GPT-5.6 Sol Ultra Arrives in Codex with Subagent-Powered Ultra Mode
OpenAI
GPT-5.6 Sol Ultra, a subagent-orchestrating variant of GPT-5.6 Sol, is rolling out to OpenAI Codex following the June 26 limited preview. The 'Ultra Mode' spawns specialized parallel subagents rather than a single sequential agent — scoring 91.9% on Terminal-Bench 2.1 versus 88.0% for GPT-5.5. The Codex CLI shipped v0.143.0-alpha.36 on July 5. Broader rollout beyond the initial partner cohort is projected for mid-to-late July.
Why it matters
Sol Ultra embeds multi-agent parallelism at the model level — a structural difference from how Claude Code and Cursor orchestrate agents — potentially setting a new ceiling on agentic coding benchmarks.
Importance: 3/5
First subagent-native coding agent from a frontier lab; SOTA on Terminal-Bench 2.1 at 91.9%.
Sources
official
Previewing GPT-5.6 Sol | OpenAI