diff --git a/src/app/(jury)/jury/competitions/[roundId]/projects/[projectId]/evaluate/page.tsx b/src/app/(jury)/jury/competitions/[roundId]/projects/[projectId]/evaluate/page.tsx
index 361561c..ccdd869 100644
--- a/src/app/(jury)/jury/competitions/[roundId]/projects/[projectId]/evaluate/page.tsx
+++ b/src/app/(jury)/jury/competitions/[roundId]/projects/[projectId]/evaluate/page.tsx
@@ -398,7 +398,8 @@ export default function JuryEvaluatePage({ params: paramsPromise }: PageProps) {
   const coiRequired = evalConfig?.coiRequired ?? true
 
   // Determine COI state: declared via server or just completed in this session
-  const coiDeclared = coiCompleted || coiStatus !== undefined
+  // coiStatus is null when no COI record exists, truthy when declared
+  const coiDeclared = coiCompleted || (coiStatus != null)
   const coiConflict = coiHasConflict || (coiStatus?.hasConflict ?? false)
 
   // Check if round is active
diff --git a/src/components/shared/file-viewer.tsx b/src/components/shared/file-viewer.tsx
index 4f12f60..43c60d5 100644
--- a/src/components/shared/file-viewer.tsx
+++ b/src/components/shared/file-viewer.tsx
@@ -490,28 +490,21 @@ function BulkDownloadButton({ projectId, fileIds }: { projectId: string; fileIds
     try {
       const result = await refetch()
       if (result.data && Array.isArray(result.data)) {
-        // Download each file via fetch+blob to handle cross-origin URLs
+        // Each URL already has Content-Disposition: attachment from the server,
+        // so we can trigger native downloads by navigating to each URL.
+        // Use hidden iframes to download multiple files without navigating away.
         for (let i = 0; i < result.data.length; i++) {
           const item = result.data[i] as { downloadUrl: string; fileName?: string }
           if (item.downloadUrl) {
-            try {
-              const response = await fetch(item.downloadUrl)
-              const blob = await response.blob()
-              const blobUrl = URL.createObjectURL(blob)
-              const link = document.createElement('a')
-              link.href = blobUrl
-              link.download = item.fileName || `file-${i + 1}`
-              document.body.appendChild(link)
-              link.click()
-              document.body.removeChild(link)
-              URL.revokeObjectURL(blobUrl)
-            } catch {
-              // Fall back to opening in new tab if fetch fails
-              window.open(item.downloadUrl, '_blank')
-            }
-            // Small delay between downloads
+            const iframe = document.createElement('iframe')
+            iframe.style.display = 'none'
+            iframe.src = item.downloadUrl
+            document.body.appendChild(iframe)
+            // Clean up iframe after download starts
+            setTimeout(() => document.body.removeChild(iframe), 10_000)
+            // Small delay between downloads to avoid browser throttling
             if (i < result.data.length - 1) {
-              await new Promise((resolve) => setTimeout(resolve, 500))
+              await new Promise((resolve) => setTimeout(resolve, 800))
             }
           }
         }
@@ -520,7 +513,7 @@ function BulkDownloadButton({ projectId, fileIds }: { projectId: string; fileIds
     } catch {
       toast.error('Failed to download files')
     } finally {
-      setDownloading(false)
+      setTimeout(() => setDownloading(false), 1000)
     }
   }
 
@@ -598,7 +591,7 @@ function FileDownloadButton({ file, className, label }: { file: ProjectFile; cla
   const [downloading, setDownloading] = useState(false)
 
   const { refetch } = trpc.file.getDownloadUrl.useQuery(
-    { bucket: file.bucket, objectKey: file.objectKey },
+    { bucket: file.bucket, objectKey: file.objectKey, forDownload: true, fileName: file.fileName },
     { enabled: false }
   )
 
