ImportError: No module named 'mypackage' during ReadTheDocs autodoc build

ImportError in RTD Build Environment

The ReadTheDocs build logs report ImportError: No module named 'mypackage' when the Sphinx autodoc extension attempts to import the target module. Local builds succeed because the package is installed globally or the source directory is present on the local sys.path.

Environment Constraints

ReadTheDocs utilizes a clean virtual environment that installs only the dependencies specified in requirements.txt. Because the package source is not part of the documentation repository or listed as a dependency, the module is unavailable during the build process.

Configuration Uncertainty

There is an unresolved decision regarding the most stable method to expose the package path to the build environment. Options include modifying sys.path within conf.py, packaging the module as a pip-installable dependency for requirements.txt, or configuring the PYTHONPATH environment variable.

Specific Questions

• What is the recommended method for making a local package available to autodoc in a ReadTheDocs build?
• Does adding a relative path to sys.path in conf.py ensure reproducibility across different Python versions used by RTD?
• Is there a documented way to include a local package via .readthedocs.yml without modifying conf.py?