Improve CI infrastructure for pre-commit#2110

EliahKagan

On CI, the pre-commit job has two shortcomings:

It runs on a machine far more powerful than necessary, since anything slow should not be done in pre-commit at all (since some developers may run pre-commit locally).
We've haven't been using any automated means of keeping the pre-commit hook versions up to date, and as a results some of them are quite old. This includes ruff. (There is an external integration that can keep pre-commit hooks up to date on GitHub, but it requires providing access to the repository to an external service. This is sometimes a tradeoff worth making, but it's one we've avoided doing here for this purpose, I think rightly.)

These have both become easier to address recently:

A lighter-weight ubuntu-slim runner is available. Running it on that should work as well and be as fast, and give an indication that we're doing too much in pre-commit if that is ever not the case. It also frees up an ubuntu-latest runner, potentially making CI finish slightly earlier in some PRs where there have been a lot of pushes.
Dependabot now supports pre-commit as a beta ecosystem, so it can keep them up to date. I've tested this in my fork; the resulting grouped PR looks like EliahKagan#5. It's not ideal that the ecosystem is still in beta, but I think it's worth using--and if it turns out to have bugs I haven't yet observed, then this is an oppportunity for me to report them.

This PR uses the ubuntu-slim runner to run pre-commit on CI, and enables Dependabot version updates for pre-commit hooks.

Copilot

Pull request overview

Adjusts CI configuration to make the pre-commit lint job run on a lighter runner and enables Dependabot updates for pre-commit hook versions, keeping hook tooling (e.g., ruff) current without relying on external integrations.

Changes:

Switch lint workflow job runner from ubuntu-latest to ubuntu-slim.
Enable Dependabot beta ecosystems and add grouped monthly updates for pre-commit hooks.
Minor YAML normalization in Dependabot config (remove unnecessary quoting).

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File Description

.github/workflows/lint.yml	Moves the lint job to ubuntu-slim to reduce CI resource usage for pre-commit.
.github/dependabot.yml	Enables beta ecosystems and adds pre-commit ecosystem updates grouped into a single PR.

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EliahKagan

Note that this PR (intentionally) does not upgrade any actual pre-commit hooks. Dependabot should open a PR to do that once this merges.

EliahKagan added 2 commits March 9, 2026 14:29

EliahKagan requested a review from Copilot March 9, 2026 19:34

Copilot started reviewing on behalf of EliahKagan March 9, 2026 19:37 View session

Copilot AI reviewed Mar 9, 2026

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EliahKagan commented Mar 9, 2026

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EliahKagan marked this pull request as ready for review March 9, 2026 19:44

EliahKagan deleted the pre-commit-infra branch March 9, 2026 19:45

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Improve CI infrastructure for pre-commit#2110