Hook commands get an extra preparation step before they start

Hooks are your own commands or scripts that Claude Code runs at set moments. Before starting a hook, Claude Code now runs an extra step on the hook's environment variables, the values passed to the command.

In a diskless session, which keeps nothing on disk, a command or script hook that got past the check meant to hold it back is not run. That case is now reported as a proper error rather than a bare message.