feat(desktop): view-once image attachments (sender toggle + recipient lightbox + tombstone)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/desktop/src/lib/useConversationMessages.ts

@@ -70,7 +70,12 @@ function rowToMessage(row: Record<string, unknown>): MessageWithCipher {
 }
 
 export function useConversationMessages({ conversationId, userId, deviceId }: Args): State & {
-  send: (text: string, images?: File[], replyToId?: string | null) => Promise<void>;
+  send: (
+    text: string,
+    images?: File[],
+    replyToId?: string | null,
+    opts?: { viewOnce?: boolean },
+  ) => Promise<void>;
   refresh: () => Promise<void>;
   pending: OutboxItem[];
   retryPending: (id: string) => void;
@@ -559,7 +564,12 @@ export function useConversationMessages({ conversationId, userId, deviceId }: Ar
   );
 
   const send = useCallback(
-    async (text: string, images: File[] = [], replyToId: string | null = null) => {
+    async (
+      text: string,
+      images: File[] = [],
+      replyToId: string | null = null,
+      opts: { viewOnce?: boolean } = {},
+    ) => {
       const trimmed = text.trim();
       if ((!trimmed && images.length === 0) || !conversationId || !userId || !deviceId) return;
       const priv = privateKeyRef.current;
@@ -631,6 +641,14 @@ export function useConversationMessages({ conversationId, userId, deviceId }: Ar
           ...(dims.width !== undefined ? { width: dims.width } : {}),
           ...(dims.height !== undefined ? { height: dims.height } : {}),
         });
+        // Stamp the view-once flag on each handle the caller requested it
+        // for. The flag rides inside the encrypted payload (so peers can
+        // render the locked card without leaking who-sent-what to the
+        // server) AND lands on the public message_attachments row via
+        // insertAttachmentRow below (where the mark-viewed RPC enforces it).
+        if (opts.viewOnce) {
+          res.handle.viewOnce = true;
+        }
         handles.push(res.handle);
         blobNonceHexByHandleId.set(res.handle.id, bytesToPgHex(res.nonce));
       }