perf(booth): optimize assets and result flow

WebP reduces UI payload; JPEG keeps portrait saves compatible.\nFinish ends the visit without prompting another portrait.

lib/ai/orchestrator.ts

@@ -41,7 +41,7 @@ export async function orchestrateGeneration(
     // Simulate generation delay (2 seconds)
     await new Promise((r) => setTimeout(r, 2000));
     return {
-      imageUrl: style.sampleResult || style.thumbnail || "/assets/styles/sample_clay_pink.png",
+      imageUrl: style.sampleResult || style.thumbnail || "/assets/styles/jack_o_lantern_sensei.webp",
       providerUsed: "demo_mock",
       modelUsed: "demo-simulator",
       durationMs: Date.now() - startTime,

lib/config.ts

@@ -47,7 +47,7 @@ const defaultConfig: BoothConfig = {
     accentColor: "#06b6d4",
     surfaceColor: "#170f29",
     textColor: "#ffffff",
-    logoUrl: "/assets/brand/shanghai_karate_logo.png",
+    logoUrl: "/assets/brand/shanghai_karate_logo.webp",
     logoWidth: 260,
   },
   camera: {
@@ -164,20 +164,20 @@ const defaultConfig: BoothConfig = {
       zh: "扫码保存至手机相册",
     },
     downloadLabel: {
-      en: "Save Portrait",
-      zh: "保存高清照",
+      en: "Save",
+      zh: "保存",
     },
     wechatSaveTip: {
-      en: "In WeChat: Long press photo above to save directly!",
-      zh: "微信提示：长按上方图片即可直接保存到相册！",
+      en: "In WeChat, long-press the photo to save it.",
+      zh: "微信中长按照片即可保存。",
     },
     printLabel: {
       en: "Print Photo",
       zh: "打印照片",
     },
     startOverLabel: {
-      en: "Train Again (Start Over)",
-      zh: "再拍一张",
+      en: "Finish",
+      zh: "完成",
     },
     instagramShareLabel: {
       en: "Share Photo",

lib/storage.ts

@@ -1,5 +1,6 @@
 import fs from "fs";
 import path from "path";
+import sharp from "sharp";
 import { validateAndSanitizeImage } from "@/lib/security";
 
 export interface GenerationRecord {
@@ -202,26 +203,34 @@ export async function persistImageFile(
     return { imageUrl: imageInput, filename: "" };
   }
 
-  // If it's a data URL or raw base64
-  if (imageInput.startsWith("data:image/") || imageInput.startsWith("data:application/")) {
-    const validation = validateAndSanitizeImage(imageInput, 15 * 1024 * 1024);
-    if (validation.valid && validation.extension) {
-      const ext = validation.extension; // Strictly "jpg" | "png" | "webp"
-      const filename = `${safeId}.${ext}`;
-      const filePath = path.join(IMAGES_DIR, filename);
+  const persistJpeg = async (inputBuffer: Buffer) => {
+    const sourcePath = path.join(IMAGES_DIR, `${safeId}.source`);
+    const filename = `${safeId}.jpg`;
+    const jpegPath = path.join(IMAGES_DIR, filename);
+    fs.writeFileSync(sourcePath, inputBuffer);
 
-      const base64Data = validation.sanitizedBase64!.split(",")[1];
-      fs.writeFileSync(filePath, Buffer.from(base64Data, "base64"));
-
-      // Automatically apply school branding: logo (top-left), WeChat QR (bottom-right), and footer text
+    try {
+      // Apply the existing branding before encoding the final downloadable image.
       try {
         const { applyWatermarkToFile } = await import("@/lib/watermark");
-        await applyWatermarkToFile(filePath);
+        await applyWatermarkToFile(sourcePath);
       } catch (wmErr) {
         console.warn("[Storage] Watermark application skipped:", wmErr);
       }
 
+      await sharp(sourcePath).jpeg({ quality: 92, mozjpeg: true }).toFile(jpegPath);
       return { imageUrl: `/api/images/${filename}`, filename };
+    } finally {
+      if (fs.existsSync(sourcePath)) fs.unlinkSync(sourcePath);
+    }
+  };
+
+  // If it's a data URL or raw base64
+  if (imageInput.startsWith("data:image/") || imageInput.startsWith("data:application/")) {
+    const validation = validateAndSanitizeImage(imageInput, 15 * 1024 * 1024);
+    if (validation.valid) {
+      const base64Data = validation.sanitizedBase64!.split(",")[1];
+      return persistJpeg(Buffer.from(base64Data, "base64"));
     } else {
       console.warn(`[Storage Security Alert] Refused to persist invalid image: ${validation.error}`);
       return { imageUrl: imageInput, filename: "" };
@@ -258,20 +267,8 @@ export async function persistImageFile(
           15 * 1024 * 1024
         );
 
-        if (validation.valid && validation.extension) {
-          const filename = `${safeId}.${validation.extension}`;
-          const filePath = path.join(IMAGES_DIR, filename);
-          fs.writeFileSync(filePath, buffer);
-
-          // Automatically apply school branding: logo (top-left), WeChat QR (bottom-right), and footer text
-          try {
-            const { applyWatermarkToFile } = await import("@/lib/watermark");
-            await applyWatermarkToFile(filePath);
-          } catch (wmErr) {
-            console.warn("[Storage] Watermark application skipped:", wmErr);
-          }
-
-          return { imageUrl: `/api/images/${filename}`, filename };
+        if (validation.valid) {
+          return persistJpeg(buffer);
         } else {
           console.warn(`[Storage Security Alert] Remote file was not a valid image: ${validation.error}`);
         }

lib/watermark.py

@@ -17,7 +17,7 @@ def watermark_portrait(image_path_or_buffer):
     bw, bh = base.size
 
     # 1. School Logo (Top-Left)
-    logo_path = os.path.join(process_cwd(), "public", "assets", "brand", "shanghai_karate_logo.png")
+    logo_path = os.path.join(process_cwd(), "public", "assets", "brand", "shanghai_karate_logo.webp")
     if os.path.exists(logo_path):
         logo = Image.open(logo_path).convert("RGBA")
         target_logo_w = int(bw * 0.28)

lib/watermark.ts

@@ -16,7 +16,7 @@ export async function applyWatermarkToFile(filePath: string): Promise<void> {
 
   try {
     const baseDir = process.cwd();
-    const logoPath = path.join(baseDir, "public", "assets", "brand", "shanghai_karate_logo.png");
+    const logoPath = path.join(baseDir, "public", "assets", "brand", "shanghai_karate_logo.webp");
     const qrPath = path.join(baseDir, "public", "assets", "brand", "dojo_qr.png");
 
     const baseImage = sharp(filePath);