[http-client-python] Remove setuptools warnings for pygen template directories

[msyyc]

Description

Building @typespec/http-client-python with current setuptools reports warnings that the data-only template directories are absent from the package configuration:

Package 'pygen.codegen.templates' is absent from the `packages` configuration.
Package 'pygen.codegen.templates.packaging_templates' is absent from the `packages` configuration.

generator/setup.py uses find_packages() with include_package_data=True, while generator/MANIFEST.in recursively includes the Jinja templates. Since the template directories do not contain __init__.py, find_packages() does not discover them, but recent setuptools versions treat them as importable packages and warn about the ambiguous configuration.

Reproduction

From packages/http-client-python:

npm run build

The warnings are emitted while building the pygen wheel.

Current behavior

The wheel currently appears complete: pygen-0.1.0-py3-none-any.whl contains all 44 .jinja2 template files, including the seven files under pygen/codegen/templates/packaging_templates. This is therefore a packaging-configuration warning rather than a known missing-artifact bug.

Expected behavior

The pygen package configuration should explicitly and unambiguously include its template data, and building the wheel should not emit the missing-package warnings.

Acceptance criteria

• Building the pygen wheel does not report that pygen.codegen.templates or pygen.codegen.templates.packaging_templates is absent from the package configuration.
• All existing Jinja templates remain present in the built wheel.
• jinja2.PackageLoader("pygen.codegen", "templates") and the packaging-template loader continue to work from an installed wheel.
• Add or update a packaging test that verifies the required template files are included in the wheel.

[github-actions]

🎯 Issue Triage

This is a packaging configuration issue in @typespec/http-client-python where find_packages() does not discover template directories lacking __init__.py, causing recent setuptools versions to emit warnings about pygen.codegen.templates being absent from the package configuration.

Category: Bug

Area: emitter:client:python

⚠️ No reproduction provided as TypeSpec code (this is a Python packaging issue — reproduction is running npm run build from packages/http-client-python).

🔍 Analysis

• Root cause: generator/setup.py uses find_packages() which only discovers directories with __init__.py. The template directories (pygen/codegen/templates and pygen/codegen/templates/packaging_templates) contain only .jinja2 files without __init__.py, so they're not discovered as packages. Recent setuptools versions detect this ambiguity and emit warnings.
• Current behavior: The wheel is still built correctly (all 44 .jinja2 files are included via MANIFEST.in + include_package_data=True), but warnings are emitted.
• Fix approaches:
  1. Switch from find_packages() to find_namespace_packages() or explicitly list packages
  2. Add empty __init__.py files to template directories
  3. Migrate to pyproject.toml with [tool.setuptools.package-data] for explicit data file configuration
• No duplicate found after searching for similar setuptools/packaging issues in this repo.

📝 Suggested next steps

• Update generator/setup.py (or migrate to pyproject.toml) to explicitly declare pygen.codegen.templates as a data package (e.g., using packages=find_packages() + ["pygen.codegen.templates", "pygen.codegen.templates.packaging_templates"] or package_data)
• Verify the fix eliminates warnings when building the wheel
• Add/update packaging test to verify all required .jinja2 template files are present in the built wheel

Generated by Agentic Triage