Release Notes

Released on 2026-03-02.

Bug fixes

• Disallow negative narrowing for isinstance() or issubclass() checks involving type[] types (#23598)
• Fix binary operations between an instance of a NewType of float and an instance of Any/Unknown (#23620)
• Fix bug where ty would think that a Callable with a variadic positional parameter could be a subtype of a Callable with a positional-or-keyword parameter (#23610)
• Fix inference of t.__mro__ if t is an instance of type[Any] (#23632)
• Fix overloaded callable assignability for unary Callable targets (#23277)
• Limit recursion depth when displaying self-referential function types (#23647)
• Ensure that python -m ty works even when ty was installed into an ephemeral virtual environment (#2852)

LSP server

• Add support for the LSP protocol's "type hierarchy" feature (#23566)

Type checking

• Add more ParamSpec validation for P.args and P.kwargs (#23640)
• Ban nested Required/NotRequired, and ban them both outside of TypedDict fields (#23627)
• Detect inconsistent generic base class specializations that appear in the same MRO (#23615)
• Detect invalid uses of @final on non-methods (#23604)
• Add partial support and validation for Unpack when used with tuple types (#23651)
• Recurse into tuples and nested tuples when applying special-cased validation of arguments passed to isinstance() and issubclass() (#23607)
• Reject ellipsis literals in odd places in type/annotation expressions (#23611)
• Reject functions with PEP-695 type parameters that shadow type parameters from enclosing scopes (#23619)
• Reject generic metaclasses parameterized by type variables (#23628)
• Treat dataclass_transform dataclasses as neither frozen nor non-frozen (#23366)
• Validate that type variable defaults don't reference later type parameters or type parameters out of scope (#23623)

Typeshed

• Sync vendored typeshed stubs (#23642). Typeshed diff

Contributors

• @Hugo-Polloli
• @zanieb
• @sharkdp
• @mtshiba
• @carljm
• @charliermarsh
• @sinon
• @BurntSushi
• @oconnor663
• @AlexWaygood
• @zsol

Install ty 0.0.20

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.20/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.20/ty-installer.ps1 | iex"

Download ty 0.0.20

Release Notes

Released on 2026-02-26.

Bug fixes

• Fix panic in diagnostic rendering when attempting to render a code frame pointing to leading whitespace (#23458)
• Fix panics and incorrect inference stemming from incorrectly considering overloads in another file as being associated with a function in the file being checked (#21977)
• Fix panic when attempting to narrow the type of a dictionary key that was assigned using a multi-target assignment, e.g. x = y = {"a": 1} (#23523)
• Fix infinite hang on mutually recursive TypeAliasType definitions (#23397)

LSP server

• Fix inlay hints for starred unpacking targets (#23454)

Core type checking

• Fix assignability, subtyping and equivalence checks relating to typing.Generator prior to Python 3.13 (#23386)
• Understand that a scope's control flow terminates after await foo() if foo returns typing.Awaitable[typing.Never] or similar (#23479)
• Implement stricter handling of calls to instances of type[T] types (#23472)
• Support basic type narrowing for case {...}: patterns in match statements (#23462)
• Fix bugs that could manifest in incorrect overload evaluation, false-positive complaints regarding assert_type calls or false-positive redundant-cast diagnostics by reimplementing the equivalence type relation as mutual subtyping of top and bottom materializations (#23428)
• Fix equality and __contains__ narrowing with PEP-695 type aliases (#23545)
• Support _value_ annotations on enum classes (#22228)

Improvements to diagnostics

• Improve diagnostics when attempting to specialize non-generic types (#23516)
• Render subdiagnostics when --output-format=github is specified (#23455)

Performance

• Add a cached method for calculating the intersection of two types (#23547)
• Add a cached method for calculating the union of two types (#23565)
• Reduce the threshold above which Literal types in unions are upcasted to nominal-instance types in situations where the union type is recursively defined (#23521)
• Control flow: isolate the calculation of "loop header reachability" in a dedicated, cached function (#23520)

Contributors

• @AlexWaygood
• @silamon
• @ibraheemdev
• @Hugo-Polloli
• @charliermarsh
• @knutwannheden
• @oconnor663
• @carljm
• @mtshiba

Install ty 0.0.19

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.19/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.19/ty-installer.ps1 | iex"

Download ty 0.0.19

Release Notes

Released on 2026-02-20.

