homeassistant") == "2024.6.0"
+    assert hacs_config.get("render_readme") is True
+
+
+def test_hacs_json_minimum_version_supports_runtime_data(hacs_config: dict) -> None:
+    """Advertised HA floor must support ConfigEntry.runtime_data (added in 2024.6)."""
+    advertised = tuple(int(part) for part in hacs_config.get("homeassistant", "").split("."))
+    assert advertised >= (2024, 6, 0)
+
+
+def test_license_exists_and_non_empty() -> None:
+    """Verify LICENSE file exists and is non-empty."""
+    assert LICENSE_PATH.exists(), f"LICENSE file does not exist at {LICENSE_PATH}"
+    content = LICENSE_PATH.read_text(encoding="utf-8").strip()
+    assert len(content) > 0
+    assert "MIT License" in content
+    assert "NestQuest Contributors / Maniacs Mansion" in content
+
+
+def test_readme_exists_and_contains_required_sections() -> None:
+    """Verify README.md exists and documents HACS installation, manual installation, and test commands."""
+    assert README_PATH.exists(), f"README.md does not exist at {README_PATH}"
+    content = README_PATH.read_text(encoding="utf-8")
+    assert len(content.strip()) > 0
+
+    # Title and overview
+    assert "NestQuest - House Chaos Coordination" in content
+    assert "Home Assistant custom integration" in content
+
+    # Installation methods
+    assert "HACS" in content
+    assert "Manual Installation" in content or "manual installation" in content.lower()
+    assert "custom_components/nestquest" in content
+
+    # Developer Setup and Testing commands
+    assert "uv sync" in content
+    assert "uv run pytest" in content
+
+
+def test_readme_hacs_points_at_public_github_mirror() -> None:
+    """Verify README directs HACS users to the public GitHub mirror, not the private Gitea repo."""
+    content = README_PATH.read_text(encoding="utf-8")
+    assert "https://github.com/talon2king/NestQuest" in content
+    assert "https://code.cubecraftlabs.com/Maniacs_Mansion/NestQuest" in content
+    assert content.index("https://github.com/talon2king/NestQuest") < content.index(
+        "https://code.cubecraftlabs.com/Maniacs_Mansion/NestQuest"
+    )
+
+
+def test_hacs_directory_structure() -> None:
+    """Verify directory structure matches HACS integration expectations."""
+    assert MANIFEST_PATH.exists(), f"Integration manifest does not exist at {MANIFEST_PATH}"
+    with open(MANIFEST_PATH, encoding="utf-8") as f:
+        manifest = json.load(f)
+    assert manifest.get("domain") == "nestquest"
diff --git a/tests/test_harness.py b/tests/test_harness.py
new file mode 100644
index 0000000..b947990
--- /dev/null
+++ b/tests/test_harness.py
@@ -0,0 +1,86 @@
+"""Contract test for the mock-only homeassistant harness in conftest.py."""
+
+from __future__ import annotations
+
+import asyncio
+import importlib.metadata
+import inspect
+import sys
+from unittest.mock import MagicMock
+
+import pytest
+
+import conftest
+
+from conftest import _HA_MODULES, _ensure_mock_only
+
+
+def test_mock_only_harness_contract(monkeypatch):
+    """The harness is mock-only: shaped mocks everywhere, fail-fast on real HA."""
+    # Every required homeassistant module in sys.modules is a mock stand-in
+    # with the shaped surface, and parent-package attributes point at them.
+    for name in _HA_MODULES:
+        assert isinstance(sys.modules[name], MagicMock), f"{name} is not a mock"
+
+    config_entries = sys.modules["homeassistant.config_entries"]
+    assert config_entries.ConfigFlow is conftest._ConfigFlowBase
+    assert config_entries.OptionsFlowWithConfigEntry is (
+        conftest._OptionsFlowWithConfigEntryBase
+    )
+    assert sys.modules["homeassistant"].config_entries is config_entries
+    assert sys.modules["homeassistant.core"].callback is conftest._callback_decorator
+    assert sys.modules["homeassistant.data_entry_flow"].RESULT_TYPE_FORM == "form"
+
+    # No homeassistant distribution is installed in this suite's own venv.
+    with pytest.raises(importlib.metadata.PackageNotFoundError):
+        importlib.metadata.version("homeassistant")
+
+    # Fail-fast paths: a findable real HA module, or one preloaded in
+    # sys.modules, both abort collection with a UsageError.
+    real_spec = MagicMock(origin="/fake/site-packages/homeassistant/__init__.py")
+    monkeypatch.setattr(conftest, "_find_spec", lambda name: real_spec)
+    with pytest.raises(pytest.UsageError, match="mock-only"):
+        _ensure_mock_only()
+
+    monkeypatch.setattr(conftest, "_find_spec", lambda name: None)
+    monkeypatch.setitem(sys.modules, "homeassistant", MagicMock(name="real-module"))
+    with pytest.raises(pytest.UsageError, match="mock-only"):
+        _ensure_mock_only()
+
+
+async def test_hass_and_registry_run_on_the_running_test_loop(hass, make_entry):
+    """hass.loop is the test's own loop and the registry spins no private loop."""
