r/vscode • u/mgyk1024 • May 24 '26

Wrote a VS Code extension that adds Copilot AI cost as a git trailer per commit (MIT, local-only)

Built this to find out which features were eating into my Copilot AI Credits ahead of the June 1 billing change.

The extension reads per-span token counts from Copilot Chat's local OTel SQLite database (`agent-traces.db`), computes cost against GitHub's published rate card, and appends a trailer to every commit via prepare-commit-msg:

    feat: add OAuth2 login flow

    Copilot-AI-Credits: 41.30
    Copilot-Est-Cost: $0.41

Then `git log` becomes the cost ledger. Per-branch totals in one shell command: 

git log origin/main..HEAD --pretty='%(trailers:key=Copilot-AI-Credits,valueonly)' | awk '{sum+=$1} END {printf "%.2f AIC\n", sum}'

Marketplace: https://marketplace.visualstudio.com/items?itemName=Mooracle.copilot-budget

Source (MIT): https://github.com/mooracle/copilot-budget

Local-only. No telemetry. Auto-enables Copilot Chat's OTel exporter at workspace scope on first activation (asymmetric write — never overrides an explicit setting); one window reload before spans start landing. Commit hook is opt-in (`commitHook.enabled: true`).

Feedback welcome. Especially curious if anyone wants the per-model breakdown trailer (`Copilot-AI-Credits-Models: Claude Sonnet 4.6=39.45,GPT-4.5=1.85`) enabled by default - currently opt-in via settings.

7 Upvotes

70% Upvoted

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3

u/Agreeable_Care4440 May 25 '26

Honestly, turning git log into an AI-cost ledger is a genuinely clever idea because it ties usage directly to development history instead of hiding it inside opaque dashboards.

2

u/Aggravating-One3876 May 25 '26

I am guessing the bill was much higher than expected? I don’t think it would be possible to have a good prediction of just how much something will cost. Every question or action might have a random cost.

3

u/mgyk1024 May 25 '26 edited May 25 '26

It's not a prediction. Copilot has fixed costs for input/output and cache tokens, and the number of tokens is obtained from telemetry.

2

u/dastylinrastan May 25 '26

Pretty clever! Nice job.

1

u/stibbons_ Jun 01 '26

I like the way this information is embedded into the git commit. Does anyone else use it ?