Split SimpleFIN connections by institution

Group discovered SimpleFIN accounts by institution and create a
separate SyncConnection per institution so each bank appears as
its own card in the UI.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/services/bankSync.ts

@@ -35,7 +35,7 @@ export const bankSyncApi = {
     api.post<SyncConnection>('/bank-sync/plaid/complete-link', { publicToken }),
 
   connectSimpleFin: (setupToken: string) =>
-    api.post<SyncConnection>('/bank-sync/simplefin/connect', { setupToken }),
+    api.post<SyncConnection[]>('/bank-sync/simplefin/connect', { setupToken }),
 
   discoverAccounts: (connectionId: string) =>
     api.get<DiscoveredAccount[]>(`/bank-sync/connections/${connectionId}/discover-accounts`),

frontend/src/views/settings/SettingsView.vue

@@ -728,12 +728,16 @@ function loadPlaidScript(): Promise<void> {
 async function connectSimpleFin() {
   simpleFinLoading.value = true
   try {
-    const { data: conn } = await bankSyncApi.connectSimpleFin(simpleFinToken.value)
+    const { data: newConnections } = await bankSyncApi.connectSimpleFin(simpleFinToken.value)
+    for (const conn of newConnections) {
       connections.value.unshift(conn)
       syncIntervals[conn.id] = conn.syncIntervalMinutes
+    }
     showSimpleFinDialog.value = false
     simpleFinToken.value = ''
-    openMappingDialog(conn)
+    if (newConnections.length > 0) {
+      openMappingDialog(newConnections[0])
+    }
   } catch (err: any) {
     errorMessage.value = err.response?.data?.error || 'Failed to connect via SimpleFIN. Check your setup token.'
     showError.value = true

src/Purrse.Api/Controllers/BankSyncController.cs

@@ -59,7 +59,7 @@ public class BankSyncController : ControllerBase
         => Ok(await _bankSyncService.CompletePlaidLinkAsync(UserId, request));
 
     [HttpPost("simplefin/connect")]
-    public async Task<ActionResult<SyncConnectionResponse>> ConnectSimpleFin(CreateSimpleFinConnectionRequest request)
+    public async Task<ActionResult<List<SyncConnectionResponse>>> ConnectSimpleFin(CreateSimpleFinConnectionRequest request)
         => Ok(await _bankSyncService.CreateSimpleFinConnectionAsync(UserId, request));
 
     [HttpGet("connections/{id}/discover-accounts")]

src/Purrse.Api/Services/BankSyncService.cs

@@ -180,26 +180,32 @@ public class BankSyncService : IBankSyncService
 
     // --- SimpleFIN Flow ---
 
-    public async Task<SyncConnectionResponse> CreateSimpleFinConnectionAsync(Guid userId, CreateSimpleFinConnectionRequest request)
+    public async Task<List<SyncConnectionResponse>> CreateSimpleFinConnectionAsync(Guid userId, CreateSimpleFinConnectionRequest request)
     {
         var accessUrl = await _simpleFin.ExchangeSetupTokenAsync(request.SetupToken);
 
         var config = new Dictionary<string, string> { ["AccessUrl"] = accessUrl };
         var accounts = await _simpleFin.GetAccountsAsync(config);
-        var institutionName = accounts.FirstOrDefault()?.Institution ?? "SimpleFIN Connection";
+        var encryptedAccessUrl = _encryption.Encrypt(accessUrl);
 
+        var groupedByInstitution = accounts.GroupBy(a => a.Institution ?? "SimpleFIN Connection");
+        var connectionIds = new List<Guid>();
+
+        foreach (var group in groupedByInstitution)
+        {
             var connection = new SyncConnection
             {
                 Id = Guid.NewGuid(),
                 UserId = userId,
                 Provider = SyncProvider.SimpleFIN,
-            InstitutionName = institutionName,
-            EncryptedAccessToken = _encryption.Encrypt(accessUrl)
+                InstitutionName = group.Key,
+                EncryptedAccessToken = encryptedAccessUrl
             };
 
             _db.SyncConnections.Add(connection);
+            connectionIds.Add(connection.Id);
 
-        foreach (var account in accounts)
+            foreach (var account in group)
             {
                 _db.LinkedAccounts.Add(new LinkedAccount
                 {
@@ -211,10 +217,17 @@ public class BankSyncService : IBankSyncService
                     LastKnownBalance = account.Balance
                 });
             }
+        }
 
         await _db.SaveChangesAsync();
 
-        return await GetConnectionAsync(userId, connection.Id);
+        var results = new List<SyncConnectionResponse>();
+        foreach (var id in connectionIds)
+        {
+            results.Add(await GetConnectionAsync(userId, id));
+        }
+
+        return results;
     }
 
     // --- Account Linking ---

src/Purrse.Core/Interfaces/Services/IBankSyncService.cs

@@ -19,7 +19,7 @@ public interface IBankSyncService
     Task<SyncConnectionResponse> CompletePlaidLinkAsync(Guid userId, CreatePlaidConnectionRequest request);
 
     // SimpleFIN flow
-    Task<SyncConnectionResponse> CreateSimpleFinConnectionAsync(Guid userId, CreateSimpleFinConnectionRequest request);
+    Task<List<SyncConnectionResponse>> CreateSimpleFinConnectionAsync(Guid userId, CreateSimpleFinConnectionRequest request);
 
     // Account linking
     Task<List<DiscoveredAccountResponse>> DiscoverAccountsAsync(Guid userId, Guid connectionId);