Codex model discovery: expose model-advertised `ultra` effort for GPT-5.6

[cossio]

Summary

Claudian 2.0.30 added dynamic Codex model discovery in f1516a7, which should let GPT-5.6 variants and their model-specific reasoning efforts flow from the Codex app-server into the picker.

One advertised effort is still deliberately removed:

const EXCLUDED_REASONING_EFFORTS = new Set(['ultra']);

in src/providers/codex/models.ts.

Observed Codex catalog

With Codex CLI 0.141.0, the app-server/model catalog available to my account reports:

Model	Advertised reasoning efforts	Default
gpt-5.6-sol	low, medium, high, xhigh, max, ultra	low
gpt-5.6-terra	low, medium, high, xhigh, max, ultra	medium
gpt-5.6-luna	low, medium, high, xhigh, max	medium

The catalog describes ultra as maximum reasoning with automatic task delegation. Claudian currently filters it during normalization, so Sol and Terra cannot select it even though the provider advertises it.

Request

Please make Codex reasoning efforts capability-driven all the way through:

• expose ultra for models that advertise it, currently Sol and Terra;
• do not expose it for models that do not advertise it, such as Luna;
• preserve the app-server descriptions and model-specific defaults;
• forward the selected effort through Codex thread/turn requests as with the existing levels.

If ultra is intentionally excluded because its automatic delegation semantics are incompatible with Claudian, please document that limitation and the specific incompatibility.

Suggested acceptance checks

• A discovered Sol or Terra model shows Low, Medium, High, XHigh, Max, and Ultra.
• A discovered Luna model stops at Max.
• Selecting Ultra survives provider switching and conversation resume.
• Unit tests cover catalogs where only some models advertise ultra.

Thanks for adding dynamic model discovery—this request is only for the remaining model-advertised effort level.

[YishenTu]

i deliberately hide ultra for now since it's super consuming and has less marginal effort. will keep monitoring if more user require ultra in effort list.

[github-actions]

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