fix: prevent empty negativeText from being sent to Bedrock image API (#1479)

Co-authored-by: Norihiko Imura <norihiko@Norihikos-Air.lan>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: 3 people

packages/cdk/lambda/utils/models.ts

@@ -805,7 +805,7 @@ const createBodyImageAmazonGeneralImage = (params: GenerateImageParams) => {
           (params.textPrompt.find((x) => x.weight > 0)?.text || '') +
           ', ' +
           params.stylePreset,
-        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text,
+        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text || undefined,
         images: [params.initImage],
         similarityStrength: Math.max(params.imageStrength || 0.2, 0.2), // Min 0.2
       },
@@ -819,7 +819,7 @@ const createBodyImageAmazonGeneralImage = (params: GenerateImageParams) => {
           (params.textPrompt.find((x) => x.weight > 0)?.text || '') +
           ', ' +
           params.stylePreset,
-        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text,
+        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text || undefined,
         image: params.initImage,
         maskImage: params.maskImage,
         maskPrompt: params.maskPrompt,
@@ -834,7 +834,7 @@ const createBodyImageAmazonGeneralImage = (params: GenerateImageParams) => {
           (params.textPrompt.find((x) => x.weight > 0)?.text || '') +
           ', ' +
           params.stylePreset,
-        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text,
+        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text || undefined,
         image: params.initImage,
         maskImage: params.maskImage,
         maskPrompt: params.maskPrompt,
@@ -850,7 +850,7 @@ const createBodyImageAmazonGeneralImage = (params: GenerateImageParams) => {
           (params.textPrompt.find((x) => x.weight > 0)?.text || '') +
           ', ' +
           params.stylePreset,
-        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text || '',
+        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text || undefined,
       },
       imageGenerationConfig: imageGenerationConfig,
     };
@@ -869,7 +869,7 @@ const createBodyImageAmazonAdvancedImage = (params: GenerateImageParams) => {
       taskType: 'COLOR_GUIDED_GENERATION',
       colorGuidedGenerationParams: {
         text: params.textPrompt.find((x) => x.weight > 0)?.text || '',
-        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text,
+        negativeText: params.textPrompt.find((x) => x.weight < 0)?.text || undefined,
         referenceImage: params.initImage,
         colors: params.colors!,
       },