Function project_context_request 

pub fn project_context_request(
    buffer_id: u64,
    path: Option<&Path>,
    line_count: u32,
) -> ContextRequest

Build the owned context-request the host hands a producer (host→guest, one-way).

A non-UTF-8 path drops to None rather than failing the trigger: a context producer keys off the tree, not the path text, so an un-representable path costs it nothing. (Same call as project_decoration_context makes, for the same reason.)