Function is_native_source_path 

pub fn is_native_source_path(path: &str) -> bool

Whether path names a native (.brink) source file, compared case-insensitively — [file_language] narrowed to a boolean, and public for the same reason has_recognized_source_extension is (issue #2368): brink-lsp carried two of its own ad-hoc, case-sensitive ext == "brink" copies (crates/brink-lsp/src/backend.rs’s is_native_path and crates/brink-lsp/src/backend/projects.rs’s function of the same name) for a classification this crate already performs correctly — a real .BRINK file on a case-insensitive filesystem must classify identically to .brink, not silently fall through to “not native” the way ext == "brink" alone would.