“Everyone’s in a race to replace GitHub”: Zed launches Delta because agents made pull requests obsolete

Something of a consensus has emerged from the developer fraternity in 2026 — GitHub, a platform built substantively for human developers, is no longer fit for purpose.

Part of the problem is sheer volume. Agents can generate, revise and submit code at a cadence GitHub wasn’t designed for, placing growing pressure on infrastructure built for humans working through commits, branches and pull requests. But there’s also a more fundamental question about the interaction model itself: when much of the reasoning behind a change happens inside a conversation with an agent, a pull request presents reviewers with the resulting diff while leaving much of the journey that produced it elsewhere.

At the heart of all of this, of course, is GitHub’s reliability problems. The platform logged hundreds of incidents over the 12 months leading into June, as monthly commit volume rocketed from around 1 billion across the whole of 2025 to 1.4 billion a month by April. By August, GitHub said this figure had jumped to 2.9 billion commits each month.

The growing load has manifested in some fairly spectacular outages, including a near-eight-hour disruption in August, with web and API error rates reaching around 20% at the height of the incident.

As Nathan Sobo, co-founder and CEO of developer platform company Zed, puts it in a blog post published on Wednesday, “everyone is in a race to replace GitHub right now,” with a number of players in the technology sphere working on alternative tooling. That includes Zed itself, which has announced the public beta of Delta — a collaborative environment where developers and coding agents work, review and revise code together in shared threads rather than pull requests.

At the heart of Zed’s pitch is the idea that the pull request is ill-suited to coding agents, and tells reviewers little about the reasoning behind their decisions.

“Since GitHub introduced pull requests over 15 years ago, they’ve become the standard way to ask teammates to review changes to your codebase.”

“Since GitHub introduced pull requests over 15 years ago, they’ve become the standard way to ask teammates to review changes to your codebase,” Sobo writes. “But with agents generating so much code, the diffs we’re asking each other to review have mushroomed.”

The question, then, is what collaboration should look like when agents are producing more of the code?

From A(tom) to Zed

Zed, for the uninitiated, started out with a somewhat narrower remit. Founded in 2021 by veterans of GitHub’s Atom editor team — Sobo himself spent nine years there — Zed emerged as a high-performance, multiplayer code editor built in Rust. When The New Stack tested the beta in 2023, the emphasis was on responsiveness and real-time collaboration; by 2025, AI editing and agentic features had become central to the product.

It has been clear for some time, however, that Zed’s ambitions extend beyond the editor. When the company announced a $32 million round of funding led by Sequoia Capital in August 2025, it also teased DeltaDB, a new kind of operation-based version control system designed to record code changes at edit-level granularity.

Fast-forward to August, and Zed revealed Delta itself in private beta, pitching it as a multiplayer environment where developers can code with agents, share their ongoing threads with teammates and review changes with the original agent context intact.

Multiple participants iterating on a prompt.

Wednesday’s public beta launch brings that idea out into the open, and takes direct aim at one of GitHub’s defining features: the pull request.

Picking up the thread

The central concept behind Delta is the thread: a running record of an agent-assisted coding task in which the conversation and the files being changed remain connected. A developer can hand an agent a job, continue discussing and refining it, and later share that entire body of work with somebody else.

Each thread can work against its own copy of a project, which means multiple pieces of work can proceed independently without every agent touching the same checked-out files. Teammates can join an existing thread or create a separate review thread to examine a proposed change, question the agent that produced it and try revisions before feeding accepted changes back into the original work.

DeltaDB sits underneath that model, recording activity at a finer level than Git. Instead of waiting for a developer to package work into a commit, it captures individual events as they happen — including code edits and activity within the conversation — and uses that history to keep participants synchronized.

Zed calls those individual records “deltas.”

Git hasn’t gone the way of the dodo quite yet, though. Delta currently works with Git repositories, and developers can continue using branches, commits and remotes as usual. DeltaDB effectively adds another layer of history between commits, preserving the intermediate human and agent activity that Git would otherwise discard.

