Fix shared collection deserialization

Co-Authored-By: Claude <noreply@anthropic.com>

rust/CLAUDE.md

@@ -98,7 +98,7 @@ The project has completed foundational components (crypto, storage, models) and
 
 ## Commit Guidelines
 
-### Pre-commit Checklist
+### Pre-commit Checklist (RUN BEFORE EVERY COMMIT!)
 
 **CRITICAL: CI will fail if ANY of these checks fail. Run ALL commands and ensure they ALL pass.**
 

rust/src/api/models.rs

@@ -170,7 +170,7 @@ pub struct Collection {
     pub id: i64,
     pub owner: CollectionUser,
     pub encrypted_key: String,
-    pub key_decryption_nonce: String,
+    pub key_decryption_nonce: Option<String>,
     pub name: Option<String>,
     pub encrypted_name: Option<String>,
     pub name_decryption_nonce: Option<String>,

rust/src/commands/export.rs

@@ -181,9 +181,18 @@ async fn export_account(storage: &Storage, account: &Account, filter: &ExportFil
         );
 
         // Decrypt collection key
+        // Shared collections don't have key_decryption_nonce - they use a different mechanism
+        let Some(ref key_nonce) = collection.key_decryption_nonce else {
+            log::warn!(
+                "Collection {} appears to be shared (no key_decryption_nonce), skipping for now",
+                collection.id
+            );
+            continue;
+        };
+
         let collection_key = match decrypt_collection_key(
             &collection.encrypted_key,
-            &collection.key_decryption_nonce,
+            key_nonce,
             master_key,
             secret_key,
         ) {