GPT-5.6 Sol, Terra, and Luna Land in OpenAI's Codex Model Catalog

Model strings for three unreleased GPT-5.6 variants have surfaced in the Codex IDE source code, each with a 272K context window and configurable reasoning depth.

A routine Codex update merged on July 5 added three new GPT-5.6 model identifiers to the Amazon Bedrock catalog: openai.gpt-5.6-sol, openai.gpt-5.6-terra, and openai.gpt-5.6-luna. The diff, spanning just a few dozen lines in the model-provider-info and Bedrock catalog modules, registers each variant alongside existing GPT-5.4 and GPT-5.5 entries.

Every GPT-5.6 variant ships with a 272,000-token context window through Bedrock. More notably, the update imports new ReasoningEffort and ReasoningEffortPreset types — suggesting users will be able to dial thinking depth up or down per query. That feature lands in the shadow of GPT-5.5's widely documented 516-token reasoning ceiling, which Codex users discovered caps complex responses at a hard limit.

The code drop follows OpenAI's late-June preview of GPT-5.6 Sol and the US government's request for a staggered, vetted rollout. The appearance of three distinct variants — not just Sol — in production tooling indicates the full family is approaching general availability, with Codex likely serving as the first paid-subscriber integration point.

Sources: GitHub diff, The Verge, HN discussion