Code kept as written (an example's `ui.tsx`, a file in a marked directory) is edited like any file: `tcm edit` writes it out, and `tcm update <file> --into <namespace>` saves it back as written, not as definitions.
A file without an extension (`Dockerfile`, `Makefile`) or a hidden one (`.gitignore`) is kept as written, not read as code: added into a namespace, written out by `tcm edit` under its own name (a hidden one's dot and all), checked and saved back with `--into`, patched, and exported as it's named.