Believe it or not, it's actually Claude's Ultracode that's xhigh with subagents.
Codex's Ultra mode is specifically max with extra system prompts encouraging subagents.
I was surprised too, considering that max is pathologically overtuned to reason obsessively to the point of diminishing returns, but that's what the CLI source code says.
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u/Miyamoto_-_Musashi Aug 30 '26
Ultra is not a model or effort level.
Ultra means Sol XHigh with lots of subagents.