DeepMind's Philipp Schmid Builds One Agent Three Times, Deleting Code Each Pass

AI Engineer · youtube · 2026-09-15

At AI Engineer, Google DeepMind's Philipp Schmid builds the same GitHub PR review agent three ways on stage, deleting code each pass: a hand-written Python loop, then an agent framework with auto-generated schemas — both refuse a weather question — and finally a remote sandboxed agent that just searches and answers, because nothing told it what its tools were for.

Version three runs in a hosted sandbox with a network proxy that injects credentials on outbound requests (the agent never sees the token) and an allowed-domain list; loops, tool routing, session state, and context compaction all move server-side. What remains yours: instructions, rules, capabilities as skill files, and evals.

His closing heuristic: if your harness gets more complex as models improve, you're overengineering it — some teams have replaced thousands of lines of orchestration with a few hundred lines of markdown.

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