Correct Python Order Processing virtual environment setup - #8

Purpose

• Correct the documented virtual environment creation command to create .venv, matching the activation command.
• Use the activated environment's python -m pip, add Windows creation/activation instructions and explain that the environment belongs in order_processor.
• Add explicit child-folder interpreter selection guidance without inventing extension-generated debug configuration.
• Change only README.md; preserve application code, dependencies, runtime, DTS provider, local settings and infrastructure.

Does this introduce a breaking change?

[ ] Yes
[x] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[x] Documentation content changes
[ ] Other... Please describe:

How to Test

• Get the code

git clone https://github.com/Azure-Samples/durable-functions-order-processing-python.git
cd durable-functions-order-processing-python
git checkout python-order-venv-docs-20261002-033112-a93ad1ad

• Test the code

1. Enter order_processor and follow the revised README environment creation, activation and dependency installation steps for the chosen OS.
2. In the activated environment, run python -m compileall -q function_app.py models.py, python -m pip check, and python -c "import azure.durable_functions; import function_app".
3. Open order_processor in VS Code, explicitly select its .venv interpreter and select the child app/environment if project initialization is requested.
4. With a correctly configured, available DTS backend and Azurite, verify first F5, function indexing and order orchestration completion separately.

Recorded local evidence on the unchanged source candidate over base 04f2de4c171bcb654cf355875ef232a6c3fce13b: compilation, dependency consistency and real application imports passed in a project-local child virtual environment; the actual Functions worker indexed six functions and host health returned HTTP 200.

What to Check

Verify that the following are valid

• The documented creation and activation commands both refer to order_processor/.venv.
• Dependency installation uses the activated environment rather than an unrelated interpreter.
• Windows PowerShell and Command Prompt activation guidance is present.
• Gallery-generated initialization/F5 configuration and interpreter activation still need actual interactive verification.

Other Information

Related to microsoft/vscode-azurefunctions#5182.

This README-only draft does not resolve the extension-generated F5 bug reported in that issue: the repository has no tracked .vscode configuration to correct. Existing local-settings/DTS documentation drift remains separate and unchanged. Local indexing supplied nonsecret DTS environment inputs, but the unavailable backend prevented listener connections; no orchestration completed. Actual gallery/first-F5 UI, Azure deployment, cloud smoke and infrastructure build gates were not run. Manual imports and host health are not proof of debug task environment selection. No release or manifest-pin change is included. Review/CLA and remaining acceptance gates are still required; no merge or issue closure is requested.