Module discovery
First-party modules
First-party modules are Python files that are part of your project source code.
By default, ty searches for first-party modules in the project's root directory or the src
directory, if present.
If your project uses a different layout, configure the project's
environment.root
in your pyproject.toml
or ty.toml
. For example,
if your project's code is in an app/
directory:
then set environment.root
in your pyproject.toml
to ["./app"]
:
Third-party modules
Third-party modules are Python packages that are not part of your project or the standard library.
These are usually declared as dependencies in a pyproject.toml
or requirements.txt
file
and installed using a package manager like uv or pip. Examples of popular third-party
modules are requests
, numpy
and django
.
ty searches for third-party modules in the configured Python environment.
Python environment
The Python environment is used for discovery of third-party modules.
By default, ty will attempt to discover a virtual environment.
First, ty checks for an active virtual environment using the VIRTUAL_ENV
environment variable. If
not set, ty will search for a .venv
directory in the project root or working directory. ty only
supports discovery of virtual environments at this time.
Note
When using project management tools, such as uv or Poetry, the run
command usually automatically
activates the virtual environment and will be detected by ty.
The Python environment may be explicitly configured using the
environment.python
setting or
--python
flag.
When setting the environment explicitly, non-virtual environments can be provided.