Mateo Cerri

2026-10-12

Giving my agent tools that show their work

Every session my agent reinvented the same helpers: diffing two PNGs, taking a census of a log directory, trimming a noisy trace. And every session it wrote files the same way, through opaque heredocs in the shell, invisible in review. Two small plugins fixed both habits.

Scriptbox is a closed-world registry of reusable scripts. Helpers get a canonical home with a purpose header and a descriptive name, and the agent lists them on demand instead of rewriting them. Save once, reuse by name.

Patchflow makes edits auditable. Anchor-based atomic batch edits: path, anchor, replacement, expected match count, with a dry run first. One reviewable call instead of N silent writes.

The live demo: renaming a field type across 70 files of a benchmark happened in a single patchflow call. That call is the whole philosophy. Agents that cost fewer tokens and show their work. Two more plugins in the family (slim-output, wsl-shim) share it.

Recap

Takeaway. There is a specific pleasure in fixing a small thing well and knowing strangers will trip over it less. Open source runs on that feeling as much as on the code.

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