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dpc · Apr 12, 2026

LLM Reviews in cargo-crev

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There has been lots of chatting about software supply chain security recently, motivated by popular package exploits. Well, I have some relevant news: cargo-crev now supports LLM-assisted code reviews. Go try it! Read on to get more information and background. History # I started working on Crev in 2018. The idea was (is) simple: if each of us (developers) reviewed at least some of our…

There has been lots of chatting about software supply chain security recently, motivated by popular package exploits.</p>

Well, I have some relevant news: cargo-crev</a> now supports LLM-assisted code reviews. Go try it!</p>

Read on to get more information and background.</p>

History#</a> </h2>

I started working on Crev in 2018. The idea was (is) simple: if each of us (developers) reviewed at least some of our dependencies, and then we could share and distribute such reviews between each other with the help of a Web of Trust, we could get a good review coverage of the ecosystem, gain more trust in our supply chains, report back issues upstream and improve overall health of the open source ecosystem.</p>

cargo-crev</code> was an attempt to implement such a system, for the language ecosystem I cared about most — Rust.</p>

If I may say so, on a technical level I'm satisfied with the UX and flow that was achieved. However, around 2020 I lost my enthusiasm for this project.</p>

Why? Because it became apparent that no matter how well cargo-crev</code> actually works, the biggest obstacle to fully realize the idea was lack of time by developers.</p>

Reviewing code, even superficially, is a lot of effort and it takes a very long time. And it does not feel nearly as satisfying as actually creating something new — writing code.</p>

Open Source community was already overburdened with just maintaining code. Asking developers to take on yet another unpaid responsibility of trying to secure supply chains is just asking too much.</p>

LLMs getting good at finding issues#</a> </h2>

Just a few weeks ago I was reading some articles about new LLM models finding non-trivial security issues, and Linux kernel and curl developers admitting that after a deluge of mostly worthless slop security reports they used to complain about, now they tend to receive actually worthwhile AI-assisted bug and security reports. It reminded me about cargo-crev</code> and I realized that AI can actually fill the gap that made me doubt it.</p>

I'm not trying to overhype LLMs. But the fact is that they can do, and in high volume, what developers themselves have no time for: the 90/10 security scanning that was otherwise quite hard to automate.</p>

An LLM can easily and reliably check if a code version published on https://crates.io matches the code published in git.</p>

An LLM can easily scan build.rs</code> and the rest of the code and look if anything looks out of place.</p>

It is actually very hard to hide key-stealing malware in a package that was supposed to format units, etc.</p>

Especially in Rust, doing things that are wrong or out of place creates a lot of noise, making such code easy to notice, even by an LLM reviewer.</p>

It might not be a silver bullet, but it is definitely better than doing nothing.</p>

How to use it#</a> </h2>

Note: In the initial release cargo-crev</code> supports only Claude Code agent. If you're interested in adding support for other coding agents, it should be relatively easy — most scaffolding is already there. Feel free to chat and create a PR.</p>

Since version 0.27 cargo-crev</code> has a built-in review loop.</p>

cargo crev ai review-loop --iterations 10</span></span></code></pre>

which will start the agent 10 times, each time selecting and reviewing a single dependency.</p>

The agent will produce&update a single shell script that can be used to conveniently review and sign all reviews.</p>

While the above is meant as a standard mass-review flow, the core built-in agent review skill is available as an output of:</p>

cargo crev ai skill review</span></span></code></pre>

and it should be easy for anyone to modify it and/or build their own LLM-assisted workflows.</p>

How it works#</a> </h2>

The core change is that Crev's reviews now have fields to indicate that an LLM was used for the review</a>.</p>

The rest is just relatively minor functionality to make producing LLM reviews convenient end to end.</p>

For people skeptical of LLMs, options to ignore LLM-generated reviews have been and will be added where appropriate. You can just ignore the slop reviews if you don't trust them, fine with me.</p>

How well</em> it works#</a> </h2>

While working on this feature and testing it myself, I have produced quite a few LLM-assisted reviews</a>. Judge by yourself.</p>

To me these meet the bar of being useful. And they turned some spare capacity from my Claude subscription into something that I otherwise would not be able to do myself.</p>

Summary#</a> </h2>

This is only an initial attempt at harnessing the AI in cargo-crev. There still might be lots of things to improve and extend, but we have to start somewhere.</p>

If you like the idea and find it promising, I encourage you to try it out, give some feedback, and submit improvements.</p>

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