# Competing Implementations Lab

This lab asks DeepSeek V4 Pro and Sonnet 5 to implement the same frozen contract independently and concurrently. Each worker writes only its isolated worktree; the Terra root keeps the canonical workspace unchanged until evidence selects one patch.

Selection uses tests, benchmark results, maintainability evidence, patch review, and integration effort. Model identity and majority preference are inadmissible. The extra implementation is justified only when matched trials show enough quality gain to offset doubled calls and comparison work.

Both candidates are independently hosted persistent Unix app-server workers with equal goal/turn, warning, and finalization policy. The judge can inspect, trace, steer, pause, continue, detach, finalize, fully stop, fork, or cancel either candidate without granting them control over one another. Client/host failure therefore cannot silently discard a candidate's history, evidence, or isolated patch.
