LangChain says Open SWE now moves model choice into the harness, sending each task to the cheapest model that passes quality tests. Median cost per task dropped 64%. The post's quoted reply says DeepSeek v4.1 Flash handles orchestration, implementation, and verification well, with frontier models kept for harder edge cases.
agree - most orchestration steps don't need a frontier model
for Open SWE we moved model choice into the harness, so each task goes to the cheapest model that still does the job, tested against quality. median cost per task dropped 64%
https://www.langchain.com/blog/how-to-build-a-model-router-in-the-harness
the more i use deepseek v4.1 flash, the harder it is to justify using a frontier model for everything. a few more things i’ve noticed: 1. it’s insanely good as an orchestrator. i can let it coordinate coding tasks, testing, research, and subagents without burning frontier-model money. 2. once the plan is clear, it handles repetitive implementation work extremely well. 3. i’ve started using it for verification too: reviewing code changes, running checks, and catching obvious mistakes is cheap enough to do constantly. i still bring in opus or sol for harder edge cases... but deepseek is doing more and more of the actual work.View quoted post on X
Source: Harrison Chase · x.comPublished · added here
