feat(studio): MCP-clients editor + federated entry rendering (v0.22.0)

The viral-bridge story now has a UI surface. Settings →
MCP Clients lists every configured server, shows last-
discovery health (green dot + tool count, red dot + error
kind), and offers Add / Remove / Refresh.

Add-server dialog: name (no dots), endpoint, optional
api_key_env, optional notes. On submit the hub persists +
re-runs discovery in one round-trip; the Store fills with
synthetic `mcp.<name>.<tool>` entries the operator can see
immediately.

StoreItem now carries `kind` and `provider`. Federated
entries route through a bridge — no install bundle to
download — and Studio's install button renders accordingly
(via the existing "Not installable" path; the Phase-2
follow-up adds an explicit "Configure bridge" call-to-action).

Settings dialog grew to 520×640 with a SingleChildScrollView
so the additional panels don't crowd. Channel pill, system-AI
panel, MCP-clients panel all coexist without a redesign.

Signed-off-by: flemming-it <stefan.a.flemming@googlemail.com>

lib/data/hub.dart

@@ -339,6 +339,55 @@ class HubService {
     );
   }
 
+  /// Snapshot of every configured MCP server.
+  Future<List<McpClientInfo>> listMcpClients() async {
+    final r = await _client.listMcpClients();
+    return _mapMcpClients(r);
+  }
+
+  /// Re-run discovery against every configured MCP server on
+  /// the running daemon. Returns the same shape as listMcpClients.
+  Future<List<McpClientInfo>> refreshMcpClients() async {
+    final r = await _client.refreshMcpClients();
+    return _mapMcpClients(r);
+  }
+
+  Future<List<McpClientInfo>> addMcpClient({
+    required String name,
+    required String endpoint,
+    String apiKeyEnv = '',
+    String description = '',
+  }) async {
+    final r = await _client.addMcpClient(
+      name: name,
+      endpoint: endpoint,
+      apiKeyEnv: apiKeyEnv,
+      description: description,
+    );
+    return _mapMcpClients(r);
+  }
+
+  Future<List<McpClientInfo>> removeMcpClient(String name) async {
+    final r = await _client.removeMcpClient(name);
+    return _mapMcpClients(r);
+  }
+
+  List<McpClientInfo> _mapMcpClients(ListMcpClientsResponse r) {
+    return r.clients
+        .map(
+          (s) => McpClientInfo(
+            name: s.config.name,
+            endpoint: s.config.endpoint,
+            apiKeyEnv: s.config.apiKeyEnv,
+            description: s.config.description,
+            toolCount: s.toolCount,
+            errorKind: s.errorKind,
+            message: s.message,
+          ),
+        )
+        .toList();
+  }
+
   /// Active channel + per-channel daemon status snapshot.
   Future<ChannelStatusSnapshot> channelStatus() async {
     final r = await _client.channelStatus();
@@ -394,6 +443,8 @@ class HubService {
             iconUrl: e.iconUrl,
             screenshotUrls: e.screenshotUrls,
             docsUrl: e.docsUrl,
+            kind: e.kind,
+            provider: e.provider,
           ),
         )
         .toList();
@@ -924,6 +975,36 @@ class ChannelStatusSnapshot {
   });
 }
 
+/// One configured MCP server plus the last-discovery report.
+/// Surfaced by Studio's MCP-clients editor in Settings.
+class McpClientInfo {
+  final String name;
+  final String endpoint;
+  final String apiKeyEnv;
+  final String description;
+  /// Number of tools the last discovery returned. 0 before
+  /// discovery has run or on failure.
+  final int toolCount;
+  /// Empty on success; otherwise one of:
+  ///   invalid_endpoint / not_implemented / network / http /
+  ///   server / parse / env_missing.
+  final String errorKind;
+  /// Human-readable diagnostic.
+  final String message;
+
+  const McpClientInfo({
+    required this.name,
+    required this.endpoint,
+    required this.apiKeyEnv,
+    required this.description,
+    required this.toolCount,
+    required this.errorKind,
+    required this.message,
+  });
+
+  bool get healthy => errorKind.isEmpty && toolCount > 0;
+}
+
 /// Filesystem paths the daemon owns. Studio's Doctor page
 /// surfaces these as "Open" buttons so Windows operators who
 /// never touch a shell can still inspect everything via the OS
@@ -1078,6 +1159,15 @@ class StoreItem {
   /// Explicit docs URL override. When empty, the hub falls back
   /// to the well-known raw-README paths off [repository].
   final String docsUrl;
+  /// "native" (downloadable bundle) or "federated" (routes
+  /// through a bridge — MCP, n8n, …). Empty falls back to
+  /// "native".
+  final String kind;
+  /// Provider id for federated entries. Empty for native.
+  /// E.g. "filesystem" for an `mcp.filesystem.read_file` tool.
+  final String provider;
+
+  bool get isFederated => kind == 'federated';
 
   const StoreItem({
     required this.name,
@@ -1098,5 +1188,7 @@ class StoreItem {
     required this.iconUrl,
     required this.screenshotUrls,
     required this.docsUrl,
+    required this.kind,
+    required this.provider,
   });
 }