+    # hass.loop is the very loop the async test runs on (HA running-loop
+    # contract): code scheduling on hass.loop lands on the test loop itself.
+    assert hass.loop is asyncio.get_running_loop()
+    ran = []
+
+    async def _scheduled():
+        ran.append(True)
+
+    await hass.loop.create_task(_scheduled())
+    assert ran == [True]
+
+    # ListenerRegistry never spins its own event loop (no resource leak) and
+    # dispatch is a plain coroutine: sync listeners run inline, async awaited.
+    registry = hass.registry
+    assert not hasattr(registry, "_loop")
+    assert inspect.iscoroutinefunction(registry.dispatch_options_update)
+
+    calls = []
+
+    def _sync_listener(h, entry):
+        calls.append(("sync", entry.entry_id, h is hass))
+
+    entry = make_entry(entry_id="disp")
+    registry.add("disp", _sync_listener)
+    await registry.dispatch_options_update(entry)
+    assert calls == [("sync", "disp", True)]
+
+    async def _async_listener(h, entry):
+        calls.append(("async", entry.entry_id))
+
+    registry.add("disp", _async_listener)
+    calls.clear()
+    await registry.async_dispatch_options_update(entry)
+    assert calls == [("sync", "disp", True), ("async", "disp")]
\ No newline at end of file
diff --git a/tests/test_lifecycle.py b/tests/test_lifecycle.py
new file mode 100644
index 0000000..b12ed36
--- /dev/null
+++ b/tests/test_lifecycle.py
@@ -0,0 +1,199 @@
+"""Tests for the setup/unload lifecycle of NestQuest."""
+from __future__ import annotations
+
+import asyncio
+
+from conftest import make_config_entry, make_hass, wire_entry_to_registry
+
+from custom_components.nestquest import DOMAIN, async_setup_entry, async_unload_entry
+from custom_components.nestquest.const import DOMAIN as DOMAIN_CONST
+
+
+def _wire(entry, registry):
+    return wire_entry_to_registry(entry, registry)
+
+
+async def test_setup_stores_runtime_data_in_hass_data(hass, make_entry) -> None:
+    entry = _wire(make_entry(), hass.registry)
+    assert await async_setup_entry(hass, entry) is True
+    assert entry.entry_id in hass.data[DOMAIN]
+    assert hass.data[DOMAIN][entry.entry_id] is entry.runtime_data
+
+
+async def test_setup_runtime_data_has_entry_id_and_options(hass, make_entry) -> None:
+    entry = _wire(make_entry(options={"horizon_days": 7}), hass.registry)
+    await async_setup_entry(hass, entry)
+    runtime = entry.runtime_data
+    assert runtime.entry_id == entry.entry_id
+    assert runtime.options == {"horizon_days": 7}
+    assert callable(runtime.remove_update_listener)
+
+
+async def test_unload_returns_true_and_removes_hass_data(hass, make_entry) -> None:
+    registry = hass.registry
+    entry = _wire(make_entry(), registry)
+    assert await async_setup_entry(hass, entry) is True
+    assert registry.size == 1
+    assert await async_unload_entry(hass, entry) is True
+    assert hass.data == {}
+    assert DOMAIN not in hass.data
+    assert entry.runtime_data is None
+    assert registry.size == 0
+
+
+async def test_unload_of_one_entry_keeps_domain_while_other_remains(
+    hass, make_entry
+) -> None:
+    """Unloading one of two entries keeps DOMAIN alive with the other entry."""
+    registry = hass.registry
+    entry_a = _wire(make_entry(entry_id="entry_a"), registry)
+    entry_b = _wire(make_entry(entry_id="entry_b"), registry)
+    assert await async_setup_entry(hass, entry_a) is True
+    assert await async_setup_entry(hass, entry_b) is True
+    assert set(hass.data[DOMAIN]) == {"entry_a", "entry_b"}
+
+    assert await async_unload_entry(hass, entry_a) is True
+    assert DOMAIN in hass.data
+    assert set(hass.data[DOMAIN]) == {"entry_b"}
+    assert hass.data[DOMAIN]["entry_b"] is entry_b.runtime_data
+    assert entry_a.runtime_data is None
+    assert entry_b.runtime_data is not None
+    assert registry.size == 1
+
+    assert await async_unload_entry(hass, entry_b) is True
+    assert DOMAIN not in hass.data
+    assert hass.data == {}
+    assert entry_b.runtime_data is None
+    assert registry.size == 0
+
+
+async def test_unload_is_idempotent(hass, make_entry) -> None:
+    entry = _wire(make_entry(), hass.registry)
+    assert await async_setup_entry(hass, entry) is True
+    assert await async_unload_entry(hass, entry) is True
+    assert await async_unload_entry(hass, entry) is True
+    assert DOMAIN not in hass.data
+    assert hass.data == {}
+
+
+async def test_unload_without_setup_returns_true(hass, make_entry) -> None:
+    entry = _wire(make_entry(), hass.registry)
+    assert await async_unload_entry(hass, entry) is True
+    assert DOMAIN not in hass.data
+    assert hass.data == {}
+
+
+async def test_unload_clears_entry_runtime_data(hass, make_entry) -> None:
+    entry = _wire(make_entry(), hass.registry)
+    await async_setup_entry(hass, entry)
