Field notes
The ESR Blog
Field notes from building an AI team that actually ships: what agents can and cannot do, what running them really costs, and why AI tools fail in practice.
What AI agents can and cannot do today
Three weeks of running an AI agent fleet against a real production codebase, with every outcome in an append-only ledger. What landed, what did not, and the one limitation everything else follows from.
August 3, 2026 · 3 min read · Frank Tan
The real cost of running an AI team
$1.64 across 56 routed model calls in fourteen days — and a cost dashboard that reported $0.00 the whole time. Our actual metering data, with the caveats stated.
August 3, 2026 · 3 min read · Frank Tan
Why AI tools fail in practice
Not hallucination. The interesting failure is the one where everything reports green and nothing works. A running list of the ways our own tools lied to us.
August 3, 2026 · 4 min read · Frank Tan