fix: enforce brand colors in infographic generation + enrichment prompts

Strict black bg + emerald green in DEFAULT_INSTRUCTIONS, enrichment prompt, and negativePrompt on all Imagen calls. Blocks purple/blue at every generation point.

Author: codercatdev

app/api/cron/check-research/route.ts

@@ -686,7 +686,7 @@ Return ONLY a JSON object:
         "list": { "items": ["Item 1", "Item 2"], "icon": "🚀" },
         "comparison": { "leftLabel": "A", "rightLabel": "B", "rows": [{ "left": "...", "right": "..." }] },
         "mockup": { "deviceType": "browser | phone | terminal", "screenContent": "..." },
-        "imagePrompts": ["Infographic 2D architecture style, black background. [specific visual for this scene]. Highlighted elements filled with #15b27b. White lines connecting components and white text annotations."]
+        "imagePrompts": ["Infographic 2D architecture style. STRICTLY black (#000000) background only \u2014 no gradients, no purple, no blue. [specific visual for this scene]. Highlighted elements filled with bright green (#15b27b) only. White lines connecting components and white text annotations. Large, readable labels."]
       }
     ],
     "cta": "string - call to action"
@@ -697,7 +697,7 @@ Return ONLY a JSON object:
 Requirements:
 - 3-5 scenes totaling 60-90 seconds
 - Use at least 2 different scene types
-- Each scene MUST include 2-5 imagePrompts following this exact template: "Infographic 2D architecture style, black background. [specific visual]. Highlighted elements filled with #15b27b. White lines connecting components and white text annotations."
+- Each scene MUST include 2-5 imagePrompts following this exact template: "Infographic 2D architecture style. STRICTLY black (#000000) background only \u2014 no gradients, no purple, no blue. [specific visual]. Highlighted elements filled with bright green (#15b27b) only. White lines connecting components and white text annotations. Large, readable labels."
 - imagePrompts should describe specific 2D infographic visuals that illustrate the narration content
 - Do NOT include any script text, titles, or word overlays in the video. The narration audio carries all words.
 - Think of each imagePrompt as a frame that will be shown for 3-5 seconds while the narration plays

lib/services/gemini-infographics.ts

@@ -210,11 +210,11 @@ export function buildInfographicPrompt(
 
 /** Default infographic instructions if Sanity contentConfig is not set up */
 const DEFAULT_INSTRUCTIONS: string[] = [
-  'Infographic 2D architecture style, black background. A high-level technical architecture overview showing system components and data flow. Highlighted elements filled with #15b27b. White lines connecting components and white text annotations.',
-  'Infographic 2D architecture style, black background. A comparison chart showing key features and alternatives side by side. Highlighted elements filled with #15b27b. White lines connecting components and white text annotations.',
-  'Infographic 2D architecture style, black background. A step-by-step workflow diagram showing the process from start to finish. Highlighted elements filled with #15b27b. White lines connecting components and white text annotations.',
-  'Infographic 2D architecture style, black background. A timeline of key developments, milestones, and version releases. Highlighted elements filled with #15b27b. White lines connecting components and white text annotations.',
-  'Infographic 2D architecture style, black background. A pros and cons visual summary with clear icons and labels. Highlighted elements filled with #15b27b. White lines connecting components and white text annotations.',
+  'Infographic 2D architecture style. STRICTLY black (#000000) background only \u2014 no gradients, no purple, no blue. A high-level technical architecture overview showing system components and data flow. Highlighted elements filled with bright green (#15b27b) only. White lines connecting components and white text annotations. Large, readable text labels suitable for mobile viewing at 360px width. No watermarks.',
+  'Infographic 2D architecture style. STRICTLY black (#000000) background only \u2014 no gradients, no purple, no blue. A comparison chart showing key features and alternatives side by side. Highlighted elements filled with bright green (#15b27b) only. White lines connecting components and white text annotations. Large, readable text labels suitable for mobile viewing at 360px width. No watermarks.',
+  'Infographic 2D architecture style. STRICTLY black (#000000) background only \u2014 no gradients, no purple, no blue. A step-by-step workflow diagram showing the process from start to finish. Highlighted elements filled with bright green (#15b27b) only. White lines connecting components and white text annotations. Large, readable text labels suitable for mobile viewing at 360px width. No watermarks.',
+  'Infographic 2D architecture style. STRICTLY black (#000000) background only \u2014 no gradients, no purple, no blue. A timeline of key developments, milestones, and version releases. Highlighted elements filled with bright green (#15b27b) only. White lines connecting components and white text annotations. Large, readable text labels suitable for mobile viewing at 360px width. No watermarks.',
+  'Infographic 2D architecture style. STRICTLY black (#000000) background only \u2014 no gradients, no purple, no blue. A pros and cons visual summary with clear icons and labels. Highlighted elements filled with bright green (#15b27b) only. White lines connecting components and white text annotations. Large, readable text labels suitable for mobile viewing at 360px width. No watermarks.',
 ];
 
 // ---------------------------------------------------------------------------
@@ -318,7 +318,7 @@ export async function generateFromScenePrompts(
     // Generate horizontal (16:9)
     try {
       const hResult = await generateInfographic(
-        { prompt, aspectRatio: "16:9" },
+        { prompt, aspectRatio: "16:9", negativePrompt: "purple background, blue gradient, watermark, blurry text, small text" },
         model,
       );
       horizontal.push(hResult);
@@ -330,7 +330,7 @@ export async function generateFromScenePrompts(
     // Generate vertical (9:16)
     try {
       const vResult = await generateInfographic(
-        { prompt, aspectRatio: "9:16" },
+        { prompt, aspectRatio: "9:16", negativePrompt: "purple background, blue gradient, watermark, blurry text, small text" },
         model,
       );
       vertical.push(vResult);