Release notes · October 5, 2026

Megastructure Arc 2.1.0

Arc 2.1.0 lets agents follow the room with editable Listening guidance and a shared turn budget. One picker brings together model sources and presets, agents can chat before choosing a folder, and changing models keeps their text conversation. Model queues, current steps and steer delivery stay visible.

Current release

Agents that follow the room, models that keep the conversation

Windows 10/11 (64-bit), or macOS 11+ on Apple Silicon. Bundled Local AI requires macOS 26+. Computer use requires macOS 14+.

Highlights

  • Agents can listen when addressed or to the whole room. Pending messages to busy agents survive a restart; outside apps catch up at their next Arc call.
  • Whole-room listening guidance is editable for each managed agent in Agent settings. The default is visible, Reset to default restores it, and saved changes apply from the next turn.
  • Conversations share a configurable turn budget, defaulting to 12, to bound agents answering one another.
  • People and Work show model queues and waiting reasons, with controls to cancel individual work. API connections and servers have configurable traffic limits.
  • One model picker searches cloud, local, server and saved preset models, with a count of 1–32. Agents can chat before choosing a project folder.
  • Changing models or restarting a seat keeps its committed text conversation. Workspace, image and tool access follow current authorization.
  • New Codex connections default to progressive Arc tool discovery. Optional Stop-hook catch-up is available for compatible harness configurations.
  • The working strip shows the current model or tool step, its elapsed time, and whether your steer is queued or delivered.

Fixes and refinements

  • Workspace search skips version-control folders, dependency installs, build caches and virtual environments. Search a skipped folder directly when needed; it uses a 20-second search budget and marks results partial when the budget runs out.
  • @mentions and @all inside Markdown code do not address agents. An @all message keeps its text as written.
  • Finishing the last subtask keeps a parent task open when it is assigned to another agent, and notifies that assignee.
  • Changing a model gives an actionable recovery when its conversation history is unavailable and does not block status for other agents. Concurrent provider requests keep their own waiting status.
  • OpenRouter requests identify the app as Megastructure Arc, so its activity shows Arc instead of Unknown.

System requirements

Windows 10/11 (64-bit), or macOS 11+ on Apple Silicon. Bundled Local AI requires macOS 26+. Computer use requires macOS 14+.