Bug fixes

• Support classes dynamically created via type(...) with cyclic bases (#22792)
• Fix incorrect types inferred when unpacking mixed tuples (#23437)
• Fix stack overflow for self-referential TypeOf in annotations (#23407)
• Fix several server panics that could occur when computing semantic tokens for the current file (#23403), #23398, #23401)

LSP server

• Add code folding support (#23393)
• Add warning message when running ty server interactively (#23416)
• Exclude test-related symbols from non-first-party packages in auto-import completions (#23252)
• Fix bug where diagnostics could disappear after opening an external file (#23447)
• Remove spurious destination for Go-To Definition on variables defined in a loop (#23391)
• Use the fully qualified name when "baking" an inlay hint into the source code if the scope already contains a variable with the same name as the unqualified name (#23265)
• Resolve TypeVars in call_signature_details parameter types (#23149)

CLI

• Add --output-format to ty version (#23387)

Configuration

• Add replace-imports-with-any option (#23122)
• Support shellexpand for configuration paths (#23274)

Type checking

• Add a new diagnostic to detect invalid class patterns in match statements (#22939)
• Allow Self in ClassVar type annotations (#23362)
• Consider synthesized methods and ClassVar-qualified declarations when determining whether an abstract method has been overridden in a subclass (#23381)
• Add a diagnostic when combining Final and ClassVar (#23365)
• Fix return type of assert_never (#23389)
• Fix assert_type diagnostic messages (#23342)
• Ban PEP-613 type alias values from containing type-qualifier special forms (#23444)
• Infer LiteralString for f"{literal_str_a} {literal_str_b}" (#23346)
• Infer precise types for bit-shift operations on integer literals (#23301)
• Make [abstract-method-in-final-class] diagnostics less verbose for classes with many abstract methods (#23379)
• Improve diagnostics for abstract @final classes (#23376)
• Only perform literal promotion for implicitly inferred literals (#23107)
• Parenthesize callable types when they appear in the return annotation of other callable types (#23327)
• Consider a call to a generic function returning Never to terminate control flow (#23419)
• Support calls to intersection types (#22469)
• Validate annotated assignments to attributes on self (#23388)
• Treat a bytes-literal type as a subtype of Sequence[<constituent integers in the bytestring>] (#23329)
• Allow a string-literal argument to match against an Iterable parameter in type variable inference. (#23326)
• Support narrowing from a Callable type returning a TypeGuard type (#23280)

Performance

• Consider all code paths as being ambiguously reachable in cases with pathologically large control-flow graphs (#23399)

Typeshed

• Sync vendored typeshed stubs (#23279, Typeshed diff)

Contributors

• @toby-bro
• @Hugo-Polloli
• @MatthewMckee4
• @BurntSushi
• @ibraheemdev
• @knutwannheden
• @Glyphack
• @charliermarsh
• @AlexWaygood
• @abhijeetbodas2001
• @carljm
• @sharkdp

Install ty 0.0.18

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.18/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.18/ty-installer.ps1 | iex"

Download ty 0.0.18

Release Notes

Released on 2026-02-13.

Bug fixes

• Avoid Literal promotion for constrained TypeVars with Literal bounds (#23209)
• Fix false positives in TypeVar shadowing checks (#23222)

Core type checking

• Support generic protocols (#21902)
• Perform control-flow analysis in loops (#22794)
• Support typing.Self in attribute annotations (#23108)
• Support type narrowing in situations with calls to NoReturn functions (#23109)
• Support type narrowing and reachability analysis based on os.name checks (#23230)
• Detect overrides of Final class variables in subclasses (#23180)
• Fix bound method access on None (#23246)
• Fix method calls on subclasses of Any (#23248)
• Disallow type variables within PEP-695 type variable bounds and constraints (#22982)
• Emit error for attribute access on union where some elements lack the attribute (#23042)
• Emit error for invalid typevar defaults (#23194)
• Improve display of ParamSpecs in some situations (#23211)

