Breaking

OpenAI Opens Limited Preview of GPT-5.6 Trio: Sol, Terra and Luna

July 2, 2026 at 13:58 EDT

Foundation Models
AI Agents
Software Dev & Coding

On June 26, 2026, OpenAI officially announced the start of a limited preview of its next-generation GPT-5.6 family — Sol, Terra and Luna. For now, access is limited to roughly 20 trusted partners via the API and Codex, with general availability slated for "coming weeks."

June 26, 2026 · OpenAI

GPT-5.6 Enters Limited Preview — and Markets Bet on a July 7 Launch

OpenAI's fast-follow to GPT-5.5 lands as a three-model family under government coordination. Traders on Polymarket priced a 77% chance of general release by Tuesday, July 7 — a market guess, not an official date.

77%

Market odds of general release by July 7

~2 mo

Since GPT-5.5 shipped (Apr 23, 2026)

Configurations: Sol · Terra · Luna

TerminalBench 2.1 — coding ability

Higher is better. GPT-5.6 "Sol" tops Claude Mythos 5.

91.9%

Sol Ultra

88.8%

Sol

88.0%

Claude
Mythos 5

Sol

Flagship

Highest performance; leads coding and cyber evaluations.

Terra

Balanced

GPT-5.5-level performance at roughly half the cost.

Luna

Fast · Low-cost

Optimized for speed and the lowest price point.

Market read on the launch date

90–95%

General release by end of July

77%

Release by Tuesday, July 7

28–41%

Release on the single day July 7

Bets on an end-of-June launch missed — the "limited preview" did not count as a general release.

What developers like

Better agentic coding & long-running tasks
Gains on SWE-bench Pro
3D modeling support
Price competitiveness

What raises concern

Strict guardrails & usage limits
Access tied to government coordination
Ongoing race with Claude, Gemini & Grok

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