+    await async_unload_entry(hass, entry)
+    assert entry.runtime_data is None
+
+
+async def test_unload_removes_update_listener(hass, make_entry) -> None:
+    registry = hass.registry
+    entry = _wire(make_entry(), registry)
+    await async_setup_entry(hass, entry)
+    assert registry.size == 1
+    await async_unload_entry(hass, entry)
+    assert registry.size == 0
+
+
+async def test_options_update_triggers_reload_once(hass, make_entry) -> None:
+    registry = hass.registry
+    entry = _wire(make_entry(), registry)
+    await async_setup_entry(hass, entry)
+    entry.options = {"horizon_days": 30}
+    await registry.async_dispatch_options_update(entry)
+    assert hass.config_entries.async_reload.call_count == 1
+    assert registry.reloaded == [entry.entry_id]
+
+
+async def test_no_reload_after_unload(hass, make_entry) -> None:
+    registry = hass.registry
+    entry = _wire(make_entry(), registry)
+    await async_setup_entry(hass, entry)
+    await async_unload_entry(hass, entry)
+    await registry.async_dispatch_options_update(entry)
+    assert hass.config_entries.async_reload.call_count == 0
+
+
+async def test_three_reload_cycles_keep_single_listener(hass, make_entry) -> None:
+    registry = hass.registry
+    entry = _wire(make_entry(), registry)
+    for _ in range(3):
+        assert await async_setup_entry(hass, entry) is True
+        assert registry.size == 1
+        assert await async_unload_entry(hass, entry) is True
+        assert registry.size == 0
+    assert hass.config_entries.async_reload.call_count == 0
+
+
+async def test_three_setup_unload_cycles_leave_no_listeners(hass, make_entry) -> None:
+    """Listeners accumulate per entry (HA semantics); unload must remove them all."""
+    registry = hass.registry
+    entry = _wire(make_entry(), registry)
+    for _ in range(3):
+        await async_setup_entry(hass, entry)
+        await async_unload_entry(hass, entry)
+    assert registry._listeners.get(entry.entry_id, []) == []
+    assert registry.size == 0
+
+
+async def test_options_update_after_each_setup_invokes_exactly_one_listener(
+    hass, make_entry
+) -> None:
+    """After each setup, an options update dispatches to exactly one listener."""
+    registry = hass.registry
+    entry = _wire(make_entry(), registry)
+    for _ in range(3):
+        await async_setup_entry(hass, entry)
+        await registry.async_dispatch_options_update(entry)
+        assert hass.config_entries.async_reload.call_count == 1
+        assert registry.reloaded == [entry.entry_id]
+        await async_unload_entry(hass, entry)
+        hass.config_entries.async_reload.reset_mock()
+        registry.reloaded.clear()
+
+
+async def test_reload_setup_cycles_dispatch_reload_each_time(hass, make_entry) -> None:
+    registry = hass.registry
+    entry = _wire(make_entry(), registry)
+    for _ in range(3):
+        await async_setup_entry(hass, entry)
+        await registry.async_dispatch_options_update(entry)
+        await async_unload_entry(hass, entry)
+    assert hass.config_entries.async_reload.call_count == 3
+    assert registry.size == 0
+
+
+async def test_no_orphaned_tasks_after_unload(hass, make_entry) -> None:
+    entry = _wire(make_entry(), hass.registry)
+    await async_setup_entry(hass, entry)
+    await async_unload_entry(hass, entry)
+    pending = [task for task in asyncio.all_tasks() if task is not asyncio.current_task()]
+    assert pending == []
+
+
+async def test_setup_entry_uses_domain_constant(hass, make_entry) -> None:
+    entry = _wire(make_entry(), hass.registry)
+    await async_setup_entry(hass, entry)
+    assert set(hass.data) == {DOMAIN_CONST}
+
+
+async def test_setup_awaitable_listener_removal_supported() -> None:
+    """A coroutine-returning remover is awaited during unload."""
+    removed = []
+
+    async def _remover():
+        removed.append(True)
+
+    entry = make_config_entry(entry_id="awaitable")
+    entry.add_update_listener = lambda listener: _remover
+    hass, _registry = make_hass()
+    await async_setup_entry(hass, entry)
+    result = await async_unload_entry(hass, entry)
+    assert result is True
+    assert removed == [True]
+    assert hass.data == {}
+    assert entry.runtime_data is None
\ No newline at end of file
diff --git a/tests/test_manifest.py b/tests/test_manifest.py
new file mode 100644
index 0000000..7e74f4b
--- /dev/null
+++ b/tests/test_manifest.py
@@ -0,0 +1,86 @@
+"""Tests for the manifest.json file of NestQuest."""
+from __future__ import annotations
+
+import json
+from pathlib import Path
+
+import pytest
+
+from custom_components.nestquest.const import DOMAIN
+
+MANIFEST_PATH = Path(__file__).parent.parent / "custom_components" / "nestquest" / "manifest.json"
+
+
+@pytest.fixture
+def manifest() -> dict:
+    """Load and parse manifest.json."""
