Using codex-cli 0.121.0 with openrouter fails

What version of Codex CLI is running?

0.121.0

What subscription do you have?

pro

Which model were you using?

gpt-5.3-codex

What platform is your computer?

Darwin 25.3.0 arm64 arm

What terminal emulator and version are you using (if applicable)?

ghostty

What issue are you seeing?

I did the official suggestions: https://openrouter.ai/docs/guides/coding-agents/codex-cli

I can start and when I issue any message at the cli I get:

■ {"error":{"code":"invalid_prompt","message":"Invalid Responses API request"},"metadata":{"raw":"[\n  {\n    \"code\": \"invalid_union\",\n    \"errors\":[\n      [\n        {\n          \"code\": \"invalid_union\",\n          \"errors\": [],\n          \"note\": \"No matching discriminator\",\n\"discriminator\": \"type\",\n          \"path\": [\n            \"type\"\n          ],\n          \"message\": \"Invalid input\"\n        }\n      ],\n[\n        {\n          \"code\": \"invalid_value\",\n          \"values\": [\n            \"openrouter:datetime\"\n          ],\n          \"path\": [\n\"type\"\n          ],\n          \"message\": \"Invalid input: expected \\\"openrouter:datetime\\\"\"\n        }\n      ],\n      [\n        {\n\"code\": \"invalid_value\",\n          \"values\": [\n            \"openrouter:image_generation\"\n          ],\n          \"path\": [\n\"type\"\n          ],\n          \"message\": \"Invalid input: expected \\\"openrouter:image_generation\\\"\"\n        }\n      ],\n      [\n        {\n\"code\": \"invalid_value\",\n          \"values\": [\n            \"openrouter:experimental__search_models\"\n          ],\n          \"path\": [\n\"type\"\n          ],\n          \"message\": \"Invalid input: expected \\\"openrouter:experimental__search_models\\\"\"\n        }\n      ],\n      [\n{\n          \"code\": \"invalid_value\",\n          \"values\": [\n            \"openrouter:web_search\"\n          ],\n          \"path\": [\n\"type\"\n          ],\n          \"message\": \"Invalid input: expected \\\"openrouter:web_search\\\"\"\n        }\n      ]\n    ],\n    \"path\": [\n\"tools\",\n      15\n    ],\n    \"message\": \"Invalid input\"\n  }\n]"}}

When I downgrade back to 0.120.0 it works as expected.

What steps can reproduce the bug?

Install 0.121.0, set up a ~/.codex/config.toml matching: https://openrouter.ai/docs/guides/coding-agents/codex-cli and then start with your openrouter API key.

What is the expected behavior?

It should respond to the message without hitting any errors.

Additional information

_No response_