Update macOS runner from deprecated macos-13 to macos-26

[Copilot]

The exercises workflow was using macos-13, which was deprecated in December 2025 and is no longer available, causing the macOS job to be immediately cancelled.

Changes

• Updated .github/workflows/exercises.yml to use macos-26 (Apple Silicon/ARM beta) instead of macos-13

# Before
runs-on: ${{ matrix.os == 'linux' && 'ubuntu-24.04' || (matrix.os == 'macOS' && 'macos-13' || 'windows-2022') }}

# After
runs-on: ${{ matrix.os == 'linux' && 'ubuntu-24.04' || (matrix.os == 'macOS' && 'macos-26' || 'windows-2022') }}

Note: macos-26 is currently in beta status. This means some software may be unstable on the new platform, and there could be queueing issues as capacity is being balanced. Beta runners don't fall under the GitHub Actions SLA.

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• github.blog
  • Triggering command: /home/REDACTED/work/_temp/ghcca-node/node/bin/node /home/REDACTED/work/_temp/ghcca-node/node/bin/node --enable-source-maps /home/REDACTED/work/_temp/copilot-developer-action-main/dist/index.js (dns block)
• https://api.github.com/repos/exercism/nim/actions/jobs/62430984198
  • Triggering command: /usr/bin/curl curl -s -H Accept: application/vnd.github+json REDACTED (http block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

[ynfle]

@copilot are there options to pin the version of macos as the latest version but not use the -latest suffix
?

[Copilot]

@copilot are there options to pin the version of macos as the latest version but not use the -latest suffix
?

Yes! You can pin to specific macOS versions. Currently available options:

For Apple Silicon (Arm64):

• macos-14 or macos-14-xlarge (macOS 14)
• macos-15 or macos-15-xlarge (macOS 15)

For Intel (x64):

• macos-14-large (macOS 14)
• macos-15-large or macos-15-intel (macOS 15)

Since we currently use macos-13 without specifying architecture, we were on Intel. The closest pinned replacement would be macos-15-large or macos-15-intel.

Would you like me to change from macos-latest to a pinned version like macos-15-large?

[ynfle]

@copilot What about os version 26?

[Copilot]

@copilot What about os version 26?

macOS 26 is currently in beta status. It's available as macos-26 or macos-26-xlarge (Apple Silicon only), but GitHub notes it's marked as beta, meaning:

• Some software may be unstable on the new platform
• There could be queueing issues as capacity is being balanced
• It doesn't fall under the GitHub Actions SLA during beta

For production workflows, it's recommended to use GA (Generally Available) versions like macos-15 or stick with macos-latest which currently points to macOS-15 Arm64.

[ynfle]

@copilot let's change to the arm version of macos 26

[Copilot]

@copilot let's change to the arm version of macos 26

Updated to macos-26 (ARM/Apple Silicon beta version). Note that this is a beta runner, so you may experience some instability or queueing issues. (Commit: f90eb52)

[Copilot]

Pull request overview

This pull request attempts to update the GitHub Actions workflow to replace the deprecated macos-13 runner with macos-26. However, macos-26 is not a valid GitHub Actions runner version. The PR description states this is an Apple Silicon/ARM beta runner, but this appears to be incorrect.

Changes:

• Updates the runs-on value in .github/workflows/exercises.yml from macos-13 to macos-26

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