The devshell copied assets from the Nix store with preserved mode bits, which left files in appview/pages/static read-only and caused repeated cp permission errors on subsequent nix develop runs. Stop preserving mode so generated static files remain writable across shell entries. AI-assisted: OpenCode (openai/gpt-5.3-codex) Signed-off-by: Alessio Caiazza <code.git@caiazza.info>