Codex GPT models on chatgpt.com /codex/responses rejected `@image` turns with
`Codex error event: [OneOfParam] [input[N].content[M]] [invalid_enum_value]
Invalid value: 'input_image'. Supported values are: 'input_text'.` —
`convertToLlm`'s `fileMention` arm always emitted a `developer`-role
Responses message, but a developer-role content slot only accepts
`input_text`. #3421's prior fix only suppressed the Codex Responses Lite
header on image-bearing turns; the full transport kept rejecting the same body.
`fileMention` now uses `user` role when any attached file carries an image;
text-only mentions keep `developer` so the auto-read context still rides at
instruction priority for the agent.
Fixes#3443
roboomp
c2174a87b2