Code Is Cheap. Review Is Expensive.

For a growing share of contributions, it’s now easier to re-generate a pull request from scratch than to review the one someone sent us.

That’s a strange thing to say out loud, but it captures something real that’s happening to open source in the age of coding agents, and it’s forcing us to rethink processes we’ve taken for granted for a decade.

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The old bargain

Open source ran on a simple trade. Writing code was a scarce, expensive skill. When someone showed up with a working patch, they were handing you hours of that scarce resource for free. Reviewing it took time, sure, but review was cheaper than authorship. The contributor did the hard part.

That bargain is inverted now. Generating code is cheap and fast, but judgment isn’t. So a contribution that used to save maintainer time can now cost it, because reviewing a plausible-looking AI-generated diff can take longer than writing the change yourself.

And the diffs are very plausible, which is the trap. A polished PR description, a clean screenshot, a confident summary of what was tested — all of it is easy to produce and hard to verify. We’ve had PRs where the description said it was tested, with a nice screenshot, and then the actual code was building queries against a data warehouse the contributor almost certainly couldn’t run locally. The presentation was flawless. Whether it worked was anyone’s guess.

What review actually costs now

When code was expensive, “does this diff look reasonable?” was a good enough filter. Now it isn’t, and the reasons are worth naming:

• Local coherence, global blindness. An agent solves the one case in front of it. It doesn’t know that the CLI change also needs to land in the VS Code extension, or that a one-line “fix” is a hack that papers over the real problem.
• Plausibility is free. Every AI PR looks like it might be fine. That’s exactly why auto-closing them with another bot doesn’t work. There’s no…