From the source
Cognition replaced Opus 4.8 with Fable 5 in Devin, and despite Fable costing twice as much per token, the overall bill decreased when using the Fusion architecture with a sidekick.
- In 3,000 evaluation sessions on FrontierCode 1.1, Fable + Sidekick cost $1.86 per run versus $2.04 for Opus + Sidekick, while scoring higher (60.7 vs 54.6).
- The cost savings come from Fable's management style: it delegates more effectively, taking fewer turns and consuming less context.