LSP server

• Add hover and go-to-declaration support for subscript literals (#22837)
• Assign lower completion ranking to deprecated names in auto import (#23188)
• Improve spans of references to submodules imported in an __init__.py (#21795)
• Include conditional symbols (like datetime.UTC) in auto-import in more cases (#23249)
• Support auto-import for symbols in inlay hints (#22111)
• Include overload declarations in find-references (#23215)

Performance

• Avoid UnionBuilder overhead when creating a new union from the filtered elements of an existing union (#22352)

Other changes

• Allow discovering dependencies in system Python environments (#22994)
• Apply workspace settings to virtual files (#23228)
• Add support for --output-format=junit (#22125)
• Use a smaller diagnostic range for inconsistent-mro diagnostics (#23213)

Contributors

• @carljm
• @BurntSushi
• @charliermarsh
• @Glyphack
• @cetanu
• @AlexWaygood
• @joelostblom
• @Gankra
• @mtshiba
• @MatthewMckee4
• @Hugo-Polloli
• @sharkdp
• @alex
• @dcreager
• @oconnor663

Install ty 0.0.17

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.17/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.17/ty-installer.ps1 | iex"

Download ty 0.0.17

Release Notes

Released on 2026-02-10.

Bug fixes

• Allow stringified argument in PEP-613 alias to Optional (#23200)
• Fix fuzzer panic on slice expression in unclosed comprehension (#23146)
• Fix combinatorial explosion due to fixed-length tuple expansion in overload matching (#23190)
• Respect @no_type_check when combined with other decorators (#23177)
• Fix diagnostic location for an incorrect sub-call to a specialized ParamSpec (#23036)

LSP server

• Assign lower completions ranking to deprecated functions and classes (#23089)
• Change goto-def for class constructors to always go to class definition (#23071)
• Ensure diagnostic mode is consistent across projects inside the LSP server (#23121)
• Don't include the class Foo in autocomplete suggestions when the user is typing out Foo's bases (#23141)
• Fix parameter references across files via keyword args (#23012)
• Fix wrong inlay hints for overloaded function arguments (#23179)
• Support diagnostics in newly created files inside neovim (#23095)
• Exclude already-included classes when providing completion suggestions for class bases (#23085)

CLI

• Add support for TY_OUTPUT_FORMAT environment variable (#23123)
• Fall back to python3 found in $PATH if no environment is found (#22843)

Type checking

• Add inconsistent-mro autofix to move Generic[] to the end of the bases list (#22998)
• Add precise return-type inference for struct.unpack (#22562, #23130)
• Disallow TypeVars within ClassVars (#23184)
• Emit diagnostic on unbound call to abstract @classmethod or @staticmethod (#23182)
• Fix false-positive diagnostics when providing the total= keyword to TypedDict classes that had PEP-695 type parameters (#23114)
• Narrow both left- and right-hand operands where possible (#23084)
• Narrow chained operators (#23093)
• Narrow equality subscripts on either operand (#23104)
• Recognize __dataclass_transform__ to support SQLModel (#23070)
• Relax the attribute narrowing condition to support deeper-nested attribute type narrowing (#22440)
• Support constrained TypeVar compatibility across function boundaries (#23103)
• Support comparison methods (__gt__, etc.) where a parameter is annotated with a Literal type (#23100)
• Support partially specialized type context (#22748)
• Use type context when inferring constructor argument types (#23139)
• Validate TypedDict constructor calls for generic aliases and type[...] targets (#23113)

Performance

• Conservative narrowing places optimization (#22734)

Contributors

• @rbange
• @rayzeller
• @charliermarsh
• @11happy
• @figsoda
• @mtshiba
• @ibraheemdev
• @ngnpope
• @sakgoyal
• @oconnor663
• @ericmarkmartin
• @Hugo-Polloli
• @Glyphack
• @sharkdp
• @carljm
• @BurntSushi

Install ty 0.0.16

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.16/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.16/ty-installer.ps1 | iex"

Download ty 0.0.16

Release Notes

Released on 2026-02-04.

