OpenAI Releases Symphony - Open-Source Spec Turns Linear Into a Coding Agent Control Plane (April 28, 2026)

OpenAI on April 28, 2026 released Symphony, an open-source specification and Elixir reference implementation that converts a project-management board such as Linear into an autonomous control plane for coding agents. The repository at github.com/openai/symphony is licensed under Apache 2.0 and crossed 21,000 GitHub stars within a week of launch.

What Happened

OpenAI published the announcement on its company blog as "An open-source spec for Codex orchestration: Symphony." The release is unusual for two reasons. First, OpenAI explicitly says it does not intend to maintain Symphony as a product — it is a reference implementation meant to demonstrate how the new Codex App Server pairs with workflow tools like Linear. Second, Symphony is published as a written specification (SPEC.md) plus a working Elixir service, rather than the Python or TypeScript libraries OpenAI usually ships.

The core idea is a poll → dispatch → resolve → land loop. Symphony continuously reads open issues from a Linear-style board, spawns an isolated workspace per issue, runs a Codex agent inside that workspace, and submits a pull request with proof-of-work artifacts — CI status, complexity analysis, PR review feedback, and short walkthrough videos — for a human to approve before merging. The workflow policy lives in-repo as WORKFLOW.md, so teams version their agent prompts and runtime settings alongside their code.

Key Details

• License: Apache 2.0, public on GitHub at openai/symphony.
• Reference implementation language: Elixir — chosen for its OTP supervision tree, which fits long-running, fault-tolerant agent loops.
• Initial integration: Linear is the only issue tracker spec'd in v1. Adapters for Jira, GitHub Issues, and Asana are listed as community-contribution opportunities.
• Internal results: OpenAI says some teams saw a 500% increase in landed pull requests over the first three weeks of use.
• Companion release: Symphony is the first showcase of the Codex App Server, OpenAI's hosted runtime for long-running agent sessions launched the same day.
• GitHub momentum: 21k+ stars, 1.8k forks, and 400+ open issues at the time of writing — all within roughly seven days of public release.

What Developers Are Saying

Reaction across Hacker News, r/programming, and engineering Twitter is split between excitement and skepticism. The most upvoted Hacker News thread praises the spec-first approach, with commenters comparing it favorably to Anthropic's Model Context Protocol — both ship a written contract before tooling.

Critics note three concerns. First, the 500% PR figure is unaudited and self-reported. Second, several engineers worry the model encourages low-quality "speculative" work that managers will then need to filter, shifting cognitive load rather than reducing it. Third, the Elixir reference implementation feels at odds with most enterprise stacks, prompting calls for a Go or Rust port. DevOps.com's coverage and Help Net Security both highlighted the same trade-off: faster throughput, more review burden.

What This Means for Developers

Symphony is the clearest signal yet that OpenAI sees the next coding-agent battleground in orchestration, not generation. If you already use Linear and Codex, you can clone the repo and run an end-to-end agent control plane today — no waitlist, no SaaS fee, no telemetry beyond your own infrastructure. Teams using GitHub Issues, Jira, or Asana will need to wait for community adapters or write their own.

Even if you do not adopt Symphony directly, the spec is now the de-facto reference for what "production-grade Codex orchestration" looks like — expect competing implementations from Cursor, Cognition, Replit, and the major cloud vendors to align with the same poll-dispatch-resolve-land contract over the coming months.

What's Next

OpenAI's roadmap on the GitHub repository lists three near-term goals: a hosted demo so non-Elixir teams can try Symphony without standing up the runtime; an official Codex App Server SDK in Python and TypeScript; and adapters for additional issue trackers. Linear's CEO Karri Saarinen confirmed on X that the company will publish a first-party Symphony integration guide in May 2026. Watch the SPEC.md file for any breaking changes — the v0.1 spec is explicitly labeled as subject to revision.

Sources

• OpenAI Blog: An open-source spec for Codex orchestration: Symphony — the primary announcement.
• openai/symphony on GitHub — spec, reference implementation, and roadmap.
• Help Net Security — security and supply-chain analysis of running autonomous PRs.
• DevOps.com — coverage of the orchestration layer and operational implications.
• Geeky Gadgets — explainer on the task-based AI coding paradigm.
• MindStudio — deep dive on the 500% PR-throughput claim and Linear integration.