Meta shipped Muse Code in beta on August 5, 2026 (MarkTechPost), and with it the terminal coding agent became a four-way race: Muse Code, Claude Code, OpenAI Codex, and Google Antigravity. If you're a team of one deciding where to point your day, here's the short version before the detail: the async-agent feature war is over — everyone has it — so the decision now turns on your data terms, your real monthly cost, and how much ecosystem you need.

The one-screen answer#

The rest of this piece is the why, on the three axes that actually decide it.

Axis 1: does it train on your code? (the 2026 differentiator)#

This is new, and it's the one most benchmark roundups skip. Muse Code's headline price — roughly $0.10 per 1M input tokens on its contributor tier — is not really a discount; it's a trade. You get the cheap rate by granting Meta the right to use your sessions and code as training data (Artificial Analysis). Muse Code's standard tier (~$1.25/1M input) carries no such grant.

By contrast, Claude Code, OpenAI Codex, and Google Antigravity do not train on paid API or subscription inputs by default. So the rule is simple and it comes first: if a repository is private or client-owned, eliminate the contributor tier before you compare anything else. A few SWE-Bench points are not worth your proprietary code becoming someone's training set. This is the same "read the data terms before the price" discipline we applied to what it actually costs to run a coding agent this month.

Axis 2: what does a month actually cost you?#

Sticker price per token is the wrong unit for a solo builder — you care about the monthly bill at your real usage.

The full cost-per-completed-task method — including how output-token count, not just price, moves the bill — is laid out in our coding-agent backend comparison.

Axis 3: workflow fit — ecosystem and background agents#

All four now run persistent or asynchronous agents with git-worktree isolation, so parallel agents don't step on each other. That means "does it have background agents" is no longer a tiebreaker. What still separates them:

The decision, in order#

  1. Data first. Private or client code? Kill the contributor tier. Only paid/standard tiers survive.
  2. Cost at your real usage. Heavy daily use → flat Max/ChatGPT seat. Bursty use → metered API tokens. Background fleets → flat seat.
  3. Workflow fit. Need the richest tooling → Claude Code. Live in ChatGPT → Codex. Want Gemini + parallel orchestration → Antigravity. Cheap open/throwaway backend → Muse Code standard tier.

Meta joining the race is good news for a team of one: more competition on price and features, and a new cheap backend for the work that doesn't need your best model. Just remember which axis comes first. For the rest of this week's moves — including OpenAI's two deprecation deadlines and Claude Code's free usage window — see the Founder's Wire for the week of August 7. If you're optimizing purely for the lowest possible bill, pair this with the cheapest terminal coding agent for August 2026.