diff --git a/src/main/services/team/TeamProvisioningService.ts b/src/main/services/team/TeamProvisioningService.ts
index dcd1b195..69790de0 100644
--- a/src/main/services/team/TeamProvisioningService.ts
+++ b/src/main/services/team/TeamProvisioningService.ts
@@ -3624,18 +3624,33 @@ export class TeamProvisioningService {
               media_type: 'application/pdf',
               data: att.data,
             },
+            title: att.filename,
           });
         } else if (att.mimeType === 'text/plain') {
           // Text file → document block with text source (decode base64 → UTF-8)
-          contentBlocks.push({
-            type: 'document',
-            source: {
-              type: 'text',
-              media_type: 'text/plain',
-              data: Buffer.from(att.data, 'base64').toString('utf-8'),
-            },
-            title: att.filename,
-          });
+          const decoded = Buffer.from(att.data, 'base64').toString('utf-8');
+          if (decoded.includes('\uFFFD')) {
+            // Non-UTF-8 file: fallback to base64 document to avoid garbled content
+            contentBlocks.push({
+              type: 'document',
+              source: {
+                type: 'base64',
+                media_type: 'text/plain',
+                data: att.data,
+              },
+              title: att.filename,
+            });
+          } else {
+            contentBlocks.push({
+              type: 'document',
+              source: {
+                type: 'text',
+                media_type: 'text/plain',
+                data: decoded,
+              },
+              title: att.filename,
+            });
+          }
         } else {
           // Image (default) → image block
           contentBlocks.push({
diff --git a/src/renderer/components/team/dialogs/TaskCommentInput.tsx b/src/renderer/components/team/dialogs/TaskCommentInput.tsx
index 5694fb7c..55cdcda6 100644
--- a/src/renderer/components/team/dialogs/TaskCommentInput.tsx
+++ b/src/renderer/components/team/dialogs/TaskCommentInput.tsx
@@ -2,6 +2,7 @@ import { useCallback, useMemo, useRef, useState } from 'react';
 
 import { MarkdownViewer } from '@renderer/components/chat/viewers/MarkdownViewer';
 import { ImageLightbox } from '@renderer/components/team/attachments/ImageLightbox';
+import { FileIcon } from '@renderer/components/team/editor/FileIcon';
 import { MemberBadge } from '@renderer/components/team/MemberBadge';
 import { MentionableTextarea } from '@renderer/components/ui/MentionableTextarea';
 import { Tooltip, TooltipContent, TooltipTrigger } from '@renderer/components/ui/tooltip';
@@ -19,7 +20,7 @@ import {
   stripEncodedTaskReferenceMetadata,
 } from '@renderer/utils/taskReferenceUtils';
 import { MAX_TEXT_LENGTH } from '@shared/constants';
-import { categorizeFile, getEffectiveMimeType } from '@shared/constants/attachments';
+import { categorizeFile, getEffectiveMimeType, isImageMime } from '@shared/constants/attachments';
 import { Mic, Paperclip, Send, Trash2, X } from 'lucide-react';
 
 import type { MentionSuggestion } from '@renderer/types/mention';
@@ -254,25 +255,40 @@ export const TaskCommentInput = ({
       {/* Pending attachment previews */}
       {pendingAttachments.length > 0 ? (
         <div className="mb-2 flex flex-wrap gap-1.5">
-          {pendingAttachments.map((att, idx) => (
-            <div
-              key={att.id}
-              className="group relative size-14 cursor-pointer overflow-hidden rounded border border-[var(--color-border)] bg-[var(--color-surface)] transition-colors hover:border-[var(--color-border-emphasis)]"
-              onClick={() => setLightboxIndex(idx)}
-            >
-              <img src={att.previewUrl} alt={att.filename} className="size-full object-cover" />
-              <button
-                type="button"
-                className="absolute right-0.5 top-0.5 rounded bg-black/60 p-0.5 text-white opacity-0 transition-opacity hover:bg-red-600 group-hover:opacity-100"
-                onClick={(e) => {
-                  e.stopPropagation();
-                  removeAttachment(att.id);
-                }}
+          {pendingAttachments.map((att, idx) => {
+            const isImage = isImageMime(att.mimeType);
+            const lightboxIdx = isImage
+              ? pendingAttachments.slice(0, idx).filter((a) => isImageMime(a.mimeType)).length
+              : -1;
+            return (
+              <div
+                key={att.id}
+                className="group relative size-14 cursor-pointer overflow-hidden rounded border border-[var(--color-border)] bg-[var(--color-surface)] transition-colors hover:border-[var(--color-border-emphasis)]"
+                onClick={isImage ? () => setLightboxIndex(lightboxIdx) : undefined}
               >
-                <Trash2 size={8} />
-              </button>
-            </div>
-          ))}
+                {isImage ? (
+                  <img src={att.previewUrl} alt={att.filename} className="size-full object-cover" />
+                ) : (
+                  <div className="flex size-full flex-col items-center justify-center gap-0.5">
+                    <FileIcon fileName={att.filename} className="size-5" />
+                    <span className="max-w-[48px] truncate text-[7px] text-[var(--color-text-muted)]">
+                      {att.filename}
+                    </span>
+                  </div>
+                )}
+                <button
+                  type="button"
+                  className="absolute right-0.5 top-0.5 rounded bg-black/60 p-0.5 text-white opacity-0 transition-opacity hover:bg-red-600 group-hover:opacity-100"
+                  onClick={(e) => {
+                    e.stopPropagation();
+                    removeAttachment(att.id);
+                  }}
+                >
+                  <Trash2 size={8} />
+                </button>
+              </div>
+            );
+          })}
         </div>
       ) : null}
 
