PYTHON-6091 Pin a consistent uv binary version in CI and locally

[blink1073]

PYTHON-6091

Changes in this PR

Enforces a consistent version of uv in Evergreen CI, GitHub Actions, and local development.

• Pins the uv binary version using [tool.uv] required-version in pyproject.toml, enforced locally and read by astral-sh/setup-uv.
• Bumps the uv version to one that can install Python 3.15.
• .evergreen/scripts/install-dependencies.sh discovers uv from the toolchain (falling back to PATH, then astral download), installs the exact pinned version with uv tool install, and ensures just is present.
• Removed the toolchain-symlink bootstrap; uv/uvx/just are discovered and installed instead.

Test Plan

Tested on a spawn host and on a variety of hosts with patch build.

Checklist

Checklist for Author

• Did you update the changelog (if necessary)? N/A
• Is there test coverage? Yes
• Is any followup work tracked in a JIRA ticket? If so, add link(s). PYTHON-6084 builds on this work to clean up Python selection and installation, including pre-release versions that are not yet in the toolchain.

Checklist for Reviewer

• Does the title of the PR reference a JIRA Ticket?
• Do you fully understand the implementation? (Would you be comfortable explaining how this code works to someone else?)
• Is all relevant documentation (README or docstring) updated?

[Copilot]

🟡 Changes recommended

Windows self-updates and PATH handling can leave setup failing or the pinned tools unavailable.

Get a fresh assessment by requesting another Copilot review.

Pull request overview

Pins one uv version across local development, GitHub Actions, and Evergreen.

Changes:

• Adds the central uv version pin and documentation.
• Installs pinned tooling into dedicated binary directories.
• Updates CI and spawn-host PATH configuration.

File summaries

File	Description
pyproject.toml	Defines the required uv version.
CONTRIBUTING.md	Documents version management and installation.
.evergreen/scripts/setup-system.sh	Configures non-CI shell PATH persistence.
.evergreen/scripts/setup-dev-env.sh	Reorders dependency and Python setup.
.evergreen/scripts/install-dependencies.sh	Discovers and installs pinned tooling.
.evergreen/scripts/configure-env.sh	Establishes task-local binary paths.

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 3
• Review effort level: Balanced

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[Copilot]

🟡 Changes recommended

Version enforcement can block bootstrap installation, and the CI fallback directory is shared rather than task-local.

Get a fresh assessment by requesting another Copilot review.

Review details

Suppressed comments (3)

Previously missed (1) — in code that hasn't changed since the last review.

.evergreen/scripts/configure-env.sh:26

• The /tmp/pymongo-bin fallback is host-global, not task-local as documented. Concurrent tasks or later tasks under another user can race on, overwrite, or be unable to update the same executables; use the checkout's existing task-local .local directory instead.

.evergreen/scripts/install-dependencies.sh:84

• An unpinned uv found on the toolchain or PATH is invoked from the project root here, so the newly added required-version check rejects it before it can install that required version. Bootstrap with project config disabled for this command.

      uv tool install -q --force --from "uv${_uv_pin}" uv

.evergreen/scripts/install-dependencies.sh:102

• After an external bootstrap uv installs the pinned binary, PATH still resolves uv to that external (potentially mismatched) version. If just is absent, this command therefore fails the project's required-version check; invoke the newly installed pinned binary instead.

    uv tool install rust-just

• Files reviewed: 6/6 changed files
• Comments generated: 2
• Review effort level: Balanced

[Copilot]

🟡 Changes recommended

Shared CI paths and stale spawn-host environment files can cause races or make installed tools unavailable.

Get a fresh assessment by requesting another Copilot review.

Review details

• Files reviewed: 6/6 changed files
• Comments generated: 2
• Review effort level: Balanced

[Copilot]

🔵 Needs a closer look

The revised bootstrap does not provision a pinned uvx executable as intended.

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

.evergreen/scripts/install-dependencies.sh:84

• The new bootstrap no longer provisions uvx. The pinned PyPI uv package builds only the uv executable, while the removed toolchain bootstrap explicitly linked both uv and uvx; therefore a fresh toolchain-based setup leaves no uvx, and the astral fallback can leave an unpinned uvx beside the pinned uv. This also conflicts with the PR's stated intent to discover/install uv/uvx/just. Please create a platform-appropriate uvx alias/copy from the pinned binary after this install (including when the existing target uv already matches).

• Files reviewed: 6/7 changed files
• Comments generated: 0 new
• Review effort level: Balanced

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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