# How Kent Beck actually uses coding agents

TDD, Extreme Programming, JUnit

**If you take one thing:** `TCR skill`, red tests revert the code. his own Test && Commit || Revert discipline as an always-on agent rule, so a failing step is thrown away instead of patched.

- **Agent:** Claude Code (cli) ([source, 2026-09-08](https://github.com/KentBeck/FailureVirality/blob/973a52675fb6fb6a5b82799f1849ac25b4038762/README.md#L11))
- **Agent:** Codex (cli) ([source, 2026-09-08](https://github.com/KentBeck/FailureVirality/blob/973a52675fb6fb6a5b82799f1849ac25b4038762/README.md#L11))
- **Model:** Gemini ([source, 2025-12-01](https://substack.com/@kentbeck/note/c-183114266))
- **Review:** Reviews solo, would rather be pairing ([source, 2025-12-26](https://newsletter.kentbeck.com/p/party-of-one-for-code-review))
- **At once:** one at a time ([source, 2026-04-23](https://newsletter.kentbeck.com/p/genie-lessons-nobody-wants-agents))
- **Harness:** Rotating tools, worked live in weekly Genie Sessions ([source, 2026-04-23](https://newsletter.kentbeck.com/p/genie-lessons-nobody-wants-agents))
- **Rules file:** CLAUDE.md (96 lines), identical AGENTS.md, plus a GEMINI.md ([source, 2026-06-29](https://github.com/KentBeck/SmalltalkGenie/blob/5f12d2e50a616301b3d89a91a12fb8cebf059bd7/CLAUDE.md#L8-L9))
- **Skills:** pharo-live-image, pharo-refactor, pharo-rename-method, pharo-tdd, representation-envy-refactor ([source, 2026-07-02](https://github.com/KentBeck/SmalltalkGenie/tree/5f12d2e50a616301b3d89a91a12fb8cebf059bd7/.agents/skills))
- **MCP servers:** genie (his SmalltalkGenie, inside a live Pharo image) ([source, 2026-06-18](https://github.com/KentBeck/SmalltalkGenie/blob/5f12d2e50a616301b3d89a91a12fb8cebf059bd7/README.md#L54))

## In their words

> From 64 sessions (Codex CLI + Claude Code, Sept 2025–Sept 2026), 953 laps,

> From 64 sessions (Codex CLI + Claude Code, Sept 2025–Sept 2026), 953 laps,

> Gemini is fast & good for augmented coding. I’m getting done in hours what would have taken me days with Claude Code.

> I’ve never been able to get two agents working on the same codebase at the same time without my head exploding.

> Code review meant “another human looks at your code before it ships.” Maybe now it means “something helps you maintain awareness of what you’re building and whether the structure is staying healthy.”


Archetype (our label): Purist. Newest source: 2026-09-08.
Card: https://www.prehistoriq.com/stacks/kentbeck/ · Data: https://github.com/prehistoriq/stacks/blob/main/data/stacks/kentbeck.json