feat(chat): colle les fichiers du presse-papiers via Ctrl+V dans le composer (#181)

frontend/src/features/agents/CustomAgentChatView.tsx

@@ -57,6 +57,7 @@ interface AttachmentDraft {
   label: string;
   input: ChatAttachmentInput;
   previewUrl?: string;
+  dedupeKey?: string;
 }
 
 interface ProfileCommandDialogState {
@@ -351,6 +352,7 @@ async function clipboardFileToAttachment(file: File): Promise<AttachmentDraft> {
     previewUrl: mime.startsWith("image/")
       ? `data:${mime};base64,${contentBase64}`
       : undefined,
+    dedupeKey: fileMetadataKey(file),
     input: {
       filename,
       contentBase64,
@@ -360,6 +362,10 @@ async function clipboardFileToAttachment(file: File): Promise<AttachmentDraft> {
   };
 }
 
+function fileMetadataKey(file: File): string {
+  return `${file.name}\u0000${file.type}\u0000${file.size}\u0000${file.lastModified}`;
+}
+
 function clipboardFiles(event: ClipboardEvent<HTMLTextAreaElement>): File[] {
   const clipboardItems = event.clipboardData.items
     ? Array.from(event.clipboardData.items)
@@ -373,7 +379,7 @@ function clipboardFiles(event: ClipboardEvent<HTMLTextAreaElement>): File[] {
     .filter((file): file is File => Boolean(file));
   const seen = new Set<string>();
   return [...fromItems, ...clipboardFiles].filter((file) => {
-    const key = `${file.name}\u0000${file.type}\u0000${file.size}\u0000${file.lastModified}`;
+    const key = fileMetadataKey(file);
     if (seen.has(key)) return false;
     seen.add(key);
     return true;
@@ -958,7 +964,20 @@ export function CustomAgentChatView({
       const nextAttachments = await Promise.all(
         files.map(clipboardFileToAttachment),
       );
-      setAttachments((prev) => [...prev, ...nextAttachments]);
+      setAttachments((prev) => {
+        const known = new Set(
+          prev
+            .map((attachment) => attachment.dedupeKey)
+            .filter((key): key is string => Boolean(key)),
+        );
+        const unique = nextAttachments.filter((attachment) => {
+          if (!attachment.dedupeKey) return true;
+          if (known.has(attachment.dedupeKey)) return false;
+          known.add(attachment.dedupeKey);
+          return true;
+        });
+        return unique.length > 0 ? [...prev, ...unique] : prev;
+      });
       if (pastedText) {
         setDraft((prev) =>
           prev.slice(0, selectionStart) +