[Bug] Anthropic API Error: 400 - Tool Use Concurrency Issue with Multiple Edit Windows

Bug Description
when calling bun on my project, sometimes a second edit window appears on claude code and all subsquent messages get a ⎿  API Error: 400 due to tool use concurrency issues. Run /rewind to recover the conversation.

Environment Info

• Platform: darwin
• Terminal: iTerm.app
• Version: 2.1.7
• Feedback ID: 0c15b198-003d-4ca0-9452-9b7b9b8c397b

Errors

[{"error":"Error: {\"message\":\"Failed to export 9 events\",\"originalLine\":\"211\",\"originalColumn\":\"1336\",\"line\":\"211\",\"column\":\"1336\",\"sourceURL\":\"/$bunfs/root/claude\",\"stack\":\"Error: Failed to export 9 events\\n    at doExport (/$bunfs/root/claude:211:1336)\\n    at processTicksAndRejections (native:7:39)\",\"name\":\"Error\"}\n    at error (/$bunfs/root/claude:2225:25028)\n    at <anonymous> (/$bunfs/root/claude:205:38580)\n    at BQD (/$bunfs/root/claude:205:39124)\n    at <anonymous> (/$bunfs/root/claude:206:17366)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-14T11:30:23.119Z"},{"error":"Error: {\"message\":\"Operation timed out.\",\"originalLine\":\"205\",\"originalColumn\":\"109445\",\"line\":\"205\",\"column\":\"109445\",\"sourceURL\":\"/$bunfs/root/claude\",\"stack\":\"Error: Operation timed out.\\n    at <anonymous> (/$bunfs/root/claude:205:109445)\",\"name\":\"Error\"}\n    at error (/$bunfs/root/claude:2225:25028)\n    at <anonymous> (/$bunfs/root/claude:205:38580)\n    at BQD (/$bunfs/root/claude:205:39124)\n    at <anonymous> (/$bunfs/root/claude:206:16930)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-14T15:00:21.462Z"},{"error":"Error: 1P event logging: 5 events failed to export\n    at queueFailedEvents (/$bunfs/root/claude:211:2077)\n    at async doExport (/$bunfs/root/claude:211:1257)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-14T15:00:22.668Z"},{"error":"Error: {\"message\":\"Failed to export 5 events\",\"originalLine\":\"211\",\"originalColumn\":\"1336\",\"line\":\"211\",\"column\":\"1336\",\"sourceURL\":\"/$bunfs/root/claude\",\"stack\":\"Error: Failed to export 5 events\\n    at doExport (/$bunfs/root/claude:211:1336)\\n    at processTicksAndRejections (native:7:39)\",\"name\":\"Error\"}\n    at error (/$bunfs/root/claude:2225:25028)\n    at <anonymous> (/$bunfs/root/claude:205:38580)\n    at BQD (/$bunfs/root/claude:205:39124)\n    at <anonymous> (/$bunfs/root/claude:206:17366)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-14T15:00:22.676Z"},{"error":"Error: {\"message\":\"Operation timed out.\",\"originalLine\":\"205\",\"originalColumn\":\"109445\",\"line\":\"205\",\"column\":\"109445\",\"sourceURL\":\"/$bunfs/root/claude\",\"stack\":\"Error: Operation timed out.\\n    at <anonymous> (/$bunfs/root/claude:205:109445)\",\"name\":\"Error\"}\n    at error (/$bunfs/root/claude:2225:25028)\n    at <anonymous> (/$bunfs/root/claude:205:38580)\n    at BQD (/$bunfs/root/claude:205:39124)\n    at <anonymous> (/$bunfs/root/claude:206:16930)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-14T15:34:23.824Z"},{"error":"Error: 1P event logging: 5 events failed to export\n    at queueFailedEvents (/$bunfs/root/claude:211:2077)\n    at async doExport (/$bunfs/root/claude:211:1257)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-14T15:34:25.080Z"},{"error":"Error: {\"message\":\"Failed to export 5 events\",\"originalLine\":\"211\",\"originalColumn\":\"1336\",\"line\":\"211\",\"column\":\"1336\",\"sourceURL\":\"/$bunfs/root/claude\",\"stack\":\"Error: Failed to export 5 events\\n    at doExport (/$bunfs/root/claude:211:1336)\\n    at processTicksAndRejections (native:7:39)\",\"name\":\"Error\"}\n    at error (/$bunfs/root/claude:2225:25028)\n    at <anonymous> (/$bunfs/root/claude:205:38580)\n    at BQD (/$bunfs/root/claude:205:39124)\n    at <anonymous> (/$bunfs/root/claude:206:17366)\n    at processTicksAndRejections (native:7:39)","timestamp":"2026-01-14T15:34:25.081Z"},{"error":"Error: {\"message\":\"Operation timed out.\",\"originalLine\":\"205\",\"originalColumn\":\"109445\",\"line\":\"205\",\"column\":\"109445\",\"sourceURL\":\"/$bunfs/root/claude\",\"stack\":\"Error: Operation timed out.\\n    at <anonymous> (/$bunfs/root/claude:205:109445)\",\"name\":\"Error\"}\n    at error (/$bunfs/root/claude:2225:25028)

Note: Error logs were truncated.