# When review leaves the pull request: agent threads vs diff-only review

> Review without pull requests: Zed's Delta landed about 570 changes in agent threads. Why diff-only review breaks when agents write code, and what to keep.

Canonical URL: https://www.revix.ai/blog/review-without-prs-agent-threads

Published: 2026-09-20 · Updated: 2026-10-10 · Author: Oscar Estudillo · Category: Guides

![Title card reading Context, not comments. Schematic of an agent thread becoming shared context that arrives with the change at review.](https://www.revix.ai/images/blog/review-without-prs-agent-threads.webp)

[Zed disabled pull requests on Delta's own repository](https://zed.dev/blog/delta-public-beta) and now builds Delta inside Delta. According to Zed's public beta post, 33 people have landed about 570 changes to main without PRs.

Reviewers join the original agent conversation and see the same worktrees. They can ask the agent why a `Mutex` won over an `RwLock`. They don't have to reverse-engineer a growing diff.

This post looks at *where* review happens. For the merge-time queue, see [how agents raise PR volume](https://www.revix.ai/blog/more-prs-slower-merges).

## Zed's case for review without PRs

Zed's point: agents made diffs much larger, and the diff leaves out the decisions behind the code. In [their public beta post](https://zed.dev/blog/delta-public-beta), they say stacking smaller branches helps you navigate. It still doesn't tell you why the code looks the way it does. A teammate's agent guessing at your reasoning is a weak substitute for the thread where you made those choices.

[The New Stack coverage](https://thenewstack.io/zed-delta-github-alternative/) makes the same point. When the reasoning lives in an agent conversation, a pull request shows the result. Much of the path to it stays elsewhere.

Zed doesn't say every team must leave GitHub. Its editor repo stays on GitHub for community issues and contributions. Contributors can share Delta threads alongside PRs. Teammates who never open Delta still see a normal Git repository.

## Most teams still review in PRs

Most teams will keep GitHub, GitLab and Bitbucket pull requests for now. In many orgs, PRs are where approval, CI and CODEOWNERS run.

So the useful question is narrower. Which part of the PR model already fails when agents write most of the code?

## Diff-only review is what breaks

The PR can stay as the shipping checkpoint. What fails is review that consists only of a diff plus another comment stream.

When an agent writes the change, the intent, tradeoffs and dead ends often live in the thread. Rebuilding them from the patch is expensive. More bot comments on the PR can't restore context that was never in the diff.

Shared agent threads are one fix. Delta also describes review subthreads that carry the original agent context. Both keep the reviewer in the conversation that produced the code.

## What review needs on any surface

Thread or PR, your reviewers need feedback grounded in your team's standards and the real context of the change.

[AI code review](https://www.revix.ai/blog/what-is-ai-code-review) only helps if the tool applies that bar early. [Repo-aware review](https://www.revix.ai/blog/repo-aware-vs-diff-based-ai-code-review) covers what a diff alone misses. This post adds one more need: keep the *why* when agents write the patch.

## Where Revix fits

Revix is built for that gap: feedback grounded in your team's standards and the change's context, on the surface you already use.

## A check for your next agent-heavy change

Ask these three questions. If the weak signal matches, your review is still diff-only.

| Question                                        | Weak signal                                         |
| ----------------------------------------------- | --------------------------------------------------- |
| Where did the decisions for this change happen? | Only in a private agent chat the reviewer never saw |
| What does the reviewer get first?               | A large diff with no path through the tradeoffs     |
| What would fix a stuck review?                  | More comments on the PR, with no more context       |

If you want review grounded in your repository's standards on the PRs you already ship, connect a repo at [revix.ai](https://www.revix.ai). Every team starts with a 14 day free trial, no card required.

## Frequently asked questions

### What is Zed Delta changing about code review?

Delta puts collaboration in shared agent threads. Reviewers join the original agent conversation and worktrees instead of reconstructing intent from a growing pull request diff.

### Are pull requests going away for most teams?

Not tomorrow. Most teams still live on GitHub, GitLab, or Bitbucket PRs. Zed is still using GitHub for its public editor repo and community contributions.

### What breaks in review when agents write most of the code?

Diff-only review. The decisions already happened in the agent thread. A reviewer staring at a large diff has to reverse-engineer that context, or feed the patch to another agent that was not there.

## Related posts

- [More PRs, slower merges: when acceptance becomes the bottleneck](https://www.revix.ai/blog/more-prs-slower-merges)
- [What Is AI Code Review and How Does It Work?](https://www.revix.ai/blog/what-is-ai-code-review)