Run the root checks as parallel steps in one job

[nikobockerman]

Each root check had a job of its own through the generic mise-task.yaml wrapper, which was the only way to run them concurrently. Measured over six successful runs on main, those eight jobs spent about 103s restoring the same tools to run 5s of checks: a job is a fresh VM, so the same image boot, checkout and cache restore was paid eight times over.

GitHub Actions gained parallel steps on 2026-06-25, which run concurrently inside one job while still reporting per-step status. Move the eight checks into a single job, so the setup is paid once. A failing step is still attributed individually, and its siblings still run, so nothing is lost by no longer having a job per check.

ruff keeps its cache in the working directory, so check:ruff and check:ruff:format would now share one .ruff_cache. Point them at separate cache directories under the runner temp instead.

[Copilot]

🔵 Needs a closer look

It changes CI execution semantics and relies on a relatively new GitHub Actions feature (“parallel” steps) that should be validated in real runs to ensure expected check reporting and stability.

Pull request overview

This PR optimizes CI runtime by consolidating the repository-root “mise tool” checks into a single reusable workflow job that runs those checks concurrently via GitHub Actions’ parallel steps, reducing repeated VM setup/checkout/cache restore overhead.

Changes:

• Replaced eight separate root-check jobs in ci.yaml with a single checks-mise job that calls a reusable workflow.
• Added .github/workflows/checks-mise.yaml to run the root checks as parallel steps inside one job.
• Split Ruff cache directories between check:ruff and check:ruff:format to avoid sharing a .ruff_cache when running concurrently.

File summaries

File	Description
.github/workflows/ci.yaml	Collapses multiple root-check jobs into a single reusable-workflow job (checks-mise) and updates the final “alls-green” aggregator dependencies accordingly.
.github/workflows/checks-mise.yaml	New reusable workflow that restores mise tools once, then runs the root checks concurrently using parallel, with separate Ruff cache dirs.

Review details

• Files reviewed: 2/2 changed files
• Comments generated: 0
• Review effort level: Lite

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