Prerequisites

• Xcode 26 is available in CIPD
• Upgrade 50% of chromium bots to macOS 15.7.1 #176933 (assuming Xcode 26 requires macOS 15.7)
  • If Xcode 26 requires a higher macOS version, bots will need to be upgraded to new required version before doing this

Instructions

Make a PR with the following:

• Replace Mac version in ci.yaml to macOS 17

- os: Mac-15.5|Mac-15.7
+ os: Mac-15.7

• Replace sdk_version with 17a400

- "sdk_version": "16c5032a"
+ "sdk_version": "17a400"

• Remove presubmit: false for all mac tests
• Update simulator version to 26.0

- OS=com.apple.CoreSimulator.SimRuntime.iOS-18-2
+ OS=com.apple.CoreSimulator.SimRuntime.iOS-26-0

- OS=18.2
+ OS=26.0

- deviceOS = '18.2';
+ deviceOS = '26.0';

See example: https://github.com/flutter/packages/pull/9703/files