Ruff v0.16 turns on 413 default rules, assumes you'll autofix with an agent
Every URL the pipeline pulled into ranking for this issue — primary sources plus the supporting and contradicting findings each Researcher returned. Inline citations in the issue point back here.
Sources
Ruff v0.16.0 simonwillison.net
Ruff v0.16.0 Astral shipped a significant new version of their Ruff Python linting tool a few days ago on July 23rd. I noticed today because my various CI jobs all started failing thanks to new default Ruff checks and my unpinned “ruff” dev dependency. From Brent Westbrook’s announcement post: Ruff now enables 413 rules by default, up from 59 in previous versions. Since Ruff’s default rule set was last modified in v0.1.0 , the number of rules in Ruff has grown from 708 to 968. Many of these rul…
References
pydevtools.com - Ruff 0.16.0 default rules breakdown pydevtools.com
Users can revert to the previous conservative rule set by adding
select = ["E4", "E7", "E9", "F"]to the [lint] section of their configuration while still benefiting from the performance improvements of the v0.16.0 engine.
GitHub issue #22621 - maintainer Micha Reiser github.com
While ‘noisy’ rules without fixes are generally avoided, some are included if they catch ‘very important’ issues that developers should handle manually; the tool had grown from 708 to 968 rules since the last default update.
Simon Willison - OpenAI acquiring Astral simonwillison.net
OpenAI acquired Astral on March 19, 2026 for a reported $750M, folding Charlie Marsh and the Ruff/uv/ty engineering team into the Codex division.
Stackademic - Ruff vs Flake8 vs Pylint benchmark blog.stackademic.com
On a ~47,000-line codebase Ruff completes checks in ~180ms while Flake8 takes 8 seconds and Pylint takes 47 seconds, though Pylint still catches cross-file logical bugs that Ruff bypasses in favor of speed.
Autonoma - AI agent reliability testing getautonoma.com
Agents frequently ‘fix’ code that was already correct or introduce over-engineered solutions just to clear a linter warning; developers report ‘GhostApproval’ risks where agent-generated fixes pass linting and tests but introduce subtle security vulnerabilities.
Anaconda blog - ‘When the world begins to shift underneath your feet’ anaconda.com
Independent observers point to a lack of formal governance structures or independent-maintainer commitments in the Astral acquisition, warning of ‘priority drift’ where updates may prioritize OpenAI’s training pipelines over the general needs of Python developers.
