ci: migrate macOS runners to macos-15

[jlucaso1]

GitHub starts macOS 14 runner brownouts on October 5 and retires the image on November 2, 2026. Move the macOS CI matrix and the shared nightly/release build matrix to the supported, pinned macos-15 image.

Both jobs remain Apple Silicon. The release target remains aarch64-apple-darwin; build flags, deployment-target configuration, unsigned packaging, artifact names, permissions, and checks are unchanged. Nightly and tagged releases already call the shared build workflow.

Reference: GitHub's macOS 14 retirement notice.

Validation for 251c9edeb2bd7ae5c1cdd46c0f8bc5dae0c251b5:

• actionlint passed across all workflows, with optional shellcheck and pyflakes integrations disabled. Parsed-workflow comparison confirms only the two runner labels changed; git diff --check passed.
• CI #1136 passed all six jobs, including Linux, Windows, web, xtask, and MSRV checks.
• Real macOS job used macos-15-arm64 and aarch64-apple-darwin. Workspace checks passed; platform-sensitive tests reported 565 passed, zero failed, and three ignored.
• CodeRabbit approved this exact commit. Codex's post-readiness review completed with no findings, and no unresolved review threads remain. Cubic returned a neutral check because the repository's monthly review quota is exhausted.
• The Pages bundle build and preview publishing passed, including the downstream Pages deployment.

Nightly/release publishing was not invoked. The native release-profile build and archive generation are not exercised by PR CI; their shared workflow was syntax-checked and its only change is the runner label.

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

• Configuration used: Organization UI
• Review profile: ASSERTIVE
• Plan: Advanced
• Run ID: 46e55434-c592-4d37-82ea-c257330ebda8

📥 Commits

Reviewing files that changed from the base of the PR and between f29234e and 251c9ed.

📒 Files selected for processing (2)

• .github/workflows/build.yml
• .github/workflows/ci.yml

Included review availability: This review used your included allowance. Your plan provides up to 1 included review per hour; 0 remain after this review.

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📝 Walkthrough

Walkthrough

The build and CI workflows now use macos-15 instead of macos-14 for their macOS ARM64 jobs. Other runner selections remain unchanged.

Changes

macOS runner update

Layer / File(s)	Summary
Update macOS ARM64 runner .github/workflows/build.yml, .github/workflows/ci.yml	Both workflows now select macos-15 for the macOS ARM64 job. Other runner selections are unchanged.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~5 minutes

Change: Other

Merge Risk: ⚪ Minimal · up to 251c9

The change is limited to selecting macos-15 for the two macOS ARM64 jobs. Complete the planned CI validation before merging.

Architecture Summary

Architecture risk: 🔵 Low · up to 251c9

The changed surface does not map to a changed system, dependency edge, entrypoint, or external dependency.

Changed systems: None identified.

Architecture concerns
No architecture-level concerns identified.

Review details

Before / after behavior

• observed — Modified behavior in .github/workflows/build.yml: The macos-aarch64 matrix entry now uses the macos-15 runner instead of macos-14.
• observed — Modified behavior in .github/workflows/ci.yml: The macos-aarch64 cross-check runner changes from macos-14 to macos-15.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 0…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: migrating the macOS CI runners to macos-15.

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

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[jlucaso1]

@coderabbitai review

Please review the runner migration on commit 251c9ed while this PR remains in draft for CI validation.

[coderabbitai]

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Review finished.

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-10-05T15:25:24.509841Z	251c9ed	Draft marked ready

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