Zed shipped 570 changes to Delta after turning pull requests off on its own repo

Joining a thread works differently from cloning a branch. Zed says a teammate who joins sees the same worktrees you do and can work with them on their own machine, and that if you log off, they can keep working with the agent where you left off ^[5]. A review is a subthread with its own isolated copy of the parent thread's worktrees, so a reviewer can try a fix without disturbing the original work. Fixes made during review can be folded into the parent thread before the agent lands the change ^[7]. The example in Zed's post is a teammate asking the same agent why the author chose a Mutex instead of an RwLock ^[6].

What sits underneath is less of a departure. DeltaDB extends Git's content-based versioning with incremental versions based on deltas, and records the edits between commits alongside messages from humans and agents ^[8]. A commit is still the checkpoint you push, pull and build from, with DeltaDB retaining the work in between ^[9]. Stay out of Delta and you see a normal Git repository ^[10]. Verification still runs in CI. Zed says an agent can trigger a run with an existing CI provider and check the results before landing a change, and content-based builds inside the thread are listed as a longer-term goal ^[12].

The published usage figure is Zed's own team: 33 people, 570 changes to main since pull requests went off ^[4], which works out at about 17 changes each ^[21]. For that rate to say anything about another team, the team would have to look like this one: a single codebase, every reviewer inside Delta, and the code under review being the tool doing the reviewing. Zed excluded the harder case itself. The zed-industries/zed repository stays on GitHub for now because that is where the community finds issues and submits changes, and contributors are encouraged to share Delta threads alongside their pull requests ^[11]. For now, the company that switched pull requests off runs its best-known repository on them.

The reliability record is a different argument from the one Zed is making. The New Stack reports hundreds of GitHub incidents over the 12 months leading into June ^[16]. It also reports a near-eight-hour disruption in August, with web and API error rates reaching around 20% at the height of the incident ^[18]. Set against a 2025 monthly average near 83 million commits, the August rate GitHub reported is roughly 35 times as much traffic ^[22]. Those are load and uptime numbers. Nathan Sobo, Zed's co-founder and CEO ^[19], puts the problem in the artifact: "But with agents generating so much code, the diffs we're asking each other to review have mushroomed," he wrote ^[14]. He also wrote that "Most contenders promise better uptime on top of the same old primitives: branches, commits, and diffs" ^[13].

Delta's context reaches only the teammates who join the thread, and everyone else keeps seeing the commits and diffs they see now ^[10]. The bet is stated plainly: "We believe that threads will be the new fundamental unit of software development, and the best way to model their state is with deltas," Sobo wrote ^[15].