v0.4.0

Added

• #| header line: pipe the preceding #> block through a command and
  optionally bind the captured output to an environment variable.
  • #| CMD ARGS... => NAME — pipe block through CMD; bind stdout to $NAME.
  • #| CMD ARGS... — pipe block through CMD; stdout inherited (side effect).
  • #| => NAME — bind block content directly to $NAME without running a command.
  • #| must immediately follow a run of #> lines.
• #$ header line: run a command independently (stdin from /dev/null) and
  optionally bind the captured output to an environment variable.
  • #$ CMD ARGS... => NAME — run CMD; bind stdout to $NAME.
  • #$ CMD ARGS... — run CMD; stdout inherited (side effect).
  • The command is mandatory; omitting it is a parse error.
• Both #| and #$ tokenise their command line identically to #: lines
  (full quoting and variable substitution), excluding the trailing => NAME.
• Trailing newlines are stripped from captured output, matching shell $(...).
• Stderr from subcommands is inherited (passes through to the terminal).
• New exit code 6 (EXIT_SUBCOMMAND_FAILURE) when a subcommand exits non-zero.
• #| and #$ are forbidden inside --load-file files.
• --dry-run suppresses subcommand execution.

Changed

• All header effects (--chdir, --umask, --unset, #|, #$, environment
  bindings) are now applied immediately and in order at header-processing time.
  A subcommand can only see the options and bindings that precede it.
• Security: scripts containing #| or #$ execute commands during script
  loading, before the main interpreter is launched. Do not run herescript
  scripts from untrusted sources.
• --unset-undefined is now order-dependent: it must appear before the
  --unset directives it governs (previously documented as applying globally
  regardless of order).