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Jun 12, 2026 · Artificial Intelligence

Inside Claude Code’s Query Loop: From a Simple While Loop to an Industrial‑Grade Agent Engine

This article dissects Claude Code’s 1729‑line queryLoop, explaining its four‑layer call chain (ask → QueryEngine → query → queryLoop), the async‑generator core that streams model output, how tool calls are handled in parallel, the explicit state object, and the many error‑recovery paths that make the loop production‑ready.