fix(images): 规范 OpenAI 图像尺寸参数

apps/api/internal/clients/openai.go

@@ -65,6 +65,7 @@ func (c OpenAIClient) Run(ctx context.Context, request Request) (Response, error
 		}
 	}
 	body["model"] = upstreamModelName(request.Candidate)
+	normalizeOpenAIImageRequestBody(endpointKind, body)
 	stream := openAIEndpointSupportsStream(endpointKind) && (request.Stream || boolValue(body, "stream"))
 	ensureOpenAIStreamUsage(body, endpointKind, stream)
 	raw, contentType, err := openAIRequestPayload(endpointKind, body, request.Candidate)
@@ -171,6 +172,24 @@ func (c OpenAIClient) Run(ctx context.Context, request Request) (Response, error
 	}, nil
 }
 
+func normalizeOpenAIImageRequestBody(endpointKind string, body map[string]any) {
+	if endpointKind != "images.generations" && endpointKind != "images.edits" {
+		return
+	}
+	// OpenAI image endpoints express output geometry through size. The Gateway
+	// keeps the generic fields for capability validation and billing, but they
+	// are not valid OpenAI wire parameters.
+	for _, key := range []string{
+		"aspect_ratio",
+		"aspectRatio",
+		"resolution",
+		"width",
+		"height",
+	} {
+		delete(body, key)
+	}
+}
+
 func openAIRequestPayload(endpointKind string, body map[string]any, candidate store.RuntimeModelCandidate) ([]byte, string, error) {
 	if endpointKind != "images.edits" {
 		raw, err := json.Marshal(body)