I Cut My AI Coding Costs by 73% Without Losing Quality — Here's the Exact Setup

I Cut My AI Coding Costs by 73% Without Losing Quality — Here's the Exact Setup I was spending $15/day on AI coding tools. After two weeks of optimizing, I'm at $4/day with the same (arguably better) output quality. Here's every change I made, with real numbers. The Baseline: Where the Money Was Going Before optimization, here's what a typical day looked like: Claude Opus 4.6: $8.50 (12 calls, avg 180K context) Claude Sonnet 4.6: $3.20 (25 calls, avg 80K context) GPT-5.4: $2.10 (8 calls, avg 100K context) Misc (Mini, tools): $1.20 ──────────────────────────── Total: $15.00/day The problem was obvious once I tracked it: I was using Opus for everything . Bug fixes, test writing, documentation — all going through the most expensive model. Change 1: Task-Based Model Routing (Saved 45%) The single biggest win. I categorized every coding task and assigned the cheapest model that performs well: # model-router.yaml routing_rules : # Tier 1: Cheap & fast ($0.001-0.01 per call) documentation : m