Add heuristic parsing when command flag json is missing.

A command missing a flag json file will conservatively assume all arguments are operands. The parser can be extended to have some lightweight heuristics (e.g., consider all arguments with a `-` prefix as flags).

This can be useful to correctly parse more commands without additional effort.

Start by locating the command parser and the handling for a missing flag json file. Review any existing parser tests or command-parsing entry points before adding the lightweight heuristic described in the issue. Done means arguments with a `-` prefix can be recognized as flags while other arguments remain operands when no flag json file is available.

Written by the indexing model from the issue text.