DHH keynote: 1,000 agents on one codebase means DRY and abstractions need repricing

ccerrato147 · x · 2026-09-26

At Rails World 2026 (Sep 23), DHH laid out new rules for developing with agents: judge the result, not the code; prompt above what you know; give agents outcomes, not tasks; brief them like a coworker and walk away.

He also rethinks classic abstraction principles: abstractions existed so humans wouldn't repeat themselves, but with a thousand agents working one codebase at once, every abstraction is a door they all squeeze through — and repeating yourself now costs nothing. DRY, naming, and layers were all priced for expensive programmer hours, which no longer applies in the agent era.

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