ruff/docs/preview.md

Preview

Ruff includes an opt-in preview mode to provide an opportunity for community feedback and increase confidence that changes are a net-benefit before enabling them for everyone.

Preview mode enables a collection of newer rules and fixes that are considered experimental or unstable.

Enabling preview mode

Preview mode can be enabled with the --preview flag on the CLI or by setting preview = true in your Ruff configuration file (e.g. pyproject.toml).

Using rules that are in preview

If a rule is marked as preview, it can only be selected if preview mode is enabled. For example, consider a hypothetical rule, HYP001. If HYP001 were in preview, it would not be enabled by adding following to your pyproject.toml:

[tool.ruff]
extend-select = ["HYP001"]

It also would not be enabled by selecting the HYP category, like so:

[tool.ruff]
extend-select = ["HYP"]

Similarly, it would not be enabled via the ALL selector:

[tool.ruff]
select = ["ALL"]

However, it would be enabled in any of the above cases if you you enabled preview in your configuration file:

[tool.ruff]
extend-select = ["HYP"]
preview = true

Or, if you provided the --preview CLI flag.

To see which rules are currently in preview, visit the rules reference.