astral-sh/ty 0.0.79

on GitHub

Release Notes

Released on 2026-09-07.

Bug fixes

• Avoid dict keyword-call panics when typing is shadowed (#28292)
• Discover configs in models derived from legacy generic classes (#28397)
• Normalize recursive collection-use constraints (#28332)
• Recover cycles when constructing known class instances (#28289)

CLI

• Embed archive checksums in the shell installer (#4458)

Diagnostic improvements

• Add Literal fixes for diagnostics flagging invalid type annotations (#28185)
• Add await fixes for redundant conditions (#28169)
• Add assert_never fixes for redundant final elif branches (#28178)
• Add defensive assertion fallback for redundant elif fixes (#28179)
• Add rules to detect always-truthy and always-falsy conditions (#28034)
• Preserve deprecations on decorated callables (#28256)
• Require a direct dependency for reveal_type backport fixes (#28177)
• Suggest variable-length tuple annotations for redundant conditions (#28168)

Core type checking

• Align TypeIs and isinstance narrowing (#28193)
• Avoid falling back to Unknown when collecting type context constraints (#28297)
• Ensure f is identity(f) evaluates to Literal[True] (#28360)
• Fix callable specialization with union-valued ParamSpec (#28085)
• Infer variance through recursive protocols (#28077)
• Narrow types with ordered length comparisons (#28264)
• Preserve gradual type context during generic call inference (#28091)
• Preserve nominal subtyping for top-materialized protocols (#28271)
• Preserve outer type variables during ParamSpec inference (#28306)
• Preserve protocol intersections when narrowing gradual types (#28391)
• Promote literals in nested (non-covariant) positions (#28389)
• Reject missing attributes on type[] aliases (#28267)
• Solve formal unions using constraint-sets (#28312)
• Sync vendored typeshed stubs (#28331). Typeshed diff

Performance

• Avoid unnecessary work when building specializations (#28369)
• Bypass materialization queries for simple types (#28367)
• Cache exception suppression for context managers (#28376)
• Intern statement call predicates (#28373)
• Lazily compute argument-context specializations (#28378)
• Pre-size packed AST index chunks (#28372)
• Reduce repeated work in use-def merges (#28365)
• Skip decorator flags query for undecorated methods (#28338)

Memory usage improvements

• Avoid caching simple type specializations (#28333)
• Box cached MRO error details (#28351)
• Reuse generic aliases as MRO query keys (#28350)
• Reuse interned bound method signatures (#28346)
• Reuse stored function signatures without caching duplicates (#28347)
• Share retained use-def tables across scopes (#28313)
• Store single narrowing operations inline (#28345)
• Store uncommon signature metadata out of line (#28339)

Other changes

• Declare support for Python 3.15 (#4476)

Contributors

• @carljm
• @sharkdp
• @charliemarsh-oai
• @zsol
• @charliermarsh
• @ibraheemdev
• @AlexWaygood

Install ty 0.0.79

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://releases.astral.sh/github/ty/releases/download/0.0.79/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://releases.astral.sh/github/ty/releases/download/0.0.79/ty-installer.ps1 | iex"

Download ty 0.0.79

Verifying GitHub Artifact Attestations

The artifacts in this release have attestations generated with GitHub Artifact Attestations. These can be verified by using the GitHub CLI:

gh attestation verify <file-path of downloaded artifact> --repo astral-sh/ty

You can also download the attestation from GitHub and verify against that directly:

gh attestation verify <file-path of downloaded artifact> --bundle <file-path of downloaded attestation>