feat(studio): module-store manager (list / add / remove)

A store icon in the Store app bar opens a dialog that lists the
configured module stores + the bundled seed (with per-source module
counts), lets the operator add a store by index URL (the hub fetches +
merges it live so its modules appear immediately), and remove a store.
Backed by the new ListStores/AddStore/RemoveStore RPCs + SDK methods.
This is how a domain app's published modules (e.g. reclaim's) become
visible in the Store without touching the CLI.

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

lib/data/hub.dart

@@ -212,6 +212,21 @@ class HubService {
 
   Future<bool> healthy() => _client.healthy();
 
+  /// Configured module stores (+ the bundled seed) for the store manager.
+  Future<List<StoreSource>> listStores() => _client.listStores();
+
+  /// Register a new module store; the hub fetches + merges it live.
+  Future<AddStoreResponse> addStore({
+    required String name,
+    required String url,
+    String bearerEnv = '',
+  }) =>
+      _client.addStore(name: name, url: url, bearerEnv: bearerEnv);
+
+  /// Drop a configured store by name (the bundled seed cannot be removed).
+  Future<RemoveStoreResponse> removeStore(String name) =>
+      _client.removeStore(name);
+
   /// List of installed WASM modules, grouped by `module_name`.
   /// Built-in and federated capabilities are excluded — they
   /// don't correspond to a bundle on disk and would confuse the

lib/pages/store.dart

@@ -234,6 +234,11 @@ class _StorePageState extends State<StorePage> {
               onPressed: _openFilterDialog,
             ),
           ),
+          IconButton(
+            icon: const Icon(Icons.storefront_outlined, size: 18),
+            tooltip: 'Module stores',
+            onPressed: () => ChainStoresDialog.show(context),
+          ),
           IconButton(
             icon: const Icon(Icons.refresh, size: 18),
             tooltip: l.storeReloadTooltip,

