fix(gemini): fix Express aspect ratio and image-block error surfacing - #73
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Express/Vertex image generation rejected the responseFormat.image.aspectRatio field added in 4bfb98e (400 INVALID_ARGUMENT); it expects imageConfig.aspectRatio instead. Split the shared payload builder so each Gemini surface gets the field shape it actually supports. Also, Gemini omits `parts` entirely when it hard-blocks image generation (e.g. finishReason=IMAGE_PROHIBITED_CONTENT), which made parsing fail with a generic "missing field `parts`" instead of surfacing the finishMessage. Tested: cargo test --lib image_generator::provider_adapter::google_gemini (4/4 pass), cargo build --lib clean. By apparao.parwatikar
MegalithOfficial
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Jul 12, 2026
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Looks good to me. The payload split correctly handles the different aspect-ratio fields required by the Gemini Developer API and Vertex/Express, and the blocked-response handling now surfaces the useful finishMessage instead of a parsing error. The added tests cover both fixes well. Approved!
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Express/Vertex image generation rejected the responseFormat.image.aspectRatio
field added in 4bfb98e (400 INVALID_ARGUMENT); it expects imageConfig.aspectRatio
instead. Split the shared payload builder so each Gemini surface gets the field
shape it actually supports.
Also, Gemini omits
partsentirely when it hard-blocks image generation (e.g.finishReason=IMAGE_PROHIBITED_CONTENT), which made parsing fail with a generic
"missing field
parts" instead of surfacing the finishMessage.Tested: cargo test --lib image_generator::provider_adapter::google_gemini (4/4
pass), cargo build --lib clean.
By apparao.parwatikar