Prepare Python projects with bounded concurrency after selecting their
interpreters and workspace sources. Collect all results before reporting an
error, preserving discovery order for publication and error selection.
Share fresh registry resolutions within one install using normalized lockfile
inputs (including overrides, constraints, and extra indexes), requires-python,
and the interpreter report as the key. A per-key mutex
allows one resolution to populate the cache while identical projects wait.
Existing lockfiles retain their replay and frozen validation paths. Local
sources and direct URLs do not share fresh resolutions. Environment installs
seed and validate the shared lockfile through the existing acceptance path.
Make backend environment sharing safe for concurrent projects. Siblings wait
for one environment to finish; recursive builds track their own active keys
and reuse completed nested environments without waiting on other backend chains.
This preserves cycle diagnostics
and avoids dependency cycles between in-flight cache entries.
Add regression coverage for identical projects, frozen lockfile validation,
project dependency-rule isolation, concurrent slot replenishment, and settling failed preparation without
publishing lockfiles. Python installation exists only in pnpm v12.
Replace benchmark artifacts on reruns so the combined report and privileged
comment workflow consume current samples. Seed distinct whole-second manifest,
lockfile, and validation times in the synchronous fast-path test; equal
whole-second mtimes conservatively trigger a content check, so the prior
fixture could fail when its initial mtime landed on a second boundary.
Related to https://github.com/pnpm/pnpm/issues/14945 (item 13).
Zoltan Kochan
e53ce9a943