Add documentation page for the Cync by GE integration (#40250)

Co-authored-by: c0ffeeca7 <[email protected]>
Co-authored-by: Joost Lekkerkerker <[email protected]>

Author: 3 people

source/_integrations/cync.markdown

@@ -0,0 +1,62 @@
+---
+title: Cync
+description: Instructions on how to integrate Cync devices into Home Assistant.
+ha_release: "2025.10"
+ha_iot_class: Cloud Push
+ha_category:
+  - light
+ha_codeowners:
+  - '@Kinachi249'
+ha_domain: cync
+ha_integration_type: integration
+ha_platforms:
+  - light
+ha_quality_scale: bronze
+---
+
+The **Cync** {% term integration %} is used to integrate with smart devices sold by [GE Lighting](https://www.gelighting.com/). Cync, formerly known as "C by GE", is the name given to GE Lighting's line of smart devices.
+
+## Prerequisites
+
+- A Cync account is required to use this integration.
+- Any device you wish to add to Home Assistant must first be set up via the Cync app.
+- At least one Wi-Fi connected device is required to be set up in your Cync account.
+  - Older, Bluetooth-only Cync devices may not be recognized by the integration without a Cync bridge device.
+
+{% include integrations/config_flow.md %}
+
+{% configuration_basic %}
+Email:
+    description: Your Cync account's email address
+Password:
+    description: Your Cync account's password
+{% endconfiguration_basic %}
+
+## Supported functionality
+
+The **Cync** integration provides the following entities.
+
+### Lights
+
+- Supported operations:
+  - On/Off
+  - Brightness*
+  - Color temperature*
+  - RGB color*
+
+*If supported by device.
+
+## Known limitations
+
+- The following lighting features are not yet supported:
+  - Dynamic effects
+  - Light shows
+  - Music shows
+  - LED strip segment control
+- Cync servers only allow one instance of your account to connect at a time. If you open the Cync app while Home Assistant is running, the integration will briefly lose its connection. It will automatically reconnect after a 10 second waiting period.
+
+## Removing the integration
+
+This integration follows standard integration removal.
+
+{% include integrations/remove_device_service.md %}