Show HN: Gage – Rust based tool to scan Claude sessions for bugs, other issues
github.comGage is an open source (Apache 2) CLI + TUI that scans Claude Code session transcripts and files issues with evidence.
Yesterday it found a bug that I had approved. In the original session Claude flagged the risk. I didn't read carefully, said "go ahead", and it broke a feature. Nothing in the commit shows this. It's obvious in the session.
Sessions contain the code and the reasoning behind it. That makes them a better source for review than the diff alone.
Every issue must cite lines in the session record, so any claim traces to its source. You can review, fix, or close issues as skipped. Gage integrates with Claude Code to review and resolve issues from the transcript.
Cost: scans run under your Claude login. On a subscription they count against your plan limits. On usage-based billing they cost about $0.50 to $1.00 per session. Running it daily, I'm paying roughly $2 per issue resolved. Some are minor. Some are not.
What are the .rn files in your examples? They look like rust but perhaps I'm missing something?
These are Rune! https://rune-rs.github.io/
Gage has its own scanner runtime sandboxes each scanner task. This is for security and performance.
Python's the obvious choice for writing this sort of code but ask Google with Tensorflow and they'll tell you how that can go. If you want to sandbox properly and control program execution, Python's tough to wrangle.
Rune is a terrifically designed language for this. It's async support is so well done, it should get an award. Gage uses that for any side-effect functions and so we have both strict control over what scanners can do and language level support for performance optimizations.
Plus Rune is very Rusty and it's a pleasure to use.
If you're ever in the market for a scripting language that bears the hallmarks Rust design sensibility, Rune baby!