Introducing Muse Code and Muse Spark 1.2

Meta released Muse Spark 1.2, a coding-focused update to its Muse Spark 1.1 model, with improvements in code generation, complex debugging, codebase understanding, and end-to-end developer workflows, co-trained with Muse Code. The model is offered at $1.25 per million input tokens and $4.25 per million output tokens, but a 'contributor' version priced at $0.10/$0.20 is available if users allow Meta to use their data to improve products.

Introducing Muse Code and Muse Spark 1.2 https://research.meta.ai/blog/introducing-muse-code-and-muse-spark-1-2 Muse Spark 1.2 is a coding-focused update to Muse Spark 1.1, with improvements in code generation, complex debugging, codebase understanding, and end-to-end developer workflows. In Muse Spark 1.2, we significantly scaled up training compute on coding tasks while expanding training environment diversity. The model also maintains its strength in other key areas like general agents. ... We co-trained Muse Spark 1.2 with Muse Code to ensure the model exhibits its best performance and coding usability when paired together. The training included rejection sampled harness trajectories and recipe optimizations for goals, compaction, and subagents, alongside the integration of the Muse Code toolset to maximize harness compatibility. ... Muse Spark 1.2 was extensively trained on long-horizon coding tasks, including whole-repository generation, large end-to-end projects, and auto-research. Here's a pelican riding a bicycle SVG produced by Muse Spark 1.2 https://tools.simonwillison.net/markdown-svg-renderer url=https%3A%2F%2Fgist.github.com%2Fsimonw%2Fce974a21202b0595e36ec2a5ddb51480 : You can see the Spark 1.1 pelican from 9th July here https://simonwillison.net/2026/Jul/9/muse-spark-1-1/ . I think the 1.2 pelican is a small but material improvement. An interesting twist on pricing is that the model is offered https://developer.meta.com/ai/models/muse-spark/ as two different model IDs. muse-spark-1.2 is priced at $1.25/million input and $4.25/million output - close to Gemini 3.6 Flash $1.50/$7.50 - but if you agree to let Meta use your data "to improve our products" you can use muse-spark-1.2-contributor which is $0.10/$0.20 - a huge discount, closer to GPT-5.6 Luna $0.20/$1.20 and Gemini 3.1 Flash-Lite $0.25/$1.50 . I added those new prices to llm-prices.com https://www.llm-prices.com/ sel=muse-spark-1.2%2Cmuse-spark-1.2-contributor . Via Hacker News https://news.ycombinator.com/item?id=49187575 Tags: ai https://simonwillison.net/tags/ai , generative-ai https://simonwillison.net/tags/generative-ai , llms https://simonwillison.net/tags/llms , meta https://simonwillison.net/tags/meta , llm-pricing https://simonwillison.net/tags/llm-pricing , pelican-riding-a-bicycle https://simonwillison.net/tags/pelican-riding-a-bicycle , llm-release https://simonwillison.net/tags/llm-release , coding-agents https://simonwillison.net/tags/coding-agents