diff --git a/assets/js/chat-common.js b/assets/js/chat-common.js
index ddc13e8..804adb8 100644
--- a/assets/js/chat-common.js
+++ b/assets/js/chat-common.js
@@ -59,11 +59,52 @@ function renderMediaMessage(msg) {
 
     switch (mediaType) {
         case 'image': {
-            const thumb = effective || '';
-            const full = isValidMediaUrl(localFile) ? `/api/version/media-url.php?local=${encodeURIComponent(localFile)}` : (isValidMediaUrl(mediaExternal) ? `/api/version/media-url.php?url=${encodeURIComponent(mediaExternal)}` : (msg.media_url || ''));
-            if (thumb) {
-                return `<div class="message-media"><a href="#" data-full="${escapeHtml(full)}" onclick="openImageLightbox(this.dataset.full); return false;"><img src="${escapeHtml(thumb)}" alt="Imagen" style="cursor:zoom-in"></a></div>${content?`<div>${escapeHtml(content)}</div>`:''}`;
+            // Compute thumbnail and full image URL following chat_window heuristics
+            let thumbUrl = '';
+            if (isValidMediaUrl(localThumb)) {
+                thumbUrl = `/${localThumb}`;
+            } else if (isValidMediaUrl(localFile)) {
+                thumbUrl = `/${localFile}`;
+            } else if (isValidMediaUrl(effective) || isValidMediaUrl(mediaExternal)) {
+                const external = isValidMediaUrl(effective) ? effective : mediaExternal;
+                if (/lookaside\.fbsbx\.com|graph\.facebook\.com|facebook\.com/i.test(external)) {
+                    const m = external.match(/[?&]mid=([^&]+)/i);
+                    if (m && m[1]) {
+                        thumbUrl = `/api/version/media-url.php?id=${encodeURIComponent(m[1])}`;
+                    } else {
+                        thumbUrl = `/api/version/media-url.php?url=${encodeURIComponent(external)}`;
+                    }
+                } else {
+                    thumbUrl = external;
+                }
+            } else if (isValidMediaUrl(msg.media_url)) {
+                thumbUrl = msg.media_url;
             }
+
+            // Full URL for opening (prefer local file then external with id or url)
+            let fullUrl = '';
+            if (isValidMediaUrl(localFile)) {
+                fullUrl = `/api/version/media-url.php?local=${encodeURIComponent(localFile)}`;
+            } else if (isValidMediaUrl(mediaExternal)) {
+                let mid = '';
+                if (mediaExternal.indexOf('api/get_media.php?id=') !== -1) {
+                    const parts = mediaExternal.split('id='); mid = parts[1] ? decodeURIComponent(parts[1]) : '';
+                } else {
+                    const m = mediaExternal.match(/[?&]mid=([^&]+)/i); if (m && m[1]) mid = decodeURIComponent(m[1]);
+                }
+                if (mid) fullUrl = `/api/version/media-url.php?id=${encodeURIComponent(mid)}`;
+                else if (/^https?:\/\//i.test(mediaExternal)) fullUrl = `/api/version/media-url.php?url=${encodeURIComponent(mediaExternal)}`;
+                else fullUrl = `/api/version/media-url.php?url=${encodeURIComponent(mediaExternal)}`;
+            } else {
+                fullUrl = '';
+            }
+
+            if (isValidMediaUrl(fullUrl)) {
+                return `<div class="message-media"><a href="#" data-fullurl="${escapeHtml(fullUrl)}" onclick="openImageLightbox(this.dataset.fullurl); return false;" title="Abrir imagen"><img src="${escapeHtml(thumbUrl || fullUrl)}" alt="Imagen" class="message-media-image"></a></div>${content?`<div>${escapeHtml(content)}</div>`:''}`;
+            } else if (isValidMediaUrl(thumbUrl)) {
+                return `<div class="message-media"><img src="${escapeHtml(thumbUrl)}" alt="Imagen" class="message-media-image"></div>${content?`<div>${escapeHtml(content)}</div>`:''}`;
+            }
+
             return `<div class="text-muted"><em>Imagen no disponible</em></div>`;
         }
         case 'video': {