feat(studio): localised + explainer-rich Add module source dialog

The previous Add-source dialog was English-only and
operator-hostile — answered 'where do I install from?' without
explaining what a private module *is*. New version, DE + EN:

  - Title + intro + button labels routed through AppLocalizations
    ("Modul-Quelle hinzufügen" / "Installation fehlgeschlagen"
    instead of raw English strings).
  - 'How private modules work' explainer block (3 sentences):
    what a module is (`module.yaml` + WASM), how to package
    it (`fai pack <dir>` → .fai bundle), where to host it
    (any URL: own Forgejo / GitHub / S3), what verification the
    hub does (sha256 + signature against trust store).
  - Honest about the Studio gap: the dialog can install URLs +
    packed bundles, but unpacked source directories still
    require `fai install --link <path>` on the CLI. The
    example command lives in its own code-style box, selectable.
  - Layout: SingleChildScrollView'd so the explainer doesn't
    push the buttons off short viewports.

Studio bumped to 0.66.0; editor path-override pulls in 0.20.0.

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

lib/l10n/app_de.arb

@@ -1448,5 +1448,25 @@
       "count": {"type": "int"}
     }
   },
-  "doctorPathStudioErrors": "Studio-Fehler"
+  "doctorPathStudioErrors": "Studio-Fehler",
+  "addSourceTitle": "Modul-Quelle hinzufügen",
+  "addSourceIntro": "`{capability}` ist nicht im öffentlichen Store. Zeig dem Hub eine `.fai`-Bundle-URL oder einen lokalen Bundle-Pfad — der Hub lädt es herunter, prüft (sha256 + Signatur) und installiert.",
+  "@addSourceIntro": {
+    "placeholders": {
+      "capability": {"type": "String"}
+    }
+  },
+  "addSourceField": "URL oder Pfad zum .fai-Bundle",
+  "addSourceHint": "https://git.flemming.ai/deine-org/dein-modul/releases/download/v0.1.0/foo-0.1.0.fai",
+  "addSourceHowItWorksTitle": "Wie private Module funktionieren",
+  "addSourceHowItWorksBody": "Ein Modul ist ein Verzeichnis mit module.yaml + WASM-Artefakt. Zum Teilen: `fai pack <verzeichnis>` baut ein `.fai`-Bundle, das du beliebig hosten kannst (eigene Forgejo / GitHub / S3). Der Hub installiert per URL und prüft die Signatur gegen seinen Trust-Store.\n\nLokal entwickeln? Nimm das CLI — Studio installiert (noch) nicht aus einem unverpackten Verzeichnis:",
+  "addSourceCliExample": "fai install --link /pfad/zum/modul",
+  "addSourceInstallButton": "Installieren",
+  "addSourceCancel": "Abbrechen",
+  "installFailed": "Installation fehlgeschlagen: {error}",
+  "@installFailed": {
+    "placeholders": {
+      "error": {"type": "String"}
+    }
+  }
 }

lib/l10n/app_en.arb

@@ -1451,5 +1451,25 @@
       "count": {"type": "int"}
     }
   },
-  "doctorPathStudioErrors": "Studio errors"
+  "doctorPathStudioErrors": "Studio errors",
+  "addSourceTitle": "Add module source",
+  "addSourceIntro": "`{capability}` is not in the public store. Point the hub at a `.fai` bundle URL or a local bundle path; the hub downloads, verifies (sha256 + signature) and installs it.",
+  "@addSourceIntro": {
+    "placeholders": {
+      "capability": {"type": "String"}
+    }
+  },
+  "addSourceField": "URL or path to .fai bundle",
+  "addSourceHint": "https://git.flemming.ai/your-org/your-module/releases/download/v0.1.0/foo-0.1.0.fai",
+  "addSourceHowItWorksTitle": "How private modules work",
+  "addSourceHowItWorksBody": "A module is a directory with a module.yaml + the WASM artifact. To share it: pack it (`fai pack <dir>`) and host the resulting `.fai` bundle anywhere (your own Forgejo / GitHub / S3). The hub installs by URL and verifies the signature against its trust store.\n\nDeveloping locally? Use the CLI — Studio cannot install from an unpacked directory (yet):",
+  "addSourceCliExample": "fai install --link /path/to/module",
+  "addSourceInstallButton": "Install",
+  "addSourceCancel": "Cancel",
+  "installFailed": "Install failed: {error}",
+  "@installFailed": {
+    "placeholders": {
+      "error": {"type": "String"}
+    }
+  }
 }

