## Why
Codex-created linked worktrees do not include ignored files from the
main worktree. Bazel users who keep local overrides in `user.bazelrc`
therefore lose those settings in every new worktree.
The setup must also work on Windows and must not overwrite a file that
already exists in the worktree.
## What changed
The checked-in Codex environment now invokes
`.codex/environments/setup.py`. The script resolves the main worktree
and current worktree, then uses
`copy_from_main_worktree_to_worktree(repo_relative_path)` to copy
ignored files into new worktrees without overwriting existing
destinations.
`main()` currently copies `user.bazelrc`. Additional repository-relative
paths can be added as further calls to the same helper.
## Validation
- Ran the setup script in a linked worktree and confirmed it handles a
missing main-worktree `user.bazelrc`.
- Verified the helper copies a main-worktree file, preserves an existing
worktree file, and creates parent directories for a nested path.
Adam Perry @ OpenAI