Highlights
- UltraSave and UltraFast now pick the model per turn (#40). Jev chooses among the main, worker and utility models you configured — never a model outside that set. UltraSave prefers the cheapest capable model; UltraFast prefers the fastest. The choice sticks for the turn (keeps the prompt cache) and is re-decided after a failed tool call. Disable with the
b2_execution_tierJev lever. - Both modes keep
spawn_subagent; UltraFast's directive pushes parallel splits; both end with a quick requirement/edge-case check. - Fork: completion is published only after the durable session copy finishes.
Benchmarks (20 cases, paired)
| Comparison | Metric | Ratio | Accepted |
|---|---|---|---|
| UltraSave vs Normal | credits | 0.069 | 20/20 |
| UltraFast vs Normal | wall time | 0.509 | 20/20 |
| UltraSave vs 2.0.49 | credits | 0.067 | 19/20 |
| UltraFast vs 2.0.49 | wall time | 0.704 | 19/20 |
Jev decisions cost about US$0.01 per 20-case campaign. Escalation to the main model was not exercised by this cohort.