Ruff 0.16.0 raises its default checks from 59 to 413 and breaks CI
Simon Willison · rss · 2026-07-26
Simon Willison reports that Ruff v0.16.0, shipped by Astral on July 23, expanded the default rule set from 59 checks to 413.
That change caused his unpinned ruff dependency to break multiple CI jobs across projects like Datasette, sqlite-utils, and LLM. He notes that Ruff now catches many more severe issues by default, including syntax errors and immediate runtime errors that previously required explicit configuration.
He then ran uvx ruff@latest check . --fix --unsafe-fixes and says it fixed the bulk of the issues, with one example project reporting 1,618 errors total, 1,538 fixed and 80 remaining. He also points out that the output is detailed enough for a coding agent to act on directly, and says he used Codex and Claude Code to do the upgrades.
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