Codex CLI: GPT-5.6 Sol, Terra & Luna Now Available via Amazon Bedrock
CodexCodex CLI 0.143.0 added support for GPT-5.6 Sol, Terra, and Luna through Amazon Bedrock, giving AWS-anchored teams first-class access to OpenAI's newest model tier directly inside Codex. The release also introduces first-class support for max reasoning effort, letting developers push these models to their highest reasoning depth for complex coding tasks. This lands even though GPT-5.6 itself remains in a narrow partner preview and has not reached general availability, making Codex one of the earliest broad access paths to the new model family.
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Amazon Bedrock Gets GPT-5.6
Codex CLI 0.143.0 extended its Bedrock model catalog to include GPT-5.6 Sol, Terra, and Luna — OpenAI's newest three-tier model family, previewed on June 26, 2026. Sol is positioned as the flagship reasoning model, Terra as a balanced mid-tier option, and Luna as the fastest and most affordable of the three. Developers already running Codex against Bedrock (a pathway Codex first added first-class support for with AWS SigV4 signing and credential-based auth back in CLI 0.124.0) can now point Codex at any of the three GPT-5.6 variants without leaving their existing AWS billing and infrastructure commitments.
First-Class max Reasoning Effort
Alongside the new models, Codex now treats max as a first-class reasoning effort setting. Previously, reasoning effort configuration was more constrained; with this release, developers can explicitly dial GPT-5.6 models up to their maximum reasoning depth for demanding tasks like large refactors or multi-file debugging, trading latency for accuracy when it matters most.
Why This Matters Ahead of GA
Notably, GPT-5.6 has not yet reached general availability — OpenAI has kept it in a limited preview of roughly 20 partner organizations pending a government-requested safety review, with broader rollout expected in the days following this release. Shipping Bedrock support for GPT-5.6 inside Codex CLI ahead of that wider GA gives AWS-based enterprise teams an early, sanctioned route to the new models through their existing cloud relationship.
Also in This Release
Codex CLI 0.143.0 bundled several smaller, more technical changes alongside the model update: remote plugins are now enabled by default with an expanded npm marketplace catalog, authentication and API traffic can route through corporate system proxies on macOS and Windows, and MCP tooling now defaults to tool search rather than loading every tool upfront. These are aimed primarily at enterprise and plugin-ecosystem use cases rather than the everyday developer workflow.