Introducing Muse Code and Muse Spark 1.2
Meta’s Muse Code beta is a terminal coding agent built around Muse Spark 1.2. Its notable engineering choices are persistent asynchronous subagents, a local append-only event log for replay-exact crash recovery, approval-gated skills such as /plan and /grill, and co-training the model with the harness’s trajectories, compaction, goals, and subagent tooling.
Meta reports long-horizon coding runs exceeding 1,000 tool calls and up to 24 hours, including iterative Triton GPU-kernel optimization. Muse Code is available for macOS and Linux, while Spark 1.2 is exposed through Meta’s model API.
The release is interesting primarily as a harness-design document, not just a model announcement: the runtime, recovery semantics, and tool compatibility are treated as part of model quality. HN commenters liked the event-log and persistent-worker ideas but questioned the selective benchmark comparisons, the closed source, the rough beta experience, and Meta’s data-sharing terms. Several users also reported that the discounted contributor pricing is limited by region and requires allowing Meta to use request data for product improvement.