The OpenAI API-key rung reaches the app-server as provider=custom with no
codex model_providers id, and its model is not vendor-normalized at agent
init (only openai-codex is), so a configured "openai/gpt-5.5" now went to
codex verbatim where it was previously dropped for codex's default. When
codex's own provider serves the turn, normalize the slug the way
openai-codex does; a named custom provider's model ids pass through.
The provider lookup moves into _codex_model_provider and is passed to
_codex_wire_model, and the session comment now says model is sent for every
provider, modelProvider only for named custom providers.
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