feat(ui): add image download overlay, improve agent selector defaults

- Add hover download button with filename/size on chat image thumbnails
- Add download button and file info bar to image lightbox overlay
- Add hover download button on inline markdown images
- Increase agent selector dropdown height on desktop (sm:max-h-80)
- Select default agent (is_default) instead of first in list
- Increase session title generation timeout to 120s

internal/agent/title_generate.go

@@ -9,7 +9,7 @@ import (
 	"github.com/nextlevelbuilder/goclaw/internal/providers"
 )
 
-const titleGenerateTimeout = 30 * time.Second
+const titleGenerateTimeout = 120 * time.Second
 
 const titleSystemPrompt = `Generate a short title (max 15 words) for this conversation based on the user's message. Reply with only the title, no quotes or punctuation wrapping.`
 

ui/web/src/components/chat/agent-selector.tsx

@@ -34,7 +34,8 @@ export function AgentSelector({ value, onChange }: AgentSelectorProps) {
         const active = (res.agents ?? []).filter((a) => a.status === "active");
         setAgents(active);
         if (active.length > 0 && !active.some((a) => a.agent_key === value)) {
-          onChange(active[0]!.agent_key);
+          const defaultAgent = active.find((a) => a.is_default) ?? active[0]!;
+          onChange(defaultAgent.agent_key);
         }
       })
       .catch(() => {});
@@ -92,7 +93,7 @@ export function AgentSelector({ value, onChange }: AgentSelectorProps) {
         <div
           ref={dropdownRef}
           style={dropdownStyle}
-          className="pointer-events-auto max-h-60 overflow-y-auto rounded-lg border bg-popover p-1 shadow-md"
+          className="pointer-events-auto max-h-60 sm:max-h-80 overflow-y-auto rounded-lg border bg-popover p-1 shadow-md"
         >
           {agents.length === 0 && (
             <div className="px-3 py-2 text-sm text-muted-foreground">

ui/web/src/components/chat/media-gallery.tsx

@@ -72,19 +72,38 @@ export function MediaGallery({ items }: MediaGalleryProps) {
       {images.length > 0 && (
         <div className="grid grid-cols-1 sm:grid-cols-2 gap-2">
           {images.map((item, i) => (
-            <button
-              key={i}
-              type="button"
-              onClick={() => setLightboxIdx(i)}
-              className="relative overflow-hidden rounded-lg border cursor-pointer"
-            >
-              <img
-                src={item.path}
-                alt={item.fileName ?? ""}
-                className="h-40 w-full object-cover"
-                loading="lazy"
-              />
-            </button>
+            <div key={i} className="group relative overflow-hidden rounded-lg border">
+              <button
+                type="button"
+                onClick={() => setLightboxIdx(i)}
+                className="block w-full cursor-pointer"
+              >
+                <img
+                  src={item.path}
+                  alt={item.fileName ?? ""}
+                  className="h-40 w-full object-cover"
+                  loading="lazy"
+                />
+              </button>
+              <div className="pointer-events-none absolute inset-0 bg-gradient-to-t from-black/50 via-transparent to-transparent opacity-0 transition-opacity group-hover:opacity-100" />
+              <div className="absolute inset-x-0 bottom-0 flex items-end justify-between px-2 pb-1.5 opacity-0 transition-opacity group-hover:opacity-100">
+                <div className="flex min-w-0 flex-col text-xs text-white drop-shadow-sm">
+                  {item.fileName && <span className="truncate">{item.fileName}</span>}
+                  {item.size != null && item.size > 0 && (
+                    <span className="text-white/70">{formatSize(item.size)}</span>
+                  )}
+                </div>
+                <a
+                  href={item.path}
+                  download={item.fileName ?? "image"}
+                  onClick={(e) => e.stopPropagation()}
+                  className="shrink-0 rounded-md bg-black/60 p-1 text-white shadow-md hover:bg-black/80 transition-colors cursor-pointer"
+                  title="Download"
+                >
+                  <Download className="h-4 w-4" />
+                </a>
+              </div>
+            </div>
           ))}
         </div>
       )}
@@ -121,6 +140,8 @@ export function MediaGallery({ items }: MediaGalleryProps) {
         <ImageLightbox
           src={images[lightboxIdx]!.path}
           alt={images[lightboxIdx]!.fileName ?? ""}
+          fileName={images[lightboxIdx]!.fileName}
+          size={images[lightboxIdx]!.size}
           onClose={() => setLightboxIdx(null)}
         />
       )}

ui/web/src/components/shared/image-lightbox.tsx

@@ -1,13 +1,16 @@
 import { useEffect, useCallback } from "react";
-import { X } from "lucide-react";
+import { X, Download } from "lucide-react";
+import { formatSize } from "@/lib/file-helpers";
 
 interface ImageLightboxProps {
   src: string;
   alt?: string;
+  fileName?: string;
+  size?: number;
   onClose: () => void;
 }
 
