RETIRED MODEL

GPT-5.6 Sol (retired from Council AI)

GA July 9, 2026. 1M-token context, top-tier reasoning and coding, vision, native web search. $5/$30 per million tokens — with Terra ($2.50/$15) and Luna ($1/$6) siblings sharing the same 1M window.

See GPT-6.1 Sol See it in a council

GPT-5.6 Sol is no longer part of the Council AI lineup. It was superseded by GPT-6.1 Sol, which is available on every paid plan. The specs below are kept for reference.

This model is no longer in the Council AI lineup

GPT-5.6 Sol has been retired from Council AI. Council AI now runs GPT-6.1 Sol in its place. Existing conversations that used it still render correctly; it can no longer be added to a new council.

Specs (Sol)

Provider	OpenAI
Released	GA July 9, 2026
Context window	1,000,000 tokens
Strengths	Top-tier reasoning and coding
Vision	Text + image input
Web search	Native via Responses API
Price (in / out per 1M)	$5.00 / $30.00

The GPT-5.6 family: Sol vs Terra vs Luna

All three variants went GA on July 9, 2026 and share the 1M context window, vision input, and native web search. They differ in capability ceiling and price:

Variant	Price (in / out per 1M)	Positioning
GPT-5.6 Sol	$5.00 / $30.00	Flagship — top-tier reasoning and coding
GPT-5.6 Terra	$2.50 / $15.00	Production workhorse — 1M context at GPT-5.4 pricing
GPT-5.6 Luna	$1.00 / $6.00	High-volume tier — the new cheap production option

Terra and Luna are covered here rather than on separate pages because the spec deltas are price and ceiling, not features. All three are live in Council AI's lineup.

Best at

Agentic coding — the GPT line's tool-calling stability with a raised capability ceiling.
Hard reasoning — OpenAI's strongest reasoner now that o3 is retired; no separate specialist model needed.
Whole-repo work — 1M context finally matches Gemini and Claude on input size.
Family flexibility — prototype on Sol, ship on Terra, scale on Luna without changing context budgets.

Where it loses

Output price — $30/1M output is the joint-highest in Council's lineup outside Claude Fable 5.1.
Refactor taste — Claude Opus 4.8 and Sonnet 5 still edge it on patches engineers merge unchanged.
Real-time social data — Grok 4.5's native X search reaches data OpenAI's web search doesn't.

How Council AI runs it

All three GPT-5.6 variants — Sol, Terra, and Luna — are available on every paid Council AI plan (Plus, Pro, Ultra). In practice Sol takes the flagship seat in high-stakes councils while Terra and Luna serve as the OpenAI voice in cost-balanced ones. Each council fans your prompt out in parallel to models from up to 8 other labs, and the moderator synthesizes a consensus answer with an agreement score — so a Sol + Fable 5 + Gemini 3.5 Flash council gives you three independent frontier opinions for less than many single-vendor workflows.

Frequently asked questions

Is GPT-5.6 Sol still available on Council AI?

No. GPT-5.6 Sol has been retired from Council AI and can no longer be added to a council. Older conversations that used it still display normally.

What replaced GPT-5.6 Sol on Council AI?

GPT-6.1 Sol, which is available on every paid plan. Councils that used GPT-5.6 Sol were moved to it automatically.