+    assert MANIFEST_PATH.exists(), f"manifest.json does not exist at {MANIFEST_PATH}"
+    with open(MANIFEST_PATH, encoding="utf-8") as f:
+        data = json.load(f)
+    return data
+
+
+def test_manifest_is_valid_json(manifest: dict) -> None:
+    """Verify manifest.json is valid JSON and parsed into a dictionary."""
+    assert isinstance(manifest, dict)
+
+
+def test_manifest_domain(manifest: dict) -> None:
+    """Verify domain is nestquest."""
+    assert manifest.get("domain") == "nestquest"
+
+
+def test_manifest_domain_matches_const(manifest: dict) -> None:
+    """Verify domain matches DOMAIN constant from const.py."""
+    assert manifest.get("domain") == DOMAIN
+
+
+def test_manifest_version(manifest: dict) -> None:
+    """Verify version is a non-empty string."""
+    assert isinstance(manifest.get("version"), str)
+    assert len(manifest["version"]) > 0
+
+
+def test_manifest_config_flow(manifest: dict) -> None:
+    """Verify config_flow is True."""
+    assert manifest.get("config_flow") is True
+
+
+def test_manifest_iot_class(manifest: dict) -> None:
+    """Verify iot_class is local_polling."""
+    assert manifest.get("iot_class") == "local_polling"
+
+
+def test_manifest_requirements(manifest: dict) -> None:
+    """Verify requirements is an empty list."""
+    assert manifest.get("requirements") == []
+
+
+def test_manifest_documentation_url_is_public_github_mirror(manifest: dict) -> None:
+    """Verify documentation URL points at the public GitHub mirror."""
+    assert manifest.get("documentation") == "https://github.com/talon2king/NestQuest"
+
+
+def test_manifest_issue_tracker_url_is_public_github_mirror(manifest: dict) -> None:
+    """Verify issue_tracker URL points at the public GitHub mirror."""
+    assert manifest.get("issue_tracker") == "https://github.com/talon2king/NestQuest/issues"
+
+
+@pytest.mark.parametrize("key", ["documentation", "issue_tracker"])
+def test_manifest_urls_use_github_com(manifest: dict, key: str) -> None:
+    """Verify manifest URLs use github.com rather than the private Gitea host."""
+    url = manifest.get(key, "")
+    assert url.startswith("https://github.com/talon2king/NestQuest")
+    assert "cubecraftlabs" not in url
+
+
+@pytest.mark.parametrize(
+    "key",
+    ["name", "version", "documentation", "issue_tracker", "codeowners"],
+)
+def test_manifest_required_keys_exist_and_non_empty(manifest: dict, key: str) -> None:
+    """Verify required keys exist and are non-empty."""
+    assert key in manifest, f"Key '{key}' missing from manifest.json"
+    val = manifest[key]
+    assert val is not None, f"Key '{key}' is None"
+    assert len(val) > 0, f"Key '{key}' is empty"
diff --git a/tests/test_options_flow.py b/tests/test_options_flow.py
new file mode 100644
index 0000000..9b8dad8
--- /dev/null
+++ b/tests/test_options_flow.py
@@ -0,0 +1,376 @@
+"""Tests for the options flow of NestQuest."""
+from __future__ import annotations
+
+import ast
+import asyncio
+import json
+from pathlib import Path
+from types import SimpleNamespace
+
+import pytest
+
+from conftest import make_config_entry, make_hass, options_flow_base as _options_flow_base
+
+from custom_components.nestquest import config_flow
+from custom_components.nestquest import options_flow
+from custom_components.nestquest.const import (
+    CONF_DAY_ROLLOVER_TIME,
+    CONF_HORIZON_DAYS,
+    CONF_PANEL_IDLE_TIMEOUT,
+    DEFAULT_DAY_ROLLOVER_TIME,
+    DEFAULT_HORIZON_DAYS,
+    DEFAULT_PANEL_IDLE_TIMEOUT,
+    DOMAIN,
+)
+
+PKG_DIR = Path(options_flow.__file__).parent
+STRINGS_PATH = PKG_DIR / "strings.json"
+TRANSLATIONS_EN_PATH = PKG_DIR / "translations" / "en.json"
+
+VALID_INPUT = {
+    CONF_HORIZON_DAYS: 7,
+    CONF_DAY_ROLLOVER_TIME: "03:30",
+    CONF_PANEL_IDLE_TIMEOUT: 60,
+}
+
+
+def _run(coro):
+    return asyncio.new_event_loop().run_until_complete(coro)
+
+
+def _make_hass():
+    return make_hass()
+
+
+def _make_entry(entry_id: str = "test_entry", options: dict | None = None, data: dict | None = None):
+    return make_config_entry(entry_id=entry_id, options=options, data=data)
+
+
+def _make_flow(entry) -> options_flow.NestQuestOptionsFlow:
+    """Create an options flow instance bound to a stubbed config entry."""
+    flow = options_flow.NestQuestOptionsFlow(config_entry=entry)
+    flow.hass = SimpleNamespace()
+    return flow
+
+
+def _schema_values(schema) -> dict:
+    """Extract the per-field default values from a real voluptuous schema."""
