NVIDIA's Switchyard Routes Claude Code on 113 Hardcoded Strings and Ignores Your Prompt

Last Updated on August 19, 2026 by Editorial Team Author(s): Chew Loong Nian – AI ENGINEER Originally published on Towards AI. Why this landed now I counted every string NVIDIA’s new agent router matches on. There are 113 of them. Exactly one is ever tested against your prompt rather than against your tool output — and it is a phrase Claude Code wrote, not you. After the lead, the article explains why NeMo Switchyard’s stage router decisioning is largely hardcoded: it relies on a single Rust file containing twelve static string tables plus one compaction marker, and it matches substrings against tool names, shell command lines, and tool output (with only a single four-word phrase matched from conversation text when context is compacted). It details how the router scores signals using hardcoded error severities, “spinning”/“exploring” recovery-state heuristics, and a tanh-based confidence score whose threshold of 0.5 means corroboration is required (e.g., a lone Python traceback can be ignored). The piece then walks through the architecture (TOML config with LLM clients/targets/routes, a libsy algorithm crate, and protocol translation), the agent-loop timing (decisions per LL…