An open-source spec for orchestration: Symphony

Six months ago, while working on an internal productivity tool, our team made a controversial (at the time) decision: we’d build our repo with no human-written code. Every line in our project repository had to be generated by Codex.

To make that work, we redesigned our engineering workflow from the ground up. We built an agent-friendly repository, invested heavily in automated tests and guardrails, and treated Codex as a full-fledged teammate. We documented that journey in our previous blog post on harness engineering ⁠ .

And it worked, but then we ran into the next bottleneck: context switching.

Agents only start working on tasks that aren’t blocked, so execution unfolds naturally and optimally in parallel for this DAG (a sequence of execution steps). For example, we marked the React upgrade as blocked on a migration to Vite. As expected, agents started upgrading React only after the migration to Vite was complete. Agents can also create work themselves. During implementation or review, they often notice improvements that fall outside the scope of the current task: a performance issue, a refactoring opportunity, or a better architecture. When that happens, they simply file a new issue that we can evaluate and schedule later—many of these follow-up tasks also get picked up by agents. While we oversee this process, agents stay organized and keep work moving forward.

In addition to helping with the active work, the development workflow is now something agents know and follow. The development workflow—work on an issue, check out a repo, put it in progress so the PM knows it’s being worked on, add the PR, move it to the Review status, attach videos, etc.—is now captured in a simple WORKFLOW.md file. All of this is a process that humans followed, but it was never documented. Rather than relying on this implicit set of steps, we now document it, and Symphony ensures agents follow it. This lets us build agents that work alongside us. If we decide that agents should also attach self-reflection to finished work, we’ll add that to the WORKFLOW.md , and Symphony will guide the agents to that step.

To solve this new problem, we built a system called Symphony . Symphony ⁠ (opens in a new window) is an agent orchestrator that turns a project-management board like Linear into a control plane for coding agents. Every open task gets an agent, agents run continuously, and humans review the results.

This post explains how we created Symphony—resulting in a 500% increase in landed pull requests on some teams—and how to use it to turn your own issue tracker into an always-on agent orchestrator.

Even as they get easier to use, coding agents—whether accessed through web apps or CLI—are still interactive tools.