Constant WORKSPACE_ROOT_PLACEHOLDER 

pub const WORKSPACE_ROOT_PLACEHOLDER: &'static str;

The literal placeholder a declared command carries where the server’s workspace root belongs.

Defined by the LANGUAGE crate, not here. It is a token of the documents this server executes, and the AWL checker refuses a harness path setting by the same spelling this module splices — one definition in the crate both already depend on is that agreement, where a second copy would be the drift. The literal a harness path setting carries where the box’s workspace root belongs.

Braces are literal text to the AWL lexer and to the worker SDK’s command template ($name/${name} are its only parameter forms), so a value carrying this checks clean and — if it ever reached a launch unexpanded — would fail loudly on a nonexistent {workspace_root} path rather than silently launching somewhere else.