Add support for OpenAI's gpt-5.2-codex

[PeterDaveHello]

Add support for OpenAI GPT-5.2-Codex model

Pre-Submission checklist

Please complete all items before asking a LiteLLM maintainer to review your PR

• I have Added testing in the tests/litellm/ directory, Adding at least 1 test is a hard requirement - see details
  • Not needed for static model info update?
• I have added a screenshot of my new test passing locally
• My PR passes all unit tests on make test-unit
  • make test-unit failed: ModuleNotFoundError: No module named 'litellm_enterprise.proxy.common_utils.check_responses_cost' in tests/test_litellm/integrations/test_responses_background_cost.py
• My PR's scope is as isolated as possible, it only solves 1 specific problem

CI (LiteLLM team)

CI status guideline:

• 50-55 passing tests: main is stable with minor issues.
• 45-49 passing tests: acceptable but needs attention
• <= 40 passing tests: unstable; be careful with your merges and assess the risk.

• Branch creation CI run
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• CI run for the last commit
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• Merge / cherry-pick CI run
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Type

🆕 New Feature

Changes

Add support for OpenAI GPT-5.2-Codex model

References:

• https://openai.com/index/introducing-gpt-5-2-codex/
• https://platform.openai.com/docs/models/gpt-5.2-codex
• https://platform.openai.com/docs/pricing

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Project	Deployment	Review	Updated (UTC)
litellm	Ready	Preview, Comment	Jan 14, 2026 6:57pm

[ishaan-jaff]

lgtm

[PeterDaveHello]

@ishaan-jaff thanks for the prompt review. Is it possible that you can also help me take a look at #18660? Many thanks!