ty 0.0.93 Previews Diagnostic Baselines for Projects With Existing Type Errors, While 0.0.92 Added SARIF Output
ty 0.0.93, released October 28, adds diagnostic baselines as a preview feature, configured through a baseline setting and ty check --update-baseline; the format may change.
Overview
The Python type checker ty, developed in the astral-sh/ty repository, released version 0.0.93 on October 28, 2026. According to its release notes, the release lists diagnostic baselines under “Preview features”, described as a way “to help adopt ty in projects with existing errors”. Neighbouring releases 0.0.92 (October 26), 0.0.94 (October 28) and 0.0.95 (October 29) each list their own changes.
What the Baseline Feature Does
The 0.0.93 notes show the setting as a baseline key under [tool.ty] in pyproject.toml, with the example value ty-baseline.json. They say that running ty check --update-baseline records existing diagnostics, and that subsequent checks “filter matching diagnostics from CLI output and show them as hints in the language server”.
The notes also carry a stability warning: “The baseline format may change while the feature is in preview.”
Other Changes in 0.0.93
The same release lists Django, type-narrowing and performance entries. Among them are a fix for narrowing of strings and integers compared with enum members, and a performance entry reading “Optimize Linux x86-64 ty releases with LLVM BOLT”, according to the 0.0.93 release notes. Bug fixes include a panic when checking truthiness in a loop and a hang when negating recursive unions of instance types.
Neighbouring Releases
Version 0.0.92, published October 26, added SARIF output. Its release notes list “Emit SARIF reports with ty check --output-format sarif” under CLI changes, alongside four Django-related entries under core type checking, such as inferring the types of Django model primary keys.
Version 0.0.94 is a bug-fix release. Its notes include “Fix Linux x86-64 startup on older kernels”, plus fixes for panics involving a comprehension filter, diagnostic sorting and a chained assignment with a missing value. The release notes do not state whether the startup fix relates to any earlier change.
Version 0.0.95 lists six bug fixes and three language-server changes, according to its release notes. The language-server entries concern inlay hints and argument hint edits, such as placing variable type inlay hints after grouping parentheses.
What Is Not Stated
The release notes do not say when baselines are expected to leave preview, and they do not describe how the baseline file is meant to be reviewed or shared in version control. They do not compare the feature with the baseline mechanisms of other type checkers. The Machine Herald has previously reported on Meta’s Pyrefly, another Rust-built Python type checker, but none of the ty release notes mention it.
All four releases covered here carry version numbers in the 0.0.x series.