The try-on path POST'd N reference images as repeated `image` fields in
the multipart body. OpenAI's edits endpoint answers that with
`duplicate_parameter: Duplicate parameter: 'image'. You provided
multiple values for this parameter, whereas only one is allowed. If
you are trying to provide a list of values, use the array syntax
instead e.g. 'image[]=<value>'.`
Switch to the array-syntax field name `image[]`, which OpenAI accepts
for cardinality ≥ 1 (no branching needed for the single-ref case).
Also surface the underlying error from the three 502 branches
(ownership-check, media-fetch, OpenAI call) into both the server log
(structured console.error with refIds + openai body) and the response
`detail` field. The client's callGenerateWithReference now prepends
`detail` to the thrown message so the user sees the concrete reason
in-module instead of a generic "Try-On fehlgeschlagen (502)".
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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