Issue
The documented Flux Dev request contract accepts input.width and
input.height, but the public endpoint consistently returns a square image
for a valid non-square request.
The response structure also differs from the documented response:
- Documented:
output.image_url
- Actual:
output.result
Endpoint
black-forest-labs-flux-1-dev
Request payload
{
"input": {
"prompt": "A simple cinematic landscape at sunset",
"negative_prompt": "",
"width": 1024,
"height": 576,
"num_inference_steps": 4,
"guidance": 1.0,
"seed": 12345,
"image_format": "jpeg"
}
}
Both dimensions are within the documented 256–1536 range and divisible by 64.
Reproduction 1 — /runsync
Request ID:
sync-cfd15f9c-b088-4d41-91fb-c3f769a5d533-e2
Result:
Requested: 1024x576
Returned URL field: output.result
Number of returned URL candidates: 1
Raw downloaded JPEG dimensions: 1024x1024
Provider cost: $0.012
Reproduction 2 — /run followed by /status/{id}
Result:
Requested: 1024x576
Final status: COMPLETED
Returned URL field: output.result
Number of returned URL candidates: 1
Raw downloaded JPEG dimensions: 1024x1024
Provider cost: $0.012
Verification method
The only returned URL was downloaded immediately with cURL. The raw JPEG bytes
were inspected using PHP getimagesizefromstring().
The asynchronous /run + /status path produced the same mismatch as
/runsync.
Expected result
A 1024x576 JPEG, with the documented response field:
output.image_url
Actual result
A 1024x1024 JPEG returned through:
output.result
The $0.012 provider cost appears consistent with the requested 1024x576
dimensions, but not with the dimensions of the actual returned artifact.
Issue
The documented Flux Dev request contract accepts
input.widthandinput.height, but the public endpoint consistently returns a square imagefor a valid non-square request.
The response structure also differs from the documented response:
output.image_urloutput.resultEndpoint
black-forest-labs-flux-1-devRequest payload
{ "input": { "prompt": "A simple cinematic landscape at sunset", "negative_prompt": "", "width": 1024, "height": 576, "num_inference_steps": 4, "guidance": 1.0, "seed": 12345, "image_format": "jpeg" } } Both dimensions are within the documented 256–1536 range and divisible by 64. Reproduction 1 — /runsync Request ID: sync-cfd15f9c-b088-4d41-91fb-c3f769a5d533-e2 Result: Requested: 1024x576 Returned URL field: output.result Number of returned URL candidates: 1 Raw downloaded JPEG dimensions: 1024x1024 Provider cost: $0.012 Reproduction 2 — /run followed by /status/{id} Result: Requested: 1024x576 Final status: COMPLETED Returned URL field: output.result Number of returned URL candidates: 1 Raw downloaded JPEG dimensions: 1024x1024 Provider cost: $0.012 Verification method The only returned URL was downloaded immediately with cURL. The raw JPEG bytes were inspected using PHP getimagesizefromstring(). The asynchronous /run + /status path produced the same mismatch as /runsync. Expected result A 1024x576 JPEG, with the documented response field: output.image_url Actual result A 1024x1024 JPEG returned through: output.result The $0.012 provider cost appears consistent with the requested 1024x576 dimensions, but not with the dimensions of the actual returned artifact.