Seedream image generation in the server was still split across the generic text2image path and the legacy multipart image edit path. That shape does not match Volcengine Seedream 4.5, which expects JSON requests to /v1/images/generations for both text2image and img2img, with reference images carried through the image field.
Constraint: Seedream 4.5 and 5.0 use /v1/images/generations rather than the older multipart /v1/images/edits contract
Constraint: Existing Gemini and other image routes must keep their current behavior unchanged
Rejected: Keep using /v1/images/edits for Seedream img2img | upstream rejects the request body shape
Rejected: Special-case the CLI input contract | the server route adapter owns upstream normalization
Confidence: high
Scope-risk: moderate
Reversibility: clean
Directive: Keep Seedream routes on the JSON generations path; do not reintroduce multipart edits for these models without revalidating the upstream API contract
Tested: go test ./internal/server; go test ./...; go build -o /tmp/popiartserver-verify ./cmd/popiartserver; test-server txt2img/img2img/img2video smoke with Seedream 4.5 + Vidu
Not-tested: Seedream 5.0 live smoke against the test server
wtgoku
张正强