Virtual Model Variants — brainstormrouter/fast|cheap|quality

2026-03-23

What We Built

Three virtual model names that resolve to optimal concrete models using live performance data:

• brainstormrouter/fast → lowest latency (uses ModelPerformanceTracker latencyMean)
• brainstormrouter/cheap → lowest cost meeting quality floor (default 0.7)
• brainstormrouter/quality → highest quality score

Selection uses Thompson sampling arms from the 7-day performance window. Min 10 samples required. Filters out models with low validity (<0.5).

Lockstep Checklist

• [x] API: Virtual model resolution in router
• [x] Tests: 9 tests for identification, resolution per variant, edge cases
• [x] Docs: Ship log