Run ensurepip before pip fallback (uv-created venvs lack pip)

[swoboda1337]

When the penv is created by uv, pip is not included. If the external uv fails to install uv into the penv (e.g. timeout), the pip fallback fails with No module named pip.

Fix by running ensurepip to bootstrap pip before the pip fallback. ensurepip is a Python stdlib module that installs pip from a bundled wheel — no network needed.

DEBUG: uv not found in penv, attempting install
DEBUG: python_exe=/root/.platformio/penv/bin/python
DEBUG: external_uv_executable=/usr/local/bin/uv
Warning: uv installation via external uv timed out after 300s
Error: uv installation via pip failed with exit code 1
DEBUG: stderr: /root/.platformio/penv/bin/python: No module named pip

Related: esphome/esphome#15074

Summary by CodeRabbit

• Chores
  • Improved virtual environment setup process with enhanced package initialization to ensure more reliable dependency installation in edge cases.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 4bbe7959-2384-4a40-9624-d2fba1e7a28a

📥 Commits

Reviewing files that changed from the base of the PR and between 658ebd7 and f8cff21.

📒 Files selected for processing (1)

• builder/penv_setup.py

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📝 Walkthrough

Walkthrough

When the uv package manager is unavailable in a created virtual environment, the fallback installation mechanism now runs python -m ensurepip --default-pip before attempting pip install uv. Ensurepip failures are silently ignored, preserving existing error handling.

Changes

Cohort / File(s)	Summary
Virtual Environment Setup builder/penv_setup.py	Added ensurepip invocation (with 60s timeout and captured output) as a robustness measure prior to pip-based uv installation in the fallback path when uv is unavailable in the created venv.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

Possibly related PRs

• Fall back to pip when external uv fails to install uv into penv #387: Directly modifies builder/penv_setup.py's uv installation fallback logic with alternative control flow adjustments.
• Remove use of pip in espidf.py to create the venv #265: Imports and relies on penv-provided uv executables; changes to penv_setup.py's fallback behavior affect its functionality.
• Use uv for creating penv when available #268: Related to penv creation and uv-installation fallback mechanisms in builder/penv_setup.py.

Poem

🐰 A little pip was stuck inside the warren so deep,
We whispered ensurepip to wake it from sleep,
Then uv bloomed like carrots in the spring—
With timeouts and silence, we fixed everything! 🥕✨

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically describes the main change: running ensurepip before attempting pip fallback in uv-created virtual environments that lack pip.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[Jason2866]

@coderabbitai full review

[coderabbitai]

✅ Actions performed

Full review triggered.

[Jason2866]

@swoboda1337 Well the change makes sense. Thx!
But i doubt, when already that deep in issues, this will be the rescue