Bug fixes

• Add support for resolving imports of packages installed into Debian/Ubuntu dist-packages directories (#22466)
• Avoid not-iterable false positives when iterating over an instance of an intersection type with only negated elements (#22089)
• Fix support for stringized annotations in very large files (#22913)
• Don't emit Liskov diagnostics for methods with mangled names (#23062)
• Enforce that a Final symbol cannot be reassigned even after a conditional binding (#22986)
• Fix TypedDict construction from existing TypedDict values (#22904)
• Fix Self resolution for classes nested within methods (#22964)
• Fix bidirectional inference with PEP 695 union type aliases (#22988)
• Fix edge-case bugs when narrowing tagged unions in match statements (#22870)
• Fix false-positive diagnostics when iterating over an instance of an intersection that includes a TypeVar of which the upper bound is a union where the union includes a non-iterable type (#22117)
• Fix lookup of __contains__ to respect descriptors (#23056)
• Fix narrowing of nonlocal variables with conditional assignments (#22966)
• Fix several bugs that could affect NewTypes of NewTypes of float (#22997)
• Fix several type narrowing bugs involving PEP-695 type aliases (#22894)
• Fix spurious query cycles in decorated functions with parameter defaults, for improved performance and improved determinism (#23014)
• Fix unary and comparison operators for TypeVars with union bounds (#22925)
• Understand functions as method descriptors even if they are decorated with a decorator annotated as returning a PEP-695 alias to a Callable type (#22902)
• dataclass_transform: Fix visibility of field specifiers when models are nested inside methods (#23069)

LSP server

• Fix hover showing Unknown for bare Final instance attributes (#23003)
• Improve support for goto-type, goto-declaration, hover, and highlighting of string annotations (#22878)
• Include setters and deleters when renaming properties (#22999)
• Show type qualifiers like Final in on-hover hints (#23005)

Configuration

• Add new unused-type-ignore-comment rule (#22790)
• Add a mechanism to ignore/warn/select all rules (#22832)
• Support multiple workspace folders in a single ty LSP server instance (#22953)
• Only add ./src as a search path if ./src/__init__.py(i) does not exist (#22851)

Type checking

• Add a diagnostic detecting if a variable is declared as Final but never has any bindings (#23001)
• Add a diagnostic detecting overridden comparison dunder methods on order=True dataclasses (#22689)
• Add a hint to invalid-argument-type and invalid-assignment diagnostics if a variable is annotated with a type from the numbers module (#22931, #22938)
• Add diagnostic hint on unresolved-reference to suggest using "list" instead of "List" (#22827)
• Add new diagnostic for invalid dataclass field orders (#19825)
• Allow a subclass method with a positional-only parameter to override a superclass method without that parameter if the parameter in the subclass method has a default value (#23037)
• Allow self-referential imports outside the global scope (#22963)
• Ban ... in odd places inside tuple specializations (#22889)
• Ban Required, NotRequired and ReadOnly in parameter annotations (#22888)
• Ban legacy TypeVar bounds or constraints from containing type variables (#22949)
• Ban multiple unpacked variadic tuples in a tuple specialization (#22884)
• Detect generic Callables in the return type of function signatures (#22954)
• Detect invalid isinstance() and issubclass() calls against TypedDict classes (#22887)
• Detect invalid issubclass() calls against Protocol classes with non-method members (#22896)
• Detect invalid attempts to subclass Protocol[] and Generic[] simultaneously (#22948)
• Emit a diagnostic on incorrect applications of the legacy convention for specifying positional-only parameters (#22943)
• Emit an error if a TypeVarTuple is used to subscript Generic or Protocol without being unpacked (#22952)
• Fallback to metaclass __getattr__ or __getattribute__ when looking up attributes on class objects (#22985)
• Fix a bug where an overridden type in a dataclass subclass would not be respected if the dataclass subclass field had a default value but the superclass field did not (#22965)
• Improve bidirectional type inference involving PEP-695 type aliases (#22989)
• Improve detection of invalid NewTypes with generic bases (#22961)
• Improve reachability analysis when evaluating the truthiness of expressions that involve variables that may not be bound in all code paths (#22971)
• Improve the error message if ** is used with a non-mapping in the context of a call to an overloaded function (#22921)
• Infer ParamSpec from class constructors for callable protocols (#22853)
• Move the location of some invalid-overload diagnostics (#22933)
• Point to an overload with an invalid @final decorator when emitting invalid-overload errors for invalid @final decorators (#22893)
• Avoid false positives when iterating over an instance of an intersection with only negated elements by preserving "pure negation" types in descriptor lookups (#22907)
• Promote Literal types when inferring elements for very large unannotated tuples, for improved performance (#22841)
• Recognize functions with stub bodies in Protocol classes as implicitly abstract (#22838)
• Reduce false positives involving heterogeneous dicts by tracking dictionary literal keys as individual places (#22882)
• Reduce false positives when subscripting classes generic over TypeVarTuples (#22950)
• Remove special handling for Any() in match class patterns (#23011)
• Support type[None] in type expressions (#22892)
• Support legacy namespace packages declared using pkg_resources.declare_namespace (#22987)
• Sync vendored typeshed stubs (#23006), Typeshed diff
• Validate signatures of dataclass __post_init__ methods (#22730)