lib/l10n/app_localizations.dart

@@ -3967,6 +3967,66 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'Studio errors'**
   String get doctorPathStudioErrors;
+
+  /// No description provided for @addSourceTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'Add module source'**
+  String get addSourceTitle;
+
+  /// No description provided for @addSourceIntro.
+  ///
+  /// In en, this message translates to:
+  /// **'`{capability}` is not in the public store. Point the hub at a `.fai` bundle URL or a local bundle path; the hub downloads, verifies (sha256 + signature) and installs it.'**
+  String addSourceIntro(String capability);
+
+  /// No description provided for @addSourceField.
+  ///
+  /// In en, this message translates to:
+  /// **'URL or path to .fai bundle'**
+  String get addSourceField;
+
+  /// No description provided for @addSourceHint.
+  ///
+  /// In en, this message translates to:
+  /// **'https://git.flemming.ai/your-org/your-module/releases/download/v0.1.0/foo-0.1.0.fai'**
+  String get addSourceHint;
+
+  /// No description provided for @addSourceHowItWorksTitle.
+  ///
+  /// In en, this message translates to:
+  /// **'How private modules work'**
+  String get addSourceHowItWorksTitle;
+
+  /// No description provided for @addSourceHowItWorksBody.
+  ///
+  /// In en, this message translates to:
+  /// **'A module is a directory with a module.yaml + the WASM artifact. To share it: pack it (`fai pack <dir>`) and host the resulting `.fai` bundle anywhere (your own Forgejo / GitHub / S3). The hub installs by URL and verifies the signature against its trust store.\n\nDeveloping locally? Use the CLI — Studio cannot install from an unpacked directory (yet):'**
+  String get addSourceHowItWorksBody;
+
+  /// No description provided for @addSourceCliExample.
+  ///
+  /// In en, this message translates to:
+  /// **'fai install --link /path/to/module'**
+  String get addSourceCliExample;
+
+  /// No description provided for @addSourceInstallButton.
+  ///
+  /// In en, this message translates to:
+  /// **'Install'**
+  String get addSourceInstallButton;
+
+  /// No description provided for @addSourceCancel.
+  ///
+  /// In en, this message translates to:
+  /// **'Cancel'**
+  String get addSourceCancel;
+
+  /// No description provided for @installFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'Install failed: {error}'**
+  String installFailed(String error);
 }
 
 class _AppLocalizationsDelegate

lib/l10n/app_localizations_de.dart

@@ -2322,4 +2322,40 @@ class AppLocalizationsDe extends AppLocalizations {
 
   @override
   String get doctorPathStudioErrors => 'Studio-Fehler';
+
+  @override
+  String get addSourceTitle => 'Modul-Quelle hinzufügen';
+
+  @override
+  String addSourceIntro(String capability) {
+    return '`$capability` ist nicht im öffentlichen Store. Zeig dem Hub eine `.fai`-Bundle-URL oder einen lokalen Bundle-Pfad — der Hub lädt es herunter, prüft (sha256 + Signatur) und installiert.';
+  }
+
+  @override
+  String get addSourceField => 'URL oder Pfad zum .fai-Bundle';
+
+  @override
+  String get addSourceHint =>
+      'https://git.flemming.ai/deine-org/dein-modul/releases/download/v0.1.0/foo-0.1.0.fai';
+
+  @override
+  String get addSourceHowItWorksTitle => 'Wie private Module funktionieren';
+
+  @override
+  String get addSourceHowItWorksBody =>
+      'Ein Modul ist ein Verzeichnis mit module.yaml + WASM-Artefakt. Zum Teilen: `fai pack <verzeichnis>` baut ein `.fai`-Bundle, das du beliebig hosten kannst (eigene Forgejo / GitHub / S3). Der Hub installiert per URL und prüft die Signatur gegen seinen Trust-Store.\n\nLokal entwickeln? Nimm das CLI — Studio installiert (noch) nicht aus einem unverpackten Verzeichnis:';
+
+  @override
+  String get addSourceCliExample => 'fai install --link /pfad/zum/modul';
+
+  @override
+  String get addSourceInstallButton => 'Installieren';
+
+  @override
+  String get addSourceCancel => 'Abbrechen';
+
+  @override
+  String installFailed(String error) {
+    return 'Installation fehlgeschlagen: $error';
+  }
 }

