Bun 1.3.13 SIGSEGV at 0x8 in WebKit GC (PolymorphicAccessJITStubRoutine) during long session

Summary

Claude Code CLI died mid-session with a Bun segfault in the WebKit JIT/GC cleanup path. Session had been running for ~3m 12s (191812ms elapsed) with normal tool use; crash was unprompted.

Versions

• Claude Code: 2.1.119
• Bun: 1.3.13 (0aa3dbc9) Linux x64 baseline
• OS: Ubuntu 22.04.5 LTS, kernel 6.19.9
• CPU features: sse42 popcnt avx avx2 avx512
• glibc: 2.35

Crash

\\\
panic(main thread): Segmentation fault at address 0x8
\\\

Bun's own crash-report page attributes it to the WebKit variant destructor during garbage collection, specifically \PolymorphicAccessJITStubRoutine\ cleanup.

Redacted crash dump already submitted to Bun:
https://bun.report/1.3.13/B_10aa3dbcmgggkEuhogC4i5mnF+xyQ29o96Fk386oFg786oFou4hpF2qm+nFqoir5F+9xq5Forx05F8ok05F4wlwwE2p1gnGqln67F8hm67F_____A2AQ

Runtime snapshot at crash

• Elapsed: 191812ms | User: 14976ms | Sys: 2933ms
• RSS: 82.44MB | Peak: 0.45GB | Faults: 1267
• Args: \claude --dangerously-skip-permissions\
• Exit: \Illegal instruction (core dumped)\

Repro

Not currently reproducible on demand — happened once during a normal session (file reads, memory writes, bash tool calls, one WebFetch). Filing so the bun.report fingerprint can be correlated if others report the same stack.

Impact

SSH session to the host (mark1nvidia) was torn down when \claude\ died, losing conversation state in the terminal scrollback. No persistent data loss (memory files are on disk).