“We now build and collaborate on Delta entirely within Delta.”

Sobo notes that Zed has already disabled pull requests on Delta’s own repository and now develops the product through Delta threads instead. Since doing so, the company says 33 developers have landed 570 changes to main without using pull requests.

“We now build and collaborate on Delta entirely within Delta,” he writes.

Zed disables PRs on its own Delta repo

An intermediate step

It’s worth noting that this is still very much an intermediate step. And for Zed’s own internal development, Sobo expects that intermediary period to be fairly brief. He says the company is only “a few months away” from leaving GitHub behind, with developers focused exclusively on Delta already having little reason to visit GitHub because their conversations, reviews and handoffs now take place inside Delta.

There are still some pieces to disentangle. Zed’s next major dependency is Git storage, which it intends to bring into DeltaDB, while CI and releases also need to move away from GitHub. Sobo sees CI as largely a solved problem, however, and says Zed expects to integrate with existing options rather than build another system simply for the sake of replacing GitHub.

Zed’s main open-source code editor repository will remain in place for now, where an established contributor community already reports problems and proposes code changes. Those contributors can use Delta to expose the agent session behind their work, while still submitting the final change through a conventional pull request, leaving the Git experience unchanged for collaborators who don’t use Delta.

That public repository presents a different problem from Zed’s internal development, given the hundreds of external developers contributing to the project each month.

“We’re moving more thoughtfully with Zed’s public repo because we have hundreds of monthly contributors who depend on that workflow,” Sobo tells The New Stack. “GitHub has an established social component that will take longer to replace, and we’re not going to strand contributors to prove a point. We’re only going to move our community layer when we can offer something better.”

There are other signs of that continued dependency. One item currently on Delta’s roadmap is repository-based access, which will use a GitHub repository’s existing permissions to determine who can access shared Delta threads.

Delta is available as a desktop app for macOS, Linux and Windows, with a browser version for viewing, sharing and reviewing threads. It will remain free throughout the public beta, with paid individual and team plans to follow; Zed says there will always be a free version.

A common thread: Reinventing code collaboration

Of course, Zed is far from alone in tyring to reinvent code collaboration for the agentic era. SpaceX-owned Cursor formally launched Origin in August, bringing Git repository hosting, pull requests and its coding agents under the same roof, while still allowing existing GitHub repositories to remain the source of truth.

GitLab, too, is working on a “next-generation source-code management” project dubbed Project Switch, currently in private beta.

“I believe the thread will replace the commit or branch as the fundamental unit of software development.”

For Sobo, Delta’s claim to differentiation starts with the basic unit around which it’s being built.

“I believe the thread will replace the commit or branch as the fundamental unit of software development,” Sobo explains.

Commits, in his view, will continue to provide useful checkpoints. What they don’t preserve is everything that happens between them: the discussion with an agent, the decisions made along the way and the incremental changes that eventually produce the committed code. That’s the gap Zed wants DeltaDB to fill, with the thread rather than the commit serving as the fuller record of how a piece of software came together.

“Delta’s advantage is that we’re building around the thread from the start, including the infrastructure underneath it,” Sobo continues.

Sobo argues that preserving incremental edits alongside the agent conversation gives subsequent collaborators something a conventional diff cannot: the ability to enter the work where the previous developer left it, and continue interacting with the same agent and context, rather than reconstructing the thinking behind a change after the fact.

Delta’s bet is that the central object of software development should become the ongoing interaction between developer and agent, with the resulting code attached to that history rather than presented later as an isolated diff.

“I expect lots of viable products will compete on the agent experience, with a common infrastructure underneath.”

Sobo expects the next era to echo the structure of the Git era, with competing developer platforms built on top of a common technical foundation.

“On consolidation, we look at how the last era played out. Git became the common foundation because it was open and everyone could build on it,” Sobo says. “GitHub won the layer above through network effects. I expect lots of viable products will compete on the agent experience, with a common infrastructure underneath.”

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