iOS Simulator panel: claude-ios-sim crashes (SIGABRT) on attach via CoreImage Metal binary archive

Summary

The claude-ios-sim helper bundled in Claude.app crashes with SIGABRT every time a simulator is attached, so the iOS Simulator panel never opens. Selecting a device on the "attach a simulator" screen bounces straight back to that same screen.

Crashed 7 times in a row today, identical signature each time. The MCP tool reports Claude Code iOS Simulator is restarting after a crash. Try again in 1s. on every subsequent call.

Root cause (from the crash report)

An unhandled Objective-C exception while CoreImage loads a precompiled Metal binary archive. _MTLBinaryArchive loadFromURL: ends up passing nil into +[NSArray arrayWithObjects:count:], which throws, and the helper has no handler, so it aborts.

9   libobjc.A.dylib   objc_exception_throw
10  CoreFoundation    -[__NSPlaceholderArray initWithObjects:count:]
11  CoreFoundation    +[NSArray arrayWithObjects:count:]
12  Metal             __39-[_MTLDevice recordBinaryArchiveUsage:]_block_invoke
13  libdispatch       _dispatch_client_callout
14  libdispatch       _dispatch_once_callout
15  Metal             -[_MTLDevice recordBinaryArchiveUsage:]
16  Metal             -[_MTLBinaryArchive loadFromURL:error:]
17  Metal             -[_MTLBinaryArchive initWithOptions:device:url:error:]
18  CoreImage         +[CIKernelLibrary(Internal) internalBinaryArchiveWithName:device:]
19  CoreImage         CI::PrecompiledUberFunctions::PrecompiledUberFunctions(CI::MetalContext const*)

exception: EXC_CRASH (SIGABRT), termination: Abort trap: 6, faulting process claude-ios-sim (com.anthropic.claude.ios-sim).

Note frames 13–15: the throw happens inside a dispatch_once. Once that block has thrown, the once token stays set, which may explain why every retry after the first fails the same way rather than recovering.

Environment

• macOS 27.0 (26A428)
• Mac16,8 (Apple Silicon)
• Xcode 27.0 (27A266a)
• Claude.app 1.52386.6
• 4 booted simulators on the machine at the time

Steps to reproduce

1. Boot an iOS simulator and install a dev-client app on it.
2. Open the iOS Simulator panel in Claude and pick that device (or call the simulator MCP's attach).
3. attach returns success, then the next call (screenshot) fails with the restarting-after-crash message. The panel returns to the device picker.

What I ruled out

• Memory. The app under test had grown to 1.88 GB; restarting it brought that to 980 MB and the crash was byte-for-byte identical. System-wide memory was 67% free throughout.
• A specific device. Same crash on attach regardless of which simulator is selected.
• The simulator itself. xcrun simctl io <udid> screenshot and Maestro flows against the same device work fine throughout, so the device and the app on it are healthy — it's only the helper that dies.

Impact

The live panel is unusable. Driving the simulator via xcrun simctl and Maestro still works, so it's a degraded experience rather than a blocker, but screenshots and taps through the Claude panel are unavailable.

Crash reports are at ~/Library/Logs/DiagnosticReports/claude-ios-sim-*.ips if fuller logs would help.