Contributors

• @charliermarsh
• @stefanvanburen
• @ibraheemdev
• @abhijeetbodas2001
• @MichaReiser
• @dcreager
• @PrettyWood
• @sharkdp
• @oconnor663
• @Feiyang472
• @denyszhak
• @mtshiba
• @AlexWaygood
• @11happy
• @BurntSushi
• @carljm
• [@Gankra](...

Release Notes

Released on 2026-01-26.

Bug fixes

• Consider keyword arguments when unpacking a variadic argument (#22796)
• Fix binary operator false-positive for constrained TypeVars (#22782)
• Fix docstring rendering for literal blocks after doctests (#22676)
• Fix false-positive unsupported-operator for "symmetric" TypeVars (#22756)
• Fix panic when overriding a final method using an assignment (#22831)
• Fix unary operator false-positive for constrained TypeVars (#22783)
• Fix generic functions with a generic (ParamSpec) decorator (#22544)
• Fix memo.changed_at assertion panics (#22498)

LSP server

• Look up attributes on metaclasses for Go to Definition (#22758)
• Suppress type inlay hints for leading-underscore assignments (#22855)

Configuration

• Add allowed-unresolved-imports setting (#22800)

Other changes

• Add assert-type-unspellable-subtype diagnostic, for failed assert_type() where the actual type is a subtype of the named type that can't be spelled in a type expression (#22815)
• Add a new empty-body return code for functions with stub bodies that have non-None return annotations (#22846)
• Add diagnostic disambiguation for different type aliases with the same name (#22852)
• Add support for dict literals and dict() calls as default values for parameters with TypedDict types (#22161)
• Add support for subscripts on intersections (#22654)
• Avoid duplicate syntax errors for await outside functions (#22826)
• Emit an error if the same type parameter appears more than once in a Generic[] subscript (#22738)
• Emit diagnostic for unimplemented abstract method on @Final class (#22753)
• Fix GitLab Code Quality output format for empty diagnostics (#22833)
• Fix assignment in decorated method causing Unknown fallback (#22778)
• Fix false negative when using a non-runtime-checkable protocol in a match class pattern (#22836)
• Improve completion rankings for raise-from/except contexts (#22775)
• Improve invalid assignment diagnostics with type context (#22643)
• Improve support for kwarg splats in dictionary literals (#22781)
• Infer TypedDict types with >=1 required key as being always truthy (#22808)
• Point to an overload with an invalid @final decoator when emitting invalid-overload errors for invalid @final decorators (#22812)
• Require both *args and **kwargs when calling a ParamSpec callable (#22820)
• Stricter validation of TypedDict definitions (#22811)
• Support recursive and stringified annotations in functional typing.NamedTuples (#22718)
• Support solving generics involving PEP 695 type aliases (#22678)
• Use a more lenient fallback type for failed namedtuple() and NamedTuple calls (#22765)
• Use type context from augmented assignment dunder calls (#22540)
• Check that starred arguments in function calls are iterable (#22805)

