Preserve option terminator in subcommand arguments for subcommand to process

[shadowspawn]

Problem

The option delimiter is stripped during top level pass of arguments by root command before the subcommand sees the arguments. This works for internal subcommands (action handler) because the following arguments are marked as having been processed. This does not work for external subcommands which just get the arguments without the option terminator and following options get processed as normal.

Issue: #2530

Solution

Leave the option terminator and the remaining arguments as "unknown" for the subcommand to reprocess. This works for both internal and external commands.

The option terminator tests were weak. Beefed them up to cover the external case and more besides.

This is a change in core behaviour, so marking PR as semver-major.

ChangeLog

• Breaking: preserve option terminator in subcommand arguments until subcommand parsing, so passed to external subcommand (Preserve option terminator in subcommand arguments for subcommand to process #2577)

[Copilot]

Pull request overview

This PR changes Commander’s option-terminator (--) handling so that when the parent command is dispatching to a subcommand (including executable subcommands), the delimiter and remaining arguments are preserved for the subcommand to reprocess—fixing the external-subcommand case described in #2530.

Changes:

• Update parseOptions to retain -- and remaining args as unknown when the first operand is a known subcommand, so dispatch passes them through unchanged (including to executable subcommands).
• Expand and strengthen tests around -- handling across top-level parsing, in-process subcommands, default commands, and executable subcommands.
• Refactor the delimiter tests to use a shared helper for consistent option setup.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
lib/command.js	Preserves -- for subcommand dispatch by moving the delimiter and remaining args into unknown when a subcommand is detected.
tests/args.literal.test.js	Adds broader coverage for delimiter behavior, including executable subcommand pass-through and multiple edge cases.

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