Fix build_tools missing from sdist causing uv cached installs to fail

[hemildesai]

Change

• Include build_tools/ in the source distribution via MANIFEST.in so that cached builds from uv (and pip) can resolve setup.py's top-level imports

setup.py imports from build_tools at the top level:

from build_tools.build_ext import CMakeExtension, get_build_ext
from build_tools.te_version import te_version
from build_tools.utils import cuda_archs, cuda_version, ...

The __legacy__ build backend in pyproject.toml adds the source root to sys.path, so these imports work when building directly from the source tree. However, build_tools/ is not included in the sdist because:

1. MANIFEST.in did not list it
2. build_tools/ is not discovered by find_packages() (it's a standalone directory at the repo root, not under transformer_engine/)

When uv caches the sdist and later builds a wheel from it, the sdist is extracted to a temporary directory where build_tools/ is absent, causing a ModuleNotFoundError. Passing --no-cache to uv works around this by forcing a fresh build from the full source tree.

Added build_tools to MANIFEST.in:

 recursive-include transformer_engine/common/include *.*
+recursive-include build_tools *.py *.txt

• python setup.py sdist produces a tarball that contains build_tools/

$ tar tzf dist/transformer_engine-*.tar.gz | grep build_tools
transformer_engine-2.13.0.dev0+82f7ebeb/build_tools/
transformer_engine-2.13.0.dev0+82f7ebeb/build_tools/VERSION.txt
transformer_engine-2.13.0.dev0+82f7ebeb/build_tools/__init__.py
transformer_engine-2.13.0.dev0+82f7ebeb/build_tools/build_ext.py
transformer_engine-2.13.0.dev0+82f7ebeb/build_tools/jax.py
transformer_engine-2.13.0.dev0+82f7ebeb/build_tools/pytorch.py
transformer_engine-2.13.0.dev0+82f7ebeb/build_tools/te_version.py
transformer_engine-2.13.0.dev0+82f7ebeb/build_tools/utils.py

Type of change

• Documentation change (change only to the documentation, either a fix or a new content)
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Infra/Build change
• Code refactoring

Checklist:

• I have read and followed the contributing guidelines
• The functionality is complete
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[greptile-apps]

Greptile Summary

This PR fixes a build bug where uv (and pip) cached sdist installs would fail with a ModuleNotFoundError because build_tools/ was missing from the source distribution.

• setup.py imports from build_tools at the top level (build_ext, te_version, utils), but build_tools/ was never included in the sdist — it wasn't listed in MANIFEST.in and isn't discovered by find_packages() since it sits at the repo root, not under transformer_engine/.
• The fix adds recursive-include build_tools *.py *.txt to MANIFEST.in, which captures all Python source files and VERSION.txt (read by te_version.py at build time).
• The wheel_utils/ subdirectory (Dockerfiles, shell scripts) is correctly excluded since those are only used for CI/CD wheel building, not by setup.py.

Confidence Score: 5/5

• This PR is safe to merge — it is a minimal, well-scoped build infrastructure fix with no functional code changes.
• The change is a single line addition to MANIFEST.in that correctly includes the build_tools/ directory in the sdist. The *.py *.txt pattern covers exactly the files needed by setup.py during builds. There are no code logic changes, no new dependencies, and no risk of regression.
• No files require special attention.

Important Files Changed

Filename	Overview
MANIFEST.in	Adds recursive-include build_tools *.py *.txt to include the build_tools/ package in the source distribution, fixing ModuleNotFoundError when building from cached sdists (e.g., with uv). The *.py *.txt pattern covers all files needed by setup.py.

Flowchart

flowchart TD
    A["uv/pip install transformer_engine"] --> B["Build sdist from source tree"]
    B --> C["Cache sdist tarball"]
    C --> D["Extract sdist to temp directory"]
    D --> E{"build_tools/ present?"}
    E -->|"Before fix: No"| F["ModuleNotFoundError\nsetup.py cannot import build_tools"]
    E -->|"After fix: Yes"| G["setup.py imports build_tools successfully"]
    G --> H["Build wheel from sdist"]
    H --> I["Install wheel"]

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