-export function ImageLightbox({ src, alt, onClose }: ImageLightboxProps) {
+export function ImageLightbox({ src, alt, fileName, size, onClose }: ImageLightboxProps) {
   const handleKeyDown = useCallback(
     (e: KeyboardEvent) => {
       if (e.key === "Escape") onClose();
@@ -20,24 +23,47 @@ export function ImageLightbox({ src, alt, onClose }: ImageLightboxProps) {
     return () => document.removeEventListener("keydown", handleKeyDown);
   }, [handleKeyDown]);
 
+  const displayName = fileName || alt || "image";
+
   return (
     <div
-      className="fixed inset-0 z-[100] flex items-center justify-center bg-black/80 backdrop-blur-sm"
+      className="fixed inset-0 z-[100] flex flex-col items-center justify-center bg-black/80 backdrop-blur-sm"
       onClick={onClose}
     >
-      <button
-        type="button"
-        onClick={onClose}
-        className="absolute top-4 right-4 rounded-full bg-black/50 p-2 text-white hover:bg-black/70 transition-colors cursor-pointer"
-      >
-        <X className="h-5 w-5" />
-      </button>
+      <div className="absolute top-4 right-4 flex items-center gap-2">
+        <a
+          href={src}
+          download={displayName}
+          onClick={(e) => e.stopPropagation()}
+          className="rounded-full bg-black/50 p-2 text-white hover:bg-black/70 transition-colors cursor-pointer"
+          title="Download"
+        >
+          <Download className="h-5 w-5" />
+        </a>
+        <button
+          type="button"
+          onClick={onClose}
+          className="rounded-full bg-black/50 p-2 text-white hover:bg-black/70 transition-colors cursor-pointer"
+        >
+          <X className="h-5 w-5" />
+        </button>
+      </div>
       <img
         src={src}
         alt={alt ?? "image"}
-        className="max-h-[90vh] max-w-[90vw] rounded-lg object-contain"
+        className="max-h-[85vh] max-w-[90vw] rounded-lg object-contain"
         onClick={(e) => e.stopPropagation()}
       />
+      {(fileName || (size != null && size > 0)) && (
+        <div
+          className="mt-3 flex items-center gap-2 rounded-full bg-black/60 px-4 py-1.5 text-sm text-white/90"
+          onClick={(e) => e.stopPropagation()}
+        >
+          {fileName && <span className="max-w-[300px] truncate">{fileName}</span>}
+          {fileName && size != null && size > 0 && <span className="text-white/50">·</span>}
+          {size != null && size > 0 && <span className="text-white/60">{formatSize(size)}</span>}
+        </div>
+      )}
     </div>
   );
 }

ui/web/src/components/shared/markdown-renderer.tsx

@@ -166,18 +166,32 @@ export function MarkdownRenderer({ content, className }: MarkdownRendererProps)
           },
           img({ src, alt, ...props }) {
             const resolvedSrc = isFileLink(src) ? toFileUrl(src!, token) : src;
+            const displayName = alt || fileNameFromHref(src ?? "");
             return (
-              <img
-                src={resolvedSrc}
-                alt={alt ?? "image"}
-                className="max-w-sm rounded-lg border shadow-sm cursor-pointer hover:opacity-90 transition-opacity"
-                loading="lazy"
-                onClick={(e) => {
-                  e.preventDefault();
-                  if (resolvedSrc) openLightbox(resolvedSrc, alt ?? "image");
-                }}
-                {...props}
-              />
+              <span className="group/img relative inline-block overflow-hidden rounded-lg border shadow-sm">
+                <img
+                  src={resolvedSrc}
+                  alt={alt ?? "image"}
+                  className="block max-w-sm cursor-pointer hover:opacity-90 transition-opacity"
+                  loading="lazy"
+                  onClick={(e) => {
+                    e.preventDefault();
+                    if (resolvedSrc) openLightbox(resolvedSrc, alt ?? "image");
+                  }}
+                  {...props}
+                />
+                {resolvedSrc && (
+                  <a
+                    href={resolvedSrc}
+                    download={displayName}
+                    onClick={(e) => e.stopPropagation()}
+                    className="absolute top-1.5 right-1.5 flex items-center justify-center rounded-md bg-black/60 p-1 text-white shadow-md opacity-0 transition-opacity group-hover/img:opacity-100 hover:bg-black/80 cursor-pointer"
+                    title="Download"
+                  >
+                    <Download className="h-4 w-4" />
+                  </a>
+                )}
+              </span>
             );
           },
           table({ children, ...props }) {