Contributors

• @AlexWaygood
• @maifeeulasad
• @RasmusNygren
• @ntBre
• @Imbuzi
• @dhruvmanila
• @ibraheemdev
• @carljm
• @Hugo-Polloli
• @charliermarsh
• @MichaReiser
• @bxff
• @felixscherz
• @denyszhak

Install ty 0.0.14

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.14/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.14/ty-installer.ps1 | iex"

Download ty 0.0.14

Release Notes

Released on 2026-01-21.

Bug fixes

• Fix --force-exclude when excluding entire directories (#22595)
• Fix missing syntax highlighting for aliased import names (#22675)
• Highlight interpolated-parts in t-strings (#22674)
• Fix the inferred MRO of functional namedtuple classes (#22722)
• Make special cases for subscript inference exhaustive, ensuring that the special casing for tuple subscripts is applied when a union of tuples or an alias to a tuple type is subscripted (#22035)

LSP server

• Improve completion suggestions inside class definitions (#22571)
• Improve performance of completions (#22630)
• Remove completion suggestions for redundant re-exports that share the same top-most module (#22581)

Core type checking

• Add basic support for overloads in ParamSpec (#21946)
• Allow ... as a default value for any parameter if the function is in an if TYPE_CHECKING block (#22624)
• Allow if type(x) is Y narrowing for types other than class-literal types (#22729)
• Avoid overload errors when detecting dataclass-on-tuple (#22687)
• Avoid reporting overload errors for successful union variants (#22688)
• Ban NewTypes with generic bases (#22653)
• Fix PEP 695 type aliases not expanding in overload resolution (#22589)
• Fix the return type for synthesized NamedTuple.__new__ methods (#22625)
• Emit diagnostics for NamedTuple, TypedDict, Enum or Protocol classes decorated with @dataclass (#22672)
• Emit invalid-type-form diagnostics for stringified annotations where the quoted expression is invalid (#22752)
• Infer the implicit type of cls in __new__ methods (#22584)
• Make ModuleType and object attributes available on namespace packages (#22606)
• Make NamedTuple(...) and namedtuple(...) calls stricter (#22601)
• Narrow on bool and byte subscripts (#22684)
• Narrow on negative subscript indexing (#22682)
• Override __file__ to str when applicable on imported modules (#22333)
• Add bidirectional inference for comprehensions (#22564)
• Recognize string-literal types as subtypes of Sequence[Literal[chars]] (#22415)
• Add right-hand-side narrowing for if Foo is type(x) expressions (#22608)
• Add simple syntactic validation for the right-hand side of PEP-613 type aliases (#22652)
• Add support for passing typename and field_names by keyword argument to collections.namedtuple() calls (#22660)
• Add support for starred unpacking in class bases (#22591)
• Validate constructor arguments when a class is used as a decorator (#22377)
• Validate field names for typing.NamedTuple(...) (#22599)
• Add diagnostic on overridden __setattr__ and __delattr__ in frozen dataclasses (#21430)
• Fix unary operators on NewTypes of float or complex (#22605)

Configuration

• Support overriding respect-type-ignore-comments (#22615)

Diagnostics

• Don't add a subdiagnostic pointing to the TypeVar definition if the TypeVar is Self (#22646)
• Show final search path instead of "and 1 more paths" (#22776)
• Group type[] elements together when displaying union types (#22592)

Performance

• Cache ClassType::nearest_disjoint_base (#22065)

Other changes

• Sync vendored typeshed stubs (#22590, Typeshed diff

Contributors

• @bxff
• @jhartum
• @thejchap
• @AlexWaygood
• @charliermarsh
• @RasmusNygren
• @mswart
• @MatthewMckee4
• @11happy
• @ibraheemdev
• @sinon
• @MichaReiser
• @carljm
• @BurntSushi
• @dhruvmanila
• @oconnor663
• @zanieb

Install ty 0.0.13

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.13/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.13/ty-installer.ps1 | iex"

Download ty 0.0.13

Release Notes

Released on 2026-01-14.

