Zed Launches Delta, a Standalone App Built for AI Agents Writing Your Code

Zed just had one of its busiest weeks. The team shipped v1.15 of the editor with a handful of quality-of-life improvements, and simultaneously announced Delta, a brand-new standalone application that rethinks what a coding environment looks like when AI agents are doing most of the writing.

The v1.15 headliner: diffing against your default branch

The most immediately useful addition in v1.15 is a new git.diff_base setting. Before this, Zed's editor gutters, file-status colors, and git: diff command only showed changes relative to your last commit (HEAD). Now you can choose to show all current-branch changes against the default branch's merge base instead. That distinction matters a lot in practice.

If you're three days into a feature branch with 40 commits, the old behavior only told you what you hadn't committed yet. The new "default_branch" mode tells you everything your branch has changed relative to main -- the full picture of your work, right in the gutter. The setting is also available as "Diff Against Default Branch" in the editor controls menu , so you don't need to touch a config file to try it.

Credit goes to community contributor samuelcolvin for an earlier implementation that the Zed team built on top of.

Web dev improvements worth knowing

Web developers also get linked editing for custom elements in JSX and TSX, and Emmet completions in return and arrow-function bodies. The linked editing piece is the more impactful one: if you rename a custom element tag like <custom-el>, its matching closing tag updates automatically. Previously this only worked for standard HTML elements.

A few other smaller additions round out the release:

• Support for dragging files from the Project Panel to external apps on macOS and Linux Wayland.
• A new gutter.git_gutter_width setting to configure the width of Git diff indicators.
• Support for self-hosted Sweep Next Edit models via any OpenAI-compatible endpoint, giving teams running private inference a path to edit predictions without sending code to a third party.
• Copilot users will need to re-authenticate, as Zed is decoupling session management for chat and edit predictions.

The bigger announcement: Delta enters private beta

Alongside the v1.15 release, Zed introduced Delta, a multiplayer environment for coding with agents and reviewing what they build, and began inviting the first users into its private beta. Delta keeps code and conversations connected, so developers and agents can work together with the full context of how the code came to be.

Delta is not a plugin or a new panel inside the Zed editor. It is its own standalone app, built from scratch around a new idea: the conversation between you and an agent is the actual source of your software, and your tooling should treat it that way. The team decided a new application was necessary because retrofitting DeltaDB into the existing Zed editor would have meant disrupting the workflows of hundreds of thousands of daily users.

What DeltaDB actually does

At the core of Delta is DeltaDB, a custom version control layer. To understand why it's different, think about what Git captures: snapshots you explicitly freeze with a commit. Unlike Git, DeltaDB records every operation that happens in between commits, assigns each one a stable identity, and links each change to the conversation -- usually with an AI agent -- that produced it.

The underlying technology is CRDT-based. CRDTs (Conflict-free Replicated Data Types) are a class of data structures that can be merged across multiple machines without coordination, which is what makes real-time multiplayer editing possible without a central locking server. DeltaDB replicates the conversation and the worktree together, in real time, for everyone in a thread.

Delta is designed to work with existing Git repositories, ensuring that edits and discussions are captured between commits without disrupting traditional workflows. Teammates who never open Delta just see a normal git repo.

What you can actually do in Delta

• Inline review on live code: By moving away from traditional commit-based commenting, Delta allows for persistent, anchored feedback on any line of code, regardless of whether it was authored by a human or an agent.
• Real-time multiplayer threads: Share a thread link and teammates join as first-class participants who can comment, co-edit prompts, or pick up work without needing a commit or push.
• Claude Code integration: Terminal Claude Code sessions sync live into Delta threads via the open Agent Client Protocol (ACP), with full conversation and code history visible to collaborators.
• Browser access with no install: Delta.dev runs the same Rust app compiled to WebAssembly, so teammates can open threads in a browser with no install.
• Cloud runners: Move work to a cloud machine, close your laptop, and the agent keeps going while its conversation and code stay synchronized with the thread.

The problem Delta is solving

The core friction Delta targets is the gap between where code gets written and where it gets reviewed. In most agent-assisted workflows today, an agent produces a large diff, you review it in a PR, and the conversation that generated that code lives somewhere else entirely -- in a chat window, a Slack thread, or just in your head. Delta is the second half of a plan Zed has been executing for years: to build the best place to write code, then make it the best place to talk about code. When they first started out, not everyone understood why you'd want to have a conversation inside your IDE. Then came agents, and now talking about code is how software gets written.

The interface is also designed specifically for the volume of output agents produce. Rather than collapsing diffs or truncating transcripts, Delta keeps everything visible and renders it at full speed. The thread is treated as a document: your cursor works anywhere in it, and comments attach to the exact text or code line they're about.

Availability and pricing

The first invites to the private beta have gone out, with more users being invited over the coming weeks. You can sign up for early access at zed.dev/deltadb. No pricing has been announced for Delta yet.

The Zed editor itself remains available now on macOS, Windows, and Linux. The Personal plan is free forever with 2,000 edit predictions per month; Pro is $10/month with unlimited predictions and hosted models. Business is $30 per seat per month and adds org-wide model policies, data governance, and role-based access controls.

Zed plans to open-source DeltaDB with an optional paid service, the same model it uses for the editor itself. Whether Delta eventually folds back into Zed or remains a separate product is still an open question, but the team has been explicit that DeltaDB will eventually come to the editor too.