diff --git a/pyproject.toml b/pyproject.toml
index f4e7dc9..75f2b14 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -29,6 +29,10 @@ dependencies = [
     "pathsim",
     "numpy>=1.15,<2",
     "scipy>=1.2",
+    # If a dependency ships native code that can't be installed in Pyodide,
+    # tag it with `; sys_platform != 'emscripten'` so a normal pip install
+    # still pulls it eagerly but micropip in the browser skips it. Pair
+    # this with a defensive re-export in `pathsim_vehicle/__init__.py`.
 ]
 
 [project.optional-dependencies]