v3: fixed rich content extraction heuristics

src/components/JournalCard.tsx

@@ -38,10 +38,28 @@ export function JournalCard(
     navigate(dumpUrl(dump));
   }
 
-  const thumbnailUrl = dump.kind === "file" &&
-      dump.fileMime?.startsWith("image/")
-    ? `${API_URL}/api/files/${dump.id}?v=${dump.fileSize ?? 0}`
-    : (dump.richContent?.thumbnailUrl ?? null);
+  const rawThumbnail =
+    dump.kind === "file" && dump.fileMime?.startsWith("image/")
+      ? `${API_URL}/api/files/${dump.id}?v=${dump.fileSize ?? 0}`
+      : (dump.richContent?.thumbnailUrl ?? null);
+
+  // Route external HTTP thumbnails through the server proxy to avoid
+  // mixed-content blocks when the frontend is served over HTTPS.
+  const thumbnailUrl = (() => {
+    if (!rawThumbnail) return null;
+    try {
+      const u = new URL(rawThumbnail);
+      if (
+        u.protocol === "http:" && u.hostname !== "localhost" &&
+        u.hostname !== "127.0.0.1"
+      ) {
+        return `${API_URL}/api/proxy-image?url=${
+          encodeURIComponent(rawThumbnail)
+        }`;
+      }
+    } catch { /* relative URL */ }
+    return rawThumbnail;
+  })();
 
   const fallbackIcon = dump.kind === "file"
     ? (() => {