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Show HN: I made a heatmap diff viewer for code reviews

(0github.com)
262 points lawrencechen | 2 comments | 30 Oct 25 14:21 UTC | HN request time: 0.548s | source

0github.com is a pull request viewer that color-codes every diff line/token by how much human attention it probably needs. Unlike PR-review bots, we try to flag not just by "is it a bug?" but by "is it worth a second look?" (examples: hard-coded secret, weird crypto mode, gnarly logic, ugly code).

To try it, replace github.com with 0github.com in any pull-request URL. Under the hood, we split the PR into individual files, and for each file, we ask an LLM to annotate each line with a data structure that we parse into a colored heatmap.

Examples:

https://0github.com/manaflow-ai/cmux/pull/666

https://0github.com/stack-auth/stack-auth/pull/988

https://0github.com/tinygrad/tinygrad/pull/12995

https://0github.com/simonw/datasette/pull/2548

Notice how all the example links have a 0 prepended before github.com. This navigates you to our custom diff viewer where we handle the same URL path parameters as github.com. Darker yellows indicate that an area might require more investigation. Hover on the highlights to see the LLM's explanation. There's also a slider on the top left to adjust the "should review" threshold.

Repo (MIT license): https://github.com/manaflow-ai/cmux

Show context
kburman ◴[30 Oct 25 18:17 UTC] No.45763248[source]▶
It’s an interesting direction, but feels pretty expensive for what might still be a guess at what matters.

I’m not sure an LLM can really capture project-specific context yet from a single PR diff.

Honestly, a simple data-driven heatmap showing which parts of the code change most often or correlate with past bugs would probably give reviewers more trustworthy signals.

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1. CuriouslyC ◴[30 Oct 25 20:50 UTC] No.45765157[source]▶
This is not that expensive with Gemini, they give free keys that have plenty of req/day, you can upload your diff + a bundle of the relevant part of the codebase and get this behavior for free, at least for a small team with ~10-20 PR's / day. If you could run this with personal keys, anyhow.
replies(1): >>45766386 #
2. fluoridation ◴[30 Oct 25 22:57 UTC] No.45766386[source]▶
Might just be me, but I understood "expensive" in terms of raw computation necessary to get the answer. Some things aren't really worth computing, even if it's someone else footing the bill.