lib/l10n/app_localizations_en.dart

@@ -2327,4 +2327,40 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get doctorPathStudioErrors => 'Studio errors';
+
+  @override
+  String get addSourceTitle => 'Add module source';
+
+  @override
+  String addSourceIntro(String capability) {
+    return '`$capability` is not in the public store. Point the hub at a `.fai` bundle URL or a local bundle path; the hub downloads, verifies (sha256 + signature) and installs it.';
+  }
+
+  @override
+  String get addSourceField => 'URL or path to .fai bundle';
+
+  @override
+  String get addSourceHint =>
+      'https://git.flemming.ai/your-org/your-module/releases/download/v0.1.0/foo-0.1.0.fai';
+
+  @override
+  String get addSourceHowItWorksTitle => 'How private modules work';
+
+  @override
+  String get addSourceHowItWorksBody =>
+      'A module is a directory with a module.yaml + the WASM artifact. To share it: pack it (`fai pack <dir>`) and host the resulting `.fai` bundle anywhere (your own Forgejo / GitHub / S3). The hub installs by URL and verifies the signature against its trust store.\n\nDeveloping locally? Use the CLI — Studio cannot install from an unpacked directory (yet):';
+
+  @override
+  String get addSourceCliExample => 'fai install --link /path/to/module';
+
+  @override
+  String get addSourceInstallButton => 'Install';
+
+  @override
+  String get addSourceCancel => 'Cancel';
+
+  @override
+  String installFailed(String error) {
+    return 'Install failed: $error';
+  }
 }

lib/main.dart

@@ -27,7 +27,7 @@ import 'widgets/widgets.dart';
 /// Studio's own build version. Bump on every UI commit so the
 /// running app self-identifies — visible in the sidebar header
 /// and quick-glance proof that you're seeing the current build.
-const String kStudioVersion = '0.65.1';
+const String kStudioVersion = '0.66.0';
 
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();

lib/pages/flows.dart

@@ -15,6 +15,7 @@ import 'package:flutter/material.dart';
 
 import '../data/flow_run_driver.dart';
 import '../data/hub.dart';
+import '../l10n/app_localizations.dart';
 