Bug fixes

• Avoid panic that could occur when casting an object to a TypedDict or union of TypedDicts (#22509)
• Fix incorrect narrowing for if type(x) == y (#22531)
• Fix stack overflow with recursive type aliases containing tuple types (#22543)
• functools.total_ordering: ensure the signatures of generated methods reflect the signature of the user-provided method (#22496)
• Support dataclass_transform as a function call (#22378)
• Use the top materialization of classes for if type(x) is y narrowing. For example, if type(x) is tuple will cause the type of x to be intersected with tuple[object, ...] rather than tuple[Unknown, ...]. (#22553)
• Avoid emitting Liskov violations with respect to a grandparent class if such violations could not be fixed without introducing Liskov violations with respect to a parent class (#22484)
• Fix interaction between classmethod, contextmanager, and Self (#22407)
• Check contravariant type variable bounds contravariantly in specialization inference (#22488)
• Fix false positive for bounded type parameters with NewType (#22542)

Type checking

• Add support for dynamic type() classes (#22291, #22499, #22537, #22480)
• Add support for functional namedtuple creation (#22327, #22573, #22575, #22574)
• Add a diagnostic for non-decorator uses of final (#22555)
• Add diagnostic to catch generic enums (#22482)
• Add diagnostics for __init_subclass__ argument mismatch (#22185)
• Add diagnostics to validate TypeIs and TypeGuard definitions (#22300)
• Apply type narrowing to walrus targets (#22369)
• Detect invalid @total_ordering applications in non-decorator contexts (#22486)
• Fix @Todo type for starred expressions (#22503)
• Improve disambiguation of types in diagnostics (#22547)
• Include type parameters in the display for generic Callable types (#22435)
• Infer type[Unknown] for calls to type() when overload evaluation is ambiguous (#22569)
• Support assignment to unions of TypedDicts (#22294)
• Use the key and value parameter types as type context for __setitem__ dunder calls (#22148)
• Narrow the right-hand side of ==, !=, is and is not conditions when the left-hand side is not narrowable (#22511)

LSP server

• Fix __file__ type in completions to show str instead of str | None when the inferred type is str (#22510)
• Improve rendering of ReST directives in docstrings (#22512)

Contributors

• @eclbg
• @RasmusNygren
• @carljm
• @drbh
• @AryanBagade
• @bxff
• @ibraheemdev
• @charliermarsh
• @AlexWaygood

Install ty 0.0.12

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.12/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.12/ty-installer.ps1 | iex"

Download ty 0.0.12

Release Notes

Released on 2026-01-09.

Bug fixes

• Fix super() with TypeVar-annotated self and cls parameter (#22208)
• Only consider fully static pivots when deriving transitive constraints (#22444)

LSP server

• Don't show diagnostics for excluded files (#22455)
• Fix goto definition for relative imports in third-party files (#22457)
• Improve completion ranking based on origin and exact match (#22460)
• Rank top-level module symbols above most other symbols (#22465)

Configuration

• Enable unused-ignore-comment by default (#22474)

Performance

• Improve UnionBuilder performance by changing Type::is_subtype_of calls to Type::is_redundant_with (#22337)
• Optimize union building for unions with many enum-literal members (#22363)-

Other changes

• Declare support for Python 3.14 (#2407)
• Remove dark-mode handling from PyPI-uploaded README (#2422)

Contributors

• @dhruvmanila
• @AlexWaygood
• @charliermarsh
• @BurntSushi
• @MichaReiser
• @dcreager

Install ty 0.0.11

Install prebuilt binaries via shell script

curl --proto '=https' --tlsv1.2 -LsSf https://github.com/astral-sh/ty/releases/download/0.0.11/ty-installer.sh | sh

Install prebuilt binaries via powershell script

powershell -ExecutionPolicy Bypass -c "irm https://github.com/astral-sh/ty/releases/download/0.0.11/ty-installer.ps1 | iex"

Download ty 0.0.11