+    return {
+        marker.schema: marker.default()
+        for marker in schema.schema
+        if hasattr(marker, "schema")
+    }
+
+
+def test_options_flow_reachable_via_configure_button() -> None:
+    """The config flow exposes async_get_options_flow returning the options flow."""
+    entry = _make_entry()
+    handler = config_flow.NestQuestConfigFlow.async_get_options_flow(entry)
+    assert isinstance(handler, options_flow.NestQuestOptionsFlow)
+    assert handler.config_entry is entry
+
+
+def test_options_flow_get_options_flow_is_ha_callback() -> None:
+    """async_get_options_flow is wrapped by the homeassistant.core.callback decorator."""
+    assert getattr(
+        config_flow.NestQuestConfigFlow.async_get_options_flow, "__ha_callback__", False
+    ) is True
+
+
+def test_options_flow_constructs_through_2024_6_surface() -> None:
+    """The handler constructs against the mocked 2024.6 base and inherits its contract."""
+    entry = _make_entry(options={CONF_HORIZON_DAYS: 21})
+    flow = options_flow.NestQuestOptionsFlow(config_entry=entry)
+    assert isinstance(flow, _options_flow_base())
+    assert flow.config_entry is entry
+    assert flow.options == {CONF_HORIZON_DAYS: 21}
+
+
+def test_options_flow_submits_through_2024_6_surface() -> None:
+    """The handler can be submitted through the mocked 2024.6-shaped surface."""
+    entry = _make_entry()
+    handler = config_flow.NestQuestConfigFlow.async_get_options_flow(entry)
+    result = _run(handler.async_step_init(dict(VALID_INPUT)))
+    assert result["type"] == "create_entry"
+    assert result["title"] == "NestQuest"
+    assert result["data"] == VALID_INPUT
+
+
+def test_options_flow_shows_form_initially() -> None:
+    """The init step shows a form."""
+    flow = _make_flow(_make_entry())
+    result = _run(flow.async_step_init(None))
+    assert result["type"] == "form"
+    assert result["step_id"] == "init"
+
+
+def test_options_flow_schema_is_voluptuous() -> None:
+    """The form's data_schema is a real voluptuous Schema (no dict fallback)."""
+    flow = _make_flow(_make_entry())
+    result = _run(flow.async_step_init(None))
+    import voluptuous as vol
+
+    assert isinstance(result["data_schema"], vol.Schema)
+
+
+def test_options_flow_prefills_from_defaults() -> None:
+    """Without stored options, the form pre-fills with the constant defaults."""
+    flow = _make_flow(_make_entry())
+    result = _run(flow.async_step_init(None))
+    values = _schema_values(result["data_schema"])
+    assert values[CONF_HORIZON_DAYS] == DEFAULT_HORIZON_DAYS
+    assert values[CONF_DAY_ROLLOVER_TIME] == DEFAULT_DAY_ROLLOVER_TIME
+    assert values[CONF_PANEL_IDLE_TIMEOUT] == DEFAULT_PANEL_IDLE_TIMEOUT
+
+
+def test_options_flow_prefills_from_entry_options() -> None:
+    """Stored entry options win over entry data and defaults."""
+    entry = _make_entry(
+        options={
+            CONF_HORIZON_DAYS: 21,
+            CONF_DAY_ROLLOVER_TIME: "05:45",
+            CONF_PANEL_IDLE_TIMEOUT: 120,
+        },
+        data={
+            CONF_HORIZON_DAYS: 99,
+            CONF_DAY_ROLLOVER_TIME: "23:59",
+            CONF_PANEL_IDLE_TIMEOUT: 999,
+        },
+    )
+    result = _run(_make_flow(entry).async_step_init(None))
+    values = _schema_values(result["data_schema"])
+    assert values[CONF_HORIZON_DAYS] == 21
+    assert values[CONF_DAY_ROLLOVER_TIME] == "05:45"
+    assert values[CONF_PANEL_IDLE_TIMEOUT] == 120
+
+
+def test_options_flow_falls_back_to_entry_data() -> None:
+    """Pre-upgrade entries without options fall back to entry.data."""
+    entry = _make_entry(
+        data={
+            CONF_HORIZON_DAYS: 10,
+            CONF_DAY_ROLLOVER_TIME: "01:15",
+            CONF_PANEL_IDLE_TIMEOUT: 90,
+        }
+    )
+    result = _run(_make_flow(entry).async_step_init(None))
+    values = _schema_values(result["data_schema"])
+    assert values[CONF_HORIZON_DAYS] == 10
+    assert values[CONF_DAY_ROLLOVER_TIME] == "01:15"
+    assert values[CONF_PANEL_IDLE_TIMEOUT] == 90
+
+
+def test_options_flow_schema_applies_stored_defaults() -> None:
+    """A real voluptuous validate({}) fills every field from the stored defaults."""
+    entry = _make_entry(
+        options={
+            CONF_HORIZON_DAYS: 21,
+            CONF_DAY_ROLLOVER_TIME: "05:45",
+            CONF_PANEL_IDLE_TIMEOUT: 120,
+        }
+    )
+    result = _run(_make_flow(entry).async_step_init(None))
+    assert result["data_schema"]({}) == {
+        CONF_HORIZON_DAYS: 21,
+        CONF_DAY_ROLLOVER_TIME: "05:45",
+        CONF_PANEL_IDLE_TIMEOUT: 120,
+    }
+
+
+def test_options_flow_schema_coerces_field_types() -> None:
+    """The schema validates the expected field types via voluptuous."""