 class FlowsPage extends StatefulWidget {
   /// Pre-load this flow when the editor first builds. Studio
@@ -121,10 +122,14 @@ class _FlowsPageState extends State<FlowsPage> {
       return updated;
     } catch (e) {
       if (mounted) {
+        final l = AppLocalizations.of(context);
+        final msg = l != null
+            ? l.installFailed(e.toString())
+            : 'Install failed: $e';
         ScaffoldMessenger.of(context).removeCurrentSnackBar();
         ScaffoldMessenger.of(context).showSnackBar(
           SnackBar(
-            content: Text('Install failed: $e'),
+            content: Text(msg),
             behavior: SnackBarBehavior.floating,
           ),
         );
@@ -189,83 +194,99 @@ class _AddModuleSourceDialogState extends State<_AddModuleSourceDialog> {
   @override
   Widget build(BuildContext context) {
     final theme = Theme.of(context);
+    final l = AppLocalizations.of(context)!;
     return AlertDialog(
-      title: const Text('Add module source'),
-      content: SizedBox(
-        width: 480,
-        child: Column(
-          mainAxisSize: MainAxisSize.min,
-          crossAxisAlignment: CrossAxisAlignment.start,
-          children: [
-            Text(
-              '`${widget.capability}` is not in the public store. '
-              'Point the hub at a `.fai` bundle URL or a local bundle path '
-              'and the hub will install + verify it.',
-              style: theme.textTheme.bodySmall?.copyWith(
-                color: theme.colorScheme.onSurfaceVariant,
+      title: Text(l.addSourceTitle),
+      content: ConstrainedBox(
+        constraints: const BoxConstraints(maxWidth: 520),
+        child: SingleChildScrollView(
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            crossAxisAlignment: CrossAxisAlignment.start,
+            children: [
+              Text(
+                l.addSourceIntro(widget.capability),
+                style: theme.textTheme.bodySmall?.copyWith(
+                  color: theme.colorScheme.onSurfaceVariant,
+                ),
               ),
-            ),
-            const SizedBox(height: 16),
-            TextField(
-              controller: _ctrl,
-              autofocus: true,
-              onChanged: (v) => setState(() => _source = v.trim()),
-              decoration: const InputDecoration(
-                labelText: 'URL or path to .fai bundle',
-                hintText: 'https://example.com/foo-0.1.0.fai',
-                border: OutlineInputBorder(),
-                isDense: true,
+              const SizedBox(height: 16),
+              TextField(
+                controller: _ctrl,
+                autofocus: true,
+                onChanged: (v) => setState(() => _source = v.trim()),
+                decoration: InputDecoration(
+                  labelText: l.addSourceField,
+                  hintText: l.addSourceHint,
+                  border: const OutlineInputBorder(),
+                  isDense: true,
+                ),
               ),
-            ),
-            const SizedBox(height: 12),
-            Container(
-              padding: const EdgeInsets.all(10),
-              decoration: BoxDecoration(
-                color: theme.colorScheme.surfaceContainerHigh,
-                borderRadius: BorderRadius.circular(6),
-              ),
-              child: Column(
-                crossAxisAlignment: CrossAxisAlignment.start,
-                children: [
-                  Text(
-                    'Developing a local module?',
-                    style: theme.textTheme.labelMedium?.copyWith(
-                      fontWeight: FontWeight.w600,
+              const SizedBox(height: 12),
+              Container(
+                padding: const EdgeInsets.all(12),
+                decoration: BoxDecoration(
+                  color: theme.colorScheme.surfaceContainerHigh,
+                  borderRadius: BorderRadius.circular(6),
+                ),
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(
+                      l.addSourceHowItWorksTitle,
+                      style: theme.textTheme.labelMedium?.copyWith(
+                        fontWeight: FontWeight.w600,
+                      ),
                     ),
-                  ),
-                  const SizedBox(height: 4),
-                  Text(
-                    'Studio installs from URLs + packed bundles only. For an '
-                    'unpacked source directory, use the CLI:',
-                    style: theme.textTheme.bodySmall?.copyWith(
-                      color: theme.colorScheme.onSurfaceVariant,
+                    const SizedBox(height: 6),
+                    Text(
+                      l.addSourceHowItWorksBody,
+                      style: theme.textTheme.bodySmall?.copyWith(
+                        color: theme.colorScheme.onSurfaceVariant,
+                      ),
                     ),
-                  ),
-                  const SizedBox(height: 6),
-                  SelectableText(
-                    'fai install --link /path/to/module',
-                    style: theme.textTheme.bodySmall?.copyWith(
-                      fontFamily: 'JetBrains Mono',
-                      fontSize: 11,
-                      color: theme.colorScheme.onSurface,
+                    const SizedBox(height: 6),
+                    Container(
+                      padding: const EdgeInsets.symmetric(
+                        horizontal: 8,
+                        vertical: 4,
+                      ),
+                      decoration: BoxDecoration(
+                        color: theme.colorScheme.surface,
+                        borderRadius: BorderRadius.circular(4),
+                      ),
+                      child: SelectableText(
+                        l.addSourceCliExample,
+                        style: TextStyle(
+                          fontFamily: 'JetBrains Mono',
+                          fontFamilyFallback: const [
+                            'Menlo',
+                            'Consolas',
+                            'Courier New',
+                            'monospace',
+                          ],
+                          fontSize: 11,
+                          color: theme.colorScheme.onSurface,
+                        ),
+                      ),
                     ),
-                  ),
-                ],
+                  ],
+                ),
               ),
-            ),
-          ],
+            ],
+          ),
         ),
       ),
       actions: [
         TextButton(
           onPressed: () => Navigator.of(context).pop(),
-          child: const Text('Cancel'),
+          child: Text(l.addSourceCancel),
         ),
         FilledButton(
           onPressed: _source.isEmpty
               ? null
               : () => Navigator.of(context).pop(_source),
-          child: const Text('Install'),
+          child: Text(l.addSourceInstallButton),
         ),
       ],
     );