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Meta Launches Muse Code, a Terminal-Based AI Coding Agent Built on Proprietary Muse Spark 1.2

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NathanTechnology Editor · Technical Lead
Published · Updated
According to TechCrunch and VentureBeat, Meta released Muse Code — a beta terminal-based AI coding agent for large repositories — alongside the Muse Spark 1.2 model on August 5, 2026. Muse Code installs with a single command, runs persistent background agents, and is entirely proprietary, putting Meta in direct competition with Anthropic's Claude Code and OpenAI's Codex.

What Is Muse Code? Launch, Core Capabilities, and Requirements

Meta released Muse Code on August 5, 2026, described by CEO Mark Zuckerberg in a social media post as able to "accomplish 'complete software engineering tasks across large repos,'" according to TechCrunch (E1). The tool is currently available in beta (E1). Zuckerberg said the agent's tasks include "planning changes, writing code, validating the results" (E2).

According to TechCrunch, Muse Code can be installed with a single command and is powered by Meta's previously released coding model, Muse Spark (E3). VentureBeat's own hands-on test on a Mac mini confirmed the one-line installer worked as advertised, downloading a 97 MB package and prompting a sign-in — but the agent stopped short of running any task, reporting that no models were visible and that payment was "required to finish setting up your account" (E20).

Technical Design: Architecture, Safety, and Parallel Execution

Zuckerberg said that in testing, Muse Code "build six features for a game simultaneously with no collisions," according to TechCrunch (E4). VentureBeat reported that Muse Code is a full harness, installable on macOS or Linux with a single curl command, co-trained with the model that powers it, and — like the Muse Spark models behind it — entirely proprietary (E8).

Per Meta's blog post as cited by VentureBeat, Muse Code uses "persistent async background agents" that "remain active throughout each session, rather than being spawned for individual tasks, helping avoid redundant information gathering," carrying out next steps on their own and choosing when to report back to the main agent (E10). VentureBeat also reported that every model call, tool run, approval, and edit is appended to a local event log before execution — a single source of truth that Meta says makes the runtime "replay-exact and restart-safe" (E11).

Benchmark Performance: How Muse Spark 1.2 Stacks Up

VentureBeat compiled benchmark results comparing Muse Spark 1.2 (running in Muse Code) against rival models:

BenchmarkMuse Spark 1.2Rival scores
SWE-Bench Verified (original Muse Spark, April 2026)77.4Claude Opus 4.6: 80.8; Gemini 3.1 Pro: 80.6 (E12)
Terminal-Bench 2.182.9%GPT-5.6 Terra (Codex): 81.8%; Grok 4.5 (Grok Build): 81.6%; Claude Opus 5 (max effort, Claude Code): 86.7% (E13)
DeepSWE 1.159.3% (3rd place)Opus 5: 65.0%; GPT-5.6 Terra: 64.8% (E14)
Meta internal coding benchmark70.6%GPT-5.6 Terra: 65.4%; Gemini 3.6 Flash: 63.9%; Opus 5: 79.4% (E15)

Across every benchmark VentureBeat cited, Claude Opus 5 posted the top score. VentureBeat also reported that Muse Spark 1.2 improves on the prior 1.1 version by 6.7 points on Terminal-Bench and 6.3 points on DeepSWE (E16). Separately, Meta pointed Muse Spark 1.2 at GPU kernel optimization and let it run for more than 1,000 tool calls over up to 24 hours on NVIDIA Hopper hardware, according to VentureBeat (E17).

Pricing Model: Standard Tier vs. Contributor Tier

VentureBeat reported two distinct pricing tiers for Muse Spark 1.2:

TierInput (per million tokens)Output (per million tokens)Cached inputRate limitData use
Standard$1.25$4.25$0.153,000 requests/minNot used to train Meta's models (E18)
Contributor$0.10$0.20$0.00260 requests/minPrompts and completions may be used to train future Meta models (E19, E21)

VentureBeat noted the contributor tier is roughly 12x and 21x cheaper than standard on input and output tokens respectively, in exchange for explicit permission to use prompts and completions for training (E19). VentureBeat added that the contributor tier's much tighter rate limit — 60 requests per minute versus 3,000 for standard — signals it's aimed at individuals and small experiments rather than production workloads (E21).

