What is Co-Review?
Building with a coding agent is fast. Change by change, each diff looks fine, and months later the codebase works but no longer feels like yours: you don’t know where things live or why they’re built the way they are.
Co-Review is a review tool with IDE features — not an IDE. You open something as a review, comment on a line, a diagram node or a design step, and the agent that did the work answers in the thread, from the code, and waits for your verdict before it changes anything. It is built on Eclipse Theia, so code navigation, search, Git and language servers are the real thing; everything unrelated to reviewing is removed.
Four ways to review
Section titled “Four ways to review”Co-Review is not only for whole-repository reviews. The same tool covers four jobs, each one command away, and in every one the agent sets up the review and takes a first pass before you see it (how each workflow goes):
- A whole repository — open the entire codebase as one review to get it back in your head, or to check your own work. An overview shows where to start and how the areas connect, the agent can take a first pass with findings grouped by area, and coverage tracks which files you’ve read. See Review a whole repository.
- Your change — the agent’s diff, a branch against its base, a commit, or a
.patch/.difffile opened as a pull-request page, with line comments, suggested edits and one verdict. See Review a change or pull request. - Someone else’s pull request — the agent reads it, checks out its code and takes the first pass; you decide what goes back to the author, and your verdict posts to GitHub as one review with line comments and suggestions. See Someone else’s pull request.
- A design, before the code — review the plan, not the source: a design written as a foldable L1 · L2 · L3 tree with Mermaid diagrams, where the agent revises from your comments and only builds what you approve. See Design before the code and Design documents.
What you can review
Section titled “What you can review”- Code – a line, a range, a function, a file, a folder or the whole repository. Comments are anchored to the code’s symbol and Tree-sitter tokens, so they follow it through edits and moves, and say when the code they are on has changed.
- Designs – rendered Markdown with a foldable L1 / L2 / L3 design tree, where every step can take a comment. See Design documents.
- Diagrams – Mermaid diagrams, down to a single node or edge.
- Pull requests – diffs and
.patch/.difffiles as pull-request pages, with the code around them; verdicts can post to GitHub.
How a review goes
Section titled “How a review goes”- Claude Code opens its change in Co-Review and flags what deserves attention as proposed findings.
- You read and comment. Select a few lines and Ask Agent, or leave a plain comment.
- The agent answers in the thread from its own context – it knows what it built and why.
- You Submit review: Approve, Request changes or Comment, with a message. The agent gets every open comment, applies accepted suggestions, and comes back for another round.