Fix: compress cover uploads and raise API payload limit

api/server.js

@@ -27,11 +27,12 @@ function sendJson(response, statusCode, payload) {
 async function readJsonBody(request) {
   const chunks = [];
   let size = 0;
+  const maxPayloadSizeBytes = 8 * 1024 * 1024;
 
   for await (const chunk of request) {
     size += chunk.length;
-    if (size > 1024 * 1024) {
-      throw new Error("Payload too large");
+    if (size > maxPayloadSizeBytes) {
+      throw new Error("Payload too large (max 8MB)");
     }
     chunks.push(chunk);
   }

app.js

@@ -94,11 +94,11 @@ coverFileInput.addEventListener("change", async (event) => {
   }
 
   try {
-    const dataUrl = await fileToDataUrl(file);
+    const dataUrl = await imageFileToOptimizedDataUrl(file);
     coverUrlInput.value = dataUrl;
   } catch (error) {
     console.error(error);
-    alert("Impossible de charger cette image.");
+    alert("Impossible de charger/comprimer cette image.");
   } finally {
     input.value = "";
   }
@@ -299,7 +299,7 @@ gameForm.addEventListener("submit", async (event) => {
       return;
     } catch (error) {
       console.error(error);
-      alert("Impossible d'enregistrer ce jeu via l'API.");
+      alert(`Impossible d'enregistrer ce jeu via l'API: ${error.message}`);
     }
   }
 
@@ -977,6 +977,50 @@ function fileToDataUrl(file) {
   });
 }
 
+async function imageFileToOptimizedDataUrl(file) {
+  const originalDataUrl = await fileToDataUrl(file);
+  const image = await loadImageFromDataUrl(originalDataUrl);
+
+  const maxWidth = 240;
+  const maxHeight = 320;
+  const scale = Math.min(1, maxWidth / image.width, maxHeight / image.height);
+  const targetWidth = Math.max(1, Math.round(image.width * scale));
+  const targetHeight = Math.max(1, Math.round(image.height * scale));
+
+  const canvas = document.createElement("canvas");
+  canvas.width = targetWidth;
+  canvas.height = targetHeight;
+  const ctx = canvas.getContext("2d");
+  if (!ctx) {
+    throw new Error("canvas unavailable");
+  }
+
+  ctx.drawImage(image, 0, 0, targetWidth, targetHeight);
+  let quality = 0.82;
+  let optimized = canvas.toDataURL("image/jpeg", quality);
+
+  // Stay comfortably below API payload thresholds.
+  while (optimized.length > 380_000 && quality > 0.45) {
+    quality -= 0.08;
+    optimized = canvas.toDataURL("image/jpeg", quality);
+  }
+
+  if (optimized.length > 520_000) {
+    throw new Error("image too large after compression");
+  }
+
+  return optimized;
+}
+
+function loadImageFromDataUrl(dataUrl) {
+  return new Promise((resolve, reject) => {
+    const image = new Image();
+    image.onload = () => resolve(image);
+    image.onerror = () => reject(new Error("image decode failed"));
+    image.src = dataUrl;
+  });
+}
+
 function updateScannerStatus(message) {
   if (scannerStatus) {
     scannerStatus.textContent = message;