/resume crashes with SIGTRAP on macOS ARM64 (v2.1.19)

Description

The /resume command crashes with zsh: trace trap claude when selecting a conversation thread to resume.

Environment

• Claude Code Version: 2.1.19
• OS: macOS 15.5 (24F74)
• Architecture: Apple Silicon ARM64 (Mac16,5)
• Terminal: zsh

Steps to Reproduce

1. Run claude
2. Type /resume
3. Start selecting a thread from the conversation list
4. Crash: zsh: trace trap claude

Crash Details

From macOS crash report (~/Library/Logs/DiagnosticReports/2.1.19-2026-01-24-125852.ips):

Exception:       EXC_BREAKPOINT (SIGTRAP)
Signal:          Trace/BPT trap: 5
Faulting Thread: "Bun Pool 6" (#34)

Stack Trace:
  0: claude + 0x16cd3b0
  1: claude + 0x11f1648
  2: claude + 0x4bea20
  3: claude + 0x3ccf10
  4: claude + 0x51bbbc
  5: libsystem_pthread.dylib  _pthread_start
  6: libsystem_pthread.dylib  thread_start

Reproducibility

100% - Crashes on any thread selection attempt. Multiple crash reports generated (10+ crashes today).

Workarounds Attempted

• rm -rf ~/.claude/cache - No effect
• rm -rf ~/.claude/*.lock - No effect
• Verified ~/.claude/settings.json is valid JSON - No corruption found

Additional Context

• The crash occurs in a Bun thread pool worker, suggesting it happens during async conversation loading/parsing
• This is a deliberate crash (assertion failure or panic), not a memory corruption
• Crash reports are available in ~/Library/Logs/DiagnosticReports/2.1.19-*.ips

Crash Report

<details>
<summary>Full crash report header</summary>

{
  "procName": "2.1.19",
  "codeSigningID": "com.anthropic.claude-code",
  "codeSigningTeamID": "Q6L2SF6YDW",
  "cpuType": "ARM-64",
  "exception": {
    "type": "EXC_BREAKPOINT",
    "signal": "SIGTRAP",
    "codes": "0x0000000000000001, 0x00000001042f93b0"
  },
  "termination": {
    "namespace": "SIGNAL",
    "indicator": "Trace/BPT trap: 5",
    "code": 5
  }
}

</details>