fix(ci): make pytest deps importable in Bazel venv on Linux

[benfdking]

Problem

The Bazel Lint job has been failing on essentially every PR. The failure isn't the PR code — the Rust build/tests pass, but the hermetic Python test targets fail uniformly:

//:pytest_py310  FAILED
//:pytest_py311  FAILED
//:pytest_py312  FAILED
//:pytest_py313  FAILED
  → pytest_py3XX_venv_venv/bin/python3: No module named pytest

...even though the venv-sync step right above logs + pytest==9.0.3 as installed. Because it's independent of the diff, PRs have been merging with a red Bazel Lint check.

Root cause

uv_python_venv (in cargo_build.bzl) installs deps into the standalone interpreter's sysconfig purelib via uv pip install --prefix. Relocated standalone Python builds on Linux don't auto-add that purelib to sys.path, so python3 -m pytest can't import pytest. macOS auto-discovers it, which is why the targets pass locally but fail on ubuntu-latest.

Fix

In .hacking/scripts/pytest_uv.sh, resolve purelib from the interpreter itself (sysconfig.get_path("purelib")) and prepend it to PYTHONPATH before invoking pytest. This is exactly where uv installed the packages, so imports resolve deterministically on all platforms. No-op on macOS (already on the path).

Verified bazelisk test --config=ci //:pytest_py313 still passes locally; the Linux behavior is verified by this PR's CI run.

🤖 Generated with Claude Code

[github-actions]

Benchmark for 19ce05f

Click to view benchmark

Test	Base	PR	%
DepthMap::from_parent	61.7±0.47µs	61.5±0.30µs	-0.32%
fix_complex_query	12.8±0.11ms	13.2±0.09ms	+3.13%
fix_superlong	177.5±8.10ms	181.7±7.58ms	+2.37%
parse_complex_query	4.3±0.06µs	4.2±0.02µs	-2.33%
parse_expression_recursion	7.5±0.05µs	7.3±0.10µs	-2.67%
parse_simple_query	1085.0±6.15ns	1057.5±9.15ns	-2.53%

[github-actions]

Benchmark for 01acbcd

Click to view benchmark

Test	Base	PR	%
DepthMap::from_parent	61.4±0.67µs	61.0±0.62µs	-0.65%
fix_complex_query	12.8±0.11ms	12.7±0.06ms	-0.78%
fix_superlong	172.3±3.03ms	173.9±4.96ms	+0.93%
parse_complex_query	4.2±0.02µs	4.2±0.02µs	0.00%
parse_expression_recursion	7.1±0.03µs	7.4±0.04µs	+4.23%
parse_simple_query	1076.1±15.55ns	1083.5±5.92ns	+0.69%

[codspeed-hq]

Merging this PR will not alter performance

✅ 6 untouched benchmarks
⏩ 6 skipped benchmarks¹

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_{Comparing fix/bazel-pytest-pythonpath (1a7ab01) with main (db085d7)}

Footnotes

1. 6 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