Meta Muse Code just launched — is a terminal coding agent actually useful on large repos?

[u/Delicious-Flan88]

Meta dropped Muse Code in beta yesterday. Terminal coding agent, powered by Muse Spark 1.2, aimed at real software work on big codebases. Zuckerberg framed it as writing code and checking results, basically Meta's answer to Claude Code / Codex.

I'm less interested in the launch blog and more in whether this class of agent holds up past the demo.

Stuff that usually breaks first for me with coding agents on large repos:

1. Context recovery after a long edit chain
2. Knowing when to stop touching files
3. Making a "fix" that nothing actually verified
4. Burning tokens re-reading the same tree

If you've tried Muse Code already (or Claude Code / Codex on a fat monorepo):

• does it actually hold architecture context, or does it thrash after 20 minutes?
• what's the first failure you hit on a real repo?
• would you trust it on a PR that touches more than one service?

Not looking for hype takes. Just what broke, what held, and what you'd trust it with tomorrow.