add session-based connection management and React dashboard

Backend: adds JDBC session support, login/status/logout endpoints, and
new DTOs (AuthResponse, ConnectionStatusResponse, LoginResult). Frontend
replaces the Vite boilerplate with a Dashboard, ServiceCard, and
ConnectModal backed by a typed API client.

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

backend/src/main/java/com/vaessl/app/connection/ConnectionController.java

@@ -1,13 +1,26 @@
 package com.vaessl.app.connection;
 
+import java.time.Instant;
+import java.time.temporal.ChronoUnit;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
 import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.DeleteMapping;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
 import org.springframework.web.bind.annotation.RequestBody;
 import org.springframework.web.bind.annotation.RestController;
 
+import com.vaessl.app.dto.AuthResponse;
 import com.vaessl.app.dto.ConnectionRequest;
-import com.vaessl.app.dto.ConnectionResponse;
+import com.vaessl.app.dto.ConnectionStatusResponse;
+import com.vaessl.app.dto.LoginResult;
 
+import jakarta.servlet.http.HttpServletRequest;
+import jakarta.servlet.http.HttpSession;
 import jakarta.validation.Valid;
 import lombok.RequiredArgsConstructor;
 
@@ -15,10 +28,63 @@ import lombok.RequiredArgsConstructor;
 @RequiredArgsConstructor
 public class ConnectionController {
 
+    private static final String SUFFIX = "_CONNECTION_ID";
+
     private final ConnectionService connectionService;
 
     @PostMapping("/login")
-    public ResponseEntity<ConnectionResponse> loginResponse(@Valid @RequestBody ConnectionRequest request) {
-        return ResponseEntity.ok(connectionService.login(request));
+    public ResponseEntity<AuthResponse> login(
+            @Valid @RequestBody ConnectionRequest request,
+            HttpServletRequest httpReq) {
+
+        LoginResult result = connectionService.login(request);
+
+        HttpSession session = httpReq.getSession(true);
+        session.setAttribute(request.serviceType() + SUFFIX, result.connectionId());
+
+        if (result.expiresAt() != null) {
+            long secs = Instant.now().until(result.expiresAt(), ChronoUnit.SECONDS);
+            session.setMaxInactiveInterval((int) Math.max(secs, 300));
+        }
+
+        return ResponseEntity.ok(new AuthResponse(request.serviceType(), result.expiresAt()));
+    }
+
+    @GetMapping("/connections/status")
+    public ResponseEntity<List<ConnectionStatusResponse>> getStatus(HttpServletRequest httpReq) {
+        HttpSession session = httpReq.getSession(false);
+        if (session == null) {
+            return ResponseEntity.ok(List.of());
+        }
+
+        List<ConnectionStatusResponse> statuses = new ArrayList<>();
+        Collections.list(session.getAttributeNames()).stream()
+                .filter(k -> k.endsWith(SUFFIX))
+                .forEach(k -> {
+                    String serviceType = k.replace(SUFFIX, "");
+                    Long id = (Long) session.getAttribute(k);
+                    ConnectionStatusResponse status = connectionService.getConnectionStatus(serviceType, id);
+                    if (status != null) statuses.add(status);
+                });
+
+        return ResponseEntity.ok(statuses);
+    }
+
+    @DeleteMapping("/connections/{serviceType}")
+    public ResponseEntity<Void> logout(
+            @PathVariable("serviceType") String serviceType,
+            HttpServletRequest httpReq) {
+
+        HttpSession session = httpReq.getSession(false);
+        if (session != null) {
+            session.removeAttribute(serviceType + SUFFIX);
+            boolean hasMore = Collections.list(session.getAttributeNames()).stream()
+                    .anyMatch(k -> k.endsWith(SUFFIX));
+            if (!hasMore) {
+                session.invalidate();
+            }
+        }
+
+        return ResponseEntity.noContent().build();
     }
 }

backend/src/main/java/com/vaessl/app/connection/ConnectionProvider.java

@@ -1,5 +1,7 @@
 package com.vaessl.app.connection;
 
+import java.time.Instant;
+
 import com.vaessl.app.dto.ConnectionRequest;
 import com.vaessl.app.dto.ConnectionResponse;
 
@@ -16,4 +18,8 @@ public interface ConnectionProvider {
     ConnectionEntity connectionToEntity(ConnectionRequest request, ConnectionResponse response);
 
     void updateToRepository(ConnectionEntity existing, ConnectionResponse response);
+
+    default Instant getTokenExpiry(ConnectionEntity entity) {
+        return null;
+    }
 }

backend/src/main/java/com/vaessl/app/connection/ConnectionService.java

@@ -1,5 +1,6 @@
 package com.vaessl.app.connection;
 
+import java.time.Instant;
 import java.util.List;
 import java.util.Map;
 import java.util.stream.Collectors;
@@ -8,6 +9,8 @@ import org.springframework.stereotype.Service;
 
 import com.vaessl.app.dto.ConnectionRequest;
 import com.vaessl.app.dto.ConnectionResponse;
+import com.vaessl.app.dto.ConnectionStatusResponse;
+import com.vaessl.app.dto.LoginResult;
 import com.vaessl.app.exception.WrongServiceTypeException;
 
 @Service
@@ -23,7 +26,7 @@ public class ConnectionService {
         this.cRepository = cRepository;
     }
 
-    public ConnectionResponse login(ConnectionRequest request) {
+    public LoginResult login(ConnectionRequest request) {
 
         ConnectionProvider provider = providerRegistry.get(request.serviceType());
 
@@ -37,13 +40,27 @@ public class ConnectionService {
 
         ConnectionEntity existing = provider.findUniqueConnectionEntry(request);
 
+        ConnectionEntity saved;
         if (existing != null) {
             provider.updateToRepository(existing, response);
+            saved = existing;
         } else {
             ConnectionEntity newEntity = provider.connectionToEntity(request, response);
-            cRepository.save(newEntity);
+            saved = cRepository.save(newEntity);
         }
 
-        return response;
+        return new LoginResult(saved.getId(), response.expiresAt());
     }
-}
+
+    public ConnectionStatusResponse getConnectionStatus(String serviceType, Long connectionId) {
+        ConnectionEntity entity = cRepository.findById(connectionId).orElse(null);
+        if (entity == null) return null;
+
+        ConnectionProvider provider = providerRegistry.get(serviceType);
+        Instant expiresAt = (provider != null) ? provider.getTokenExpiry(entity) : null;
+        boolean connected = expiresAt == null || expiresAt.isAfter(Instant.now());
+
+        return new ConnectionStatusResponse(serviceType, entity.getAppUrl(),
+                entity.getUsername(), expiresAt, connected);
+    }
+}

backend/src/main/java/com/vaessl/app/connection/Endpoint.java

@@ -1,7 +1,9 @@
 package com.vaessl.app.connection;
 
 public enum Endpoint {
-    HOMEBOX_LOGIN("/api/v1/users/login"), LOGIN("/login");
+    HOMEBOX_LOGIN("/api/v1/users/login"),
+    LOGIN("/login"),
+    CONNECTION_STATUS("/connections/status");
 
     private final String value;
 

backend/src/main/java/com/vaessl/app/connection/HomeBoxConnectionProvider.java

@@ -97,6 +97,11 @@ public class HomeBoxConnectionProvider implements ConnectionProvider {
         }
     }
 
+    @Override
+    public Instant getTokenExpiry(ConnectionEntity entity) {
+        return (entity instanceof HomeboxEntity he) ? he.getExpiresAt() : null;
+    }
+
     private record HomeboxLoginResponse(String token, String attachmentToken, Instant expiresAt) {
     }