@@ -607,42 +600,18 @@ function FileDownloadButton({ file, className, label }: { file: ProjectFile; cla
     try {
       const result = await refetch()
       if (result.data?.url) {
-        // Try fetch+blob first (works on desktop, some mobile browsers)
-        try {
-          const response = await fetch(result.data.url)
-          if (!response.ok) throw new Error('fetch failed')
-          const blob = await response.blob()
-          const blobUrl = URL.createObjectURL(blob)
-          const link = document.createElement('a')
-          link.href = blobUrl
-          link.download = file.fileName
-          // iOS Safari needs the link in the DOM
-          link.style.display = 'none'
-          document.body.appendChild(link)
-          link.click()
-          // Delay cleanup for iOS
-          setTimeout(() => {
-            document.body.removeChild(link)
-            URL.revokeObjectURL(blobUrl)
-          }, 100)
-        } catch {
-          // Fallback: open in new tab (iOS Safari often blocks blob downloads)
-          // Open synchronously via a link click to avoid popup blockers
-          const link = document.createElement('a')
-          link.href = result.data.url
-          link.target = '_blank'
-          link.rel = 'noopener noreferrer'
-          link.style.display = 'none'
-          document.body.appendChild(link)
-          link.click()
-          setTimeout(() => document.body.removeChild(link), 100)
-        }
+        // The presigned URL includes Content-Disposition: attachment header,
+        // so the browser will natively download the file (works on iOS Safari too).
+        // Use window.location.href for same-tab navigation which triggers download
+        // without popup blockers interfering.
+        window.location.href = result.data.url
       }
     } catch (error) {
       console.error('Failed to download file:', error)
       toast.error('Failed to download file')
     } finally {
-      setDownloading(false)
+      // Small delay before clearing state so the button doesn't flash
+      setTimeout(() => setDownloading(false), 1000)
     }
   }
 
diff --git a/src/lib/minio.ts b/src/lib/minio.ts
index 6518f7f..e32e7ab 100644
--- a/src/lib/minio.ts
+++ b/src/lib/minio.ts
@@ -84,11 +84,17 @@ export async function getPresignedUrl(
   bucket: string,
   objectKey: string,
   method: 'GET' | 'PUT' = 'GET',
-  expirySeconds: number = 900 // 15 minutes default
+  expirySeconds: number = 900, // 15 minutes default
+  options?: { downloadFileName?: string }
 ): Promise<string> {
   let url: string
   if (method === 'GET') {
-    url = await minio.presignedGetObject(bucket, objectKey, expirySeconds)
+    // If downloadFileName is set, include Content-Disposition: attachment header
+    // so the browser triggers a native download (works on iOS Safari, all browsers)
+    const respHeaders = options?.downloadFileName
+      ? { 'response-content-disposition': `attachment; filename="${options.downloadFileName}"` }
+      : undefined
+    url = await minio.presignedGetObject(bucket, objectKey, expirySeconds, respHeaders)
   } else {
     url = await minio.presignedPutObject(bucket, objectKey, expirySeconds)
   }
diff --git a/src/server/routers/file.ts b/src/server/routers/file.ts
index dbcc7f9..e3d7d9a 100644
--- a/src/server/routers/file.ts
+++ b/src/server/routers/file.ts
@@ -15,6 +15,8 @@ export const fileRouter = router({
       z.object({
         bucket: z.string(),
         objectKey: z.string(),
+        forDownload: z.boolean().optional(),
+        fileName: z.string().optional(),
       })
     )
     .query(async ({ ctx, input }) => {
@@ -109,7 +111,9 @@ export const fileRouter = router({
         }
       }
 
-      const url = await getPresignedUrl(input.bucket, input.objectKey, 'GET', 900) // 15 min
+      const url = await getPresignedUrl(input.bucket, input.objectKey, 'GET', 900,
+        input.forDownload ? { downloadFileName: input.fileName || input.objectKey.split('/').pop() || 'download' } : undefined
+      ) // 15 min
 
       // Log file access
       await logAudit({
@@ -699,7 +703,9 @@ export const fileRouter = router({
       // Generate signed URLs for each file
       const results = await Promise.all(
         files.map(async (file) => {
-          const downloadUrl = await getPresignedUrl(file.bucket, file.objectKey, 'GET', 900)
+          const downloadUrl = await getPresignedUrl(file.bucket, file.objectKey, 'GET', 900,
+            { downloadFileName: file.fileName }
+          )
           return {
             fileId: file.id,
             fileName: file.fileName,