@@ -280,13 +296,15 @@ export const TaskCommentInput = ({
         <ImageLightbox
           open
           onClose={() => setLightboxIndex(null)}
-          slides={pendingAttachments.map((att) => ({
-            src: att.previewUrl,
-            alt: att.filename,
-            title: att.filename,
-          }))}
+          slides={pendingAttachments
+            .filter((att) => isImageMime(att.mimeType))
+            .map((att) => ({
+              src: att.previewUrl,
+              alt: att.filename,
+              title: att.filename,
+            }))}
           index={lightboxIndex}
-          showCounter={pendingAttachments.length > 1}
+          showCounter={pendingAttachments.filter((a) => isImageMime(a.mimeType)).length > 1}
         />
       ) : null}
 
diff --git a/src/renderer/hooks/useAttachments.ts b/src/renderer/hooks/useAttachments.ts
index 07f024d7..48210114 100644
--- a/src/renderer/hooks/useAttachments.ts
+++ b/src/renderer/hooks/useAttachments.ts
@@ -270,19 +270,17 @@ export function useAttachments(options?: UseAttachmentsOptions): UseAttachmentsR
       const items = event.clipboardData?.items;
       if (!items) return;
 
-      const supportedFiles: File[] = [];
+      const pastedFiles: File[] = [];
       for (const item of Array.from(items)) {
         if (item.kind === 'file') {
           const file = item.getAsFile();
-          if (file && categorizeFile(file) !== 'unsupported') {
-            supportedFiles.push(file);
-          }
+          if (file) pastedFiles.push(file);
         }
       }
 
-      if (supportedFiles.length > 0) {
+      if (pastedFiles.length > 0) {
         event.preventDefault();
-        void addFiles(supportedFiles);
+        void addFiles(pastedFiles);
       }
     },
     [addFiles]
diff --git a/src/renderer/hooks/useComposerDraft.ts b/src/renderer/hooks/useComposerDraft.ts
index 9b0554a0..81be33f6 100644
--- a/src/renderer/hooks/useComposerDraft.ts
+++ b/src/renderer/hooks/useComposerDraft.ts
@@ -420,19 +420,17 @@ export function useComposerDraft(teamName: string): UseComposerDraftResult {
       const items = event.clipboardData?.items;
       if (!items) return;
 
-      const supportedFiles: File[] = [];
+      const pastedFiles: File[] = [];
       for (const item of Array.from(items)) {
         if (item.kind === 'file') {
           const file = item.getAsFile();
-          if (file && categorizeFile(file) !== 'unsupported') {
-            supportedFiles.push(file);
-          }
+          if (file) pastedFiles.push(file);
         }
       }
 
-      if (supportedFiles.length > 0) {
+      if (pastedFiles.length > 0) {
         event.preventDefault();
-        void addFiles(supportedFiles);
+        void addFiles(pastedFiles);
       }
     },
     [addFiles]
diff --git a/src/renderer/utils/attachmentUtils.ts b/src/renderer/utils/attachmentUtils.ts
index d1ec8a85..9b23efcf 100644
--- a/src/renderer/utils/attachmentUtils.ts
+++ b/src/renderer/utils/attachmentUtils.ts
@@ -22,6 +22,9 @@ export function validateAttachment(file: File): { valid: true } | { valid: false
   if (cat === 'unsupported') {
     return { valid: false, error: `Unsupported file type: ${file.name}` };
   }
+  if (file.size === 0) {
+    return { valid: false, error: `File "${file.name}" is empty` };
+  }
   if (file.size > MAX_FILE_SIZE) {
     return { valid: false, error: `File "${file.name}" exceeds 10MB limit` };
   }
diff --git a/tsconfig.json b/tsconfig.json
index 7711a5ed..d1b421bc 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -1,8 +1,8 @@
 {
   "compilerOptions": {
-    "target": "ES2020",
+    "target": "ES2023",
     "module": "ESNext",
-    "lib": ["ES2020", "DOM", "DOM.Iterable"],
+    "lib": ["ES2023", "DOM", "DOM.Iterable"],
     "jsx": "react-jsx",
     "strict": true,
     "esModuleInterop": true,