+    flow = _make_flow(_make_entry())
+    result = _run(flow.async_step_init(None))
+    schema = result["data_schema"]
+    validators = {marker.schema: validator for marker, validator in schema.schema.items()}
+    assert validators[CONF_HORIZON_DAYS] is int
+    assert validators[CONF_DAY_ROLLOVER_TIME] is str
+    assert validators[CONF_PANEL_IDLE_TIMEOUT] is int
+
+
+@pytest.mark.parametrize("bad_horizon", [0, -5])
+def test_options_flow_rejects_non_positive_horizon(bad_horizon: int) -> None:
+    """Zero or negative horizon values yield a field-level error, no exception."""
+    flow = _make_flow(_make_entry())
+    result = _run(
+        flow.async_step_init({**VALID_INPUT, CONF_HORIZON_DAYS: bad_horizon})
+    )
+    assert result["type"] == "form"
+    assert result["errors"] == {CONF_HORIZON_DAYS: "invalid"}
+
+
+def test_options_flow_rejects_malformed_time_not_a_time() -> None:
+    """Non-HH:MM strings are rejected with invalid_time."""
+    flow = _make_flow(_make_entry())
+    result = _run(
+        flow.async_step_init({**VALID_INPUT, CONF_DAY_ROLLOVER_TIME: "noon"})
+    )
+    assert result["type"] == "form"
+    assert result["errors"] == {CONF_DAY_ROLLOVER_TIME: "invalid_time"}
+
+
+def test_options_flow_rejects_malformed_time_out_of_range() -> None:
+    """Out-of-range HH:MM values are rejected with invalid_time."""
+    flow = _make_flow(_make_entry())
+    result = _run(
+        flow.async_step_init({**VALID_INPUT, CONF_DAY_ROLLOVER_TIME: "25:99"})
+    )
+    assert result["type"] == "form"
+    assert result["errors"] == {CONF_DAY_ROLLOVER_TIME: "invalid_time"}
+
+
+def test_options_flow_rejects_pasted_unicode_superscript_time() -> None:
+    """Pasted Unicode digits like '²²:²²' yield a field-level error, no exception."""
+    flow = _make_flow(_make_entry())
+    result = _run(
+        flow.async_step_init({**VALID_INPUT, CONF_DAY_ROLLOVER_TIME: "²²:²²"})
+    )
+    assert result["type"] == "form"
+    assert result["errors"] == {CONF_DAY_ROLLOVER_TIME: "invalid_time"}
+
+
+@pytest.mark.parametrize("bad_timeout", ["abc", 0, -10, 10])
+def test_options_flow_rejects_invalid_idle_timeout(bad_timeout) -> None:
+    """Non-numeric or too-low idle timeouts yield a field-level error."""
+    flow = _make_flow(_make_entry())
+    result = _run(
+        flow.async_step_init({**VALID_INPUT, CONF_PANEL_IDLE_TIMEOUT: bad_timeout})
+    )
+    assert result["type"] == "form"
+    assert result["errors"] == {CONF_PANEL_IDLE_TIMEOUT: "invalid"}
+
+
+def test_options_flow_creates_entry_with_three_keys() -> None:
+    """A valid submit creates an entry with exactly the three validated keys."""
+    flow = _make_flow(_make_entry())
+    result = _run(flow.async_step_init(dict(VALID_INPUT)))
+    assert result["type"] == "create_entry"
+    assert result["title"] == "NestQuest"
+    assert set(result["data"]) == {
+        CONF_HORIZON_DAYS,
+        CONF_DAY_ROLLOVER_TIME,
+        CONF_PANEL_IDLE_TIMEOUT,
+    }
+    assert result["data"] == VALID_INPUT
+
+
+def test_options_flow_create_entry_data_lands_in_entry_options_and_reloads_once() -> None:
+    """The flow's created data is written to entry.options and reloads exactly once."""
+    hass, registry = _make_hass()
+    entry = _make_entry()
+    entry.add_update_listener = lambda listener: registry.add(entry.entry_id, listener)
+
+    # Simulate setup registering the merged lifecycle update listener.
+    from custom_components.nestquest import async_setup_entry
+
+    _run(async_setup_entry(hass, entry))
+
+    # Run the options flow and apply its created data to entry.options like HA does.
+    flow = _make_flow(entry)
+    result = _run(flow.async_step_init(dict(VALID_INPUT)))
+    assert result["type"] == "create_entry"
+    entry.options = dict(result["data"])
+
+    _run(registry.dispatch_options_update(entry))
+    assert hass.config_entries.async_reload.call_count == 1
+    assert registry.reloaded == [entry.entry_id]
+    assert entry.options == VALID_INPUT
+
+
+def test_options_flow_validation_never_raises() -> None:
+    """Validation returns errors instead of raising for arbitrary junk input."""
