Agentic harness comparison
Muse Code vs OpenAI Codex
Muse Code supports terminal, CI and SDK workflows with Meta subscriptions or separately billed API credentials; Codex supports ChatGPT-plan and API routes. Compare the actual OS/build, permission mode and billing credential. Muse's discounted Contributor terms exclude sensitive inputs, while Standard and subscription access have different data and usage terms.
Details last verified October 2, 2026
Meta
Muse Code
Terminal, CI, and session SDK · Agentic
OpenAI
OpenAI Codex
Desktop, CLI, IDE and cloud · Agentic
| Specification | Muse Code | OpenAI Codex |
|---|---|---|
| Vendor | ||
| Vendor | Meta | OpenAI |
| Runs in | ||
| Runs in | Terminal, CI, and session SDK | Desktop, CLI, IDE and cloud |
| Editor support | ||
| Editor support | Any (editor-agnostic) | Terminal beside any editor, VS Code / Cursor / Windsurf, JetBrains, Xcode, Codex desktop, Cloud |
| Autonomy | ||
| Autonomy | Agentic | Agentic |
| Pricing model | ||
| Pricing model | Hybrid | Hybrid |
| Requires changing editor | ||
| Requires changing editor | No | No |
Dates refer to the linked source’s publication or capture unless it explicitly states when the benchmark was measured. Values we could not confirm are shown as “Not verified” rather than estimated.
Muse Code
Muse Code is Meta's coding agent for the terminal and CI, with a session protocol and TypeScript SDK. It supports the Muse Spark family; the current overview and configuration docs still name muse-spark-1.2 as the default, separately from available Spark 1.3. macOS, Linux and Windows are documented, with platform-specific feature limits. Parallel workflows depend on the installed build and rollout.
Best for
- Terminal and CI coding tasks
- Piloting enabled multi-agent workflows
- Teams using the Meta Model API
Watch out
October 2 sources list Everyday $5/month, High $15 (5x) and Power $50 (20x); regional benefits can vary. The subscription-linked CLI credential does not cover additional API keys, which bill pay-as-you-go. Standard Spark 1.3/1.2 token rates are $1.25 input / $0.15 cached / $4.25 output per MTok; Contributor rates are $0.10 / $0.002 / $0.20 with training permission and lower team quotas. Meta forbids confidential, sensitive or personal inputs on Discounted Services. Standard no-training is not zero retention. Auto-review and an OS sandbox are the defaults, with safe commands and workspace writes potentially proceeding automatically. Workflows are unavailable in the documented current Apple silicon macOS artifact; Windows lacks voice and session messaging. Changelog 1.4.2 is a client version with no release date recovered.
OpenAI Codex
OpenAI's coding agent is available in desktop, terminal, supported IDE and cloud surfaces. ChatGPT sign-in uses plan credits and workspace policy; API-key sign-in uses separate Platform billing and organisation policy.
Best for
- Delegated coding tasks
- Existing OpenAI commitments
Watch out
ChatGPT sign-in uses Codex plan credits, whose rates differ from API prices. Do not estimate subscription task allowances from Platform token tariffs. Standard GPT-6.1 Sol rates are 50 input / 2.5 cached input / 250 output credits per million tokens; no separate cache-write charge. Plus is $20/month; Pro tiers are $100/$200/$500; Business Standard is $20/user/month with annual billing (two-user minimum), $25 monthly; Enterprise is negotiated. Pro has no five-hour limit, while Plus/Standard Business local-message estimates are not fixed caps; weekly limits and shared Work/Codex usage still apply. Fast mode bills at 2.5x included subscription credits or 2x purchased/pay-as-you-go credits; Astra Ultrafast is 8x or 6x respectively and requires eligible access such as Pro 500. These are billing multipliers, not speed guarantees (https://learn.chatgpt.com/docs/pricing; https://learn.chatgpt.com/codex/agent-configuration/speed). GPT-6.1 Sol access is rolling out on Plus/Pro/Business/Enterprise/Edu; Enterprise/Edu admins must enable it. Free/Go desktop Luna access is rollout-dependent. Model availability varies by account, surface and client version (https://learn.chatgpt.com/docs/models). API-key sign-in supports local desktop/CLI/IDE work and uses Platform billing; cloud features such as GitHub review and Slack require ChatGPT sign-in (https://learn.chatgpt.com/docs/auth). GPT-5.4/mini retired from ChatGPT-authenticated Codex on August 31; GPT-5.5 retirement is scheduled for October 14, 2026, with API availability unaffected. Pick a currently supported Sol/Luna replacement. Linux/WSL2 uses bubblewrap with a user-namespace-dependent bundled fallback; native Windows has its own sandbox and WSL1 is unsupported from CLI v0.115.0 (https://learn.chatgpt.com/docs/sandboxing).
Common questions
Muse Code vs OpenAI Codex
Answered from the verified figures on this page rather than general guidance.
Do I have to change editor to use Muse Code or OpenAI Codex?
How are Muse Code and OpenAI Codex priced?
Is Muse Code or OpenAI Codex better for large refactors?
Will my project rules transfer between Muse Code and OpenAI Codex?
Is Codex still billed per seat or per message?
Do coding agents replace code review?
Should we harden MCP before rolling out a coding agent?
Next step
Which one fits
Autonomy and editor constraints decide this far more reliably than a benchmark score.
If most of your week is small, frequent edits, an assistive workflow beats delegation and an agentic harness sits idle while billing. If you regularly hand over work spanning many files, the reverse is true.
Where one tool requires changing editor and the other does not, that difference usually outweighs any capability gap across a team — rollouts fail on adoption, not capability.
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