Add cost tracking to vet output

[andrewlaack]

It would be useful for vet to report the cost of each run (token usage, API spend, etc.) as part of its output. This would help when comparing vet against other code review tools on cost efficiency.

Not sure exactly how this should surface, it could be a summary line at the end of the run, a flag to opt into verbose cost reporting, or something else. Open to suggestions on the right approach.

[arjunpatel7]

Yes agree! It would be wonderful to have a summary and token usage/cost output. It would also be good to inform or check useres about token level rate limits as well when using providers. Or, provide some sort of message there.

I ran into this issue recently where I had to switch providers (Anthropic -> Gemini) because my tier on API key usage was too low. I didn't want to use agentic hardness mode as I wanted to preserve my rate limits there as well.

Additionally, it's hard to tell why a run was successful if no issues were found. Because we can't see how thorough a successful run is, it's hard to understand what the product is doing.

[andrewlaack]

@arjunpatel7 One thing you can do is run with vet -vv, which will show more log information, including the cost information.

I was planning to add this to normal outputs, but since this works, I'm not totally convinced I should / it is sufficiently useful to show by default.

[arjunxplorer]

Opened a PR for this: #215

It adds a run-level cost/token summary to normal vet output (stderr by default, and a top-level usage object in JSON), so you no longer need -vv to see spend. Happy to adjust the UX if you'd rather have this opt-in instead of on by default.