[BUG] iOS Simulator panel reports 'Xcode is installed but not selected' on Xcode 26.6 / macOS 26.5 despite correct xcode-select

Summary

The desktop app's iOS Simulator panel refuses to attach with the error below, even though xcode-select is verifiably configured correctly. The same MCP server's headless build action works fine; only the panel-related actions (attach, launch) fail.

Xcode is installed but not selected. Run `sudo xcode-select -s /Applications/Xcode.app/Contents/Developer` to use the Claude Code iOS Simulator.

Running the suggested command (it completed silently as expected) and fully restarting the Claude desktop app changes nothing; the error is identical on every attach attempt across multiple sessions.

Environment

• Claude desktop app: 1.26832.0 (macOS)
• macOS: 26.5.2 (25F84), Darwin 25.5.0
• Xcode: 26.6 (17F113), single install at /Applications/Xcode.app (not a symlink)
• Machine: MacBook Air (dedicated dev machine)

Evidence the system state is correct

All of the following succeed on the same machine while attach fails:

$ xcode-select -p
/Applications/Xcode.app/Contents/Developer

$ env -i /usr/bin/xcode-select -p        # clean environment, no DEVELOPER_DIR
/Applications/Xcode.app/Contents/Developer

$ xcrun --find simctl
/Applications/Xcode.app/Contents/Developer/usr/bin/simctl

$ xcodebuild -checkFirstLaunchStatus; echo $?
0

• xcodebuild builds an iOS Simulator app successfully (both directly and through the MCP server's own build action).
• xcrun simctl can boot a simulator, install the built .app, launch it, and take screenshots.
• DEVELOPER_DIR is not set anywhere (no shell profile entries).
• Note: /var/db/xcode_select_link does not exist on this macOS version, while xcode-select -p still resolves correctly even under env -i. If the panel's preflight checks for that legacy symlink path specifically, that would explain the false negative on macOS 26.

Steps to reproduce

1. macOS 26.x with Xcode 26.6 installed and selected (verify with env -i /usr/bin/xcode-select -p).
2. In a Claude Code desktop session, call the iOS Simulator control tool with {"action": "attach"} (with or without a booted simulator).
3. It returns the "Xcode is installed but not selected" error; the suggested sudo command and an app restart do not change the outcome.

Expected

The panel attaches (a simulator was booted with the target app installed and running, verified via simctl).

Possibly related

Similar breakage is reported for newer Xcode/macOS combinations in #79991, #80472, and #81520 (Xcode 27 / macOS 27 beta). This report is the released Xcode 26.6 on released macOS 26.5.2, so the supported-version path seems affected too.