1 files changed, 36 insertions, 0 deletions
diff --git a/packages/lsp/src/language.ts b/packages/lsp/src/language.ts
new file mode 100644
index 0000000..214294e
--- /dev/null
+++ b/packages/lsp/src/language.ts
@@ -0,0 +1,36 @@
+/**
+ * Language ID mapping from file extensions.
+ */
+
+const extensionMap: Record<string, string> = {
+	".ts": "typescript",
+	".tsx": "typescriptreact",
+	".mts": "typescript",
+	".cts": "typescript",
+	".js": "javascript",
+	".jsx": "javascriptreact",
+	".mjs": "javascript",
+	".cjs": "javascript",
+	".json": "json",
+	".lua": "lua",
+	".luau": "luau",
+	".py": "python",
+	".rs": "rust",
+	".go": "go",
+	".md": "markdown",
+	".yaml": "yaml",
+	".yml": "yaml",
+	".toml": "toml",
+	".css": "css",
+	".html": "html",
+	".sh": "shellscript",
+	".bash": "shellscript",
+	".zsh": "shellscript",
+};
+
+export function languageId(filePath: string): string {
+	const dotIdx = filePath.lastIndexOf(".");
+	if (dotIdx === -1) return "unknown";
+	const ext = filePath.slice(dotIdx).toLowerCase();
+	return extensionMap[ext] ?? "unknown";
+}