Tutorials, deep dives and product notes — built for developers.
GPT-6.1 Sol replaced GPT-6 Sol after seven days: +4 index points, +12 on Terminal-Bench 4.0, and a cache rate halved to $0.10. It also dropped the "none" reasoning setting, uses 10-30% more output tokens, and is measurably slower.
Cut AI coding agent costs by 80-97%. DeepSeek V4 Pro cache hits cost $0.003625/1M with 89.9% hit rate. Tiered model stacks save 94%. Batch APIs, structured prompts, iteration limits, and more — with a real before/after comparison: $8,500 to $235/month.