Fanning out agents to read every component file is a tempting shape for accessibility review. It demos well in a small project. In a real codebase with hundreds of components, multiple routes, and several active branches, it's a budget problem. You're paying LLM rates for work a deterministic audit engine does in JavaScript. The asymmetry is the point. Rule checks against a rendered DOM are deterministic JavaScript, not LLM tokens. The agent's leverage is in the judgment: choosing the right alt text, the right label, applying the edit at the right place in source. Spend tokens on revisions, not discovery. This morning I ran that loop against a deployed React app. A browser-side audit returned 29 violation types from the live DOM. The agent opened only the two source files those violations pointed to, applied fixes, and that was the work. No file walk, no codebase scan. The cost shape A naive agent scan walks every component file: read, reason, report. Cost grows with the size of the repo.…