What Garboard does and does not write

This page used to be easier to write and it was wrong. Our own README said Garboard “writes a comment — never repo contents, never merge”. The second clause is true. The first was not, and a security reviewer would have found it in about five minutes by reading the App’s permission grant.

Here is what is actually true.

The review path writes exactly two things

When Garboard reviews a pull request, it writes:

1. one comment, upserted — edited in place on later pushes rather than added to;
2. one check run on the commit.

That is the whole write surface of a review. It does not touch your files.

Fix and Forge do write, and are the only paths that do

Two features write code, and both are things you asked for by name:

Fix proposes a correction to a finding. When you accept it, it commits the corrected file onto the pull request’s own head branch. Your branch, your pull request, your review.

Forge drafts new infrastructure from a description. It commits files and opens a pull request — a normal one, that a human reads and merges or closes.

Both produce a change that a person reviews. Neither merges anything.

And both are gated: a fix or a draft goes through review.RunChecks, the same function your own pull requests go through. Garboard cannot write something its own rules would reject.

What is true across every path

• No apply. No code path runs terraform apply or tofu apply.
• No cloud credentials. Garboard has none. It cannot write to your cloud because it has nothing to write with.
• No merge. Nothing Garboard does merges a pull request. Ever.
• Your pipeline still owns your infrastructure. The only thing that changes your cloud is the thing that changed it before.

Why say it this way instead of the shorter version

Because the shorter version was false, and on this page in particular that matters more than elsewhere. This is the negative-space page — the one a security reviewer reads to decide whether the rest of the documentation is written by people who check things.

Getting caught overclaiming here would cost more than the sentence ever bought. The narrower claim is also the stronger one: “no apply, no cloud credentials, no merge, and every write is a change a human reviews” survives an audit, and “only ever a comment” does not.

How to verify it yourself

Look at the GitHub App’s permission grant. Garboard asks for what it needs to read code, write a comment, post a check run, and — if you use Fix or Forge — push a branch. There is no cloud role, no OIDC trust relationship, and nothing that could reach your provider account.