Release notes · September 21, 2026

Megastructure Arc 1.9.9

Arc 1.9.9 lets Arc-managed agents set reminders and wait for a task, a background job, or a timer, adds a Thinking level per agent, and keeps self-hosted models streaming through long replies.

Current release

Reminders and waits for agents

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

Highlights

  • Managed agents can now remind themselves and wait. A wait yields until a task, an exact background shell job, or a time condition is satisfied, with an optional timeout; the room shows the saved note, deadline, and delivery state with a Cancel control, and the resumed agent receives a compact packet naming the trigger and the result. The same follow-ups are available through arc_wake_when, POST /v1/wakes, and the arc remind and arc wait commands.
  • Agent settings for API and self-hosted agents gain a Thinking control (Model default, Off, Minimal, Low, Medium, High), sent as the standard reasoning_effort field. Off stops DeepSeek-style thinking on servers that honour it, so a small step budget is no longer spent reasoning before the first tool call.
  • Self-hosted servers always stream replies, so the response deadline is an idle limit between tokens rather than a cap on the whole reply, and each step may use a quarter of the context window; a 15 token-per-second local model can now write a large file in one call. A first reply without a tool call adds a standing reminder instead of counting against the turn, and raw tool-call markup returned as text is treated as a protocol leak, never as the answer.
  • The hub daemon records its version and executable, and the desktop replaces a daemon from an older Arc release that is serving its database, at start and whenever one appears, without ever replacing a newer one. The arc-daemon app start command no longer silently attaches to a daemon of another version.
  • Normalised Megastructure name across the app.

Fixes and refinements

  • Waits accept explicit nulls for unused conditions, their delivery is held until the waiting turn is durably journaled, restart recovery reconciles task and job outcomes, and cancelling also removes queued follow-ups and survives a restart. Cancelling a loop’s outstanding wait pauses that cycle instead of leaving it stuck.
  • Managed agents’ file-lock paths are repaired before they reach the hub: an absolute path inside the project folder is sent repo-relative, and a leading-slash spelling of a project file drops the slash. The tool result names the repair so the model learns the convention.
  • A migration repeats the output-budget lift for API and self-hosted agents that a stale pre-1.9.8 daemon had pinned to 1,800 tokens after the earlier fix; deliberate limits are kept.

System requirements

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