1.6% Direct API Call Ratio

Description

Sebastian Raschka's quantification, derived from the leaked source, that only 1.6% of the Claude Code codebase directly invokes the Anthropic model API while the other 98.4% is harness engineering (orchestration, compaction, tool plumbing, permission pipeline, caching, memory, telemetry). Became the most-cited single statistic from the leak in technical discussions because it quantifies precisely what competitors gained access to — the non-model IP.

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src-20260409-5acfec94bd6e