Open-source agent splits Sol planning from local Qwen 3.8 27B coding, cutting cost 4x
GapNew4766 · reddit · 2026-09-30
The AtomicBot team details the design of their Fusion planner/worker mode: an orchestrator that is read-only by force (refusing mutating tool calls instead of removing tools, preserving the KV cache), task contracts declaring provided/required symbols with one-line semantics to prevent workers from implementing same-named functions with swapped fields, disposable in-memory workers parallelized via llama-server --parallel, and status read from disk rather than worker replies. In a benchmark of three small 3D games, Sol for everything cost $0.75 in 6.6 minutes; Sol planning + local Qwen 3.8 27B on one RTX 3090 cost $0.17 in 43.4 minutes; fully local was free but took 114 minutes. Known gaps: contracts check names, not meaning, and there's no merge step. MIT-licensed on GitHub.
Related event: Cloud Planner Plus Local Coder Cuts API Costs by 77%(3 posts)→
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