fix(ci): isolate pytest-check-links so Max Versions matrix can collect

[paddymul]

Problem

The Python / Test (Max Versions) matrix fails at "Run tests" with exit code 1, before any test runs:

pluggy._manager.PluginValidationError: Plugin 'check-links' for hook 'pytest_collect_file'
hookimpl definition: pytest_collect_file(path: 'Any', parent: 'pytest.Collector') -> 'CheckLinks | None'
Argument(s) {'path'} are declared in the hookimpl but can not be found in the hookspec

Seen on run 27550697421 (hit while another PR was open; fixing it properly here).

Cause

Fully deterministic in the pytest version:

• Max Versions installs with uv sync --resolution=highest, pulling pytest 9.1.0.
• pytest 9.0 removed the legacy path (py.path) argument from the pytest_collect_file hookspec.
• pytest-check-links 0.10.1 caps pytest<9 in its own metadata, so the max-versions resolve can't use it and backtracks to 0.9.1 (no cap), installing it next to pytest 9.1.
• 0.9.1's hookimpl still declares path, so pluggy's startup validation raises PluginValidationError and aborts collection for the entire unit suite.

This is unrelated to test content and distinct from the post-summary polars/pyo3 SIGABRT (exit 134) that scripts/run_pytest_tolerant.sh handles — this is exit 1 during collection. It only hits Max Versions; the locked matrices use an older pytest where the plugin loads fine.

pytest-check-links is docs tooling, not a buckaroo runtime dependency — only the CheckDocs job runs pytest --check-links (checks.yml). It has no business in the Max Versions matrix.

Fix

• Move pytest-check-links out of the shared dev deps into a dedicated linkcheck dependency-group, pinned >=0.10.1 with an explicit pytest<9 belt.
• Install linkcheck only in CheckDocs (--group linkcheck).
• Exclude it from Max Versions with --no-group linkcheck, mirroring the existing --no-group datacompy.

Verification

• Reproduced locally: pytest 9.1.0 + pytest-check-links 0.9.1 → PluginValidationError; pytest 8.4.2 → loads fine.
• Faithful max-versions resolve (--resolution=highest ... --no-group linkcheck): pytest-check-links absent, all 1212 unit tests collect with no error.
• CheckDocs env (--group linkcheck): pytest-check-links 0.10.1 under pytest<9, --check-links option registered, plugin loads cleanly.
• Unit suite passes locally (2 unrelated artifact_test failures are pre-existing in this checkout — they need a built dist artifact and fail identically on main).

🤖 Generated with Claude Code

[github-actions]

📦 TestPyPI package published

pip install --index-strategy unsafe-best-match --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ buckaroo==0.14.20.dev27551847546

or with uv:

uv pip install --index-strategy unsafe-best-match --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ buckaroo==0.14.20.dev27551847546

MCP server for Claude Code

claude mcp add buckaroo-table -- uvx --from "buckaroo[mcp]==0.14.20.dev27551847546" --index-strategy unsafe-best-match --index-url https://test.pypi.org/simple/ --extra-index-url https://pypi.org/simple/ buckaroo-table

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