Muse Spark 1.2 was trained with its coding agent

Meta co-trained Muse Spark 1.2 with Muse Code, including extended coding tasks, context compaction, subagents and the agent’s own tools. The surrounding execution environment was part of the training process.

That is the feature Simon Willison singles out: reliable sequences of tool calls increasingly determine whether a model can carry a project through to completion.

At the August 5 launch, the standard API cost $1.25 per million input tokens and $4.25 per million output tokens. The contributor version cost $0.10 and $0.20, respectively, in exchange for letting Meta use the data to improve its products. The discount changes the data agreement as well as the bill.