ci: save pre-commit cache only from the default branch

[juenglin]

Description

This is a CI infrastructure change; there is no separate tracking issue.

.github/workflows/pre-commit.yml used a single actions/cache step that both restored and saved. GitHub scopes caches by ref, so every PR merge ref (refs/pull/N/merge) saved its own ~260 MB copy of identical hook environments that no other run can read, steadily consuming the per-repository cache quota.

Changes:

• Split the single cache step into actions/cache/restore and actions/cache/save (same pinned SHA). Gate the save with github.ref_name == github.event.repository.default_branch so pull requests restore the shared cache but stop creating per-PR duplicates. !cancelled() keeps a push that fails lint from discarding the valid hook environments, and the save is skipped on an exact key hit to avoid re-saving identical content.
• Keep the full Python patch version in the primary key, but add a minor-version restore-keys prefix. A runner-image patch bump (3.14.7 -> 3.14.8) then misses the exact key, warm-starts from the previous cache via the prefix, and re-saves once, instead of exact-hitting a stale minor-only entry and rebuilding the hook environments on every run.
• Add ctk-next to the push branches. It is the default branch of the private mirror, so the save also refreshes there; the branch does not exist upstream, so the trigger never fires here and this file stays byte-identical across both repositories.

Net effect: each repository keeps about one Linux + one Windows entry instead of a pair per pull request, and the Windows cache is preserved.

Checklist

• New or existing tests cover these changes.
• The documentation is up to date with these changes.

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[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 94139a0 and 5aebb5e.

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• .github/workflows/pre-commit.yml

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📝 Summary

Summary by CodeRabbit

• Chores
  • Updated automated pre-commit checks to run for changes pushed to both main and ctk-next.
  • Updated the Python version used by the checks and refined how their cached data is restored and saved, helping keep the checks consistent across runs.

Walkthrough

The pre-commit workflow now runs on pushes to ctk-next as well as main. It sets Python 3.14 through an environment variable and uses separate cache restore and save steps with conditional saving.

Changes

Pre-commit workflow

Layer / File(s)	Summary
Configure Python and cache lifecycle .github/workflows/pre-commit.yml	The workflow adds the ctk-next push trigger and configures Python 3.14 through PYTHON_VERSION. Cache restoration uses the resolved Python version and configuration hash, with a minor-version restore prefix. Cache saving runs only when the job is not cancelled, the ref is the default branch, and restoration did not find an exact cache hit.

Suggested reviewers: rwgk

Priority: ⬇️ Low

Change: Other

Merge Risk: ⚪ Minimal · up to 5aebb

The workflow preserves the intended cache-refresh behavior while limiting writes to the repository’s default branch. No actionable merge-blocking risk remains.

• Autopilot · Keep fixing CodeRabbit findings and required CI, and resolving merge conflicts

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[jpascucci-nv]

Seems fine.

[juenglin]

/ok to test 5aebb5e

[github-actions]

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