Unclear It is not clear which source supplies the fastMode value that overrides --fast-mode.
What
Claude Code has a new command-line option, --fast-mode, that you add when starting it. It accepts only two values, on and off; any other value is ignored. The option is hidden, so it does not appear in the help text.
If a fastMode value is already set somewhere else, that value wins and the option is ignored. Otherwise the option decides whether fast mode is used.
Why
This gives a way to choose fast mode for a single launch without changing settings, which is likely most useful for programs that start Claude Code themselves.
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It is not clear which source supplies the `fastMode` value that overrides `--fast-mode`.