Meta's Enterprise AI Push and Cost Positioning

Alexandr Wang, Meta's AI chief who leads Meta Superintelligence Labs, told the Wall Street Journal that Muse Code "can be an incredibly good option, especially from a cost perspective," for a lot of workflows and use cases, as reported by TechCrunch (E5). TechCrunch also reported that in June 2026, Meta expanded beyond its core advertising-focused AI use and entered the enterprise AI market with an agent aimed at customer service and support (E6).

According to VentureBeat, Meta's release of Muse Code in beta alongside Muse Spark 1.2 puts the company in direct competition with Anthropic's Claude Code, OpenAI's Codex, and the broader field of agentic coding harnesses (E7).

Strategic Shift: From Open-Source Llama to Proprietary Muse Code

Asked on X whether Muse Code would be open-sourced, Zuckerberg replied "I'll have more to share on that soon," with VentureBeat noting he teased that open source may be in the cards for Muse Spark or another product entirely (E9).

VentureBeat reported that by early 2026, the Llama model family had been downloaded roughly 1.2 billion times, averaging about a million downloads a day (E22). By late 2025, however, Chinese open-weight models from DeepSeek, Alibaba, and Zhipu AI accounted for some 41% of downloads on Hugging Face, which VentureBeat said eroded "Llama's claim to leadership of the very movement it started" (E23).

VentureBeat dated the end of the Llama open-source era to April 8, 2026, when Meta Superintelligence Labs shipped the original Muse Spark — described by Wang as "the most powerful model that Meta has released" — as Meta's first proprietary model: cloud-only, with no downloadable weights and no self-hosting (E24). Asked at the time whether Llama development would continue, a Meta spokesperson told VentureBeat only that "our current Llama models will continue to be available as open source," staying silent on future ones (E25).

What This Means

The evidence points to a company competing on price and workflow persistence rather than raw benchmark leadership: Wang frames Muse Code's appeal around cost (E5), and the contributor tier undercuts the standard tier by roughly 12x on input and 21x on output tokens (E19) — yet on every benchmark VentureBeat cited, Muse Spark 1.2 trails Claude Opus 5, from 82.9% versus 86.7% on Terminal-Bench 2.1 to 70.6% versus 79.4% on Meta's own internal benchmark (E13, E15). That cost-first posture coincides with a retreat from the open-weight strategy that built Llama's roughly 1.2-billion-download base (E22): Muse Spark and Muse Code are both proprietary (E8, E24), even as Chinese open-weight models took roughly 41% of Hugging Face downloads by late 2025 (E23) and Meta's spokesperson and CEO both left the door only narrowly open on future open-source releases (E9, E25).

📊 Evidence

FAQ

What is Muse Code?

Muse Code is a terminal-based AI coding agent Meta released in beta on August 5, 2026, for handling software engineering tasks — planning changes, writing code, and validating results — across large code repositories. It installs with a single command and is powered by Meta's Muse Spark model.

How much does Muse Spark 1.2 cost?

The standard tier costs $1.25 per million input tokens and $4.25 per million output tokens ($0.15 for cached input), with a 3,000 requests-per-minute limit, and prompts are not used for training. The contributor tier costs $0.10 per million input tokens and $0.20 per million output tokens ($0.002 cached), capped at 60 requests per minute, in exchange for allowing Meta to use the data for training.

Will Meta open-source Muse Code?

Meta has not confirmed this. When asked on X, Zuckerberg said only "I'll have more to share on that soon," and a Meta spokesperson previously said only that current Llama models will remain open source, without addressing future models.

📎 Sources

  1. techcrunch.com
  2. venturebeat.com
N
NathanTechnology Editor · Technical Lead

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