lib/widgets/chain_stores_dialog.dart

@@ -0,0 +1,196 @@
+// Module-store manager — list the configured module stores (+ the
+// bundled seed), add a store by index URL, or remove one. The hub merges
+// every store's modules into one searchable index, so adding a store
+// (e.g. a domain app's published modules) makes them appear in the Store.
+
+import 'package:chain_client_sdk/chain_client_sdk.dart';
+import 'package:flutter/material.dart';
+
+import '../data/error_presentation.dart';
+import '../data/hub.dart';
+import '../theme/tokens.dart';
+
+class ChainStoresDialog extends StatefulWidget {
+  const ChainStoresDialog._();
+
+  static Future<void> show(BuildContext context) => showDialog(
+        context: context,
+        builder: (_) => const ChainStoresDialog._(),
+      );
+
+  @override
+  State<ChainStoresDialog> createState() => _ChainStoresDialogState();
+}
+
+class _ChainStoresDialogState extends State<ChainStoresDialog> {
+  late Future<List<StoreSource>> _future;
+  final _name = TextEditingController();
+  final _url = TextEditingController();
+  bool _busy = false;
+
+  @override
+  void initState() {
+    super.initState();
+    _reload();
+  }
+
+  void _reload() =>
+      setState(() => _future = HubService.instance.listStores());
+
+  @override
+  void dispose() {
+    _name.dispose();
+    _url.dispose();
+    super.dispose();
+  }
+
+  Future<void> _add() async {
+    final name = _name.text.trim();
+    final url = _url.text.trim();
+    if (name.isEmpty || url.isEmpty) return;
+    setState(() => _busy = true);
+    try {
+      final r = await HubService.instance.addStore(name: name, url: url);
+      if (!mounted) return;
+      _name.clear();
+      _url.clear();
+      ScaffoldMessenger.of(context)
+          .showSnackBar(SnackBar(content: Text(r.message)));
+      _reload();
+    } catch (e) {
+      if (mounted) {
+        showFaiErrorSnack(context, 'store.add', e,
+            title: 'Could not add store');
+      }
+    } finally {
+      if (mounted) setState(() => _busy = false);
+    }
+  }
+
+  Future<void> _remove(String name) async {
+    try {
+      final r = await HubService.instance.removeStore(name);
+      if (!mounted) return;
+      ScaffoldMessenger.of(context)
+          .showSnackBar(SnackBar(content: Text(r.message)));
+      _reload();
+    } catch (e) {
+      if (mounted) {
+        showFaiErrorSnack(context, 'store.remove', e,
+            title: 'Could not remove store');
+      }
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final theme = Theme.of(context);
+    return AlertDialog(
+      title: const Text('Module stores'),
+      content: SizedBox(
+        width: 540,
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          crossAxisAlignment: CrossAxisAlignment.stretch,
+          children: [
+            Text(
+              'The hub merges modules from every store below into one index. '
+              'Add a store index URL to make its modules installable here.',
+              style: theme.textTheme.bodySmall
+                  ?.copyWith(color: theme.colorScheme.onSurfaceVariant),
+            ),
+            const SizedBox(height: ChainSpace.md),
+            Flexible(
+              child: FutureBuilder<List<StoreSource>>(
+                future: _future,
+                builder: (c, snap) {
+                  if (snap.connectionState == ConnectionState.waiting) {
+                    return const Padding(
+                      padding: EdgeInsets.all(16),
+                      child: Center(child: CircularProgressIndicator()),
+                    );
+                  }
+                  final stores = snap.data ?? const <StoreSource>[];
+                  return ListView(
+                    shrinkWrap: true,
+                    children: [
+                      for (final s in stores)
+                        ListTile(
+                          dense: true,
+                          leading: Icon(
+                            s.removable
+                                ? Icons.cloud_outlined
+                                : Icons.inventory_2_outlined,
+                            size: 18,
+                          ),
+                          title: Text(s.name),
+                          subtitle: Text(
+                            s.url.isEmpty
+                                ? '${s.moduleCount} modules · bundled'
+                                : '${s.url}\n${s.moduleCount} modules',
+                          ),
+                          isThreeLine: s.url.isNotEmpty,
+                          trailing: s.removable
+                              ? IconButton(
+                                  icon: const Icon(Icons.delete_outline),
+                                  tooltip: 'Remove',
+                                  onPressed: () => _remove(s.name),
+                                )
+                              : const Icon(Icons.lock_outline, size: 16),
+                        ),
+                    ],
+                  );
+                },
+              ),
+            ),
+            const Divider(),
+            Text('Add a store', style: theme.textTheme.titleSmall),
+            const SizedBox(height: ChainSpace.sm),
+            Row(
+              children: [
+                Expanded(
+                  flex: 2,
+                  child: TextField(
+                    controller: _name,
+                    decoration: const InputDecoration(
+                      labelText: 'Name',
+                      isDense: true,
+                    ),
+                  ),
+                ),
+                const SizedBox(width: ChainSpace.sm),
+                Expanded(
+                  flex: 4,
+                  child: TextField(
+                    controller: _url,
+                    decoration: const InputDecoration(
+                      labelText: 'Index URL (https:// or file://)',
+                      isDense: true,
+                    ),
+                    onSubmitted: (_) => _add(),
+                  ),
+                ),
+              ],
+            ),
+          ],
+        ),
+      ),
+      actions: [
+        TextButton(
+          onPressed: () => Navigator.of(context).pop(),
+          child: const Text('Close'),
+        ),
+        FilledButton(
+          onPressed: _busy ? null : _add,
+          child: _busy
+              ? const SizedBox(
+                  width: 16,
+                  height: 16,
+                  child: CircularProgressIndicator(strokeWidth: 2),
+                )
+              : const Text('Add store'),
+        ),
+      ],
+    );
+  }
+}

lib/widgets/widgets.dart

@@ -16,5 +16,6 @@ export 'chain_log_viewer.dart';
 export 'chain_module_sheet.dart';
 export 'chain_pill.dart';
 export 'chain_settings_dialog.dart';
+export 'chain_stores_dialog.dart';
 export 'chain_status_dot.dart';
 export 'chain_system_ai_editor.dart';