Hard problem 01
Open-weight models that stopped after one tool call
- Problem
- Open-weight models served over an Anthropic-style messages transport narrated a plan, made one tool call and stopped. That made them useless as coding agents.
- What I did
- Tested the first hypothesis, prompt caching; disabling it alone did not fix the stall, so I rejected it.
- Rebuilt the lane as a Vercel AI SDK loop over an OpenAI-compatible endpoint through a self-hosted LiteLLM proxy, with explicit stop conditions.
- A bridge from the coding tools to AI SDK tools, with reply caps, abort propagation and a git-gated submit.
- Result
- Open models run full tool loops, two earlier drivers were retired, and the Claude lane is unchanged. Tool-call success rates were not benchmarked.