+    junk = {CONF_HORIZON_DAYS: None, CONF_DAY_ROLLOVER_TIME: None, CONF_PANEL_IDLE_TIMEOUT: None}
+    flow = _make_flow(_make_entry())
+    result = _run(flow.async_step_init(junk))
+    assert result["type"] == "form"
+    assert result["errors"] == {
+        CONF_HORIZON_DAYS: "invalid",
+        CONF_DAY_ROLLOVER_TIME: "invalid_time",
+        CONF_PANEL_IDLE_TIMEOUT: "invalid",
+    }
+
+
+@pytest.fixture
+def strings() -> dict:
+    """Load and parse strings.json."""
+    assert STRINGS_PATH.exists(), f"strings.json does not exist at {STRINGS_PATH}"
+    with open(STRINGS_PATH, encoding="utf-8") as f:
+        return json.load(f)
+
+
+@pytest.fixture
+def translations_en() -> dict:
+    """Load and parse translations/en.json."""
+    assert TRANSLATIONS_EN_PATH.exists(), (
+        f"translations/en.json does not exist at {TRANSLATIONS_EN_PATH}"
+    )
+    with open(TRANSLATIONS_EN_PATH, encoding="utf-8") as f:
+        return json.load(f)
+
+
+def test_options_strings_present_and_matching(strings: dict, translations_en: dict) -> None:
+    """Both string files carry identical options step/error strings."""
+    assert strings.get("options") == translations_en.get("options")
+    options = strings["options"]
+    init = options["step"]["init"]
+    assert init["title"]
+    assert init["description"]
+    data = init["data"]
+    for key in (CONF_HORIZON_DAYS, CONF_DAY_ROLLOVER_TIME, CONF_PANEL_IDLE_TIMEOUT):
+        assert data.get(key), f"Missing field name for '{key}'"
+    errors = options["errors"]
+    for key in ("invalid", "invalid_time"):
+        assert errors.get(key), f"Missing error string for '{key}'"
+
+
+def test_options_strings_no_raw_keys(strings: dict, translations_en: dict) -> None:
+    """No placeholder/raw keys appear in the options strings."""
+
+    def check(value) -> None:
+        if isinstance(value, dict):
+            for key, val in value.items():
+                assert val, f"Empty string value for key '{key}'"
+                check(val)
+        elif isinstance(value, str):
+            assert value.strip() != ""
+
+    check(strings["options"])
+    check(translations_en["options"])
+
+
+def test_options_flow_no_plain_dict_schema_fallback() -> None:
+    """No try/except ImportError fallback for voluptuous in the options flow module."""
+    py_file = Path(options_flow.__file__)
+    tree = ast.parse(py_file.read_text(encoding="utf-8"), filename=str(py_file))
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Try):
+            handlers = node.handlers or []
+            has_import_error_handler = any(
+                getattr(handler.type, "id", getattr(handler.type, "attr", None))
+                == "ImportError"
+                for handler in handlers
+            )
+            assert not has_import_error_handler, (
+                f"Plain-dict schema fallback (try/except ImportError) found in {py_file.name}:{node.lineno}"
+            )
+
+
+def test_options_flow_subclasses_options_flow_with_config_entry() -> None:
+    """NestQuestOptionsFlow subclasses config_entries.OptionsFlowWithConfigEntry."""
+    base = _options_flow_base()
+    assert issubclass(options_flow.NestQuestOptionsFlow, base)
+    assert options_flow.NestQuestOptionsFlow.__bases__ == (base,)
+
+
+def test_options_flow_no_hardcoded_domain_or_db_filename() -> None:
+    """The options flow module does not hardcode the domain or db filename."""
+    py_file = Path(options_flow.__file__)
+    tree = ast.parse(py_file.read_text(encoding="utf-8"), filename=str(py_file))
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Constant) and isinstance(node.value, str):
+            assert node.value != DOMAIN, (
+                f"Hard-coded domain string in {py_file.name}:{node.lineno}"
+            )
+            assert node.value != "nestquest.db", (
+                f"Hard-coded database filename in {py_file.name}:{node.lineno}"
+            )
\ No newline at end of file
diff --git a/tests/test_store.py b/tests/test_store.py
new file mode 100644
index 0000000..95866b4
--- /dev/null
+++ b/tests/test_store.py
@@ -0,0 +1,151 @@
+"""Tests for store.py of NestQuest."""
