Thorsten Ball: agents don't need unit tests
Thorsten Ball says more than half of human written unit tests become useless once the program works, and agents do not need the same ladders. Lachlan Donald says that is exactly backwards for large codebases.
The big disagreement
Thorsten Ball says agents do not need unit tests the way humans do
Thorsten Ball argues that TDD and unit tests exist because of human limits, short-term memory and distraction, and wagers over half of all human written unit tests become useless once the program works. Lachlan Donald replied that good unit tests matter more with agents, because they define behavior at the finest grain and keep the context loop small.
Unit tests are behavior specifications that scale with codebase size.
Receipts
Bun's ahead-of-time compilation starts Claude Code 24% faster
Jarred Sumner posted numbers from an early preview of Bun plus JSC with ahead-of-time compilation: 24% faster startup, 48% lower memory and 46% lower CPU for the Claude Code CLI. In a follow-up he says Claude Code is now 304 MB instead of 430 MB, and that TypeScript 6 runs faster in Bun AoT than in Bun JIT.
Other workloads are different though, TypeScript 6 runs faster in Bun AoT than in Bun JIT now
How they actually work
Pocock ships /retro, and a prompt to audit your last 25 sessions
Matt Pocock shipped v1.3 of his skills with /retro included, the session-reading prompt he posted earlier in the week, saying there was too much hype behind it not to ship.