feat(files): add download=true query param for Content-Disposition attachment header

internal/http/files.go

@@ -1,6 +1,7 @@
 package http
 
 import (
+	"fmt"
 	"log/slog"
 	"mime"
 	"net/http"
@@ -132,6 +133,11 @@ func (h *FilesHandler) handleServe(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", ct)
 	}
 
+	// Trigger browser download with original filename when ?download=true
+	if r.URL.Query().Get("download") == "true" {
+		w.Header().Set("Content-Disposition", fmt.Sprintf(`attachment; filename="%s"`, filepath.Base(absPath)))
+	}
+
 	http.ServeFile(w, r, absPath)
 }
 

ui/web/src/lib/file-helpers.ts

@@ -165,6 +165,11 @@ export function toFileUrl(path: string): string {
   return `/v1/files/${basename}`;
 }
 
+/** Append ?download=true to a URL for Content-Disposition: attachment. */
+export function toDownloadUrl(url: string): string {
+  return url + (url.includes("?") ? "&" : "?") + "download=true";
+}
+
 /** Determine MediaItem kind from MIME type */
 export function mediaKindFromMime(mime: string): "image" | "video" | "audio" | "document" | "code" {
   if (mime.startsWith("image/")) return "image";