[SYS-034] v2.1.113 native binary switch terminates running sessions on upgrade — API Error: terminated

Summary

Upgrading to v2.1.113 hard-terminates any active Claude Code sessions mid-run with 'API Error: terminated'. The v2.1.113 changelog notes the CLI now spawns a native binary instead of bundled JavaScript — this architectural change kills running sessions when the upgrade completes.

Reproduction

1. Have one or more active Claude Code sessions running (agents, pipeline work, etc.)
2. Run npm install -g @anthropic-ai/claude-code@2.1.113 in another terminal
3. Active sessions immediately terminate with 'API Error: terminated'
4. All in-progress agent work is lost with no recovery

Compound failure

The session termination hit simultaneously with xterm mouse tracking escape codes flooding the terminal (a known CC escape code leak bug), making the failure invisible until the session was already dead.

Impact

• All running agents killed without warning or checkpoint
• In-progress pipeline scripts (data builds, model retraining) die mid-write — risk of corrupt output files
• Paper trading monitors killed — live system goes dark
• No recovery path — must restart everything from scratch and audit for partial writes

What should happen

The upgrade should either:

• Warn that running sessions will be terminated before proceeding
• Complete the upgrade without killing active sessions (graceful handoff)
• At minimum: document in the changelog that the native binary switch kills active sessions

Environment

• Upgraded from v2.1.111 → v2.1.113
• Windows 10, multiple active agent sessions running
• npm install showed libvips EBUSY warning (related: existing SYS-014 bug) but completed
• Sessions terminated immediately after install completed