Constant DEV_URL_ENV 

pub const DEV_URL_ENV: &str = "WATERUI_DEV_URL";

The environment variable that carries the dev-server URL to a debug app.

Every launch channel reduces to this name: desktop spawns it directly, simctl launch forwards it as SIMCTL_CHILD_WATERUI_DEV_URL, devicectl device process launch carries it in the -e environment dictionary, and Android ships it as the waterui.env.WATERUI_DEV_URL intent extra that the generated MainActivity turns back into an environment variable before the runtime initializes.