+from __future__ import annotations
+
+import ast
+import asyncio
+from pathlib import Path
+from unittest.mock import AsyncMock, MagicMock
+
+from custom_components.nestquest import store
+from custom_components.nestquest.const import SQLITE_DB_FILENAME
+
+
+def _run(coro):
+    return asyncio.new_event_loop().run_until_complete(coro)
+
+
+def _make_hass(config_dir: Path, execute: bool = True):
+    hass = MagicMock()
+    hass.config.path = MagicMock(return_value=str(config_dir / SQLITE_DB_FILENAME))
+    hass.async_add_executor_job = AsyncMock(
+        side_effect=(lambda fn, *a: fn(*a)) if execute else None
+    )
+    return hass
+
+
+def test_returns_absolute_path_from_config_path() -> None:
+    hass = _make_hass(Path("/config"), execute=False)
+    db_path = _run(store.async_get_db_path(hass))
+    hass.config.path.assert_called_once_with(SQLITE_DB_FILENAME)
+    assert db_path == Path("/config") / SQLITE_DB_FILENAME
+    assert db_path.is_absolute()
+
+
+def test_relative_config_path_is_normalized_to_absolute(tmp_path, monkeypatch) -> None:
+    monkeypatch.chdir(tmp_path)
+    hass = MagicMock()
+    hass.config.path = MagicMock(return_value="relative-config/" + SQLITE_DB_FILENAME)
+    hass.async_add_executor_job = AsyncMock(side_effect=(lambda fn, *a: fn(*a)))
+    db_path = _run(store.async_get_db_path(hass))
+    assert db_path.is_absolute()
+    assert db_path.name == SQLITE_DB_FILENAME
+    assert str(db_path).endswith("relative-config/" + SQLITE_DB_FILENAME)
+    assert db_path.parent.is_dir()
+    assert (tmp_path / "relative-config").is_dir()
+    assert not db_path.exists()
+
+
+def test_creates_missing_parent_directory(tmp_path) -> None:
+    nested = tmp_path / "homeassistant" / "config"
+    hass = _make_hass(nested)
+    db_path = _run(store.async_get_db_path(hass))
+    assert db_path.parent == nested
+    assert nested.is_dir()
+    assert db_path.parent.is_dir()
+    assert not db_path.exists()
+
+
+def test_two_calls_return_same_path(tmp_path) -> None:
+    hass = _make_hass(tmp_path)
+    first = _run(store.async_get_db_path(hass))
+    second = _run(store.async_get_db_path(hass))
+    assert first == second
+    assert first.parent.is_dir()
+    assert not first.exists()
+    assert not second.exists()
+
+
+def test_existing_directory_does_not_fail(tmp_path) -> None:
+    nested = tmp_path / "config"
+    nested.mkdir()
+    hass = _make_hass(nested)
+    db_path = _run(store.async_get_db_path(hass))
+    assert db_path == nested / SQLITE_DB_FILENAME
+    assert db_path.parent.is_dir()
+    assert not db_path.exists()
+
+
+def test_mkdir_runs_via_executor(tmp_path) -> None:
+    nested = tmp_path / "deep" / "nested"
+    hass = _make_hass(nested)
+    db_path = _run(store.async_get_db_path(hass))
+    assert nested.is_dir()
+    hass.async_add_executor_job.assert_called_once()
+    args, kwargs = hass.async_add_executor_job.call_args
+    fn, fn_args = args[0], args[1:]
+    assert callable(fn)
+    assert fn is store._ensure_dir
+    assert fn_args == (nested,)
+    assert kwargs == {}
+    assert db_path.parent == nested
+    assert db_path.parent.is_dir()
+    assert not db_path.exists()
+
+
+def test_executor_helper_creates_directory(tmp_path) -> None:
+    nested = tmp_path / "executor" / "made"
+    store._ensure_dir(nested)
+    assert nested.is_dir()
+    store._ensure_dir(nested)
+    assert nested.is_dir()
+
+
+def test_no_sqlite3_import_in_package() -> None:
+    pkg_dir = Path(store.__file__).parent
+    py_files = list(pkg_dir.glob("*.py"))
+    assert py_files
+    for py_file in py_files:
+        tree = ast.parse(py_file.read_text(encoding="utf-8"), filename=str(py_file))
+        for node in ast.walk(tree):
+            if isinstance(node, ast.Import):
+                for alias in node.names:
+                    assert alias.name != "sqlite3", (
+                        f"Found sqlite3 import in {py_file.name}:{node.lineno}"
+                    )
+            elif isinstance(node, ast.ImportFrom) and node.module == "sqlite3":
+                raise AssertionError(
+                    f"Found sqlite3 import in {py_file.name}:{node.lineno}"
+                )
+
+
+def test_no_file_creation_calls_in_store() -> None:
+    source = Path(store.__file__).read_text(encoding="utf-8")
+    tree = ast.parse(source, filename=str(store.__file__))
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Call):
+            func = node.func
+            if isinstance(func, ast.Name) and func.id == "open":
+                raise AssertionError(
+                    f"Found open() call in store.py:{node.lineno}"
+                )
+            if (
+                isinstance(func, ast.Attribute)
+                and func.attr == "touch"
+            ):
+                raise AssertionError(
+                    f"Found touch() call in store.py:{node.lineno}"
+                )
+    assert "touch(" not in source
+    assert "open(" not in source
+
+
+def test_container_style_path_resolves() -> None:
+    hass = _make_hass(Path("/config"), execute=False)
+    assert _run(store.async_get_db_path(hass)) == Path("/config") / SQLITE_DB_FILENAME
+
+
+def test_core_style_path_resolves(tmp_path) -> None:
+    config_dir = tmp_path / ".homeassistant"
+    hass = _make_hass(config_dir)
+    assert _run(store.async_get_db_path(hass)) == config_dir / SQLITE_DB_FILENAME
+    assert (config_dir / SQLITE_DB_FILENAME).parent.is_dir()
\ No newline at end of file
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